Archive for the ‘Aircraft ownership and maintenance’ Category

Don’t Worry—They All Do That

Tuesday, May 17th, 2016

Years ago, I used to travel throughout the country putting on technical seminars for owners of various Cessna models, together with John Frank, executive director of the Cessna Pilots Association. Whenever John and I got to the landing gear segment of the course, we made a point of asking the 20 or 30 assembled Cessna owners attending the CPA seminar for a show of hands:

“How many of you have had a problem with nose wheel shimmy?” Invariably, virtually every owner in the audience raised their hand.

“Okay, how many of you have asked your mechanic about this, only to be told that all Cessnas exhibit nose wheel shimmy, and that it’s simply ‘the nature of the beast’?”

Usually, at least half the hands remained up. That was not a very reassuring sign about the competence of the mechanics these owners were using to maintain their Cessnas.

Nose wheel shimmy normal?

Cessna Nosewheel

Nose wheel shimmy in single-engine Cessnas is not “the nature of the beast,” and is readily correctable.

Although nose wheel shimmy is extremely common in single-engine Cessnas, it can and should be fixed. Such shimmy is almost always due to one or more of the following: (1) worn torque link bushings, (2) an out-of-round or out-of-balance tire, (3) elongated holes in the shimmy dampener linkage, or (4) a defective shimmy dampener.

A mechanic who dismisses a problem like nose wheel shimmy as “the nature of the beast” and claims that “all Cessnas do that” is just copping out. If a mechanic tells you something like this, you’d be wise to seek a second opinion (and perhaps to change mechanics).

John used to make a standing offer to Cessna owners who brought their airplanes to CPA headquarters in Santa Maria, California: If he or his staff couldn’t fix the aircraft’s nose wheel shimmy, he’d buy the owner a steak dinner at the best steak joint in town.

John never had to pay for anyone’s dinner.

To the best of my knowledge, nobody ever died because of uncorrected nose wheel shimmy. But from time to time, we hear of a mechanic who dismisses a genuinely serious problem with “don’t worry about it, they all do that.” And that’s scary.

Exhaust leaks normal?

An owner who’d recently acquired a Cessna T310R noticed gritty brown stains developing on top of his left engine nacelle aft of the louvers. He also noticed some cracking and bubbling of the paint. No such symptoms were apparent on his right nacelle.

Brown stains

The owner of this 1977 Cessna T310R became concerned about the gritty brown stains behind the louvers on top of his left engine nacelle, and some bubbling of the paint. His A&P advised him not to worry about it, claiming “almost every twin Cessna has some degree of heat staining.” Bad advice.

Several A&Ps told the owner not to worry about it, because “almost every twin Cessna has some degree of heat staining.” But it still worried the owner because he was seeing these stains only on the left necelle and not on the right.

The owner then did a very smart thing: He sought a second opinion by posting a query on CPA website. I spotted his post there, and asked him if he would take some photos of the brown stains and upload them so I and others could take a look at them.

The next day, the owner posted some photos of the brown stains. I replied that I thought that those stains were probably symptomatic of a substantial exhaust leak in the vicinity of the turbocharger, and that I considered it imperative that he have the exhaust system in that area inspected thoroughly and the cause of the leak identified and remedied right away.

Not long afterwards, the owner removed the top cowling from his left engine nacelle and took several more digital photographs, which he posted to the forum. One of those photos showed considerable white powdery deposits on the turbocharger heat shield and firewall. I told the owner that this almost certainly was confirmation that he had a serious exhaust leak at or near the turbocharger. Several other owners and mechanics chimed in and urged that the owner take this situation seriously.

Turbocharger heat shield

When the top cowling was removed, the owner found white, powdery stains on the tur-bocharger heat shield and firewall, indicative of a substantial exhaust leak. The owner insisted on a pressure test of the exhaust system, which revealed a gaping leak at the turbocharger-to-tailpipe joint and a loose exhaust V-band clamp. Removing the tailpipe, cleaning up the mating flanges, and retorquing the clamp cured the leak.

“When it comes to the exhaust system of a turbocharged twin Cessna, you have to take everything seriously and you can’t be too careful,” I told the owner on the forum. “Too many people have died in these airplanes as the result of in-flight exhaust failures. At one point during the 1990s, we were averaging one fatality per month due to these problems, and the FAA very nearly wound up grounding the whole fleet. Since 1999 we have had zero exhaust accidents, due in part to all the publicity and in part to the new AD 2001-01-16 that I worked on so actively. That’s a track record I’m very proud of—and I’d hate to see it blemished.”

The owner takes command

The next day, the owner cleared his calendar and took his airplane back to the shop. “I got some raised eyebrows when I insisted that we pressure-test the system,” the owner reported. The owner decided to stick around through the procedure to make sure the exhaust system was checked thoroughly for leaks.

When the mechanic pressurized the exhaust system with shop air and started squirting soapy water on the exhaust plumbing, it was immediately apparent that there was a major leak at the junction of the turbocharger and the tailpipe. “We saw bubbles the size of a man’s fist forming between the tailpipe and the turbo,” the owner said.

The mechanic discovered that the V-band clamp that secures this joint was extremely loose. The nut on the clamping bolt could be tightened a full half-inch. But even after tightening the clamp, a second pressure test showed little improvement in the leak.

The mechanic then removed the clamp, separated the tailpipe from the turbo, cleaned the mating flanges on both the tailpipe and the turbocharger, and then reinstalled the tailpipe and clamp. A third pressure test showed no leakage whatsoever at the joint.

The owner was very happy about this outcome. He posted the details of his trip to the shop. “I want to thank everyone here who would not let me accept the word of several A&Ps who told me it was nothing,” he said. “It’s amazing what two hours of labor can accomplish.”

Not so fast!

Torque wrench

The “that feels about right” technique is unacceptable when installing exhaust V-band clamps.

But after reading the owner’s most recent post, I still had an uneasy feeling. “When your mechanic tightened the V-band clamp on the turbo-to-tailpipe joint, I hope he used a torque wrench and torqued it to the specified value,” I said. “The torque on that clamp is critical, and that particular nut should never be just tightened by hand ‘it feels right’.”

Nope, reported the owner, the A&P didn’t use a torque wrench.

“After your mechanic cleaned up the flanges on the turbocharger and tailpipe, the flanges should have been inspected with a strong light and magnifier for cracking,” I added.

Nope, the mechanic didn’t do that, either, the owner said. “Do I need to go get him re-do it, or can it wait until my next scheduled inspection?”

“Redo it,” I advised the owner, adding that when the nut is tightened “by feel” it’s invariably overtightened, putting excessive stress on the clamp in increasing the likelihood of clamp failure (which could be fatal). I pointed out that the torque is so important that each V-band clamp has a small stainless steel “torque tag” on which the correct torque is stamped.

The owner put his T310R back in the shop to have the clamp retorqued, and resolved that in the future he would take his maintenance business to another shop where the mechanics were more knowledgeable about turbocharged aircraft.

The moral is this: Any time you ask a mechanic about some mechanical discrepancy and get the response “they all do that” or “it’s the nature of the beast,” consider this a big red flag, and go get an expert second opinion. Doing so might just save your bacon.

Hangnails and Hand Transplants

Tuesday, April 12th, 2016
Engine teardown

Here’s what happens to your engine when you send it in for major overhaul. Do you really want to do this?

You know me. I believe in running engines as long as they’re demonstrably healthy, even if that means going beyond the manufacturer’s recommended TBO. Nothing disturbs me more than when I hear about owners who get talked into (or talk themselves into) euthanizing engines that are running just fine.

Case in point: Here’s an email I received from a Bonanza owner seeking a second opinion on what to do about his Continental IO-520 engine:

“The engine is now at 1500 hours (TBO is 1700) and it seems to be running very well. But here’s the bad part: it’s using a quart of oil every 4 hours, and putting a LOT of oil on the belly of the aircraft, even with an air/oil separator installed.

“So what should I do? Should I get a field overhaul, or opt for a factory rebuilt engine? (The engine does NOT have a VAR crank.) Should I consider an STC upgrade to an IO-550? I’m leaning toward using Superior Millennium cylinders, do you agree?”

I took a deep breath and counted to ten. This owner just told me that he as a fine-running engine, yet he’s already concluded it needs to be overhauled or replaced. What was he thinking? It sure wasn’t clear to me that this engine had any major issues, much less anything requiring immediate euthanasia.

Where’s the beef?

So what if it’s using a quart in 4 hours? Is that so terrible?

No, it isn’t. Continental SID97-2B is the bible when it comes to determining the airworthinss of Continental cylinders, and here what it has to say about oil consumption:

Oil consumption can be expected to vary with each engine depending on the load, operating temperature, type of oil used and condition of the engine. A differential compression check and borescope inspection should be conducted if oil consumption exceeds one quart every three hours or if any sudden change in oil consumption is experienced and appropriate action taken.

This guidance indicates that the Bonanza’s oil consumption of a quart in four hours is perfectly acceptable. Even when Continental’s oil consumption threshold of a quart in three hours is exceeded, Continental simply calls for a borescope inspection to determine if there’s really a problem. If the cylinders look okay under the borescope, the engine can remain in service despite the high oil consumption.

SID97-2B also indicates that in February 1997, Continental actually reduced the tension on the oil control rings in its cylinder assemblies to increase oil consumption to achieve improved lubrication of the cylinder bore. A certain amount of oil consumption is essential for maximum cylinder life. When it comes to oil consumption, less is not necessarily always a good thing.

Bottom line is that it’s quite likely that there’s nothing at all wrong with the engine in this owner’s Bonanza. At worst, perhaps it has a couple of worn cylinders that might need to be replaced eventually. Even that’s not clear, since the owner didn’t mention low compression readings. Maybe all he needs is some new piston rings.

A worn jug is like a hangnail

Cracked cylinder head

Cylinder problems (like this head crack) call for cylinder work, not euthaizing the whole engine.

Even if a borescope inspection reveals that the engine has a worn-out jug or two, so what? Both Continental and Lycoming cleverly designed their engines so that the cylinders were bolt-on accessories that can be repaired or replaced without removing the engine from the airframe or splitting the case. If the engine actually does have badly worn cylinders, that’s a reason to repair or replace the jugs, not to tear down the whole engine.

Think about this for a moment. If some other bolt-on engine accessory went bad—say an alternator or vacuum pump or magneto or prop governor—would you let your mechanic remove the engine and have it major overhauled? Of course not.

If you had a hangnail, would you go to a surgeon for an amputation and hand transplant? No, I didn’t think so!

