Posts Tagged ‘general aviation’

Quest for a TBO-Free Engine

Tuesday, May 13th, 2014

“It just makes no sense,” Jimmy told me, the frustration evident in his voice. “It’s unfair. How can they do this?”

Jimmy Tubbs, ECi’s legendary VP of Engineering

Jimmy Tubbs, ECi’s legendary VP of Engineering

I was on the phone with my friend Jimmy Tubbs, the legendary Vice President of Engineering for Engine Components Inc. (ECi) in San Antonio, Texas. ECi began its life in the 1940s as a cylinder electroplating firm and grew to dominate that business. Starting in the mid-1970s and accelerating in the late 1990s—largely under Jimmy’s technical stewardship—the company transformed itself into one of the two major manufacturers of new FAA/PMA engine parts for Continental, Lycoming and Pratt & Whitney engines (along with its rival Superior Air Parts).

By the mid-2000s, ECi had FAA approval to manufacture thousands of different PMA-approved engine parts, including virtually every component of four-cylinder Lycoming 320- and 360-series engines (other than the Lycoming data plate). So the company decided to take the next logical step: building complete engines. ECi’s engine program began modestly with the company offering engines in kit form for the Experimental/Amateur-Built (E-AB) market. They opened an engine-build facility where homebuilders could assemble their own ECi “Lycoming-style” engines under expert guidance and supervision. Then in 2013, with more than 1,600 kit-built engines flying, ECi began delivering fully-built engines to the E-AB market under the “Titan Engines” brand name.

Catch 22, FAA-style

ECi’s Titan Exp experimental engine

A Titan engine for experimental airplanes.
What will it take to get the FAA to certify it?

Jimmy is now working on taking ECi’s Titan engine program to the next level by seeking FAA approval for these engines to be used in certificated aircraft. In theory, this ought to be relatively easy (as FAA certification efforts go) because the Titan engines are nearly identical in design to Lycoming 320 and 360 engines, and almost all the ECi-built parts are already PMA approved for use in Lycoming engines. In practice, nothing involving the FAA is as easy as it looks.

“They told me the FAA couldn’t approve an initial TBO for these engines longer than 1,000 hours,” Jimmy said to me with a sigh. He had just returned from a meeting with representatives from the FAA Aircraft Certification Office and the Engine & Propeller Directorate. “I explained that our engines are virtually identical in all critical design respects to Lycoming engines that have a 2,000-hour TBO, and that every critical part in our engines is PMA approved for use in those 2,000-hour engines.”

“But they said they could only approve a 1,000-hour TBO to begin with,” Jimmy continued, “and would consider incrementally increasing the TBO after the engines had proven themselves in the field. Problem is that nobody is going to buy one of our certified engines if it has only a 1,000-hour TBO, so the engines will never get to prove themselves. It makes no sense, Mike. It’s not reasonable. Not logical. Doesn’t seem fair.”

I certainly understood where Jimmy was coming from. But I also understood where the FAA was coming from.

A brief history of TBO

To quote a 1999 memorandum from the FAA Engine & Propeller Directorate:

The initial models of today’s horizontally opposed piston engines were certified in the late 1940s and 1950s. These engines initially entered service with recommended TBOs of 500 to 750 hours. Over the next 50 years, the designs of these engines have remained largely unchanged but the manufacturers have gradually increased their recommended TBOs for existing engine designs to intervals as long as 2,000 hours. FAA acceptance of these TBO increases was based on successful service, engineering design, and test experience. New engine designs, however, are still introduced with relatively short TBOs, in the range of 600 hours to 1,000 hours.

From the FAA’s perspective, ECi’s Titan engines are new engines, despite the fact that they are virtually clones of engines that have been flying for six decades, have a Lycoming-recommended TBO of 2,000 hours, and routinely make it to 4,000 or 5,000 hours between overhauls.

Is it any wonder we’re still flying behind engine technology designed in the ‘40s and ‘50s? If the FAA won’t grant a competitive TBO to a Lycoming clone, imagine the difficulties that would be faced by a company endeavoring to certify a new-technology engine. Catch 22.

Preparing for an engine test cell endurance run.

Incidentally, there’s a common misconception that engine TBOs are based on the results of endurance testing by the manufacturer. They aren’t. The regulations that govern certification of engines (FAR Part 33) require only that a new engine design be endurance tested for 150 hours in order to earn certification. Granted, the 150-hour endurance test is fairly brutal: About two-thirds of the 150 hours involves operating the engine at full takeoff power with CHT and oil temperature at red-line. (See FAR 33.49 for the gory details.) But once the engine survives its 150-hour endurance test, the FAA considers it good to go.

In essence, the only endurance testing for engine TBO occurs in the field. Whether we realize it or not, those of us who fly behind piston aircraft engines have been pressed into service as involuntary beta testers.

What about a TBO-free engine?

“Jimmy, this might be a bit radical” I said, “but where exactly in FAR Part 33 does it state that a certificated engine has to have a recommended TBO?” (I didn’t know the answer, but I was sure Jimmy had Part 33 committed to memory.)

