Author: Mike Busch (page 1 of 5)

It’s About Time!

I just added ADS-B Out to my airplane. I’ve been looking forward to this moment for a very long time—48 years to be exact.

Air Facts (May 1970)

Air Facts (May 1970)
click image to read article

It was 48 years ago that my very first aviation article was published. Its title was “The Role of Computers in Air Traffic Control.” I was 26 years old at the time, not long out of college, and starting a career in computer software at the dawn of the computer age. I’d only been a pilot for five years and an aircraft owner for two.

I timidly submitted the 3,000-word manuscript to Leighton Collins (1903-1995), the dean of general aviation journalists (and Richard Collins’ dad). Leighton founded his magazine Air Facts in 1938, the first GA magazine to focus primarily on safety. In the ‘50s and ‘60s, Leighton became a pioneer in using GA airplanes to fly IFR, something that was considered risky business at the time. In 1970, I was a newly-minted CFII and Skylane owner, and Leighton was my hero and Air Facts my bible.

Leighton loved my article, and published it in the May 1970 issue of Air Facts.  I was thrilled. I was also hooked and went on to write more than 500 published aviation articles between then and now.

How big is the sky?

I’d been instrument-rated for about four years when I wrote that article, and had thought quite a bit about the differences between VFR and IFR flying:

A pilot flying VFR in clear weather is unlikely to see more than a few other aircraft on a typical flight; to him the sky seems to be a rather empty place. Yet to the pilot stuck in an IFR hold with an estimated-further-clearance time forty-five minutes away, the sky seems to be an order of magnitude more crowded. Why? Clearly there is no shortage of airspace; every VFR pilot knows that. The aircraft flying under IFR have the best equipment and the most proficient pilots aboard. Where does the congestion come from?

My conclusion was that the fundamental difference between VFR and IFR lies in who is separating aircraft. VFR pilots are responsible for their own separation, while IFR pilots rely on air traffic controllers to keep them separated from other traffic. Thus, I reasoned, the comparatively low capacity of the IFR system must be attributable to some failing on the part of controllers. Yet as someone who has spent many hours visiting ATC facilities and observing controllers at work while plugged in beside them, I can testify that these folks are amazingly sharp, skilled, and well-trained professionals who do their jobs exceptionally well.

So why can’t these hotshot controllers separate IFR aircraft nearly as efficiently as VFR pilots are able to separate themselves? My conclusion was that the very nature of the separation task is fundamentally different:

A pilot is concerned solely with the one aircraft that he’s flying, but a controller must keep track of several aircraft at once. Give a person several things to do at once—even simple things like head-patting and tummy-rubbing—and his performance in each task drops sharply. Keeping track of a high-speed airplane is considerably harder than either head-patting or tummy rubbing. Keeping track of a dozen such airplanes travelling in random directions at random altitudes is simply beyond the capabilities of any human.

Our IFR system is designed to simplify the controller’s job to the point that it is within the realm of human capability. It does this primarily by eliminating the amount of randomness the controller must deal with. It strings airplanes along a few well-defined airways/SIDs/STARs, confines them to a few standard altitudes, and sometimes slows them down to a few standard speeds. Doing these things makes the airplanes much easier for the controller to keep track of and keep separated, but it also wastes most of the available airspace and reduces the capacity of the system.

Do we really need ATC?

It seemed to me that the capacity of the IFR system could be vastly increased if we could just stop relying on controllers to separate airplanes and enable pilots to self-separate, much as they do when flying VFR. In 1970 when I wrote the article, we were right on the cusp of two major technological breakthroughs that I believed had the potential to make that possible.

GPS ConstellationOne of them was the promise of accurate satellite navigation. The Naval Research Laboratory had launched its Timation satellites in 1967 and 1969, the first ones to contain accurate atomic clocks suitable for navigation. Meantime, the Air Force’s Space and Missile System Organization was testing its more advanced system (codenamed Project 621B) for aircraft positioning between 1968 and 1971. These were the progenitors of today’s GPS system—something I could see coming in 1970, although a seriously underestimated how long it would take to become operational. The first constellation of 10 “Block-I” GPS satellites wasn’t in orbit until 1985, and the system’s full operational capability wasn’t announced until 1995.

MicroprocessorThe second breakthrough was large-scale integration (LSI)—the creation of integrated circuits containing tens of thousands of transistors on a single silicon chip—and the emergence of the microprocessor. Microprocessors weren’t yet invented in 1970 when I wrote the article, but as a computer scientist (my day job at the time) I could see them coming, too. As it turned out, Intel introduced its 4004 microprocessor in 1971, its 8008 in 1972, and the 8080 (which really put microprocessors on the map) in 1974. This watershed development made it feasible to equip even small GA airplanes with serious computing power.

The ATC system of tomorrow

Traffic DisplayIn my 1970 Air Facts article, I painted a picture of the kind of ATC system these new technologies—GPS and microcomputers—would make possible. I postulated a system in which all IFR aircraft and most VFR aircraft were equipped with a miniaturized GPS receiver that continually calculated the aircraft’s precise position and a transmitter that broadcast the aircraft’s coordinates once per second. A network of ground stations would receive these digital position reports, pass them to ATC, and rebroadcast them to all aircraft in the vicinity. A microcomputer aboard each aircraft would receive these digital position reports, compare their coordinates with the position of the host aircraft, evaluate which aircraft are potential threats, and display the position, altitude and track of those threat aircraft on a cockpit display.

Such a cockpit display would enable IFR pilots separate themselves from other aircraft, much as VFR pilots have always done. It would permit them to fly whatever random routes, altitudes and speeds they choose, giving them access to the same “big sky” that VFR pilots have always enjoyed.

I theorized that pilots are highly incentivized to self-separate and would do a much better job of it than what ground-based air traffic controllers can do. (Just imagine what driving your car would be like if you weren’t allowed to self-separate from other vehicles, and instead had to obtain clearances and follow instructions from some centralized traffic manager.)

What took so long?

NextGen controllerWhen I re-read that 1970 article today, it’s truly eerie just how closely the “ATC system of the future” I postulated then resembles the FAA’s “Next Generation Air Transportation System” (NextGen) that the FAA started working on in 2007 and plans to have fully operational in 2025. Key elements of NextGen include GPS navigation and ADS-B—almost precisely as I envisioned them in 1970.

I was wildly overoptimistic in my prediction that such a system could be developed in as little as five years. If the FAA does succeed in getting NextGen fully operational by 2025, it will be the 55th anniversary of my Air Facts article.

NextGen also includes improved pilot/controller communication (both textual and VOIP) and various improvements designed to allow use of more airspace and random routes. Sadly, it stops well short of transferring responsibility for separating IFR aircraft from ATC to pilots as I proposed in 1970—although our aircraft will have the necessary equipment to do that if the FAA would just let us. Maybe that’ll have to wait another five decades until NextNextGen is deployed (and there’s an autonomous self-piloting octocopter in every garage).

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

You Did WHAT???

Generally, aviators don’t like surprises. The good ones—like catching an unexpected 30-knot tailwind, or finding an ANR headset under the Christmas tree—are rare. The bad ones—like an inoperative self-serve fuel pump, a flat nosewheel strut, or worse-than-forecast weather at your destination—are more common.

Some of the really bad surprises involve aircraft maintenance. Since my company manages the maintenance of about 1,000 GA airplanes, I thought I’d seen just about every sort of maintenance misfortune that can befall an aircraft owner, but the one I’m about to relate has to take some sort of prize.