Why would an aircraft owner even consider major overhaul or engine replacement just because one or two cylinders might be worn out? To my way of thinking, it doesn’t matter whether an engine is at 100 hours since new or 100 hours past TBO—a sick cylinder calls for cylinder replacement, not engine replacement.

Euthanasia is a bit much

Here’s what I emailed back to the owner:

“I would NEVER consider overhauling an otherwise good-running engine just because it has high oil consumption. There’s nothing wrong with burning a quart in 4 hours, so long as your sparkplugs aren’t oil-fouled and your compressions are within acceptable limits. If things get bad enough and you find one or more cylinders with unacceptably low compression, you may want to consider replacing them. That’s why Continental makes its engines with bolt-on cylinders: so you can change them without having to overhaul the engine. The ONLY valid reason for overhauling an engine is a problem with the “bottom end” (crankcase, crankshaft, camshaft, gears, main bearings, etc.) that cannot be cured without splitting the case.

“Have you simply tried running the engine at a lower oil level on the dipstick? Big-bore Continental engines are famous for throwing out excess oil if the crankcase is overfilled. The TSIO-520s on my T310R have a 12-quart sump, but I typically run them at 8 quarts on the dipstick.

“Excessive oil on the belly is usually caused by excessive crankcase pressure. Sometimes this is due to worn cylinders that permit excessive blow-by past the rings (in which case your cylinders will show low compression readings and your oil will get dirty very quickly after each oil change). But it can also be due so something as simple as an oil filler cap that isn’t sealing properly (when did you last check the oil cap gasket?) or a leaky front crankcase seal (which is not difficult to change).

“It sounds to me as if you may be a long way from needing to major-overhaul this engine. If you do decide to overhaul it anyway, drop me another email and I’ll offer some suggestions. But I really think that any consideration of rebuild/overhaul at this point is way premature.”

Don’t obsess about the manufacturer’s published TBO. It’s just a suggestion, not a requirement or a life limit. (The engines on my Cessna T310R are made it well past 200% of TBO and were still running magnificently.) When your engine is ready for overhaul, it’ll let you know by starting to make metal or to leak oil or to crack their crankcases or spall their cam lobes or something else obvious to let you know that “it’s time.” That’s the time to overhaul them. Doing it earlier always strikes me as being a capital crime.

What’s That Going To Cost?

Friday, March 11th, 2016

Beechcraft 55 BaronOn a winter Friday evening, a Texas-based aircraft owner loaded three family members into his Baron and flew to Kansas City to attend a weekend function. One of the aircraft’s vacuum pumps failed over Oklahoma. Upon landing at Kansas City Downtown Airport (MKC), the owner asked the FBO on the field if they could replace the failed pump over the weekend, in time for his planned departure late Sunday afternoon. They said they could, and the owner gave them a go-ahead.

When the owner and his family returned to MKC on Sunday afternoon, the owner was pleased to find that the pump had been replaced as advertised. But when he gave the FBO his credit card to pay the bill, he was told that the invoice wouldn’t be ready until Monday when the bookkeeper returned to work. The FBO insisted that the owner sign a blank credit card slip to cover the work. The owner was initially unwilling to do this, but ultimately capitulated when it became obvious that was the only way to get the FBO to release his airplane.

When the FBO’s charge finally showed up on the owner’s credit card, it turned out to be over $1,900. The pump was invoiced at $1,400—well above the manufacturer’s published list price of $1,090 and almost twice the usual “street price” of $800. The labor charge was about $500 for a job that shouldn’t have taken more than an hour. The owner was upset, of course. He fired off a nastygram to the owner of the FBO and vowed never to patronize them again. But in the final analysis, the owner was stuck paying a bill he appropriately considered outrageous.

This sort of thing is hardly uncommon. I know one owner who was charged nearly $1,000 to have his Cessna 210 deiced in Memphis, another who was charged $350 for one hour in a heated hangar to melt the snow of his light twin near Boston, and yet another who was charged $180 at Washington Dulles to have two tires aired up on his Skylane.

Most of these incidents occurred at large FBOs that cater mostly to the bizjet set. But such FBOs certainly aren’t the only offenders. I heard about a mechanic who removed a leaking fuel selector valve from a Bonanza and sent it off to a well-known FAA-approved repair station for overhaul. After inspecting the valve, the repair station quoted $2,000 to overhaul it. At this point, the aircraft owner wisely intervened, directed the repair station to return the leaky valve, and sent it to another repair station in California who overhauled the valve for $375.

While these may be extreme cases, I sincerely doubt there are many aircraft owners among us who haven’t felt blindsided by what we considered to be an unreasonable maintenance invoice from time to time. (Been there, done that, got the bloodstained tee-shirt to prove it.)

The First Commandment

How much?In almost every such case, these unpleasant surprises occur because the aircraft owner authorized the work to be done without first asking what it would cost. In doing that, the owner broke the first commandment of aircraft maintenance:

Never permit a shop or mechanic to perform maintenance on your aircraft until you have received and approved a work order and cost estimate in writing. If and when you approve the work to be done, instruct the shop or mechanic explicitly not to exceed the cost estimate without first obtaining your explicit approval.

I find it amazing how often this commonsense commandment is broken. In almost every other sort of commerce, it would be absolutely unthinkable for someone to purchase goods or services without knowing what they will cost. Most of us would never buy a headset, a pair of sunglasses or a gallon 100LL without checking the price. Nor would we consider hiring a plumber to install a new water heater, a roofer to fix a leak, or Midas to replace the muffler on our car without first obtaining a quotation or estimate.

Yet more often than not, aircraft owners put their plane in the shop and authorize work to be done without obtaining even a verbal estimate, much less a written quote. Frequently, the first time they learn what the work will cost is when the work is finished and they are presented with the invoice. At that point, it is too late for them to influence the outcome; they can only complain and lick their wounds. (Show me an aircraft owner, and I’ll show you an expert complainer and wound licker.)

Why do we do this? I can think of three reasons:

  1. We’re uncomfortable asking the shop or mechanic for a cost estimate.
  2. The aircraft has a known problem, but we don’t yet understand what’s wrong sufficiently for the shop or mechanic to estimate how much work needs to be done or what parts need to be replaced.
  3. The aircraft is in the shop for an inspection, so we don’t yet know what problems are going to be found, much less what parts and labor will be needed to fix them.

Let’s consider these three cases in turn.

Case 1: Uncomfortable Asking

UncomfortableI suspect the Baron owner was uncomfortable about asking the Kansas City FBO for a cost estimate to replace his failed vacuum pump. Perhaps he felt the FBO was doing him a big favor in agreeing to do the work over the weekend. (They weren’t—their labor rate was top-dollar, and they charged time-and-a-half for the weekend labor.) Or perhaps it was because this big city FBO was one that catered largely to the bizjet crowd—you know, the “if you have to ask, you can’t afford it” guys.

Perhaps the Cessna 210 owner was uncomfortable about asking the FBO in Memphis what it would cost to deice his airplane because he thought it couldn’t possibly be enough to worry about. (He found out otherwise.) Or perhaps it was because he felt he had no alternative but to have the airplane deiced, no matter what it cost. (There’s always an alternative.)

Whatever the precise reason for their discomfort, their failure to ask what the work would cost before authorizing it cost them dearly. It never makes sense to purchase goods or services without first asking what they will cost.

Purchasing aircraft maintenance is just like any other purchase. The fact that it is not your field of expertise should never intimidate you into failing to asking key threshold questions like “what’s that going to cost?” In fact, the less you know about something, the more questions you should ask before making a decision.

Never feel embarrassed to ask for an estimate before authorizing work to be done on your aircraft. The only time it’s bad form to ask the price is when someone gives you a gift!

Case 2: Don’t Know What’s Wrong

DunnoSure, but what if you don’t know what’s wrong? Say you put the airplane in the shop because the engine has started running rough, but you don’t know why. How can you possibly ask your shop or mechanic for a cost estimate under such circumstances?

My answer is simple: Never ask a shop or mechanic to fix a problem unless you know what’s wrong. That’s like going in for surgery before your illness is diagnosed. Aircraft owners do this all the time, and it’s an expensive mistake.

Aircraft owners need to do as much troubleshooting as they possibly can before putting their aircraft in the shop. In my view, it’s primarily the owner’s job to troubleshoot and the mechanic’s job to fix. It’s often difficult or impossible for a mechanic to reproduce problems in the maintenance hangar. If we owners don’t diagnose a problem before we put our aircraft in the shop, our mechanic often has no choice but to resort to guesswork, trying various things and hoping he gets lucky. When mechanics guess, owners pay through the nose.

Returning to your rough-running engine: In a perfect world, you’ll use your digital engine monitor and well-honed troubleshooting skills to diagnose the problem: e.g., a clogged fuel nozzle or faulty bottom spark plug in cylinder #3. Then, you’ll put your aircraft in the shop and obtain a cost estimate to fix the problem.

But what if you can’t figure out why the engine is running rough? In that case, you put your aircraft in the shop and authorize your mechanic to spend up to two hours (or whatever seems reasonable to you) troubleshooting the problem, and instruct him to report back to you with his diagnosis. (NEVER give the mechanic carte blanche; always specify a troubleshooting budget!) Only then, when the problem has been diagnosed, do you ask for a cost estimate to fix the problem and (if the estimate is acceptable) authorize the repair.

Case 3: Annual Inspection

Annual InspectionIn the case of an annual inspection (where by definition you don’t know what problems will be found), my advice is similar. Put your aircraft in the shop and authorize your mechanic to perform the inspection (which is normally done at an agreed-to flat rate) and prepare a detailed list of discrepancies with a cost estimate to fix each one. (Make sure he understands that he is NOT authorized to perform any repairs or order any parts yet!) At this point, sit down with the mechanic, go over the discrepancy list and estimates in detail, and come to agreement on exactly what repairs are to be done and what they will cost. Only then should you authorize the repair work to proceed.

No matter what the situation is, there is never a good reason to authorize a shop or mechanic to perform maintenance on your aircraft until you have received a detailed written estimate of what it will cost. If the shop or mechanic won’t provide one to you, you’re your airplane elsewhere. Always know what it will cost before you say “go ahead.”

When it comes to aviation maintenance, it’s not impolite to ask what something is going to cost. It’s mandatory.

Five Secrets of Cost-Effective Maintenance

Wednesday, February 17th, 2016

Under the FARs, performing maintenance is the job of an A&P mechanic or FAA-approved repair station, but managing maintenance is the aircraft owner’s job. In essence, the FAA looks at each aircraft owner as the Director of Maintenance of a one-aircraft aviation department. Unfortunately, few owners know how do do this important job, and most do it very poorly. Many owners leave it to their A&Ps to manage their maintenance, and then many times wind up unhappy with the outcome.