“Actually, it doesn’t,” Jimmy answered. “The only place TBO is addressed at all is in FAR 33.19, where it says that ‘engine design and construction must minimize the development of an unsafe condition of the engine between overhaul periods.’ But nowhere in Part 33 does it say that any specific overhaul interval must be prescribed.”

“So you’re saying that engine TBO is a matter of tradition rather than a requirement of regulation?”

“I suppose so,” Jimmy admitted.

“Well then how about trying to certify your Titan engines without any TBO?” I suggested. “If you could pull that off, you’d change our world, and help drag piston aircraft engine maintenance kicking and screaming into the 21st century.”

An FAA-inspired roadmap

I pointed out to Jimmy that there was already a precedent for this in FAR Part 23, the portion of the FARs that governs the certification of normal, utility, aerobatic and commuter category airplanes. In essence, Part 23 is to non-transport airplanes what Part 33 is to engines. On the subject of airframe longevity, Part 23 prescribes an approach that struck me as being also appropriate for dealing with engine longevity.

Since 1993, Part 23 has required that an applicant for an airplane Type Certificate must provide the FAA with a longevity evaluation of metallic  wing, empennage and pressurized cabin structures. The applicant has the choice of three alternative methods for performing this evaluation. It’s up to the applicant to choose which of these methods to use:

  • “Safe-Life” —The applicant must define a “safe-life” (usually measured in either hours or cycles) after which the structure must be taken out of service. The safe-life is normally established by torture-testing the structure until it starts to fail, then dividing the time-to-failure by a safety factor (“scatter factor”) that is typically in the range of 3 to 5 to calculate the approved safe-life of the structure. For example, the Beech Baron 58TC wing structure has a life limit (safe-life) of 10,000 hours, after which the aircraft is grounded. This means that Beech probably had to torture-test the wing spar for at least 30,000 hours and demonstrate that it didn’t develop cracks.
  • “Fail-Safe” —The applicant must demonstrate that the structure has sufficient redundancy that it can still meet its ultimate strength requirements even after the complete failure of any one principal structural element. For example, a three-spar wing that can meet all certification requirements with any one of the three spars hacksawed in half would be considered fail-safe and would require no life limitation.
  • “Damage Tolerance” —The applicant must define a repetitive inspection program that can be shown with very high confidence to detect structural damage before catastrophic failure can occur. This inspection program must be incorporated into the Airworthiness Limitations section of the airplane’s Maintenance Manual or Instructions for Continued Airworthiness, and thereby becomes part of the aircraft’s certification basis.

If we were to translate these Part 23 (airplane) concepts to the universe of FAR Part 33 (engines):

  • Safe-life would be the direct analog of TBO; i.e., prescribing a fixed interval between overhauls.
  • Fail-safe would probably be impractical, because an engine that included enough redundancy to meet all certification requirements despite the failure of any principal structural element (e.g., a crankcase half, cylinder head or piston) would almost surely be too heavy.
  • Damage tolerance would be the direct analog of overhauling the engine strictly on-condition (based on a prescribed inspection program) with no fixed life limit. (This is precisely what I have been practicing and preaching for decades.)

How would it work?

SavvyAnalysis chart

Engine monitor data would be uploaded regularly to a central repository for analysis.

Jimmy and I have had several follow-on conversations about this, and he’s starting to draft a detailed proposal for an inspection protocol that we hope might be acceptable to the FAA as a basis of certifying the Titan engines on the basis of damage tolerance and eliminate the need for any recommended TBO. This is still very much a work-in-progress, but here are some of the thoughts we have so far:

  • The engine installation would be required to include a digital engine monitor that records EGTs and CHTs for each cylinder plus various other critical engine parameters (e.g., oil pressure and temperature, fuel flow, RPM). The engine monitor data memory would be required to be dumped on a regular basis and uploaded via the Internet to a central repository prescribed by ECi for analysis. The uploaded data would be scanned automatically by software for evidence of abnormalities like high CHTs, low fuel flow, failing exhaust valves, non-firing spark plugs, improper ignition timing, clogged fuel nozzles, detonation and pre-ignition. The data would also be available online for analysis by mechanics and ECi technical specialists.
  • At each oil-change interval, the following would be required: (1) An oil sample would be taken for spectrographic analysis (SOAP) by a designated laboratory, and a copy of the SOAP reports would be transmitted electronically to ECi; and (2) The oil filter would be cut open for inspection, digital photos of the filter media would be taken, when appropriate the filter media would be sent for scanning electron microscope (SEM) evaluation by a designated laboratory, and the media photos and SEM reports would be transmitted electronically to ECi.
  • At each annual or 100-hour inspection, the following would be required: (1) Each cylinder would undergo a borescope inspection of the valves, cylinder bores and piston crowns using a borescope capable of capturing digital images, and the borescope images would be transmitted electronically to ECi; (2) Each cylinder rocker cover would be removed and digital photographs of the visible valve train components would be transmitted electronically to ECi; (3) The spark plugs would be removed for cleaning/gapping/rotation, and digital photographs of the electrode ends of the spark plugs would be taken and transmitted electronically to ECi; and (4) Each cylinder would undergo a hot compression test and the test results be transmitted electronically to ECi.