Sooty exhaust trailIt involves the owner of a Cirrus SR22—I’ll call him Mark—who was starting to get a bit concerned about the increasing oil consumption of his Continental IO-550-N engine. He was starting to notice increased oil on the belly behind the righthand tailpipe, and a buildup of sooty deposits inside that tailpipe. A maintenance-involved owner and a pretty sharp cookie, Mark’s suspicion was that the oil consumption was probably the result of lead-contaminated oil control rings in the right-bank cylinders (#1, #3, and #5). The presence of oily deposits on the #3 and #5 spark plugs seemed to confirm that theory.

Mark flew his airplane to a well-known Cirrus Service Center for further evaluation. The shop’s Director of Maintenance (DOM)—I’ll call him Steve—told Mark that he’d do a thorough borescope examination of the cylinders once the engine had cooled, and report back on what he found.

Bad news

Photo from A&P

This low-resolution photo from the A&P wasn’t adequate to determine the condition of the cam.

The next day, Mark received an ominous voicemail from Steve that started off with the words “Bad news…” and went on to say that the engine had “metal contamination” and “spalled cam lobes and lifters.” Mark also received a couple of low-resolution photos from Steve showing the SR22’s engine with the #3 and #5 cylinders removed, together with a statement that “the engine needs to be torn down.”

Needless to say, Mark was shocked. He had not given the shop permission to remove any cylinders. He’d only authorized a borescope inspection. Furthermore, the metal contamination diagnosis made no sense to Mark, because shortly before he took his plane to the shop, he’d performed an oil change and cut open the oil filter and found it clean as a whistle. Something wasn’t adding up. Mark bit his tongue and replied to Steve’s email by asking where the shop proposed to send the engine for teardown, and indicating that Mark was going to investigate alternative engine shops.

At this point, Mark contacted me for advice, and emailed me the low-resolution photos he’d received from Steve. I looked at the photos and told Steve that I didn’t see anything obvious wrong with his cam lobes, but that the quality of the photos was just too poor for me to offer an opinion as to the condition of his cam. I referred Mark to Continental’s Service Information Directive SID05-1B that provided very specific inspection criteria for assessing the airworthiness of cams and lifters on Continental engines. In pertinent part, SID05-1B says:

dental pick“If the visual cam lobe inspection reveals the presence of indentations or crack-like features in the surface along the cam lobe apex, use a sharp pick or awl and lightly move its tip over the suspect surface area. If the suspect feature has any depth, the pick tip will repeatedly catch in the groove or pits. If the indentation or crack is determined to have depth, the cam must be examined by a [Continental Motors] service representative to determine any additional steps required. If the cam lobe inspection only reveals normal signatures and there is no positive indication of any distress depth, …no further action is required.”

After studying SID05-1B carefully, Mark drove to the Service Center armed with a camera, an inspection light and a sharp dental pick, determined to carry out his own SID05-1B cam inspection and satisfy himself whether the condition of his cam truly warranted an engine teardown. Upon arriving at the shop, he made a beeline for the maintenance hangar.

You did WHAT???

engine on pallet

Mark was totally unprepared for what he saw when he entered the hangar: His SR22 had no engine or propeller! As he approached the airplane, he discovered his engine sitting on a wooden pallet on the floor of the hangar. Apparently, the shop’s mechanics had removed it from the airplane without obtaining his authorization, asking for his permission, or even notifying him of what they intended to do. Mark was floored.

Cylinders #3 and #5 had been loosely reattached to the palleted engine in preparation for shipping it to the engine shop. Mark had one of the shop’s mechanics remove those cylinders so Mark could perform the cam inspection that he’d come there to do. He dutifully ran the sharp dental pick over the surfaces of all the exposed cam lobes (per SID05-1B) and could not find a single crack, pit, or other feature deep enough to catch the tip of the pick. Mark took a bunch of high-resolution photos of the cam lobes and sent them to me. They revealed only normal swirl wear patterns, with no evidence of significant distress.

Mark next asked for a sit-down meeting with both Steve and his boss (the shop’s owner). He gave them each a copy of Continental SID05-1B, walked them though the pertinent language, described how he’d probed the lobes with his sharp dental pick, showed them his high-resolution photos, and argued that Steve had simply been wrong in his assertion that the cam was spalled. He also pointed out that the shop had removed two cylinders without his authorization, and then removed the entire engine without his authorization. Mark insisted that the shop reinstall the cylinders on the engine and reinstall the engine in the airplane at the shop’s sole expense.

malpracticeThe shop owner was not amused. However, after considering the compelling evidence of Steve’s malpractice that Mark had presented, plus the complete lack of documentation showing that Mark had approved any of the disassembly that the shop had done, the owner appropriately concluded that he had little choice but to do the right thing. (I’d have loved to be a fly on the wall in that office after Mark left and the shop’s owner had his tête-à-tête with Steve.)

About a week later, Mark flew his airplane home from the shop, vowing never to return. On the flight home, he discovered the engine’s idle stop badly misadjusted and the propeller installed 180 degrees from the proper position. Rather than risk taking the airplane back to the Service Center, Mark decided to pay a local A&P to correct those two items.

Over the coming weeks, Mark discovered that his problem with excessive oil consumption had vanished. The shop installed new rings on the #3 and #5 pistons before reinstalling the cylinders, and apparently that cured the problem that had prompted this painful misadventure in the first place.

At least that was a pleasant surprise.

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

I Don’t Fly Enough

It’s not how much we fly that matters, it’s how much we don’t

The average owner-flown GA airplane flies less than 100 hours a year. I fly my Cessna 310 more than that, at least 120 hours a year. But I don’t fly it enough.

Take 2017 for example:

  • In April, I flew to San Diego to give a talk at a FAASTeam safety event.
  • I also made another flight to Camarillo to teach at the AOPA Regional Fly-In.
  • In June, I flew from California to Knoxville, Tennessee, to attend and speak to the annual convention of the Flying Physicians Association and visit friends.
  • Over the July 4th weekend, I made a quick trip to Los Angeles to attend a Pentatonix concert at the Hollywood Bowl.
  • In late July, I made my annual pilgrimage to Oshkosh for AirVenture week, roughly 2,000 nm each way.
  • In August, I was supposed to make a trip to Dallas for an expert witness deposition in an air crash case, but it was cancelled at the last minute when the case settled.
Mike's 2017 trip

My 8,500 nm trip during Fall 2017.

Then in September and October, I went on an amazing nine-week transcontinental trip that took me from California to:

  • Norman, Oklahoma for the next AOPA Regional Fly-In;
  • Lawrence, Massachusetts for a two-day GA Engine Summit meeting with the FAA;
  • Nashville, Tennessee to speak at the Cirrus Owners and Pilots Association annual migration
  • Jackson, Tennessee where I performed an annual inspection on the aircraft at the facilities of Tennessee Aircraft Services;
  • Back to New England to visit my sisters in Boston and teach at the AOPA Regional Fly-In at Groton, Connecticut;
  • Outer Banks of North Carolina for some quiet time to work on my book and write some articles;
  • Raleigh and Charlotte to visit with friends and relatives, and to fly with another CFI to obtain my Flight Review and Instrument Proficiency Check;
  • Florida to visit with friends in Ft. Lauderdale and teach at the year’s final AOPA Regional Fly-In in Tampa;
  • Charlotte, North Carolina to pick up my brother-in-law;
  • Jackson, Tennessee to drop of my colleague Paul New who’d taught with me in Tampa;
  • Amarillo, Texas for fuel and sleep; and finally
  • California to drop my brother-in-law at Chino, then have lunch with a friend at Hawthorne, and finally return to home base at Santa Maria.

In early November, less than a week after returning home from this amazing 8,500 nm trip, I flew to Las Vegas, Nevada for my company’s annual corporate retreat…my final flight of 2017 in the Cessna 310.

I didn’t fly enough

Months I didn't fly

Months I didn’t fly my airplane during 2017.