The essence of good maintenance management can be boiled down to five simple rules. Follow these five principles religiously and you’ll discover that you have a safer and more reliable aircraft while simultaneously spending a whole lot less on maintenance.

Maintenance ShopRule 1. Choose the right shop

To use a building-trades analogy, an aircraft owner’s job is to act as the “general contractor” for his aircraft maintenance. The owner hires skilled tradesmen—maintenance shops, mechanics and other technicians—to do the necessary maintenance work, then manages them to ensure they perform as desired and that they come in within schedule and budget, and occasionally fires them if they don’t perform to expectations.

The owner’s most important job by far is the first one: hiring the right shop, mechanic or technician for the job. If you hire the right person for the job, the rest tends to work out well. If you hire the wrong person, the best management skills in the world may not be sufficient to rescue the situation.

Many owners don’t take this responsibility seriously enough. Often, they simply use the shop at their home base because it’s convenient to do so. Or they choose a mechanic because he seems friendly. Or one that some aircraft owner friend has nice things to say about.

Doing the job right requires much more “due diligence” than that. You need to interview a prospective shop or mechanic just as you would a prospective employee. What do you look for in such an interview? Lots of things, but the most important attributes you should look for are what I call “the three C’s.” The mechanic (or the shop’s director of maintenance) must be competent, communicative, and cooperative.

  • Competent means that the mechanic or DOM has as much experience as possible with your particular make and model of aircraft. A mechanic’s “total time” is far less important than his “time in type” with your particular make and model. Just because a mechanic has done a great job on your friend’s Bonanza doesn’t mean that he’s competent to work on your Cirrus. Before you hire a mechanic, grill him about his experience with your particular make and model. Try to find someone with the most “time in type” posible.
  • Communicative means that the mechanic or DOM is committed to keeping you “in the loop” while your aircraft is in the shop—keeping you continually apprised of status, and consulting you whenever a decision needs to be made. Many mechanics are excellent at this, but many others are not—their attitude is often “you hired me because I’m an expert at what I do, so please go away, leave me alone, and let me do my job.” If a mechanic has this attitude, run (don’t walk) away.
  • Cooperative means that the mechanic or DOM is someone that you find easy to talk to, and who is willing to listen to your directions and desires and do things your way to the extent that he can (while still complying with applicable FARs). It means someone you “can do business with.” Once again, many mechanics are cooperative and customer-oriented, while others are rigid and dogmatic—they believe that there are only two ways to do something: their way and the wrong way. Dogmatic mechanics tend to view the world in black and white, while cooperative ones view it as it actually is: a thousand shades of gray. Seek out the cooperative, customer-oriented ones—avoid the dogmatic ones like the plague.

Repair EstimateRule 2. Insist on a written estimate

Your next job is to ensure that the shop doesn’t wind up presenting you with an invoice that will make you faint or take out a second mortgage. How do you accomplish that? Simple: Always make sure you know what maintenance is going to cost before you approve it.

You might think this is so obvious that it’s not worth saying. You’d be wrong. It always astonishes me how often even experienced and sophisticated owners approve maintenance without knowing what it’s going to cost, and then suffer from serious “sticker shock” when they get the invoice. It also astonishes me how often shops undertake expensive work without obtaining the owner’s explicit and informed approval.

The irony is that this couldn’t happen if it were your automobile that was in the shop for maintenance rather than your airplane. Virtually every state has laws and regulations that require automotive maintenance shops to present each client with a detailed work order and cost estimate, and to obtain the client’s explicit approval (usually in writing) before starting work. Those same laws and regulations usually prohibit the shops from exceeding the agreed-to estimate by any significant amount without going back to the client and obtaining approval of an amended estimate.

There are no such laws and regulations for aircraft maintenance facilities. Aircraft owners are generally assumed to be smart enough to find out what the work is going to cost and get it in writing before giving approval to proceed. Bad assumption! It’s amazing how often aircraft owners fail to ask the threshold question “what’s that going to cost” before approving work, and only find out the answer at invoice time when it’s too late to affect the outcome.

Ah, but what about an annual inspection, where the shop doesn’t know what things will cost until they open up the aircraft and inspect it? That’s easy, too. Owners must insist that an annual inspection be divided up into three distinct, sequential phases: inspection, approval, and repair.

During the first phase (which is typically covered by the shop’s flat rate inspection fee), the shop opens the aircraft, inspects both the physical aircraft and the maintenance records, and generates a report listing the discrepancies found. That discrepency list should clearly identify “airwothiness items” from other, lesser discrepancies. It should also include a specific repair recommendation for each discrepancy, and a specific cost estimate for parts, labor, and outside work.

During the second phase, the owner reviews the discrepancy list, recommendations and estimates. He asks questions about anything he doesn’t fully understand to ensure “informed consent.” He may want to get a second opinion on some items from another mechanic, type club tech rep, or other expert. He may want to explore various alternatives to the repair recommendations offered by the shop. At the conclusion of this phase, the owner goes back to the shop with specific direction (preferably in writing) as to which items on the list he wants repaired, and how he wants the repairs to be done.

During the third phase, the shop performs the repairs as directed, and the owner fully expects that the invoice will conform fairly closely with the written esimates that he has approved. Should unforeseen contingencies arise while doing the work (as they sometimes do), the shop must stop work, go back to the owner with an amended estimate, and obtain the owners explicit authorization to proceed (or not).

As obvious as this may seem, it’s frightening how often it doesn’t occur. Many shops engage in a practice that I call “inspect a little, fix a little, inspect a little, fix a little, lather, rinse, repeat.”  If a shop does that, then there’s no clear “decision point” at which the owner can review the discrepancy list and cost estimates, achieve informed consent, and give explicit authorization to proceed. Owners must insist that shops not operate in this fashion, and fire them if they won’t cooperate.

Rule 3. If it ain’t broke, don’t let ‘em fix it

Every aircraft service manual contains page after page of recommendations for scheduled preventive maintenance. Do this every 50 hours. Do that every 100. Do something else once a year. The lists of scheduled tasks go on and on. The service manual for my Cessna 310 has no less than 350 separate scheduled maintenance tasks.

Any owner who follows the manufacturer’s scheduled maintenance recommendations is simply throwing money down the drain. Why? Simply because the very notion of a one-size-fits-all maintenance schedule makes no sense from a scientific or engineering point of view. It makes absolutely no sense to apply the same maintenance schedule to an aircraft based in Tampa and one based in Tucson. Or one that flies 30 hours a year and another than flies 300. Or one that’s tied down outdoors and another that lives in a heated hangar. Yet that’s what the service manual recommendations call for.

ActuatorConsider this: My Cessna 310 service manual calls for removing, disassembling, cleaning, lubricating, reassembling and reinstalling the elevator, rudder, and aileron trim tab actuators every 200 hours. The service manual for virtually every Cessna single and twin model has a similar recommendation. This involves at least 6 to 8 hours of work. So if you actually “did it by the book,” you’d add roughly $3 per hour to the cost of flying just for trim tab actuator maintenance.

In the 29 years and nearly 5,000 hours that I’ve owned my Cessna 310, I’ve never disassembled or lubricated any of the three trim tab actuators. Not once! Why? Simply because they didn’t need it—and last time I looked, you don’t get extra credit for doing unnecessary maintenance.

How do I know the trim tab actuators didn’t need to be lubricated? Because I check their condition at least annually, and it takes all of two minutes to do so. The procedure is dead simple: First, climb into the cockpit and rotate the trim wheel all the way from one end of its range to the other, checking to see whether the trim wheel rotates smoothly without any sign of resistance or binding. Second, climb back out of the cockpit, walk over to the trim tab, measure how much free-play it has, and check that against the maximum allowable free-play set forth in the service manual. If the trim wheel moves smoothly through its full range, and if the trim tab does not have excessive free-play, then the trim tab actuator is just fine and doesn’t need to be messed with.

Okay, so if a Cessna trim tab actuator can go for 29 years and nearly 5,000 hours without needing to be lubricated, why does Cessna say to do it every 200 hours? Because Cessna’s service manual recommendations have to work for every airplane in the fleet, even the worst-case airplane. And there’s probably some Cessna somewhere—probably a Cessna 185 on floats up in Alaska that spends six months of the year operating off salt water and the other six months of the year locked up in a hangar because the weather is too bad to fly—that actually does need to have its trim tab actuators lubricated every 200 hours! But my airplane lives in a hangar and flies regularly, so servicing the trim tab actuators on my airplane every 200 hours would be gross overkill.

More to the point, it never makes sense to maintain a component on a fixed timetable (i.e., every so many hours or so many months) when it’s feasible to monitor the condition of the component (which takes two minutes for trim tab actuators) and maintain it only when the condition monitoring tests indicate that maintenance is actually required. We call this “condition-directed maintenance” (CDM) as opposed to “time-directed maintenance” (TDM).

CDM is always more efficient than TDM, because it causes components to be maintained only when they actually need maintenance, instead of when the manufacturer guesses it might need maintenance. Especially when the manufacturer’s guesses are heavily laced with pessimism to account for the worst-case airplane in the fleet.

We should only perform TDM when CDM is unfeasible because no practical condition-monitoring technique exists. Studies show that CDM is feasible for well over 90% of the components in our aircraft.

Many shops and mechanics insist on “doing everything by the book,” and often suggest to owners that this is required by regulation. In fact, manufacturer-recommended maintenance schedules are almost never required by regulation (unless you own an LSA), and almost always represent a huge waste of money. If your shop is one of those “do it by the book” facilities, just say “no.” And if they won’t take “no” for an answer, find another shop.

Rule 4. Don’t fix it until you’re sure what’s wrong

How many of you have had the experience of putting your aircraft in the shop to get some squawk fixed, then getting it back from the shop with an invoice, only to find on the first flight after maintenance that the squawk wasn’t fixed? Hmmm… I see a lot of hands raised, and I see a bunch of you with both hands raised. Seriously, I doubt there’s an aircraft owner who hasn’t had this experience, and most have had it multiple times.

TroubleshootingAnytime this happens, you’ve experienced a troubleshooting failure. The shop wasn’t lying on the invoice when it claimed to have spent H hours working on the problem, and D dollars in replacement parts. The problem is that the H hours of labor and the D dollars in parts didn’t fix the problem. Therefore, clearly the H hours were spent working on the wrong thing, and the D dollars were spent replacing parts that didn’t actually need to be replaced. Why? Because the shop tried to fix the problem without first thoroughly understanding its cause. That’s a troubleshooting failure!