The details still need to be ironed out, but you get the drift. If such a protocol were implemented for these engines (and blessed by the FAA), ECi would have the ability to keep very close tabs on the mechanical condition and operating parameters of each its engines—something that no piston aircraft engine manufacturer has ever been able to do before—and provide advice to each individual Titan engine owner about when each individual engine is in need of an overhaul, teardown inspection, cylinder replacement, etc.

Jimmy even thinks that if such a protocol could be implemented and approved, ECi might even be in a position to offer a warranty for these engines far beyond what engine manufacturers and overhaul shops have been able to offer in the past. That would be frosting on the cake.

I’ve got my fingers, toes and eyes crossed that the FAA will go along with this idea of an engine certified on the basis of damage tolerance rather than safe-life. It would be a total game-changer, a long overdue nail in the coffin of the whole misguided notion that fixed-interval TBOs for aircraft engines make sense. And if ECi succeeds in getting its Titan engine certified on the basis of condition monitoring rather than fixed TBO, maybe Continental and Lycoming might jump on the overhaul-on-condition bandwagon. Wouldn’t that be something?

Contracting: A Great Career Option for the Professional Pilot

Wednesday, April 16th, 2014

As much as one may love flying, it can be a tough career choice. Many pilots struggle through the food chain only to end up discouraged, if not downright hating their job. We’re all aware of the reasons: low pay, long days, little respect, too much time away from home, difficult working conditions, commuting, regulatory hassles, bankruptcies, furloughs, and ruinously expensive training.

Quite a list, isn’t it?

Ours is a small community; word gets around, and it begs the question, how many have bypassed a flying career altogether because of it? I once read a survey suggesting that most pilots would not recommend the field to their children. Of course, many vocations are in this rickety boat. Even formerly high-flying professions like physician and attorney have lost their luster. The message: “it ain’t what it used to be”.

On the other hand, life is often what we make of it. From bush flying to firefighting, there are many different gigs out there for those willing to take Frost’s road-less-traveled. For the past three years, for example, I’ve been flying as a “contract pilot” and truly enjoy it.

The Contractor

Ready to Ride

It’s kind of a generic term, since anyone who flies as an independent contractor rather than a traditional, W-2 employee fits the definition, but I’ll focus on Part 91 and 135 corporate/charter flying because that’s what I know best.

Contract pilots function as a kind of overflow labor. Operators might need temporary help in the cockpit for a variety of reasons: a full-timer is sick, on vacation, leaves the company, times out due to regulatory limitations, or is unavailable for some other reason. God forbid, maybe they ran into trouble with a checkride or medical exam. Perhaps a trip requires multiple pilots due to length or logistics.

Some companies find it advantageous to run tight on full-time labor and supplement with contract pilots since there are no annual costs for training or benefits. They only have to pay contractors when they’re actually used, so as the flight schedule ebbs and flows, they can gracefully scale their workforce up or down without the inefficiency of, say, leaving full-time, salaried pilots sitting at home for an extended period.

For the pilot, there are both pros and cons to life as a contractor.

The Pros

  • You’ve got some control over your schedule and can decline trips. I really hate doing that, because a) I don’t want the company to stop calling me, and b) you never know when things will slow down, so it’s smart to sock away some acorns for the winter. But if you’ve got a big vacation planned or your best friend is getting married? You’re ultimately in control.
  • We can work for multiple operators, which can provide a bit of protection if the flying slows down at one company.
  • You aren’t tied to a seniority system. If you’re an experienced captain at company A, you needn’t start over as the lowest-paid right seater at company B.
  • Contractors earn far more per day than full-time employees, and therefore needn’t work as many days to reach a given income level. That means better quality of life, especially if you’re married and/or have kids.
  • Contract pilots are typically paid by the day. I might have a five day trip consisting of a flight to Hawaii followed by three days on the island before flying home. That’s five days “on the clock”. It can be a more lucrative system than one where you are compensated based on flight hours. Operators are essentially purchasing your time.
  • You’ll travel the country, if not the world. Instead of a few major airports, on larger aircraft like the Gulfstream, you’ll see places you’d never dream of. Though I haven’t been there — yet — North Korea and the South Pole have both been on the table. (Random note: Jeppesen does publish charts and procedures for Pyonyang!)
  • I always get an honest sense of gratitude from the operators for whom I fly, because by definition I’m helping them out when they really need a pilot. For example, I recently got a call from a Part 91 Gulfstream operator whose pilot broke his arm in the middle of a trip. I airlined out the same day and flew that evening’s leg to Las Vegas, keeping the aircraft on schedule.

The Cons

You knew there had to be a few, right?