If you were paying attention, you’ll see the problem: I didn’t fly the plane at all during January, February, March, May, August, or December. The airplane just sat in its non-climate-controlled hangar located at KSMX roughly 8 miles from the Pacific Ocean.

During those periods of extended disuse, the oil film had plenty of time to strip off the cylinder walls, cam lobes, and lifter faces of the two Continental TSIO-520-BB engines, exposing them to corrosive attack. The interior of the Cessna 310’s airframe—which is mostly shiny aluminum with no protective primer or paint—was also so exposed. This is not a good thing for the longevity of my airframe and especially my engines.

I suspect my pattern of seasonal use is not uncommon. I suspect many GA airplanes based on less benign and temperate climates than what I have on the central coast of California might fly even more seasonally. Certainly, airplanes based in humid coastal regions like Florida and the Gulf Coast are at even higher corrosion risk during their downtime periods.

This problem is more serious than many aircraft owners realize. The #1 reason that piston aircraft engines fail to make TBO is cam and lifter corrosion, the presence of which almost always results to a premature engine teardown.

This is a problem that’s almost exclusively confined to owner-flown GA airplanes. “Working airplanes” in flight schools, air charter, freight hauling, pipeline patrol, aerial surveillance, and similar kinds of operations almost never fail to reach engine TBO and often greatly exceed it. That’s because working airplanes fly every day or at least a few times a week, so they never lose the protective oil film that protects critical engine components from corrosive attack.


Suit of armorRecognizing the risk created by my irregular pattern of flying, I’ve taken a few defensive steps to help mitigate the corrosion risk. I use a thick singe-weight oil (Aeroshell W100) that has the consistency of black strap molasses at room temperature and adheres to parts better than multigrade oils that are much thinner at room temperature (think Aunt Jemima Light). I use ASL CamGuard, which is the most effective anti-corrosion additive I’ve found (based on oil analysis results). In 2014, I installed nickel-carbide-plated cylinders on both engines, because they don’t rust like standard steel cylinders do. I keep my airplane hangared during periods of disuse. I fog the interior of the airframe with ACF-50 corrosion preventive compound every few years.

There are additional defenses I could take. A good one that is inexpensive would be to use an engine dehumidifier during periods of disuse, such as the “Engine Saver” available from Aircraft Spruce. Another one that is vastly more expensive would be to insulate and heat my hangar to hold the atmospheric temperature constant and eliminate the diurnal temperature cycle that is responsible for “morning dew.”

All these things are helpful in mitigating the corrosion risk, but none are as effective as flying the airplane every week or two. So, my New Year’s resolution is to try my best to fly at least once every two weeks during 2018.

Care to join me?

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

‘They all do that’

Years ago, I used to travel throughout the country putting on technical seminars for the Cessna Pilots Association. Whenever we got to the segment about landing gear, we made a point of asking the 20 or 30 assembled Cessna owners attending the 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.

Shimmy normal?

Cessna nose wheel

Cessna nose wheel shimmy is very common, but it can be corrected and shouldn’t be accepted as normal.

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:

  • worn torque link bushings,
  • an out-of-round or out-of-balance tire,
  • elongated holes in the shimmy dampener linkage, or
  • 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).

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

Exhaust leaks normal?

An owner of 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 exhaust stains

These brown exhaust stains on the top cowling of a Cessna turbo 310 are NOT normal!

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 online to a twin Cessna message board. I saw his post there, and asked him if he would take some digital photos of the brown stains and upload them to the forum so I and others could take a look at them.

The next day, the owner posted some photos of the brown stains on the forum. 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 significant 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

These white stains on the firewall and turbocharger heat shield are indicative of a significant exhaust leak.

“When it comes to the exhaust system of a turbocharged engine, 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 exhaust failures in twin Cessnas, and the FAA very nearly wound up grounding the whole fleet. Since 1999 there have been very few twin Cessna exhaust accidents, due in large part to AD 2001-01-16 that mandates exhaust inspections and pressure checks for these airplanes. I’d sure hate to see you blemish that record!”

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 on the  forum. “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!

But after reading the owner’s most recent posting, 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’.”

Torque wrench

When securing exhaust V-band clamps, the use of a torque wrench is absolutely essential.

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 plane 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.

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.


Something unusual happened while I was at the AOPA Regional Fly-In in Groton, Connecticut: An air crash lawsuit at which I was scheduled to testify as an expert witness had settled on the eve of trial, leaving me unexpectedly with two unencumbered weeks on my hands. I was on the East Coast with my airplane and now could spend those two weeks however I pleased. For someone who hadn’t taken a vacation in years, this was cool!

Wright Brothers National Memorial

Wright Brothers National Memorial — Kill Devil Hills, NC

I decided to spend the first week exploring the Outer Banks of North Carolina, and the second week visiting friends in Raleigh and family in Charlotte. I also made arrangements with a flight school in Raleigh to get a much-needed Flight Review and Instrument Proficiency Check.

The two-hour flight from Groton to the Outer Banks was uneventful, and the last part of it was beautifully scenic. I spent the week in a small waterfront Airbnb with a balcony overlooking the Albermarle Sound, a few miles south of Kill Devil Hills where Orville and Wilbur first flew in 1903. It was a marvelously enjoyable, productive, restorative week.

Early Sunday morning, I checked out of my Airbnb and drove my rental car back to the airport to fly to Raleigh. I turned in my rental car, taxied my plane to the departure end of the runway of the small untowered airport, picked up my IFR clearance from Cherry Point Approach Control, and performed the usual preflight runup.

Like most piston twins, my Cessna 310 has four magnetos—two for the left engine and two for the right—controlled by four toggle switches. The preflight runup involves turning the mag switches off one at a time and checking for excessive RPM drop, unacceptable roughness, or abnormal EGT indications. My routine is to sequence through the switches from left to right, shutting off the left engine’s left mag first and the right engine’s right mag last. I’ve done this thousands of times in the 30 years I’ve owned this airplane, and I must confess I perform it somewhat robotically. This time, things were different.

Uh oh!

S-1200 magneto

Bendix S-1200 magneto

As I cycle the leftmost mag switch, the left engine quits cold. Yikes! I hastily flip the mag switch back on just in the nick of time to get it running again. I cycle through the remaining three mag switches and everything appears normal. I try the leftmost switch again. The left engine quit again.

Hmmm… Turning off the left mag kills the left engine. That means the right mag must not be producing any spark. Not good.

I briefly consider departing anyway—that’s why this airplane has two mags and two engines, right?—and instantly reject that idea. A wise aviation mentor once taught me that when making aeronautical decisions, I should always think about what the NTSB probable cause report would say. “PIC departed into instrument meteorological conditions with a known mechanical deficiency.” No way.

While taxiing back to the airport ramp, I think about the consequences of scrubbing the mission. It’s Sunday. I could order a replacement magneto first thing Monday morning. If I pay for overnight shipping, the mag might arrive by mid-day Tuesday, and the airplane might be back in the air by late Tuesday afternoon. I’ll have to cancel my Tuesday training appointment in Raleigh. I’ll need to find lodging and ground transportation for two more days on the Outer Banks. There’s a rental car waiting for me in Raleigh that’s probably too late to cancel…

Wait…I’m an A&P mechanic and my emergency toolkit is in the airplane’s wing locker. Maybe I can troubleshoot this mag problem and figure out a way to fix it. Maybe it’s something simple that doesn’t require ordering a replacement mag. Maybe I can improvise some battlefield repair…

I’m grasping at straws now, and realize the chances are somewhere between slim and none. But I’ve got to give it a shot, otherwise my plans for the coming week will fall like a row of dominoes.