Inadequate troubleshooting is probably the single biggest cause of wasted maintenance dollars. Why does it happen? There are a number of reasons. One is that many aircraft problems occur only in flight and cannot be reproduced in the maintenance hangar—and if a mechanic can’t reproduce the problem, then there’s no way for him to troubleshoot it systematically, and he’s forced to resort to guesswork about the cause of the problem (and those guesses are often wrong). Another is that good troubleshooting requires excellent systems knowledge, and sometimes our mechanics don’t know some of the systems on our aircraft as well as they should (which is usually our fault for picking the wrong mechanic for the job).

Never let a mechanic try to fix something unless and until you’re quite sure that he has diagnosed the problem thoroughly and understands exactly what’s causing it. Try never to put a mechanic in the position where he has to guess what’s wrong. When mechanics guess, owners often wind up throwing money down the drain.

OverkillRule 5. Don’t overkill the problem

Finally, when your airplane has a problem and you’ve diagnosed it properly, get it fixed but don’t go overboard. I can’t tell you how many times I’ve seen airplanes go into annual with one or two weak cylinders and come out with a $20,000 top overhaul. That’s nuts. If you have one or two weak cylinders, have them repaired—or replaced if they turn out to be unrepairable—but for Pete’s sake leave the rest of the cylinders alone.

Recently, I was corresponding with a T210 owner who explained to me that at his 2007 annual inspection, the compression test revealed one cylinder that measured 50/80, so the mechanic replaced the cylinder with a new one (at a cost of $2,000). Then at the 2008 annual, another cylinder came up 50/80, and the owner decided to major the engine (at a cost of $45,000)!

Give me a break! We don’t overhaul engines because of weak cylinders! We repair the cylinders, or if they’re unrepairable we replace them. We only overhaul an engine when something goes wrong with the “bottom end” that can only be repaired by splitting the case—a spalled cam, a cracked case, a prop strike, or something like that.

This stuff really works!

That’s all there is to it:

  1. Chose the right shop—one that’s comptent, communicative, and cooperative.
  2. Insist on a written discrepancy list and estimate before approving any work.
  3. If it ain’t broke, don’t let them fix it.
  4. Don’t let them fix it until you’re sure what’s wrong.
  5. Don’t overkill the problem.

These five simple rules encapsulate the essence of good maintenance management. Follow them and you’ll wind up with a safe, reliable airplane while saving many thousands of dollars a year in unnecessary maintenance costs. My company provides professional maintenance management services, and we employ these principles every day managing the maintenance of 600 airplanes and have saved our clients millions. I guarantee they’ll work just as well for you.

Misfueled!

Monday, January 11th, 2016
Decals

Jet fuel contamination of avgas remains a killer.

On March 2, 2008, a turbonormalized Cirrus SR22 was destroyed when it crashed shortly after takeoff in Rio de Janiero, Brazil, killing all four people aboard. Shortly after the aircraft departed from runway 20, the airplane’s engine lost power, and the aircraft hit a building and exploded. Further investigation revealed that the aircraft had been refueled with Jet A instead of 100LL.

This report reminded me of an incident 16 years earlier during which my own 1979 Cessna T310R was misfueled with Jet A at San Carlos (Calif.) Airport, a busy GA airport just south of SFO. Fortunately, I caught the (mis)fueler in the act, red handed. Had I not been lucky enough to do that, I probably wouldn’t be writing this column.

Normally, I either fuel my aircraft myself (at a self-serve pump) or watch it being fueled (when avgas is supplied by truck). On this occasion, I’d radioed for the fuel truck and waited patiently for it to arrive. After 10 minutes of waiting, Mother Nature intervened and compelled me to walk into the terminal building in rather urgent search of a loo. By the time I took care of my pressing business and returned to the ramp, there was a fuel truck parked by my airplane and a lineperson pumping fuel into my right main tank.  As I approached the aircraft, I observed to my horror that the truck was labeled “JET A.”

Theoretically impossible

At first, I was not too worried, because I believed that misfueling my airplane with Jet A was physically impossible. That’s because in 1987 (the year I purchased by T310R), all turbocharged twin Cessnas became subject to Airworthiness Directive AD 87-21-02 which mandated installation of restrictor ports on all fuel filler openings. The restrictor ports were designed to make it impossible to insert an industry standard Jet A nozzle, while accommodating the smaller diameter avgas nozzle.

The AD was issued because the FAA became aware that a large number of misfueling indicents and accidents were occuring in turbocharged aircraft. These aircraft typically were prominentaly decorated by the factory with the word “Turbo” and apparently linepeople were confusing it with “Turbine” and pumping Jet A into the tanks.

So the FAA mandated that jet fuel trucks install a wide spade-shaped fuel nozzle, and that vulnerable airplanes (like turbocharged twin Cessna) have restrictor ports installed into which the wide jet fuel nozzle would not fit. This made misfueling of piston aircraft with jet fuel theoretically impossible. (They also said that it’s theoretically impossible for bumblebees to fly.)

But as I arrived at my airplane, I discovered that indeed my left main tank had been topped with Jet A. How was this possible? A subsequent investigation by the local FSDO revealed that the Jet A fuel truck at San Carlos Airport had not been fitted with the correct spade-type nozzle. (I suspect they got in trouble for that.)

Jet-A nozzle vs. avgas nozzle

Jet fuel nozzles have a wide spade top that is theoretically incapable of being inserted in an avgas fuel filler equipped with a restrictor ring—but don’t count on it!

Undoing the damage

I spent literally hours trying to find an A&P on the field that would assist me in purging the fuel system of its witches’ brew of 100LL and Jet A. That turned out to be surprisingly difficult. The fueling company was falling all overitself to be helpful (because I’m sure they feared a big lawsuit) but they had no mechanics or maintenance capabilities. There were several maintenance shops on the field, but none wanted to go near my contaminated airplane, clearly afraid of the potential liability exposure. Finally, I persuaded one maintenance manger to help me out after writing and signing an omnibus waiver absolving the shop and its mechanics of any liability in connection with their work on my aircraft.

The purging process itself was quite an eye opener. We drained the tanks as completely as possible, putting the noxious effluent into a 55-gallon drum provided by the fueling company (who had agreed to deal with the costly disposal of the nasty stuff). We disconnected the fuel line going to the engine-driven fuel pump and drained all the fuel from that as well.

Next, 5 gallons of 100LL (donated gratis by the fueling company) was poured into the main tank, and then pumped through the system using the electric boost pump and drained from the disconnected fuel line into a 5-gallon bucket.  The fuel in the bucket was tested for Jet A contamination using the paper-towel test: A few drops are placed on a paper towel and allowed to evaporate completely. Pure 100LL will not leave an oily ring on the towel, but even small amounts of Jet A contamination will leave an obvious ring. The stuff in the bucket flunked the test.

Another 5 gallons of 100LL were poured into the tank, and the process repeated. Once again, it flunked the paper-towel test. We had to repeat the procedure three more times before we were satisfied that the system was essentially kerosine-free. We reconnected the fuel line, cowled up the engine, the fueling company then topped off the airplane (again gratis), and I was finally good to go…fully six hours after the misfueling incident.

Restrictor filler & GATS jar

Be sure all your fuel filler ports have restrictor rings. The big GATS jar (available at Sportys, Aircraft Spruce, and elsewhere) does a far better job than the slim screwdriver-type testers.

Lessons learned

I learned some important lessons that day. Perhaps the most important is that it’s impossible to distinguish pure avgas and a mixture of avgas and Jet A by color alone. My main tanks had been about half-full of avgas, so after the misfueling they contained roughly a 50-50 mix. If you take a jar full of pure 100LL and another jar full of a 50-50 mix of 100LL and avgas, I guarantee you will not be able to see any difference in color or clarity between the two.

I hadn’t realized that before. I has always been taught that you sump the tanks and observe the color—100LL is blue and Jet A is straw color. What I was not taught is that a mixture of 100LL and Jet A is also blue and that you simply can’t tell the difference visually. In retrospect, I shudder to think what would have happened had I not caught that Jet A truck in front of my airplane.

I was also taught that since Jet A is significantly heavier than avgas (6.7 lbs/gal versus 5.85 lbs/gal), the Jet A and 100LL will separate just like oil and water, with the Jet A at the bottom (where the sump drain is) and the 100LL at the top. That’s true, but only if the contaminated fuel is allowed to sit for hours and hours. It turns out that 100LL and Jet A mix quite well, and the mixture takes a surprisingly long time to separate.

There are at least two good ways to distinguish pure 100LL from kerosine-contaminated 100LL. One is by odor: Jet A has a very distinctive odor that is detectable even in small concentrations. The other (and probably best) is by using the paper-towel test: Pour a sample on a paper towel (or even a sheet of white copy paper), let it evaporate, and see if it leaves an oily ring.

Nasty stuff

What effect does Jet A contamination have on a piston engine? Enough to ruin your day.

You can think of Jet A as being fuel with a zero octane rating. Any piston engine that tries to run on pure Jet A will go into instant destructive detonation. However, in real life, we almost never encounter that situation because the tanks (at least the main tank used for takeoff) is almost never completely dry when the aircraft is misfueled.

Therefore, the real-world problem is not running on pure Jet A, but on running on a mixture of 100LL and Jet A.  Depending on the mixture ratio of the two fuels, the effective octane rating can be anything between 0 and 100. A mixture with a lot of Jet A and just a little 100LL might be detectable during runup.  A 50-50 mix might not start to detonate until full power is applied, and the engine might fail 30 seconds or 3 minutes after takeoff. Just a little Jet A contamination might produce only moderate detonation that might not be noticed for hours or even weeks. Like so many other things in aviation, “it all depends.”

The Cirrus SR22 accident in Rio reminds us that the problem of misfueling is still with us, despite all the efforts of the FAA to eradicate it. We need to be vigilant. Always watch your airplane being fueled if you possibly can. Make sure its fuel filler ports are equipped with restrictor rings. Don’t just look at the fuel you drain from your sumps—sniff it, and when in doubt, pour it on a paper towel.

Buying the right plane

Thursday, December 17th, 2015

TAP CoverFinding the right airplane to buy is hard work. Who among us hasn’t spent hours looking through Controller or Aircraft Shopper Online or Trade-A-Plane or Barnstormers looking for that perfect candidate—one with low time, a fresh overhaul, new paint and interior, great avionics, and a bargain price?