  • Contractors inherit all the hassles of being your own boss. Does anyone work harder? From providing your own benefits (don’t get me started about healthcare) to paying self-employment taxes, it’s not always the carefree work-and-go-home experience of a full-time employee.
  • You pay for your own training. On a jet, the annual recurrent training costs run in the thousands. I currently allot $15,000/year for recurrent training and associated costs (airfare, hotels, food, incidentals) on my airplane. The expenses are deductible, which helps a bit, but I figure my first month’s work each year is spent digging my way back to financial “zero”.
  • You can’t control when the phone rings. That can mean short-notice trips and/or weird hours.
  • It can be hard to plan your life out when you never know what days you’ll be working. I average about 10 days a month away, so my philosophy has been to just plan my social life as usual, and make sure people know I sometimes have to reschedule or cancel.
  • Work can conflict with itself. I’ve had three operators call me for a trip on the same day. I can only be in one place at at time, so I “missed out” on two of them.
  • No guarantee of work. But then, history has shown that there are no guarantees in life or aviation for anyone, are there?
  • It can be tough getting started. As with many careers, the best entrée is knowing someone who can get you in the door. Initial start-up costs of obtaining a type rating can be a major barrier.

Throttles

I like contracting because when a trip is offered I know it’s because the operator wants to use me rather than has to use me. Contracting represents some of the best that flying has to offer: adventure, interesting destinations and passengers, phenomenal aircraft, and decent pay for the work I do.

So why don’t more people jump into contracting? Awareness, for starters. Not everyone knows about this little niche. Also, it can be tough to break in to the business. You don’t have to know someone on the inside, but it certainly helps.

The initial expense is probably the largest impediment. The best compensation is found on the larger aircraft, and that means an expensive type rating funded solely by the contractor. Some pilots speculate on their ability to get work by obtaining the type before they have a job to use it on. Unless you’re well-heeled, that’s a big financial risk, but it works out for some people.

There is a rather circuitous way around the type rating burden: start off as a salaried employee and switch to contracting after a couple of years. That way the operator pays for your training and in exchange you accumulate a significant body of experience on the airplane.

FAA to the Rescue! Not.

I should note that contracting in the Part 135 world is a bit harder than it used to be. In the old days, if you were typed and current on an aircraft, you could fly for any charter company that operated that kind of plane. It wasn’t uncommon for a contract pilot to fly for several operators. A few years ago — for reasons no one has been able to adequately explain — the FAA essentially did away with that capability.

Today, a five-figure recurrent only entitles you to work for the certificate holder under whom you trained. It doesn’t matter if you’re a veteran of ten years and 10,000 hours in a Gulfstream IV; if you went to recurrent on Company A’s OpSpec, as far as the FAA is concerned, when you move to Company B you are completely unqualified to operate a G-IV on any Part 135 flight until you’ve been through another recurrent… at your own expense, of course.

At first, this seemed like a potential deal-breaker for contract pilots, but it can help as much as it hurts. Just as the change make it harder for a contractor to work for multiple operators, it also makes it more challenging for that operator to replace a contract pilot since a successor wouldn’t be legal to fly until they went back for recurrent training.

Walking the Aviation Tightrope

Contracting does have something in common with scheduled airlines: it’s not right for everyone. If you’re the type that wants a fixed schedule or has to know exactly how much your bi-weekly paycheck is going to be, this ain’t the place. In addition to all the attributes of a good corporate or charter pilot, contracting requires the ability to run a business and cope with uneven income. Some months will be fantastic. Others, not so much. Even when business is slow, though, I get something valuable: more time at home with friends and family. Like I said at the top, life is what you make of it.

But the ability to earn a six figure income right off the bat while working a relatively small number of days? For me at least, it’s more than worth it. What I want in my flying carer is sustainability, the capacity to survive on this aviation tightrope, and ironically that’s what contracting provides. I want to fly without hating it, and that means avoiding the soul-crushing schedule and monotony of many professional flying jobs.

How Do Piston Aircraft Engines Fail?

Wednesday, April 9th, 2014

Last month, I tried to make the case that piston aircraft engines should be overhauled strictly on-condition, not at some fixed TBO. If we’re going to do that, we need to understand how these engines fail and how we can protect ourselves against such failures. The RCM way of doing that is called Failure Modes and Effects Analysis (FMEA), and involves examining each critical component of these engines and looking at how they fail, what consequences those failures have, and what practical and cost-efficient maintenance actions we can take to prevent or mitigate those failures. Here’s my quick back-of-the-envelope attempt at doing that…

Crankshaft

CrankshaftsThere’s no more serious failure mode than crankshaft failure. If it fails, the engine quits.

Yet crankshafts are rarely replaced at overhaul. Lycoming did a study that showed their crankshafts often remain in service for more than 14,000 hours (that’s 7+ TBOs) and 50 years. Continental hasn’t published any data on this, but their crankshafts probably have similar longevity.