An Open Door…

Open hangar door

Open hangar door, toolbox inside

Approaching the transient tiedown ramp, I notice a large hangar off to my right with the door wide open. I can’t believe my luck: Someone’s open on Sunday! Maybe I can get some help? I taxi toward the open hangar and shut down on the ramp in front of it. The huge hangar appears largely empty. I don’t see any people or airplanes inside, just a big red roll-around toolbox and some miscellaneous ground support equipment. A beautiful Waco open-cockpit biplane is parked on the ramp nearby.

I uncowl the left engine nacelle to inspect the right magneto and its associated wiring, but find no obvious defects. I disconnect the P-lead from the right mag, but that doesn’t fix the problem, so the problem must be inside the magneto itself. Ugh!

I walk towards the open hangar door. As I get closer, I spot a fellow puttering around deep in the bowels of the hangar. I walk over to him and muster up my most friendly smile.

“Good morning! I’m Mike, and that’s my Cessna 310,” I say, pointing at my airplane on the ramp.

“Good morning,” replied the fellow with a smile, “I’m Sam.”

“Nice to meet you, Sam,” I said. “I’ve got a problem and I’m hoping maybe you can help me.”

I proceeded to describe my plans to fly to Raleigh and my decision to scrub the takeoff because the right mag on the left engine was inoperative during my preflight runup.

“The mag completely dead?” Sam asked. “Not just fouled plugs?”

“Dead as a doornail,” I said.

“That doesn’t sound good,” Sam said as I nodded in agreement.

“Would it be possible for me to pull the plane into your hangar, so I can work on the problem?” I inquired, gesturing at the huge, vacant structure.

“Nope,” Sam replied curtly. That wasn’t the answer I was expecting, but Sam was still smiling, so I persisted.

“Any chance I could use this toolbox,” I pointed at the big red roll-around, “while I’m working on my airplane on the ramp?”

“Nope, I can’t let you do that,” Sam said, still smiling. My puzzlement continued to grow at Sam’s unexpected non-cooperation. Then I had a thought.

“Sam, are you an A&P?” He nodded in the affirmative. “Would YOU like to try troubleshooting my magneto problem?” It occurred to me perhaps he was viewing me as competition.

“Nope, I don’t have time for that. Gotta take some tourists up for a biplane ride,” Sam said. “Besides, I don’t work on magnetos; I always send them out.”  Sigh.

Ultimately, I managed to persuade Sam to lend me a ½-inch offset wrench and a small stepladder. With those and my emergency toolkit, I was able to remove the ailing magneto from the engine, disassemble it, resolve the problem, and put everything back together. Ultimately, I departed on my flight to Raleigh a few hours late, but my plans for the week remained unscathed.


Over the next few days, my mind kept returning to interaction with Sam. He seemed like such a nice fellow. Why did he act toward me in such an uncooperative fashion? What would it have cost him to let me use his empty hangar and his unused toolbox while he was up flying the Waco?

Liticaphobia means fear of being sued

The only answer I could come up with was liticaphobia: the fear of being sued. Sam undoubtedly saw me as a lawsuit waiting to happen. There’s an old joke among aircraft mechanics that the most dangerous thing in aviation is an aircraft owner with a toolbox. I’m sure that in Sam’s mind, if he facilitated my hairbrained scheme of taking a magneto apart (something he stated he’d never do himself) and then anything bad happened, he would be contributorily negligent and vulnerable to civil litigation.

Sam is not alone. In my experience, most aircraft mechanics who work on GA aircraft have a siege mentality about the possibility of being sued. This fear casts a shadow over every decision they make. It causes them to practice “defensive maintenance”—performing more maintenance than justified on the grounds of safety-of-flight—and to be secretive about errors they make for fear that disclosure might lead to litigation.

Twenty-five years ago, before I became an A&P myself, I had an eerily similar experience at an airport in Northern California. I’d flown there for a business meeting, and when I returned to the airport dressed in coat and tie, I discovered to my horror that my right main tank had been misfueled with Jet A instead of 100LL. The fueling company had no A&Ps on staff, so I started contacting the various maintenance shops on the field looking for someone who would help me get my fuel system purged. Not one was willing to touch my airplane for fear of liability. Finally, I succeeded in persuading one A&P to agree to help me if I signed a blanket waiver agreeing to hold him harmless for anything that might go wrong. This mechanic then wanted to disassemble all sorts of stuff on my airplane that didn’t need to be disassembled in order to purge the system. Ultimately, I was successful in getting my airplane flyable again, but not without a terrible struggle.


These days, I do a good deal of expert witness work in air crash lawsuits, generally on the defense side defending mechanics, shops and aviation manufacturers against claims by air crash victims. I can testify firsthand that aviation is a horribly litigious field, with way too many lawsuits for my taste.


Mechanics’ fear of being sued tends to be greatly overblown.

At the same time, I can also tell you that mechanics’ fear of being sued tends to be greatly overblown. Mechanics are rarely the target of air crash lawsuits, simply because few of them are high-net-worth individuals with enough assets to be worth suing. In the relatively few cases where mechanics and shops do get sued, these suits virtually always settle quickly within the limits of their liability insurance (typically $1 million), simply because the plaintiff lawyers understand that there’s no more money to be had. That’s why these lawsuits almost always target aircraft, engine, and component manufacturers who tend to have deeper pockets.

This paranoia about being sued is not limited to aviation. Doctors have been practicing “defensive medicine” for decades, especially those in high-risk specialties like ob/gyn and anesthesiology. Teachers have become frightened to discipline unruly kids or even give them hugs, while seesaws are disappearing from schoolyards for fear a kid might get injured. Have you purchased a ladder or bicycle or baby carriage lately and seen how many warning placards they now have? The fear level is getting ridiculous.

The incidence of US civil (tort) litigation has remained essentially flat per capita since 1975, but media coverage of litigation has skyrocketed, and that coverage is overwhelmingly skewed toward reporting cases involving huge damage awards. This has created the perception that the risk of being sued is much greater than it used to be, and that the consequences are frequently ruinous for the defendant. That’s seldom the case.

Look at the facts: According to a Harvard University study, for every 100 people hurt in an accident, 10 file a liability claim, 8 are settled within insurance limits, and only 2 actually get to court. Of those that make it to court, the plaintiff wins only 30% of the time, and in those cases the median damage award is $30,000, almost always covered by insurance.

So my appeal to shops and A&P mechanics is to maintain a reasonable amount of liability insurance ($1 million is generally adequate) and then do the right thing without paranoia about being sued if something goes wrong. Enough with the CYA already!

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

Unobtanium and Unaffordium

un·ob·tain·i·um (ˌənəbˈtānēəm)—noun informal—a highly desirable material that is hypothetical, scientifically impossible, extremely rare, costly, or fictional, or has some of these properties in combination.

My 1979 Cessna T310R

My 1979 Cessna T310R

As I write this, I’m just in the final throes of completing the annual inspection on my Cessna Turbo 310. Usually I do this myself, and it takes me three or four weeks; that’s because my turbocharged piston twin has way too many moving parts, and because I’m the world’s slowest aircraft mechanic. This year, my travel schedule didn’t permit that much downtime, so I decided to do the annual at a maintenance shop owned by a colleague, and to enlist the help of a couple of his staff A&Ps to help with the opening, closing, repairs and preventive maintenance in order get everything done in just over one week. I performed and signed off the actual “inspection part of the inspection” myself.

Hartzell/C&D cabin heater

Hartzell/C&D cabin heater

I knew going in that this was going to be a costly ordeal. I got off easy during my 2015 and 2016 annuals, but the law of large numbers caught up with me this year. To begin with, the old Southwind (Stewart Warner) combustion cabin heater got hit with a costly AD that would have required me to spend more than $3,000 overhauling the heater, and thereafter to perform frequent pressure-decay tests. I’ve hated this heater for the 30 years I’ve owned this plane. It has always been a problem child, caused me lots of grief, and I just couldn’t see shoveling more money into it. So I ordered a brand new, far superior heater designed by C&D Associates (and now manufactured by Hartzell Engine Technologies). The new heater cost $6,000 (ouch!) but will hopefully be trouble-free and AD-free going forward.