Dream on!

Common sense says you’re unlikely to find an airplane like that—and if you do, there’s probably a good reason that it’s underpriced … like maybe lost logbooks, major damage history, wing spar corrosion, an expensive AD that hasn’t been complied with, or some other big-time skeleton in the closet.

Nothing’s perfect

Many of the aircraft you see advertised are in reasonable shape, decently maintained, and worthy of consideration. But if you expect them to be in pristine condition—or even in as good condition as represented in the ads—you’ll probably be disappointed. If you have your heart set on buying a perfect airplane, you’d better buy a new one and be prepared for sticker shock. A well-equipped new Cessna 182T costs about $500,000 these days, and a Cirrus SR22 or Cessna T206H goes for about $750,000, and a Beechcraft Baron G58 now sells for $1.35 million.

If these prices are beyond your pay grade (and they sure as heck are beyond mine), you need to accept the fact that any “pre-owned” airplane you buy will be somewhat less than perfect and will require some fixing up after the purchase.

There’s absolutely nothing wrong with buying a “fixer-upper” so long as you go into the deal with your eyes open, have a good understanding of what it will cost to correct the airplane’s deficiencies, and are confident that this cost is adequately reflected in the negotiated purchase price.

High-time engine

Lycoming EngineOf course, some kinds of deficiencies are easier to deal with in this fashion than others. The easiest of all is an airplane with a high-time engine that’s close to (or beyond) TBO.

I say it’s easiest because engine time is almost always fully reflected in the selling price. In other words, an aircraft with a run-out engine is almost always priced sufficiently below the price of a similar aircraft with a zero-time engine to account for the cost of a major engine overhaul or factory-rebuilt exchange engine. I bought my own airplane with nearly run-out engines, and I’m convinced that buying an airplane with run-out engines has a lot of advantages.

One advantage is that the new owner gets to choose whether to overhaul or exchange for a factory rebuilt. If he opts to overhaul, he gets to choose the overhaul shop, the kind of cylinders he wants on his new engine, and any special items that may be desired when reinstalling the new engine (such as Teflon hoses, new Lord mounts, exhaust system repair, etc.) And that’s as it should be, since it’s the new owner who will have to live with the consequences of these decisions for years to come.

A second advantage of buying an airplane with a run-out engine (or engines) is that the seller is probably motivated to sell (rather than shell out big bucks for a major overhaul or factory rebuilt), and so may be a bit more flexible during price negotiations. In fact, I’m always a bit suspicious when I see an aircraft listed for sale with a “fresh overhaul” or unusually low engine time. I can’t help but think that the seller most likely knew he was about to get rid of the airplane when he had the engine overhauled, and it seems to me it would be mighty tempting to cut corners and minimize cost in that situation. Maybe I’m just cynical.

A third advantage of buying an airplane with an engine at or near TBO is that you might just wind up getting a pleasant surprise. After buying my T310R with engines just 100 hours shy of published TBO, I wound up flying the airplane for 600 more hours of trouble-free operation before deciding to overhaul the engines at TBO+500. With reserve for overhaul of $30/hour/engine, that wound up being a $36,000 windfall for me.

Most aircraft listed for sale have engines somewhere in between “fresh overhaul” and “run-out.” The problem here is that it’s often impossible for the buyer to know how much time he can expect to get out of the engine before overhaul. A good friend of mine—let’s call him “Frank”—bought a gorgeous 1978 Cessna T310R some years ago with mid-time RAM engines. Now RAM is arguably the country’s premier overhaul shop for TSIO-520 engines, and the engines got a clean bill of health during the pre-purchase inspection, so Frank fully expected it to be years before he’d have to think about major overhaul. At the first oil change after Frank bought the airplane, however, some ferrous metal showed up in one of the oil filters. Frank sent the filter contents to RAM, and they determined that one or more cam lobes were coming apart. Frank wound up having RAM tear down and overhaul the engine. Ouch!

Bottom line is that I think the best way to buy a used aircraft—all other things being equal—is to buy one with a high-time engine, plan to overhaul it or swap it for a factory engine shortly after the purchase, and make sure the cost of doing so is priced into the selling price.

High-time airframe

Jacked AirframeIn contrast, an airframe with beaucoup hours is much more difficult to analyze. Unlike engine time, airframe time cannot be “rolled back” by doing an overhaul. It is what it is.

High time on an airframe isn’t necessarily a bad thing. An airframe with high time has probably been flown regularly and often throughout its life. That’s good. Also, a high-time airframe usually belongs to a “working airplane” (flight school, charter, cargo, etc.), and such aircraft tend to receive better and more regular maintenance than owner-flown “hangar queens.”

In contrast, an airframe with unusually low hours is often one that has experienced lengthy periods of disuse, and unless the aircraft was based in a dry climate or stored in a heated hangar, it’s a likely candidate for having hidden corrosion damage.

Low-time airframes tend to command premium prices. Some years ago, a study of light twins listed for sale indicated nearly a linear inverse correlation between selling price and airframe hours (after adjustment for engine time and equipment), with depreciation of almost exactly $10 per airframe hour. (In other words, all other things being equal, a 6,000-hour twin sold for $30,000 less than a 3,000-hour twin.)

I’m not sure that’s rational—but market forces are often not rational. Personally, I’d be more comfortable buying a 25-year-old airplane with 4,000 hours on the airframe (average 160 hours/year) than a 25-year-old airplane with 1,000 hours on the airframe (average 40 hours/year). Of course, I’d really want more information about how those hours were distributed over the aircraft’s life, whether there were extended periods of disuse, whether the aircraft was hangared or tied down outdoors, where it was based (Tucson or Tampa), and so forth.

Very high-time airframes are another matter, however. We used to think that airframes would pretty much last forever if adequately protected from corrosion. That may still turn out to be true for some airframes (like strut-braced high-wing singles), but in recent years there has been increasing concern over the useful fatigue life of cantilever-wing airframes, particularly single- and twin-Cessnas and Beechcraft Bonanzas and Barons. There’s already a very costly spar-strap AD for high-time Cessna 400-series twins, and a good possibility of more such ADs in the future that could have a big impact on owners of high-time airframes.

As a general rule, you probably shouldn’t pay a big premium for an ultra-low-time airframe, and might even do well to be a bit suspicious of one. A mid-time airframe—with hours commensurate to its chronological age, indicating that it has been flown regularly and often—may be a more worthy candidate, not to mention a better bargain.

I warned you it wasn’t easy.

Older aircraft

1960 Cessna 210AFiguring out what model year to buy is another toughie. Market valuation of airplanes tends to drop precipitously with calendar age, and you occasionally see older aircraft for sale that have been well maintained, are corrosion-free, and are offered at what seem to be screaming bargain prices.

My advice to all but the most experienced aircraft buyers is to be wary of older airplanes, particularly older complex airplanes. There’s a good reason for their enticingly low asking prices: An older airplane can easily turn into a money pit. In fact, that may be precisely why it’s for sale.

You may figure that if the selling price is cheap enough, you can afford to spend the money to refurbish that older airplane into something really nice. Take an old, clapped-out 1960-model Cessna 210, for example, that you see in Trade-A-Plane for only $30,000. Add $30,000 for a zero-time engine, $20,000 for new paint and interior, and maybe another $15,000 to replace those old tube radios with a modern comm and GPS. So for $95,000 you’ll wind up with a first-class speed merchant, right?

Unfortunately, your “better than new” refurbished airplane won’t be worth anything close to the $95,000 you have invested in it. It might appraise at $60,000 at best, so you’ll be $35,000 underwater and in a world of hurt if you have to sell it. Unless you’re sure that you’ll be keeping the airplane for a many years, it’s generally wise to avoid purchases that involve spending substantially more than fair market value for the aircraft.

What’s worse, 1960 was the first year that Cessna produced the 210, and not surprisingly the earliest models are saddled with expensive Airworthiness Directives and maintenance problems. Cessna learned a lot from building that aircraft for 26 years, and later models of the Cessna 210 are truly outstanding airplanes. But the earliest models are… well… somewhat less outstanding.

I don’t mean to be picking on the Cessna 210 either. The same holds true for early model Bonanzas, Cherokees, Mooneys, etc. You can often buy one for a song, only to discover your new acquisition is eating you out of house and home. Unless you’re an A&P with lots of free time and looking for a “project airplane,” my advice is generally to buy the latest model year you can reasonably afford, and to avoid aircraft requiring high-ticket refurbishment.

Outdated avionics

Old Narco AvionicsThe conventional wisdom used to be that it was better to search for an airplane with suitable avionics than to buy one with older radios and refurbish the radio stack. That’s because a new radio stack increases the resale value of the aircraft only a small fraction of what it costs to buy and install. So it’s a lot more economical to let the other guy upgrade the panel than for you to do it.

These days, however, you may have little choice in the matter. We’re in the midst of a major avionics revolution, with terrestrial navaids getting phased out and GPS WAAS and ADS-B and real-time weather fast becoming a must-have for serious cross-country flight. Unless you luck out and stumble across an airplane for sale with a G-1000 or Aspen Evolution already in the panel—and that’s not terribly likely—you may have to bite the bullet and spring for the gear yourself.

Still, it’s best to find an aircraft with reasonably up-to-date avionics and minimizing the amount you’ll have to invest in electronics refurbishment. Installing a new autopilot is especially expensive, and it’s a big plus if you can find an aircraft that already has a decent autopilot installed.

Worn paint or interior

Worn SeatDon’t hesitate to buy an aircraft just because the paint or interior are getting long in the tooth. Inexperienced buyers tend to get way too hung up on cosmetics. What really counts is what’s under the paint and beneath the carpets. I’d buy a mechanically sound, corrosion-free airplane with shabby paint and interior in a heartbeat.

Think of paint and interior like you think of engines: Something that wears out and has to be redone every ten years or so. It really makes more sense for the buyer to do this after the sale than for the seller to do it before. After all, shouldn’t the new owner get to pick the paint colors and upholstery materials?

Much like engine time, the cost of paint and interior tends to be well reflected in the aircraft selling price. If you buy an aircraft with fully depreciated cosmetics, you can reasonably expect the selling price to be discounted enough to compensate for a substantial portion of the cost of refurbishment.

Mechanical discrepancies

Inspection

’

You’ve found a plane you really like a lot, and arranged to have a prebuy examination by a mechanic you trust. The inspection turns up some significant mechanical discrepancies. Now what do you do?