Crankshafts fail in three ways: (1) infant-mortality failures due to improper materials or manufacture; (2) failures following unreported prop strikes; and (3) failures secondary to oil starvation and/or bearing failure.

Over the past 15 years, we’ve seen a rash of infant-mortality failures of crankshafts. Both Cnntinental and Lycoming have had major recalls of crankshafts that were either forged from bad steel or were damaged during manufacture. These failures invariably occurred within the first 200 hours after the new crankshaft entered service. If the crankshaft survived its first 200 hours, we can be confident that it was manufactured correctly and should perform reliably for numerous TBOs.

Unreported prop strikes seem to be getting rare because owners and mechanics are becoming smarter about the high risk of operating an engine after a prop strike. There’s now an AD mandating a post-prop-strike engine teardown for Lycoming engines, and a strongly worded service bulletin for Continental engines. Insurance will always pay for the teardown and any necessary repairs, so it’s a no-brainer.

That leaves failures due to oil starvation and/or bearing failure. I’ll address that shortly.

Crankcase halvesCrankcase

Crankcases are also rarely replaced at major overhaul. They are typically repaired as necessary, align-bored to restore critical fits and limits, and often provide reliable service for many TBOs. If the case remains in service long enough, it will eventually crack. The good news is that case cracks propagate slowly enough that a detailed visual inspection once a year is sufficient to detect such cracks before they pose a threat to safety. Engine failures caused by case cracks are extremely rare—so rare that I don’t think I ever remember hearing or reading about one.

Lycoming cam and lifterCamshaft and Lifters

The cam/lifter interface endures more pressure and friction than any other moving parts n the engine. The cam lobes and lifter faces must be hard and smooth in order to function and survive. Even tiny corrosion pits (caused by disuse or acid buildup in the oil) can lead to rapid destruction (spalling) of the surfaces and dictate the need for a premature engine teardown. Cam and lifter spalling is the number one reason that engines fail to make TBO, and it’s becoming an epidemic in the owner-flown fleet where aircraft tend to fly irregularly and sit unflown for weeks at a time.

The good news is that cam and lifter problems almost never cause catastrophic engine failures. Even with a badly spalled cam lobe (like the one pictured at right), the engine continues to run and make good power. Typically, a problem like this is discovered at a routine oil change when the oil filter is cut open and found to contain a substantial quantity of ferrous metal, or else a cylinder is removed for some reason and the worn cam lobe can be inspected visually.

If the engine is flown regularly, the cam and lifters can remain in pristine condition for thousands of hours. At overhaul, the cam and lifters are often replaced with new ones, although a reground cam and reground lifters are sometimes used and can be just as reliable.

Gears

The engine has lots of gears: crankshaft and camshaft gears, oil pump gears, accessory drive gears for fuel pump, magnetos, prop governor, and sometimes alternator. These gears are made of case-hardened steel and typically have a very long useful life. They are not usually replaced at overhaul unless obvious damage is found. Engine gears rarely cause catastrophic engine failures.

Oil Pump

Failure of the oil pump is rarely responsible for catastrophic engine failures. If oil pressure is lost, the engine will seize quickly. But the oil pump is dead-simple, consisting of two steel gears inside a close-tolerance aluminum housing, and usually operates trouble free. The pump housing can get scored if a chunk of metal passes through the oil pump—although the oil pickup tube has a suction screen to make sure that doesn’t happen—but even if the pump housing is damaged, the pump normally has ample output to maintain adequate oil pressure in flight, and the problem is mainly noticeable during idle and taxi. If the pump output seems deficient at idle, the oil pump housing can be removed and replaced without tearing down the engine.

spun main bearingBearings

Bearing failure is responsible for a significant number of catastrophic engine failures. Under normal circumstances, bearings have a long useful life. They are always replaced at major overhaul, but it’s not unusual for bearings removed at overhaul to be in pristine condition with little detectable wear.

Bearings fail prematurely for three reasons: (1) they become contaminated with metal from some other failure; (2) they become oil-starved when oil pressure is lost; or (3) main bearings become oil-starved because they shift in their crankcase supports to the point where their oil supply holes become misaligned (as with the “spun bearing” pictured at right).

Contamination failures can generally be prevented by using a full-flow oil filter and inspecting the filter for metal at every oil change. So long as the filter is changed before its filtering capacity is exceeded, metal particles will be caught by the filter and won’t get into the engine’s oil galleries and contaminate the bearings. If a significant quantity of metal is found in the filter, the aircraft should be grounded until the source of the metal is found and corrected.

Oil-starvation failures are fairly rare. Pilots tend to be well-trained to respond to decreasing oil pressure by reducing power and landing at the first opportunity. Bearings will continue to function properly at partial power even with fairly low oil pressure.

Spun bearings are usually infant-mortality failures that occur either shortly after an engine is overhauled (due to an assembly error) or shortly after cylinder replacement (due to lack of preload on the through bolts). Failures occasionally occur after a long period of crankcase fretting, but such fretting is usually detectable through oil filter inspection and oil analysis).They can also occur after extreme unpreheated cold starts, but that is quite rare.