Installation of the new heater turned out to be a lot quicker and easier than I expected. Other things didn’t.

Prop Sync

One item on my squawk sheet was that the propeller synchrophaser was inoperative. I’d done sufficient troubleshooting to determine that the sensors and servo were okay, and that the problem was in the ARC SP105-B control box. I called Cessna, and was told that all rights to ARC equipment (including my control box) had been acquired by Sigma-Tek. I contacted Sigma-Tek and learned that they had no replacement boxes and no bench repair capabilities, but would sell me a maintenance manual for the SP105-B for $400.

ARC SP105-B Prop Synchrophaser

ARC SP105-B Prop Synchrophaser

I contacted every major avionics shop I could think of with bench repair capabilities, and all responded with some variant of “we used to work on those back in the day, but we no longer have that capability.” Finally, I did an exhaustive search of salvage yards to see if I could find a serviceable SP105-B control box. My search led me to Preferred Airparts in Kidron, Ohio (the largest dismantler of twin Cessnas), who said they had 40 inoperative SP105-Bs in inventory, plus one that was in “as removed” condition and “probably” was in working condition.

I purchased that one for $500 and installed it in my airplane. When I powered it up, the prop sync annunciator illuminated and the slave governor servo centered, which was encouraging. But when I test flew the airplane, I found that turning on the prop sync switch yielded a rapidly flashing annunciator (meaning the control box was not happy about something) and no prop synchronization function. Drat! My next step is to create a test harness so I can measure the sensor pulses going into the prop sync box and its output voltages to the servo motor while airborne and try to figure out what’s going on.

Positronic GM-Series Connector

Positronic GM-Series Connector

To create that test harness, I’ll need a pair of connectors (one male and one female). After an hour of Googling, I determined that the connectors in question are Positronic GM26s. I couldn’t find these connectors listed in the catalogues of any of the electronics supply houses I usually rely upon (Newark, Mouser, Digikey), so I contacted Positronic and learned that the only place that has these connectors in stock is in Puerto Rico and was rendered incommunicado by Hurricane Maria. It may be weeks before I know whether the connectors I need are obtainable. Sadly, I placarded my prop sync “inoperative” and pulled the circuit breaker per FAR 91.213(d). The prop sync saga will continue.

Flap Preselect Cable

One of the items on my inspection checklist for this year was to check all the flight control cable tensions. I was particularly interested in checking the tension on the flap retract cables, because the maintenance manual calls for those to be tensioned to 280±20 pounds. Normal cable tensiometers used in piston GA maintenance only measure up to a maximum of 100 pounds, so my flap retract cable tension hadn’t been checked for years. My colleague said he had a high-range tensiometer that measured up to 300 pounds, so we pressed that into service. As I suspected, the flap retract cable tensions were low (about 225 pounds). That meant that during a high-speed descent, the flaps might not stay fully retracted.

Broken Flap Preselect Cable

Broken Flap Preselect Cable

One of the A&Ps who was assisting me volunteered to adjust the flap retract cables, and I gratefully accepted his offer. That turned out to be a mistake. After the A&P adjusted the turnbuckles to the specified tension, he performed a functional check and found, to his horror, that the flaps would not retract. Further investigation revealed that the flap preselect cable (which runs from the flap actuator under the floorboards to the flap preselect control on the instrument panel) was now severely kinked to the point of being unrepairable. This was clearly a MIF—a “maintenance-induced foul-up”—that had turned a minor issue (low cable tension) into a major one (inoperative flaps).

We checked Cessna’s parts inventory for a replacement flap preselect cable. I expected it to be “unaffordium” but found instead that it was “unobtanium”—Textron Aviation no longer had any, and didn’t plan to make any more, ever. A Google search of the part number uncovered a used-but-serviceable one at B.A.S. Parts & Sales LLC in Greely, Colorado. We ordered it and asked for expedited shipping. Installing the new cable and rigging the flap preselect control wound up being a full-day affair.

More Ouch

Tire and Tube

Tire and Tube

My inspection revealed more costly stuff that needed to be done. Two new main landing gear tires and tubes ($700), two new brake discs ($350), 12 new brake linings ($150), and a bunch of miscellany brought the tab for this year’s “annual ordeal” to nearly $15,000—and that doesn’t include my sweat equity. Aircraft ownership isn’t for sissies…and that goes double for twins. But I do have a feeling of accomplishment that a lot of important stuff got done this time around. With luck, the next year or two will be smooth sailing…

…except for the $6,000 I will soon need to spend installing ADS-B-out…sigh.

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

The Shameful Lycoming Rod Bushing AD Affair

In late July, as tens of thousands of GA aircraft owners were converging on Oshkosh for AirVenture 2017, Lycoming published Mandatory Service Bulletin 632 titled “Identification of Connecting Rods with Non-Conforming Small End Bushings.” This was a very nasty service bulletin affecting Lycoming engines of all models that were built, rebuilt, overhauled or repaired during the past two years. Lycoming quickly published two revisions (632A and 632B) in rapid succession.

SB 632B addressed a problem with small-end connecting rod bushings (part number LW-13923) that were used in Lycoming factory new and rebuilt engines and shipped by Lycoming to overhaul shops and mechanics between November 2015 and November 2016. It turns out that there was a quality assurance problem with these bushings, and many of them had an outside diameter that did not conform with specifications. These bushings are pressed into the small end of Lycoming connecting rod assemblies using a hydraulic press. If the bushings are too small in diameter, the press-fit isn’t secure and the bushings can migrate out of the connecting rod when in service. That’s exactly what seems to have happened to a relatively small percentage of these non-conforming bushings, hence the mandatory service bulletin.

Lycoming Rod Bushings: Good vs Bad

Lycoming rod bushings.

Lycoming used these bushings in-house to build connecting rod assemblies, some of which were sold to overhaul shops and mechanics between November 2015 and February 2017, and most of which went into Lycoming factory new and rebuilt engines. Any engine that has these non-conforming bushings, whether built by the factory or overhauled or repaired in the field, are affected by SB 632B.

Why is SB 632B so nasty?

SB 632B requires that all engines that might possibly contain these non-conforming bushings have all their cylinders removed within the next 10 hours. With the cylinders removed, the securing of all small-end connecting rod bushings then must be tested using a special tool (“ST-531 Connecting Rod Bushing Press-Out Verification Tool”) to apply a calibrated force to each bushing to see if it can be displaced. If the bushing moves during this press-out test, then the connecting rod assembly must be removed from the engine and sent to Lycoming, and a new connecting rod assembly with a known-good bushing must be installed. Lycoming initially estimated that the press-out test will have approximately a 20% flunk rate, but from what we’ve been hearing that estimate may turn out to be way too optimistic.

Lycoming ST-531 Connecting Rod Bushing Press-Out Verification Tool

Lycoming ST-531 Connecting Rod Bushing Press-Out Verification Tool

As someone deeply involved in piston GA maintenance, I find what SB 632B requires to be a horrifying prospect. The requirement to remove all cylinders within 10 hours is bad enough; there is a long history of catastrophic engine failure after removal and replacement of all cylinders in the field that I’ve written about extensively. But the prospect of having 20% or 30% or 40% of the connecting rods removed and replaced in the field represents a far greater risk, because the majority of mechanics have never before performed this operation (notably tightening rod bolts to a specified stretch using a special micrometer). The rod bolts are the most highly-stressed component in the entire engine, and tightening them properly is ultra-critical. In my opinion and the opinion of every highly experienced A&P/IA I’ve spoken with, this is NOT work that should be attempted by line mechanics in the field working on engines mounted in airplanes. It really should be done only by an experienced technician in an engine shop with the engine mounted on a stand with unencumbered access.