That’s easy: First, talk to your mechanic and determine what it will cost to correct the problems. Next, present the inspection findings and repair estimates to the seller, and see if he’s willing to reduce his selling price enough to cover all, or at least most, of the repair cost. If so, you’ve got a deal; if not, you may want to pass and find another aircraft.

Some discrepancies—corrosion damage to a wing spar, for example—may be so costly to repair that they’re instant deal-breakers. But most discrepancies—say, a soft cylinder or an inoperative autopilot servo—should be readily resolvable.

I’ve seen the prospective buyer of a half-million-dollar Cessna 421C walk away from the deal because the prebuy revealed two cylinders with poor compression. In my view, that’s nuts. The cost of replacing those two jugs is less than one percent of the purchase price. The purpose of a prebuy on a 421C should be to uncover the $50,000 discrepancies, not the $5,000 ones. (If you’re buying a Bonanza or Arrow or Skylane, scale these figures down appropriately.)

Good, clean, mechanically sound, corrosion-free airplanes are getting harder and harder to find, so don’t let a good one get away because of a problem that’s easy to fix.

Why I fly high

Monday, November 23rd, 2015

I take a lot of long trips in my Cessna T310R, and more than half of them involve cruising up in the high teens and low Flight Levels, simply because those are the altitudes at which my airplane is happiest, fastest, and most efficient. But from what I’ve been able to tell, the great majority of piston pilots shy away from using the high-altitude capabilities of their airplanes. Most pilots of normally aspirated airplanes seem to confine most of their flying to altitudes of 10,000’ and below, and even many pilots of unpressurized turbocharged airplanes like mine have never flown in the Flight Levels. It’s even surprising how many pilots of pressurized birds seem averse to flying much above the low teens.

That’s a shame, because it’s at the high end of the altitude spectrum that most of our airplanes achieve their best efficiency—and in many cases, their best speed as well. I’m not just talking about turbocharged airplanes. Most normally-aspirated birds are perfectly capable of cruise altitudes well into the teens.

Look at a plain-vanilla, fixed-gear, normally-aspirated Cessna Skylane:

Cessna 182Q Range Profile

Cessna 182Q Skylane range profile page from POH.

At a low altitude like 4,000’, maximum cruise speed is 139 KTAS at 75% power. Continue climbing until the airplane “runs out of throttle” at 8,000’ and max cruise climbs to 144 KTAS. That extra 5 knots will save you 9 minutes on an 800 NM trip when you take the extra climb into account. (5:38 instead of 5:47, no big deal).

Continue climbing to 12,000’ and max cruise drops back to 139 KTAS (same as at 4,000’), but at a much more fuel-efficient 64% power (which is all you can get at that altitude with wide-open throttle). The same 800 NM trip will take 6 more minutes at 12,000’ than at 4,000’ (5:53 to be exact) because of the longer climb, but burn a whopping 12 gallons less fuel in the process—if avgas costs $5/gallon, that’s $60—and increase IFR range by a full hour and 130 NM!

How far can we take this? Don a cannula and climb to 16,000’—high enough to fly right over the Front Range of the Rocky Mountains IFR—and max cruise drops to a still-respectable 130 KTAS at a miserly 53% power. Because it takes a Skylane nearly 40 minutes to climb from sea level to 16,000’ at max gross, the 800 NM trip will take a half-hour longer than at 12,000’ (6:23), but will save 20 gallons ($100?) and increase IFR range by a full two hours compared to our 4,000’ benchmark.


Cruise
Altitude
Max
Cruise
IFR
Range

To fly an
800 NM Trip

4,000 139 K 820 NM 5:47 78 gal
8,000 144 K 840 NM 5:38 79 gal
12,000 139 K 950 NM 5:53 67 gal
16,000 130 K 1,040 NM 6:23 59 gal

Normally-aspirated, fixed-gear 182Q
(maximum gross weight, standard day, no wind,
88 gallons, 45 min reserve)


Unless you just happen to like low-and-slow, there’s no logical reason to cruise a Skylane lower than 8,000’ because doing so makes all the numbers worse: cruise speed, trip time, and range.  On the other hand, climbing to 10,000’ or 12,000’ will cost you a negligible amount of time, and reward you with substantially lower fuel burn and increased range.

These calculations are all based on zero-wind, but in real life the winds aloft are often a decisive factor in determining the best altitude to choose. If you’re headed eastbound, odds are you’ll have a tailwind—and the higher you fly, the better it’ll be.

In wintertime, climbing up high to catch favorable winds can pay off spectacularly. In the low-to-mid teens, 50 knot tailwinds are commonplace and a 70 or 80 knot tailwind is possible. Even in summer, when winds tend to be relatively light, going high can pay off. Here are some typical summer winds I pulled off of DUATS:


      6000    9000   12000   18000
 STL 2410+18 2809+12 3110+07 2917-04
 SPI 2510+18 3010+12 3211+07 2919-05
 JOT 2511+17 3012+12 3116+06 2926-07
 EVV 2509+17 3012+11 3216+07 3018-05
 IND 2411+16 3011+11 3114+07 2922-06
 FWA 2312+15 2812+10 2916+06 2926-07
 CVG 2210+15 2809+11 3012+07 3021-05
 CMH 2210+14 2710+10 2914+06 3026-07
 CRW 2108+15 2509+10 2908+06 3225-05
 AGC 2010+12 2510+09 2813+05 2930-09
 EKN 1907+13 2608+09 2810+06 3028-07
 PSB 1911+11 2509+08 2813+04 2930-11
 EMI 9900+11 2905+09 2811+05 2927-10

Even in these docile summertime conditions, we can expect 10 to 15 knots more tailwind component at 16,000’ than at 8,000’, which almost exactly offsets the TAS advantage of the lower altitude (144K vs. 130K). By climbing up high on an eastbound trip, we’ll go just as fast, burn considerably less fuel, and increase our IFR range nearly 400 NM! Not to mention that it’s almost always smoother and cooler up high. What’s not to like?

During the winter, when the winds tend to be stronger, going high on eastbound trips tends to be an even better deal, saving both time and fuel.

For turbos, it’s even better

If you’ve got a turbocharger, the argument for flying high becomes compelling, because the higher you fly in a turbo, the higher your speed, range and efficiency—at least up to the low Flight Levels in most turbocharged airplanes. These birds really shine up in the high teens and low twenties, and pilots who don’t take advantage of this capability don’t know what they’re missing.

For example, take a look at the “Range Profile” page for my Cessna T310R:

Cessna T310R Range Profile

Cessna T310R range profile page from POH.

Starting at 180 KTAS at sea level, max cruise speed at 73.6% power steadily increases with altitude to a relatively blistering 221 KTAS at FL200. (Above that altitude, available power starts dropping off fairly rapidly.)


Cruise Altitude Max
Cruise
IFR
Range
To fly an
800 NM Trip
5,000 190 K 860 NM 4:14 143 gal
10,000 199 K 890 NM 4:04 137 gal
15,000 209 K 930 NM 3:55 131 gal
20,000 221 K 970 NM 3:45 125 gal

Turbocharged, twin-engine Cessna T310R
(73.6% cruise, maximum gross weight  standard day, no wind,
163 gallons, 45 min reserve)


At the same time, range with IFR reserves climbs from 820 NM to 970 NM. Naturally, trip time and fuel burn for the proverbial 800 NM trip both drop accordingly—from 4:14 and 143 gallons at 5,000 to 3:45 and 125 gallons at FL200.

Personally, I don’t push my engines this hard. I almost always throttle back to between 60% and 65% power and settle for around 205 KTAS at FL200 at a miserly fuel burn of 26 gallons/hour, giving me a range of well over 1,000 NM with IFR reserves (or 1,200 NM if I fill my 20-gallon wing locker tank).

Once again, these figures assume no-wind conditions. Add in the wind on an eastbound trip and the results can get downright exciting. In the winter, I’ve seen my groundspeed edge above 300 knots from time to time. That’s fun! During the summer, on the other hand, I’m happy with 230 or 240 on the GPS readout.

Needless to say, you pay the piper going westbound. But if the winds aren’t too strong, it may still pay to go high rather than low. In my airplane, I gain 22 knots of true airspeed by climbing from 10,000’ to FL200. So if the headwind at FL200 is only 10 or 15 knots stronger than at 10,000’ (which is usually the case in summertime), higher is still better.

In wintertime, of course, westbound aircraft are all in the same boat, turbo or non-turbo. We bounce along at the MEA, try not to look at the groundspeed readout, hope the fillings in our teeth don’t fall out, and think about how much fun the eastbound part of the trip was (or will be).

Enjoy the high life!

If you’re one of those pilots who comes from the “I won’t climb higher than I’m willing to fall” school, you’ve got nothing to be embarrassed about. Believe me you’ve got plenty of company. But you’re also missing something really good.

Do yourself a favor: give high a try. It’s cooler and smoother up there. Your airplane flies faster and more efficiently up high. ATC will usually give you direct to just about anywhere. You’re above terrain, obstructions, and often the weather and the ice. The visibility is usually terrific. So are the tailwinds, if you’re lucky enough to be going in the right direction. Try it…you just might like it!

Assault on GA Down Under

Friday, October 9th, 2015
Nick McGlone

Nick McGlone with one of his Cessna 210s.

I just got off the phone with my good mate Nick McGlone from Sydney, Australia. For decades, Nick has operated Nautilus Air Services at Sydney’s Bankstown Airport. His firm operates a fleet of Cessna 210 Centurions whose primary mission is to haul sushi-grade fresh fish every day from Tasmania to Sydney. It’s roughly 650 miles from Sydney to Tasmania as the crow flies, about one-third of it overwater.

Now 70, Nick might just be the highest time Cessna 210 pilot in the world, with well over 30,000 hours in type. He’s also a master mechanic (they call them “LAMEs” down there) who maintains his airplanes in tip-top shape. He has to because he depends on them to be mission-ready every day.

After we exchanged a few pleasantries, Nick told me that his airplanes hadn’t flown for months and he was not confident that they would ever fly again. That stopped me dead in my tracks; he had my attention.

CASA’s War on Aging Aircraft

Nick explained to me that in recent years, Australia’s Civil Aircraft Safety Authority (CASA)—the Aussie counterpart to our FAA—had been implementing a series of draconian policies calculated to make it economically impossible for owners of legacy GA aircraft to keep them flying. He said that Bankstown Airport—traditionally the busiest GA airport in Australia—had become a virtual ghost town.

It seems that in 2014, the powers-that-be at CASA handed down a startling ruling that all operators of Australian-registered Cessnas would be required to comply with Cessna’s Supplemental Inspection Documents (SIDs). These SIDs set forth an extraordinarily extensive program of structural inspections that Cessna wants performed on a regular basis.