Thrown Connecting RodConnecting Rods

Connecting rod failure is responsible for a significant number of catastrophic engine failures. When a rod fails in flight, it often punches a hole in the crankcase (“thrown rod”) and causes loss of engine oil and subsequent oil starvation. Rod failure have also been known to cause camshaft breakage. The result is invariably a rapid and often total loss of engine power.

Connecting rods usually have a long useful life and are not normally replaced at overhaul. (Rod bearings, like all bearings, are always replaced at overhaul.) Many rod failures are infant-mortality failures caused by improper tightening of the rod cap bolts during engine assembly. Rod failures can also be caused by the failure of the rod bearings, often due to oil starvation. Such failures are usually random failures unrelated to time since overhaul.

Pistons and Rings

Piston and ring failures usually cause only partial power loss, but in rare cases can cause complete power loss. Piston and ring failures are of two types: (1) infant-mortality failures due to improper manufacturer or assembly; and (2) heat-distress failures caused by pre-ignition or destructive detonation events. Heat-distress failures can be caused by contaminated fuel (e.g., 100LL laced with Jet A), or by improper engine operation. They are generally unrelated to hours or years since overhaul. A digital engine monitor can alert the pilot to pre-ignition or destructive detonation events in time for the pilot to take corrective action before heat-distress damage is done.

Head SeparationCylinders

Cylinder failures usually cause only partial power loss, but occasionaly can cause complete power loss. A cylinder consists of a forged steel barrel mated to an aluminum alloy head casting. Cylinder barrels typically wear slowly, and excessive wear is detected at annual inspection by means of compression tests and borescope inspections. Cylinder heads can suffer fatigue failures, and occasionally the head can separate from the barrel. As dramatic as it sounds, a head separation causes only a partial loss of power; a six-cylinder engine with a head-to-barrel separation can still make better than 80% power. Cylinder failures can be infant-mortality failures (due to improper manufacture) or age-related failures (especially if the cylinder head remains in service for more than two or three TBOs). Nowadays, most major overhauls include new cylinders, so age-related cylinder failures have become quite rare.

Broken Exhaust ValveValves and Valve Guides

It is quite common for exhaust valves and valve guides to develop problems well short of TBO. Actual valve failures are becoming much less common nowadays because incipient problems can usually be detected by means of borescope inspections and digital engine monitor surveillance. Even if a valve fails completely, the result is usually only partial power loss and an on-airport emergency landing.

Rocker Arms and Pushrods

Rocker arms and pushrods (which operate the valves) typically have a long useful life and are not normally replaced at overhaul. (Rocker bushings, like all bearings, are always replaced at overhaul.) Rocker arm failure is quite rare. Pushrod failures are caused by stuck valves, and can almost always be avoided through regular borescope inspections. Even when they happen, such failures usually result in only partial power loss.

Failed Mag Distributor GearsMagnetos and Other Ignition Components

Magneto failure is uncomfortably commonplace. Mags are full of plastic components that are less than robust; plastic is used because it’s non-conductive. Fortunately, our aircraft engines are equipped with dual magnetos for redundancy, and the probability of both magnetos failing simultaneously is extremely remote. Mag checks during preflight runup can detect gross ignition system failures, but in-flight mag checks are far better at detecting subtle or incipient failures. Digital engine monitors can reliably detect ignition system malfunctions in real time if the pilot is trained to interpret the data. Magnetos should religiously be disassembled, inspected and serviced every 500 hours; doing so drastically reduces the likelihood of an in-flight magneto failure.

The Bottom Line

The bottom-end components of our piston aircraft engines—crankcase, crankshaft, camshaft, bearings, gears, oil pump, etc.—are very robust. They normally exhibit long useful life that are many multiples of published TBOs. Most of these bottom-end components (with the notable exception of bearings) are routinely reused at major overhaul and not replaced on a routine basis. When these items do fail prematurely, the failures are mostly infant-mortality failures that occur shortly after the engine is built, rebuilt or overhauled, or they are random failures unrelated to hours or years in service. The vast majority of random failures can be detected long before they get bad enough to cause an in-flight engine failure simply by means of routine oil-filter inspection and laboratory oil analysis.

The top-end components—pistons, cylinders, valves, etc.—are considerably less robust. It is not at all unusual for top-end components to fail prior to TBO. However, most of these failures can be prevented by regular borescope inspections and by use of modern digital engine monitors. Even whey they happen, top-end failures usually result in only partial power loss and a successful on-airport landing, and they usually can be resolved without having to remove the engine from the aircraft and sending it to an engine shop. Most top-end failures are infant-mortality or random failures that do not correlate with time since overhaul.

The bottom line is that a detailed FMEA of piston aircraft engines strongly suggests that the traditional practice of fixed-interval engine overhaul or replacement is unwarranted and counterproductive. A conscientiously applied program of condition monitoring that includes regular oil filter inspection, oil analysis, borescope inspections and digital engine monitor data analysis can yield improved reliability and much reduced expense and downtime.