In short, I quickly concluded that that the cure called for by Lycoming would very likely be worse than the disease, and that it’s likely that there may be more catastrophic engine failures caused by maintenance errors in performing SB 632B than would be caused by the migrating bushing problem that SB 632B addresses. After conferring with a few very experienced A&P/IAs who have much more experience maintaining Lycoming engines than I do, I also concluded that there is a far less invasive and risky and expensive method that would effectively detect bushing migration and mitigate the safety risk without creating a bigger one in the process.

Owner organizations respond

While in Oshkosh, I spoke to several Lycoming executives who indicated that they expected the FAA’s New York Aircraft Certification Office (ACO) to start the wheels in motion to issue an emergency Airworthiness Directive the following week that would mandate compliance with SB 632B. I then sought out AOPA’s David Oord, with whom I’d recently worked so successfully on dealing with the Continental camshaft gear issue. Dave and I discussed that the FAA had not issued an Airworthiness Concern Sheet (ACS) about this Lycoming bushing issue in order to solicit input from the affected aircraft owner associations, something they had promised to do when we met with the FAA Engine and Propeller Directorate at a GA engine summit meeting in 2015. Dave and I agreed that it would be appropriate for AOPA to ask the FAA to do that so we would have a reasonable time to research this issue and provide the FAA with a thoughtful response before their AD process began, and Dave promised he’d make some calls as soon as he returned to his office.

On Tuesday, Dave phoned to tell me that that he’d heard back from the FAA, and that they said they would not be able to issue an ACS because they considered the issue too time-critical. Dave pressed for input to the process from the aircraft owner community, and the FAA agreed to try to set up a conference call between aircraft owner representatives, key FAA personnel, and representatives of Lycoming. That sounded better than nothing.

The next morning, I was awakened by another phone call from Dave, who told me that the FAA was willing to do a conference call, but it had to be TODAY. Yikes! We identified several other qualified aircraft owner representatives to be on the call to represent Cessna and Piper owners, and all agreed to participate.

The call was scheduled for 3 pm Eastern. I spent two hours drafting a bullet-point document containing our questions, concerns, and proposed alternative solution to SB 632B, and emailed it to Dave, who sent it to all the participants expected to be on the call from the FAA, Lycoming, and the owner associations.


The conference call took place as scheduled and lasted for an hour. However, Lycoming declined to answer ANY of the questions we posed to them, telling us that the information was proprietary and Lycoming was sharing it solely with the FAA and no one else.

Lycoming would not tell us how many displaced bushings have been found, how many connecting rod failures had occurred due to bushing displacement, what the distribution of engine times was when bushing displacement was detected or connecting rod failure occurred. They would not tell us how many engines they expected to be affected. They would not even tell us how much the special ST-531 press-out tool would cost, or how soon they could get enough of these tools out in the field to perform the required test.

The FAA would not tell us, either, saying that they were not permitted to release any of this information without Lycoming’s permission (which clearly was not forthcoming). We spent the better part of an hour asking questions but got no answers. It was absolutely exasperating.

We spent the rest of the time on the call trying to convince Lycoming and the FAA that there was a far less invasive and risky and costly way to deal with the displaced bushing problem, and we described it to them in detail. But it became clear that Lycoming and the FAA had already decided that SB 632B was necessary, despite the maintenance-induced failure risk, and that they were not interested in considering any alternatives.

As the call concluded, I felt totally disgusted with the total lack of cooperation exhibited by Lycoming and the FAA. I have been involved in working with the FAA on numerous Airworthiness Directives during the past two decades, and this was unquestionably the most unreasonable performance I’ve seen.

Shameful and disturbing

On Thursday, we worked with Dave to create a formal joint letter to the head of the FAA’s New York ACO. In it, we expressed our disappointment in how the FAA seemed to be dealing with this issue, and included the bullet-point document I’d created outlining our questions, concerns, and recommended alternative to SB 632B. In the letter, we specifically asked the FAA to approve our proposed minimally-invasive alternative as an Alternate Means of Compliance (AMOC) as outlined at the end of the document.

Needless to say, the New York ACO convened a Corrective Action Review Board (CARB) that rubber-stamped Lycoming’s requested corrective action in record-breaking time. On August 9, the FAA issued AD 2017-16-11 mandating compliance with SB 632B and putting numerous Lycoming-powered GA aircraft on the ground and their owners in jeopardy both moneywise and (IMHO) safetywise.

I find this whole sorry episode very disturbing for several reasons.

In discussing this situation with companies like Rick Romans and Aircraft Specialties Services and Zephyr Aircraft Engines who are in the business of re-bushing Lycoming connecting rods in the field, it appears that the problem with these loose Lycoming connecting rod bushings has been well-known by industry insiders for more than a year. Several of those firms told me that they stopped installing Lycoming-supplied rod bushings many months ago in favor of PMA-equivalent bushings from Superior Air Parts that fit properly. Given that this problem has been known for quite some time, it seems to me that the FAA could and should have taken a bit more time to solicit and consider input from folks who would be most affected, especially alternative methods of addressing the problem in a less risky fashion, before publishing an emergency AD.

Furthermore, I find it unconscionable for the FAA to justify such a draconian rulemaking action on data that it refuses to disclose to the very people who will bear the burden of that rulemaking. I understand that if a manufacturer provides information to the FAA that the manufacturer identifies as proprietary, the FAA is not permitted to disclose it. But it seems to me that the FAA should be forbidden from using such proprietary data to justify issuing an AD. The federal Administrative Procedure Act (APA) guarantees that members of the public who will be affected by federal rulemaking shall have a say in the rulemaking process. I’m not a lawyer, but clearly rulemaking made in the kind of secret “star chamber” fashion that characterized AD 2017-16-11 makes a mockery of the spirit (and perhaps the letter) of the APA.

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

Wonderful news for Continental 520/550 owners!

Mandatory Service Bulletin MSB05-8B (camshaft gear) downgraded to non-mandatory. FAA will not issue AD.

In April, my blog post “Continental’s War on Camshaft Gears” I wrote about Continental Motors’ issuance of Mandatory Service Bulletin MSB05-8B intended to compel owners of Continental 520- and 550-series engines (and a few IO-470s) to preemptively replace the older-style camshaft gears with a newer-style gear that is .060” thicker (about the thickness of a penny).

MSB05-8B would have mandated that engines with the older-style gear would need to be disassembled and the new-style gear installed “within 100-hours of operation, at the next engine overhaul (not to exceed 12 years engine time in service), or whenever camshaft gear is accessible, whichever occurs first.” This would have meant that many thousands of low-time-since-overhaul engines would need to be torn down within 100 hours, and that any engine overhauled more than 12 years ago would need to be torn down before further flight.

Owners push back

When MSB05-8B hit the streets, aviation type club forums were awash with cries of disbelief, expletives, and demands for class-action lawsuits—both against Continental Motors and against the overhaul shops that elected to overhaul engines without installing the new-style camshaft gears. The uncertainty also took its toll on the resale market for Continental-powered aircraft.

My company Savvy Aviation joined a group of stakeholder representatives including AOPA, American Bonanza Society, Cirrus Owners and Pilots Association, and Twin Cessna Flyer. Our group prepared a 10-page response to the FAA on this subject that was submitted to the FAA Engine & Propeller Directorate and to the Atlanta Aircraft Certification Office on May 1. We argued forcefully that the extremely low crankshaft gear failure rate did not rise to the level of “an unsafe condition” required to justify the issuance of an AD.