Some of the inspections in Cessna's SIDs are invasive, labor-intensive, and expensive.

Some of the inspections in Cessna’s SIDs are invasive, labor-intensive, and expensive.

Some of these inspections are relatively easy, but some are extraordinarily invasive and labor-intensive and costly. The SIDs specify a complex matrix of initial and repetitive compliance times for these various inspections. The most invasive and labor-intensive ones are to be done initially when the aircraft reaches 20 years old, and then repetitively every 3, 5, or 10 years thereafter. Of course, since all Cessna 300/400-series piston twins and all 200-series singles and the vast majority of 100-series singles are 30-60 years old, all of them are now past due for these inspections.

The FAA has ruled that compliance with these SIDs is strictly voluntary—NOT compulsory—for U.S.-registered aircraft that are maintained in accordance with the U.S. FARs. But CASA’s 2014 ruling was the exact opposite, and mandates that all Australian-registered aircraft MUST comply with the SIDs, whether the aircraft are in commercial service or private use.

Nick said that this is a catastrophe for Cessna owners in Australia (and in other nations like New Zealand and Germany and Spain who have also ruled that the SIDs are compulsory). Although the FAQ on CASA’s website says that compliance with the SIDs should cost about $20,000, Nick indicated that owners are finding that the actual cost of compliance is between $80,000 and $120,000 for Cessna singles, and close to $200,000 for Cessna twins. This is more than many of these aircraft are worth—or WERE worth before CASA made its ruling. Now, says Nick, the market value of these aircraft in Australia has dropped to near-zero, and many Australian owners are being forced to crate up their aircraft and ship them for sale in the U.S. (where compliance with the SIDs is not required).

Not Just Cessnas, Not Just SIDs

This catastrophe isn’t just limited to Cessnas, either. Now that Cessna’s parent company Textron Aviation owns Beechcraft, they’re feverishly working on developing a SID program for Bonanzas and Barons and other aging Beech airplanes. CASA has made it clear that the moment these Beech SIDs are published, CASA will mandate their compliance. There is even a rumor that Piper is working on a SID program for aging Piper airplanes.

All stainless steel control cables on Australian aircraft have to be replaced by the end of 2017.

All stainless steel control cables on Australian aircraft have to be replaced by the end of 2017.

And if that wasn’t bad enough, CASA has a few other tricks up its sleeve to make operation of aging GA aircraft unaffordable in the land down under. There’s a new Australian AD issued last February that requires that all primary flight control cables that use stainless steel end fittings (as almost all do) must be replaced with new cable assemblies by the end of 2017.  And another Australian AD that requires that all propellers undergo a complete disassembly inspection every six years and a major overhaul at the prop manufacturer’s specified TBO. None of these things are mandated by the FAA for U.S.-registered airplanes, nor is there a history of accidents or incidents in either country to justify such costly maintenance burdens on the owners of GA aircraft.

Nick told me that he is convinced that Textron and perhaps other manufacturers simply want their older aircraft to go away, and that they’ve been successful in enlisting CASA and various other national CAAs in helping them to achieve that goal. All of this is shrouded in the mantle of “aviation safety” despite the fact that there’s virtually zero history of accidents being caused by structural failure, control cable failure, or failure of high-time propellers. Nick could be right.

So next time you start griping about the high cost of personal flying, you might pause and thank your lucky stars that you’re based in the U.S. and not in the land down under. Compared to the rest of the world, we American aviators have it mighty good.

The A&P Exam

Thursday, September 17th, 2015

Although I’ve been an aircraft owner since the late 1960s and heavily involved in GA maintenance since the late 1980s, I didn’t actually become an official card-carrying A&P mechanic until 2001. By the time I decided to go for my A&P ticket, I was already a pretty seasoned aircraft mechanic with a reputation for encyclopedic knowledge of aircraft systems and an aptitude for being able to troubleshoot thorny maintenance issues that had other mechanics stumped. I figured that passing the A&P exam would be a piece of cake.

I figured wrong.

An applicant for an A&P certificate must take and pass three multiple-choice 100-question knowledge tests.

An applicant for an A&P certificate must take and pass three multiple-choice 100-question knowledge tests.

By way of background, an applicant for an A&P certificate must surmount three sequential FAA-imposed hurdles. First, the applicant must prove to his FSDO that he has the minimum required experience performing maintenance on civil aircraft: 30 months on a full-time basis, or 4,800 hours on a part-time basis. Second, the applicant must take and pass three multiple-choice 100-question knowledge tests—mechanic general, mechanic airframe, and mechanic powerplant—and score at least 70% on each one. Third, the applicant must submit to an exhaustive (not to mention exhausting) oral and practical test with a Designated Mechanic Examiner—the mechanic’s equivalent to a checkride—which is normally at least a full-day affair.

When I started studying for the three A&P knowledge tests, my first surprise was the study syllabus, which struck me as being firmly anchored in the 1940s. For example, in preparing for the powerplant test, I reviewed more than 1,000 multiple-choice questions from the FAA’s “question bank” and found that the overwhelming emphasis was on radial engines, pressure carburetors, Hamilton Standard hydramatic propellers, and similar subjects of unquestionable interest to warbird buffs but of absolutely no relevance to contemporary GA aircraft of the sort that interested me. There were only a handful of questions about horizontally-opposed engines, perhaps two or three about fuel injection, only one about modern Hartzell compact hub propellers, and nothing at all about McCauleys.

The question bank for the powerplant test contained not a syllable about any technology that was less than 30 years old. Nothing about engine monitor data analysis, borescope inspections, spectrographic oil analysis, or scanning electron microscopy of oil filter contents. Nothing about compression ignition (Diesel) engines or electronic ignition systems or FADECs or lean-of-peak operation. Similarly, the airframe test was devoid of questions about composite construction (unless you count wood and fabric, which I suppose is the original composite).

To be fair to the FAA, there were actually lots of questions about “modern” 1960-vintage technologies, but they were all related to turbine and transport aircraft. To score a decent grade on the tests, it was obvious that I would need to master lots of material about turboprop and turbojet engines, air cycle machines, Roots blowers, and other esoterica that I knew I’d never remember or have any use for once the test was done.

Mastering the wrong answers

I took my three A&P knowledge tests at a local computerized testing center.

I took my three A&P knowledge tests at a local computerized testing center.

This was frustrating enough, but what really bugged me was that the “official FAA answer” to many of these multiple-choice questions was often the wrong answer. It became obvious that if I wanted to get a good score on the mechanic knowledge tests, I’d have to commit these “FAA answers” to memory even though I knew that they were the wrong answers.

Would you like to see some examples? Here are some actual questions from the 2001 FAA mechanic exam question bank, with the “official FAA answer” that would be used by the FAA to grade the exam:

#8072. Which fuel/air mixture will result in the highest engine temperature (all other factors remaining constant)?

A—A mixture leaner than a rich best-power mixture of .085.

B—A mixture richer than a full-rich mixture of .087.

C—A mixture leaner than a manual lean mixture of .060.

FAA-approved answer: C.

Discussion: Stoichiometric mixture (peak EGT) is around 15:1 or .067, so the FAA-approved answer C (“leaner than .060″ or about 17:1) would be very lean-of-peak, far leaner than most engines can run without unacceptable roughness (unless they are fuel-injected and have tuned fuel nozzles). This is definitely a mixture at which the engine would run cool, not hot. Of the three choices given, the “most correct answer” is A. The FAA-approved answer (C) is just plain wrong, and perpetuates the Old Wives’ Tale that rich mixtures are cool and lean mixtures are hot. With training like this, is it any wonder so many A&Ps blame almost every cylinder malady to LOP operation?

#8678. Why must a float-type carburetor supply a rich mixture during idle?

A—Engine operation at idle results in higher than normal volumetric efficiency.

B—Because at idling speeds the engine may not have enough airflow around the cylinder to provide proper cooling.

C—Because of reduced mechanical efficiency during idle.

FAA-approved answer: B

Discussion: None of the given answers is correct, but the FAA-approved one is the probably the worst possible choice, because it suggests that pilots should keep the mixture full-rich during idle and taxi in order to obtain proper cooling. Do you suppose that OWT explains why so many pilots taxi around at full-rich and foul the crap out of their spark plugs? Are they learning this from their A&Ps? Here’s the correct answer: “Because a very rich mixture is required for cold-starting, and aircraft carburetors don’t have a choke to provide such a rich mixture (the way automotive carbs do), so the idle mixture has to be set extremely rich … which is why as soon as the engine starts to warm up, you need to come back on the mixture control.” Of course, that answer isn’t one of the choices offered.

#8773. Carburetor icing is most severe at…

A—air temperatures between 30 and 40 degrees F.

B—high altitudes.

C—low engine temperatures.

FAA-approved answer: A

Discussion: Are you kidding me? The AOPA Air Safety Foundation briefing on carb ice states, “Icing is most likely to occur—and to be severe—when temperatures fall roughly between 50°F and 70°F and the relative humidity is greater than 60%.” It shows a gory photo of the fatal crash of a Cessna 182 caused by carb ice that formed at OAT 80°F and dewpoint 45°F. If the FAA genius who wrote this question was a pilot, it’s a sure bet that most of his experience is flying Gulfstreams, not Skylanes. (Keep in mind that to get a decent grade on the A&P knowledge test, you have to memorize these FAA-approved wrong answers, or risk failing!)

#8829. Which of the following defects would likely cause a hot spot on a reciprocating engine cylinder?

A—Too much cooling fin area broken off.

B—A cracked cylinder baffle.

C—Cowling air seal leakage.

FAA-approved answer: A

Discussion: Once again, the FAA offers three possible answers and then claims that the “wrongest” one is the one they consider correct. Every IA I’ve asked agrees with me that by far the most likely cause is a bad baffle (answer B), and none has ever seen a case where a cooling fin was broken off badly enough to create an issue.

#8982. If a flanged propeller shaft has dowel pins…

A—install the propeller so that the blades are positioned for hand propping.

B—the propeller can be installed in only one position.

C—check carefully for front cone bottoming against the pins.

FAA-approved answer: B

Discussion: Well that’s interesting. The Continental TSIO-520-BB engines on my 1979 Cessna T310R have flanged propeller shafts. Each flange has a pair of identical dowel pins spaced 180° apart. This permits my three-bladed McCauley C87 props to be installed in two possible orientations, one that results in the vertical blade pointing down when the engine stops, and the other that results in the vertical blade pointing up. According to the Cessna service manual, only one of these orientations is the correct one, so you need to be careful when installing the prop. The FAA-approved answer (B) is just plain wrong. So are the other two answers.