The Journey of a Thousand Miles

Wednesday, March 19th, 2014

For as long as I can remember, “no news” has been “good news” when it comes to rules and regulations in the world of aviation. From field approval policy to sleep apnea to CBP searches and security theatre, any diktat emanating from Washington or Oklahoma City was sure to involve increasing demands of time and money while diminishing the usefulness and enjoyment of general aviation. That was the trend.

What a breath of fresh air it is, then, to hear of a well-suported and coordinated effort in both houses of Congress to enact legislation which would eliminate formal medical certification for many aviators.

Like the House bill, the new Senate legislation would exempt pilots who make noncommercial VFR flights in aircraft weighing up to 6,000 pounds with no more than six seats from the third-class medical certification process. Pilots would be allowed to carry up to five passengers, fly at altitudes below 14,000 feet msl, and fly no faster than 250 knots.

When the bill was first offered in the House of Representatives as the General Aviation Pilot Protection Act, it seemed like a long shot. Congress is not a known for acting boldly to free Americans from the heavy yoke of regulation, so one could be forgiven for not getting their hopes up. But now things are different: there’s a matching bill in the Senate, the House iteration has 52 co-sponsors, and the Congressional General Aviation Caucus has grown to more than 250 members.

Is it a done deal, then? Not at all. There’s no guarantee of passage or that President Obama would even sign the bill into law. But the sponsors and caucus members represent a good mix from across the political spectrum, and there are no special interests of any significance who benefit from the medical certification machinery, so I believe the prospects are encouraging.

This Pilot Protection Act is exceptional for several reasons. First, it goes far beyond even the historically pie-in-the-sky proposal fronted collectively by AOPA and EAA. When was the last time that happened? I can’t recall a single example. Typically we’ll ask for X and end up feeling extraordinary fortunate to get even half of it.

That AOPA/EAA submission, by the way, has languished on the FAA’s desk for two years and has yet to be acted upon by the agency. If one needed proof of just how sclerotic the bureaucratic machine has become, this is it. The delay is egregious enough to have warranted an official apology from FAA Administrator Huerta.

Just as importantly, though, is the fact that this is a legislative move rather than a regulatory one. It’s an important distinction, because regulations are instituted with relative impunity by agencies like the FAA, while Congress passes laws that are not nearly as vulnerable to bureaucratic vagaries. In other words, if the FAA instituted the very same change in medical certification through regulatory channels, they could alter or reverse those improvements just as easily. A law, on the other hand, should prove far more durable since the Feds must comply with it whether they like it or not.

It’s a shame that this common-sense change requires a literal Act of Congress. And what does it say about the FAA that a body with 9% approval rating is coming to the rescue of the private pilot? Were it to remain in the FAA’s corner, this medical exemption would probably never see the light of day. I don’t just mean that it would not be approved, I mean it would never even be acted upon at all.

There is a certain schadenfreude which comes from watching the FAA, which is known for soliciting comments from the aviation industry only to ignore that input, suffer the same fate at the hands of the House and Senate. My only question is: what took so long? The last time Congress lent the industry a helping hand was with the General Aviation Revitalization Act. That was in 1994 — twenty years ago. While I’m thankful they’re finally getting off the bench and into the game, this boost is long overdue. I sincerely hope they will not only see it through, but look for other ways to help bring a uniquely American industry back from the brink.

An easing of the medical certification requirements will not fix all of GA’s woes. But if the journey of a thousand miles begins with a single step, perhaps this will at least get us headed in the right direction.

One final note: if you haven’t called your Representative and Senators to express strong support for H.R. 3708 and S. 2103, respectively, please do so! Unlike FAA employees, these folks are up for re-election in eight months. The closer we get to November, the more likely they are to listen.

Do Piston Engine TBOs Make Sense?

Thursday, March 13th, 2014

Last month, I discussed the pioneering work on Reliability-Centered Maintenance (RCM) done by United Airlines scientists Stan Nowlan and Howard Heap in the 1960s, and I bemoaned the fact that RCM has not trickled down the aviation food chain to piston GA. Even in the 21st century, maintenance of piston aircraft remains largely time-based rather than condition-based.

mfr_logo_montageMost owners of piston GA aircraft dutifully overhaul their engines at TBO, overhaul their propellers every 5 to 7 years, and replace their alternators and vacuum pumps every 500 hours just as Continental, Lycoming, Hartzell, McCauley, HET and Parker Aerospace call for. Many Bonanza and Baron owners have their wing bolts pulled every five years, and most Cirrus owners have their batteries replaced every two years for no good reason (other than that it’s in the manufacturer’s maintenance manual).

Despite an overwhelming body of scientific research demonstrating that this sort of 1950s-vintage time-based preventive maintenance is counterproductive, worthless, unnecessary, wasteful and incredibly costly, we’re still doing it. Why?