May and June passed with no word from Continental. Then in early July, AOPA’s Dave Oord emailed the members of our group to say that Continental was about to issue the long-awaited revised MSB and had asked to discuss it with us prior to publication. We were surprised and delighted that Continental was reaching out to us, and agreed to an electronic meeting on July 13th.

Can we talk?

Continental told us that they were planning to release a new MSB05-8C the next day, calling for repetitive visual inspections of older-style camshaft gears at every annual or 100-hour inspection (whichever was applicable to the aircraft), with gear replacement mandated at the next overhaul or case-splitting event. We learned that the FAA and Continental had uncovered only seven documented camshaft gear failures from 1964 to the present, the majority of which were unrelated to any in-flight engine anomalies. We also learned that an estimated 26,000 engines would be affected by the MSB.

Alarmingly, this was issued as a Mandatory Service Bulletin (MSB), which Continental defines as one that “has been incorporated in whole or in part into an Airworthiness Directive (AD) issued by the FAA or have been issued at the direction of the FAA by the manufacturer requiring compliance with an already-issued AD.” It was conspicuously NOT issued as a Critical Service Bulletin (CSB), which Continental defines to be a “candidate for incorporation into an FAA Airworthiness Directive.”

We made a strong appeal for Continental to issue its revision as a CSB rather than an MSB, given that the FAA had not yet decided whether an AD was warranted. We also urged the FAA to think carefully about whether such a tiny number of gear failures over such a long time period (most of which had no safety consequences) really rose to the level of “an unsafe condition” under the FAA’s guidelines for when an AD should be issued. We further argued that the repetitive inspections Continental was proposing would be staggeringly costly to owners and would not prevent a single engine failure.

To put all this in perspective, there has been only ONE in-flight camshaft gear failure in the past 53 years, and that one resulted in an uneventful on-airport forced landing. This makes the camshaft gear arguably the most reliable and least failure-prone component of the engine.

Wonderful news!

The next day, July 14th, each of us individually received a call from Continental Vice President Emmanuel Davidson, who gave us wonderful news: After carefully considering our comments and conducting further discussions with the FAA, Continental had decided to issue its revision as a non-mandatory CSB, and the FAA had decided that no AD was warranted at this time.

This was a marvelous outcome for owners of Continental-powered aircraft, and it was achieved through the most constructive and cooperative interaction I’ve ever seen between owners, a manufacturer, and the FAA (and I’ve been doing this for a long time). I sincerely hope this will become a model for how such situations are dealt with going forward. Kudos to Continental and the FAA for listening with open minds, and ultimately doing the right thing.

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

It’s Different For Cars

The owner of the late-model Cessna T206 Turbo Stationair was livid.

Takata Airbag

Takata Airbag

“Imagine your car is equipped with a Takata airbag system whose faulty inflators often rupture and spray shrapnel into drivers and passengers, resulting in at least 11 deaths in the U.S. and hundreds of injuries,” his email to me began. “But instead of being recalled by the manufacturer, you were instructed by the government that to continue driving your car legally, you were required to take it to a mechanic every 500 miles for a costly inspection at your expense. If your airbag system didn’t pass the inspection, you would be required to pay about $1,200 for a new airbag inflator, again at your expense.”

The Stationair owner was reacting to a just-issued Airworthiness Directive against the exhaust system of his Lycoming TIO-540-AJ1A engine. There are 758 of these engines currently in service. AD 2017-11-10 was apparently prompted by reports of exhaust leaks that could result in excessive carbon monoxide (CO) getting into the cabin. Some of these leaks were caused by cylinder exhaust port studs coming loose, while others were caused by cracked exhaust pipe weld joints.

Lycoming TIO-540-AJ1A

Lycoming TIO-540-AJ1A

The AD requires an initial exhaust system inspection and fastener torque check within 10 hours, and then repetitive exhaust system inspections every 25 hours and torque checks every 100 hours. The FAA estimated the cost of compliance to be $85 (one hour of labor) per required inspection, but that doesn’t take into account the burden on the owner of having to take his airplane to an A&P mechanic every 25 hours (which is half the normal oil-change interval).

Lycoming issued a service bulletin which allowed the repetitive inspection interval to be extended from 25 to 50 hours if the aircraft was equipped with a carbon monoxide detector, but inexplicably the AD does not include this provision. Lycoming presently doesn’t have a fix for this problem (although they claim they’re working on one), so there’s no way of knowing how long the owners of the 758 affected Lycoming TIO-540-AJ1A engines will be required to do these 25-hour exhaust inspections.

“Why do aircraft owners put up with this?” the Stationair owner continued. “For decades, Cessna and Lycoming have been building the same product, and they still can’t get it right. Why? Because they have no incentive to do so. If they make a design or manufacturing mistake, they just pass the costs on to their customers. Nice scam.”

I felt the owner’s pain. I fly a Cessna 310 with a cabin heater made by Stewart-Warner (Southwind), and was just hit with an AD against my heater that will force me to replace it with a new AD-free heater at my upcoming annual in October, at a cost of $6,000 in parts and probably $2,000 in labor. And as I discussed in my last blog post, the FAA is threatening to issue an AD against the camshaft gears in my two Continental TSIO-520-BB engines (and tens of thousands of other engines) that could cost owners like me a bundle.

It’s gotten so bad that when a colleague of mine recently told me he was looking to buy an airplane and was thinking about an older Mooney, I suggested he look into buying an amateur-built experimental airplane instead in order to get out from under the AD burden that has been plaguing us owners of certified airplanes.

It’s different for cars

NHTSAThe Stationair owner was right to point out that the rules are very different for motorists than they are for aircraft owners. In 1966, Congress passed The National Traffic and Motor Vehicle Safety Act (49 USC 301) that gave the Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) the authority to issue vehicle safety standards and to require manufacturers to recall vehicles that have safety-related defects or do not meet Federal safety standards.

Effectively, these NHTSA motor vehicle recalls are the automotive equivalent of Airworthiness Directives. But there’s a big difference: In most cases, the auto manufacturers are required by law to bear the cost of fixing the vehicles. The burden usually doesn’t fall on the vehicle owners.

Why isn’t there a similar law for aircraft? I’m guessing that there are just not enough folks in Congress who care about aircraft owners to support such legislation. By contrast, every member of Congress is a motorist, so the laws are spring-loaded in favor of protecting motorists. But even if the laws protecting motorists were extended to aircraft owners, the lion’s share of the AD burden wouldn’t go away.

Recall NoticeWhy? Well, for one thing, 49 USC 301 requires automobile manufacturers to bear the expense of recalls only for vehicles that are less than 10 years old. While this covers most cars that are recalled, the overwhelming majority of today’s GA fleet consists of airplanes that are more than 10 years old, frequently much more.

The lion’s share of piston GA aircraft were built in the 1960s and 1970s, and then production all but stopped in the 1980s and never came close to recovering to the levels seen in the salad days of piston GA. (My 1979 Cessna 310 is 38 years old, and it’s a “recent model” as Cessna 310s go.) So for most GA airplanes, the manufacturer would be off the hook.

In addition, the law only requires the manufacturer to pay for repair of recalled vehicles if those repairs are performed by an authorized dealer of the manufacturer. Relatively few GA owners have their maintenance performed at authorized dealers, and many makes of GA aircraft no longer have dealers; indeed, many were manufactured by companies that aren’t in business anymore. In general, GA has a far less robust support system compared to automobiles.

Changes I’d really like to see

Bureau of Automotive RepairThe laws I’d most like to see extended to GA are the ones that deal with repair facilities. Automotive repair facilities are typically regulated by the states, not by the feds. Most states require automotive repair facilities to be licensed, and have lots of state laws protecting motorists from unscrupulous repair shops. In most cases, an automotive repair shop cannot work on your car until they’ve given you a written work order itemizing the work they will do and providing a cost estimate (including parts, labor, and outside work), and obtained your signature approving the work order and estimate. Then they are required not to charge you significantly more than the agreed-to estimate.