I could go on, but you get the idea.

Mind-numbing

results.

Here’s irrefutable proof that I was able to remember all those FAA-approved wrong answers long enough to score 96, 99 and 99 on my three mechanic knowledge tests.

Well, it took me many hours of study, practice and drill to memorize all of the FAA-approved wrong answers to the thousands of multiple-choice questions in the question bank. As you can imagine, going through this mind numbing exercise was a character-building experience that greatly expanded my vocabulary (of expletives) and bolstered my respect for the cutting-edge mindset of our favorite friendly federal agency.

I guess I must’ve done a workmanlike job of studying and memorizing, because when I finally took the three FAA knowledge tests at my “Don’t try this at home, kids” LaserGrade computerized testing center, I scored 96% on the general and 99% on both the airframe and powerplant. (See Figure 1.) I don’t want to brag, but it’s a rare skill to master so many wrong answers so consistently in such a short period of time, if I do say so myself.

Once the exams were done and my scores were in the bag, I celebrated with the obligatory overnight soak of my brain’s medial temporal lobe (seat of long-term memory) in a 50-50 mixture of cheap champagne and methyl ethyl ketone, just to make absolutely sure all those FAA-approved wrong answers and Old Wives’ Tales were permanently purged from my gray matter. After all, it would certainly be embarrassing to inadvertently pass any of them on to the next generation of A&P mechanics, wouldn’t it?

Is Your Aircraft Okay to Fly?

Thursday, July 23rd, 2015

Who decides whether or not your aircraft is airworthy?

Airworthy steampEarlier this year, I wrote an article titled “Fix It Now…Or Fix It Later” that was published in a major general aviation magazine. The article discussed how to deal with aircraft mechanical problems that arise during trips away from home base. It offered specific advice about how pilots and aircraft owners can decide whether a particular aircraft issue needs to be addressed before further flight or whether it can safely wait until the aircraft gets back home. I considered the advice I offered in this article to be non-controversial and commonsense.

I was surprised when I received an angry 700-word email from a very experienced A&P/IA—I’ll call him “Damian” (not his real name)—condemning my article and accusing me of professional malfeasance in advising owners to act irresponsibly and violate various FARs. Damian’s critique started out like this:

After reading Mike Busch’s commentary “Fix It Now … Or Fix It Later,” I must take exception to most, if not all, the points made in his column. I believe his statements are misleading as to the operation of certified aircraft, to the point of being irresponsible for an A&P to suggest or imply that it’s up to the owner/operator whether or not to fly an aircraft with a known discrepancy. The FARs are quite clear on this matter, and there have been numerous certificate action levied on pilots who have operated aircraft with known discrepancies.

Damian went on to state that the FARs require that any aircraft discrepancy, no matter how minor, must be corrected and the aircraft approved for return to service “by persons authorized under FAR 43.7 (typically the holder of a mechanic certificate).” He went on to explain that the owner/operator may only approve for return to service those preventive maintenance items listed in FAR Part 43 Appendix A. He went on:

It should be noted that the FAA does not take into consideration the inconvenience or cost related to addressing a known discrepancy. Nor is it up to the owner/operator to determine the significance of a discrepancy as the FARs do not confer this discretion privilege to the owner/operator.

Damian’s attack on my article continued at great length, making it quite clear that his believe is that pilots and aircraft owners are mere “appliance operators” in the eyes of the FAA, and that only certificated mechanics are empowered to evaluate the airworthiness of an aircraft and determine whether or not it is legal and safe to fly. He ended his diatribe by saying:

I hope that others in the aviation community such as FAA Airworthiness Safety Inspectorss and aviation legal professionals weigh in on this commentary. I believe all will agree that this commentary is misleading and uninformed to the point of being irresponsible even to publish. At the very least, pilots that follows the advice of Busch’s commentary should enroll in the AOPA Pilot Protection Services plan because they’re likely to need it!

Whew! Strong stuff! If Damian is right, then the FAA had better lock me up and throw away the key. Fortunately for me, I believe he isn’t and (at least so far) they haven’t.

Where Damian Has It Wrong

Damian and I do agree on at least one thing: FAR 91.7 does indeed say quite unequivocally that it is a violation to fly an unairworthy aircraft, and that if the aircraft becomes unairworthy in flight, the PIC is obligated to discontinue the flight. I would never suggest for a moment that any pilot fly a known-unairworthy aircraft, at least without a ferry permit. That’s a no-brainer.

The much more difficult question is: Exactly how does the PIC decide whether or not an aircraft is airworthy or unairworthy, and therefore whether he is or isn’t allowed to fly it? On this question, Damian and I part company. In fact, his view and mine seem to be diametrically opposite.

Damian’s view is that almost any aircraft discrepancy requires the involvement of an A&P mechanic to evaluate and clear the discrepancy and approve the aircraft for return to service. I see absolutely nothing in the FARs to support such a position, particularly when it comes to non-commercial aircraft operated under Part 91.

To begin with, the basic airworthiness rule (FAR 91.7) is crystal clear about who is responsible for determining whether or not the aircraft may be flown. It says:

The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight.

The regulation places the burden squarely on the shoulders of the PIC. I don’t see anything there about A&Ps or repair stations having to be involved, do you?

Looking a bit deeper into the FARs, I can find only three circumstances under which a mechanic is required to get involved in making any sort of airworthiness determination on a Part 91 aircraft used for non-commercial purposes:

  1. Exactly once a year, FAR 91.409 requires that an annual inspection be performed by an A&P/IA or a Repair Station. But the other 364 days of the year, it’s the PIC who determines whether the aircraft is airworthy.
  2. When an Airworthiness Directive or Airworthiness Limitation becomes due, FAR 91.403 requires that a mechanic must certify that the AD or AL has been complied with (with rare exceptions where the PIC may do so).
  3. When an owner actually hires a mechanic to perform maintenance on an aircraft, in which case the mechanic is required to document his work and sign it off to testify that the work was performed properly. Note, however, that the mechanic’s signature in the logbook entry does NOT signify that the aircraft is airworthy, only that THE WORK PERFORMED by the mechanic was done in an airworthy fashion.

This third point is one that is frequently misunderstood by mechanics and owners alike. When I teach this stuff at IA renewal seminars, the hypothetical example I often use to illustrate this important point involves an owner who takes his aircraft to a mechanic for repair. The mechanic immediately observes that the aircraft has two obvious discrepancies: the right main landing gear tire is flat, and the left wing is missing. The owner asks the mechanic to fix the flat tire. The mechanic does so, makes a logbook entry describing the work he did on the right main landing gear, and signs it. His signature denotes only that the work he did (fixing the flat tire) was done properly. When the owner picks up the aircraft, the mechanic tells the owner, “I couldn’t help but notice that your left wing is missing. If you’ll permit me to offer you a word of friendly advice, I would not attempt to fly the aircraft until that issue is resolved.” But the missing left wing does not prevent the mechanic from signing the logbook entry. In fact, the mechanic is required by regulation to sign the logbook entry, regardless of whether the aircraft is airworthy or not. The mechanic’s signature addresses only the work performed by the mechanic, and nothing else.

The PIC’s Burden

If you’re on a trip and some aircraft discrepancy occurs – assuming the aircraft isn’t in the midst of its annual inspection and there’s no AD involved – it is up to you as PIC to determine whether or not that discrepancy makes the aircraft unairworthy or not. If you decide that it does, then you can’t fly the airplane until the airworthiness issue is rectified (and that might require hiring an A&P). On the other hand, if you decide that the discrepancy doesn’t rise to the level of making the aircraft unairworthy, then you’re free to fly home and deal with the issue later.

Under the FARs, it’s totally the PIC’s call. There’s no regulatory obligation for the PIC to consult a mechanic when making such airworthiness determinations. Having said that, however, it would certainly be a wise thing to do if you feel uncomfortable about making the decision yourself. It’s your call.

The FARs provide considerable help to the PIC in making such airworthiness determinations. FAR 91.213(d) describes a specific algorithm for deciding whether or not it’s okay to fly an airplane with various items of inoperative equipment. FAR 91.207 says that it’s okay to fly an aircraft with an inoperative ELT to a place where it can be repaired or replaced, no ferry permit required. FAR 91.209 says that position lights needn’t be working if you’re flying during daylight hours. And so on.

If your experience is anything like mine, what most of us call “squawks” are common occurrences, but the majority of them don’t rise to the level of being airworthiness items that cause us (in our capacity as PIC) to conclude that a fix is required before further flight. Even if you do encounter a genuine airworthiness problem – say a flat tire or dead battery or bad mag drop – that still doesn’t mean that you necessarily need to get a mechanic involved. The FARs provide (in Part 43 Appendix A) a list of roughly three dozen items that a pilot-rated owner or operator is permitted to perform and sign off on his own recognizance (without getting an A&P involved).

If you have a flat tire, for example, you (as a pilot-rated owner) are permitted to repair or replace it yourself. If you have a dead battery, you can charge it, service it, or even replace it. If you have a bad mag drop, the most common cause is a defective or fouled spark plug, and you’re permitted to remove, clean, gap, and replace spark plugs yourself. You are also allowed to make repairs and patches to fairings, cowlings, fabric (on fabric-covered aircraft), upholstery and interior furnishings. You can replace side windows, seat belts, hoses, fuel lines, landing and position lamps, filters, seats, safety wire, cotter pins, and more. You can even remove and install tray-mounted avionics from your panel.

Now, you might well prefer to hire an A&P to do some of these things rather than do them yourself, especially when on the road, far from your hangar and toolbox. I know I certainly would, and I’m an A&P myself. But Damian’s contention that you are compelled by the FARs to place your aircraft in the hands of an A&P any time any sort of discrepancy arises is simply not supported by the regulations.

Contrary to what Damian and many of his A&P colleagues may believe, the FAR’s place the responsibility for determining the airworthiness of the aircraft squarely on the PIC, except for once a year when an IA is required to make an airworthiness determination after performing an annual inspection

My colleague Mac McClellan pointed out to me that this closely resembles how the FAA determines whether a pilot is “airworthy.” One day every year or two or five, we pilots are required by regulation to go get an examination from an Aviation Medical Examiner who pronounces us medically fit to fly, or not. The remaining 364 or 729 or 1,824 days in between, the FAA expects us to self-certify that we’re medically fit. “Can you imagine,” Mac asked me rhetorically, “if we had to go to see an AME every time we got a sore throat or runny nose?”