In the event that the shop runs into something that might result in exceeding the original estimate, they are required to stop work, furnish you with an explanation and a revised estimate, and secure your approval of the new estimate before they may continue. These rules ensure that there will never be any surprises when you receive the final invoice.

To comply with these rules, most auto repair shops use a flat-rate price list for all the most common maintenance tasks they perform. You’ll typically pay the same price for, say, an oil change or a brake job or a tire rotation regardless of how much time the technician spent doing the work.

By contrast, most maintenance work on airplanes is done on a time-and-materials basis, often with no paperwork until the job is done. Sticker shock is rampant as a result, because often the owner doesn’t have a clue what the work will cost until it’s done. This is a bad system, and often results in hard feelings and arguments when owners feel they’ve been charged too much.

I’d love to see the state laws that govern auto repair extended so that they cover aircraft maintenance shops as well, but I’m not holding my breath. Few state legislators give a fig about aircraft owners. In the meantime, it’s up to the owner to demand a written estimate before permitting any shop to work on their aircraft, and to hold the shop to that estimate unless there’s an awfully good reason that it was exceeded.


Not long after this blog post was published by AOPA, I received a phone call from Lycoming and learned that there is some good news and some light at the end of the tunnel for owners of TIO-540-AJ1A-powered Cessna T206s affected by AD 2017-11-10.

First, Lycoming requested and the FAA approved an Alternative Means of Compliance (AMOC) that extends the exhaust inspection interval from 25 hours to 50 hours for aircraft that are equipped with a suitably sensitive carbon monoxide (CO) detector. That will halve the inspection burden and promote CO detector installation, both of which are good things.

I also learned that Lycoming has redesigned the TIO-540-AJ1A exhaust system in order to provide a permanent solution to the problem and a terminating action for the AD. The new exhaust system will be made of 321 stainless steel, in contrast with the Inconel used in the current system. Inconel has outstanding high-temperature characteristics, but it is much more brittle and harder to work with than 321 stainless, and has a much less desirable failure mode. Lycoming concluded that the Inconel system was not sufficiently flexible to deal with the dimensional changes and thermal stresses that occur as the exhaust system heats up and cools down. Most other turbocharged Lycoming engines used a stainless steel exhaust system, and Lycoming believes the new system will prove much more durable and less failure-prone than the current one.

No word yet on when production quantities of the new exhaust parts will be available or what they will cost. But it does look like the repetitive inspections mandated by AD 2017-11-10 won’t have to go on forever. –MDB

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.

Continental’s War on Camshaft Gears

Correction: AOPA has corrected a statement regarding Continental’s mandatory service bulletin and FAA airworthiness directive activity. The FAA has confirmed that it has not received any communications from Continental seeking an airworthiness directive. AOPA regrets the error.

At the end of March 2017, Continental Motors issued Mandatory Service Bulletin MSB05-8B that would require tens of thousands of Continental IO-470/520/550 engines to be torn down prematurely to replace the camshaft gear with slightly thicker gear. It required compliance within the next 100 hours of operation, or at no more than 12 years since overhaul, whichever comes first.

The replacement camshaft gear is 0.06″ thicker, and costs$1,200. Removing and reinstalling the engine is typically a $5,000 job and the engine teardown typically costs around $10,000. So this would be a very big deal for affected owners. The number of affected owners is huge. Almost every Bonanza, Baron, Cessna 200/300/400, Cirrus SR22, and Continental-powered Mooney is targeted by this expensive MSB, plus a bunch of other makes and models.

Compliance with manufacturer’s service bulletins is not generally compulsory for Part 91 operators. The FAA would have to issue an Airworthiness Directive (AD) to compel owners to comply.

Continental first introduced this thicker camshaft gear in August of 2005 and started installing it in its factory new and rebuilt engines. But it wasn’t until November 2009 that it started asking field overhaul shops to install the newer-style gear at engine overhaul. Since it did so in a service bulletin (SB97-6B), almost all overhaul shops considered it to be non-compulsory, and therefore almost all field overhauled engines had their older-style camshaft gears reused.

This means that if the FAA were to issue an AD mandating compliance with Continental’s MSB05-8B, a whole lot of low-time (and even no-time) engines would need to be torn apart. Naturally, Continental would not be picking up any of the cost of doing this (as would be the case if this was an automotive recall rather than an aviation recall). Aircraft owners would be hit with the cost, which would be in the tens of millions of dollars.

Where’s the beef?

We talked with the FAA about this, and were told that Continental had provided the FAA data about only three camshaft gear failures in support of its request for an AD. The FAA also indicated that none of these failures were new ones. A search of the FAA’s Service Difficulty Report (SDR) database uncovered a total of 13 SDRs involving the older-style camshaft gears, most of which did not involve actual failures of the gears. That’s an awfully small number considering that tens of thousands of these gears have been in service for more than 40 years.

Even if all 13 of those SDRs represented gear failures (which they did not), my back-of-the-envelope calculations suggests that this would be one failure every 7,000,000 flight hours, which would make the camshaft gear one of the most reliable components of the engine. I’m almost certain that connecting rods and crankshafts fail more often than camshaft gears do.

If these gears have been in service for more than 40 years, and if there’s no new data indicating that they’re starting to fail at an accelerated rate, why would Continental suddenly conclude that a safety issue exists that warrants asking the FAA for an AD that would cost owners tens of millions and put thousands of airplanes on the ground for weeks or months?

By the way, we checked with three major parts distributors (Aviall, Omaha, A.E.R.O.) and learned that the newer-style camshaft gear is presently backordered for two months. We expect the situation to get worse fast as news of MSB05-8B and a possible AD spreads throughout the owner and mechanic communities.

As owners started learning about MSB05-8B through type clubs, online discussion groups and the electronic aviation press, there was “panic in the streets.” Sales of affected aircraft started falling through as prospective buyers walked away from deals. Owners started talking about class-action lawsuits against overhaul shops who reused older-style camshaft gears instead of installing new ones. Some owners with aircraft undergoing annual inspections started asking whether they should be having their engines overhauled. Other owners started worrying whether it was safe to fly their aircraft.

When we contacted numerous well-known engine overhaul shops, we were surprised to find that all of them told us they had been seeing no problem with the older-style camshaft gears, and all had been reusing the gears at overhaul once they passed inspection (which almost all did). The shops were unanimous that they saw no unsafe condition that would warrant an AD.

So what the heck is Continental’s reason for making a federal case of this now? I honestly don’t know, although as you might imagine there’s an awful lot of speculation and a few conspiracy theories floating around.

Late-breaking developments

On April 20, Continental issued a press release indicating their intention to walk back the Draconian compliance requirements of MSB05-8B. In the press release, Continental promised another revision of the MSB within 15 days, and indicated that the revised document would:

  • Eliminate the preemptive camshaft gear replacement in favor of a mandatory repetitive visual inspection procedure allowing on-condition operation until the engine is overhauled or removed for some other reason.
  • Change the 100-hour or 12-year gear replacement requirement to something that owners can live with more easily.
  • Provide an alternative procedure for replacing the camshaft gear that would not require complete engine disassembly (although it would require removal from the aircraft and partial disassembly).

We sincerely hope that Continental’s revised MSB is something that aircraft owners can live with. If not, there’s going to be a huge battle. After all, we’ve been living with these gears for more than four decades, and the overhaul shops are not seeing a problem with them.

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 7,500-plus hour pilot and CFI, an aircraft owner for 45 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike’s book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from in paperback and Kindle versions.
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