Mostly, I think, because of fear of litigation. The manufacturers are afraid to change anything for fear of being sued (because if they change anything, that could be construed to mean that what they were doing before was wrong). Our shops and mechanics are afraid to deviate from what the manufacturers recommend for fear of being sued (because they deviated from manufacturers’ guidance).

Let’s face it: Neither the manufacturers nor the maintainers have any real incentive to change. The cost of doing all this counterproductive, worthless, unnecessary and wasteful preventive maintenance (that actually doesn’t prevent anything) is not coming out of their pockets. Actually, it’s going into their pockets.

If we’re going to drag piston GA maintenance kicking and screaming into the 21st century (or at least out of the 1950s and into the 1960s), it’s going to have to be aircraft owners who force the change. Owners are the ones with the incentive to change the way things are being done. Owners are the ones who can exert power over the manufacturers and maintainers by voting with their feet and their credit cards.

For this to happen, owners of piston GA aircraft need to understand the right way to do maintenance—the RCM way. Then they need to direct their shops and mechanics to maintain their aircraft that way, or take their maintenance business to someone who will. This means that owners need both knowledge and courage. Providing aircraft owners both of these things is precisely why I’m contributing to this AOPA Opinion Leaders Blog.

When are piston aircraft engines most likely to hurt you?

Fifty years ago, RCM researches proved conclusively that overhauling turbine engines at a fixed TBO is counterproductive, and that engine overhauls should be done strictly on-condition. But how can we be sure that his also applies to piston aircraft engines?

In a perfect world, Continental and Lycoming would study this issue and publish their findings. But for reasons mentioned earlier, this ain’t gonna happen. Continental and Lycoming have consistently refused to release any data on engine failure history of their engines, and likewise have consistently refused to explain how they arrive at the TBOs that they publish. For years, one aggressive plaintiff lawyer after another have tried to compel Continental and Lycoming to answer these questions in court. All have failed miserably.

So if we’re going to get answers to these critical questions, we’re going to have to rely on engine failure data that we can get our hands on. The most obvious source of such data is the NTSB accident database. That’s precisely what brilliant mechanical engineer Nathan T. Ulrich Ph.D. of Lee NH did in 2007. (Dr. Ulrich also was a US Coast Guard Auxiliary pilot who was unhappy that USCGA policy forbade him from flying volunteer search-and-rescue missions if his Bonanza’s engine was past TBO.)

Dr. Ulrich analyzed five years’ worth of NTSB accident data for the period 2001-2005 inclusive, examining all accidents involving small piston-powered airplanes (under 12,500 lbs. gross weight) for which the NTSB identified “engine failure” as either the probable cause or a contributing factor. From this population of accidents, Dr. Ulrich eliminated those involving air-race and agricultural-application aircraft. Then he analyzed the relationship between the frequency of engine-failure accidents and the number of hours on the engine since it was last built, rebuilt or overhauled. He did a similar analysis based on the calendar age of the engine since it  was last built, rebuilt or overhauled. The following histograms show the results of his study:

Ulrich study (hours)

Ulrich study (years)

If these histograms have a vaguely familiar look, it might be because they look an awful lot like the histograms generated by British scientist C.H. Waddington in 1943.

Now,  we have to be careful about how we interpret Dr. Ulrich’s findings. Ulrich would be the first to agree that NTSB accident data can’t tell us much about the risk of engine failures beyond TBO, simply because most piston aircraft engines are voluntarily euthanized at or near TBO. So it shouldn’t be surprising that we don’t see very many engine failure accidents involving engines significantly past TBO, since there are so few of them flying. (The engines on my Cessna 310 are at more than 205% of TBO, but there just aren’t a lot of RCM true believers like me in the piston GA community…yet.)

What Dr. Ulrich’s research demonstrates unequivocally is striking and disturbing frequency of “infant-mortality” engine-failure accidents during the first few years and first few hundred hours after an engine is built, rebuilt or overhauled. Ulrich’s findings makes it indisputably clear that by far the most likely time for you to fall out of the sky due to a catastrophic engine failure is when the engine is young, not when it’s old.

(The next most likely time for you to fall out of the sky is shortly after invasive engine maintenance in the field, particularly cylinder replacement, but that’s a subject for a future blog post…stay tuned!)

 So…Is there a good reason to overhaul your engine at TBO?

Engine overhaulIt doesn’t take a rocket scientist (or a Ph.D. in mechanical engineering) to figure out what all this means. If your engine reaches TBO and still gives every indication of being healthy (good performance, not making metal, healthy-looking oil analysis and borescope results, etc.), overhauling it will clearly degrade safety, not improve it. That’s simply because it will convert your low-risk old engine into a high-risk young engine. I don’t know about you, but that certainly strikes me as a remarkably dumb thing to do.

So why is overhauling on-condition such a tough sell to our mechanics and the engine manufacturers? The counter-argument goes something like this: “Since we have so little data about the reliability of past-TBO engines (because most engines are arbitrarily euthanized at TBO), how can we be sure that it’s safe to operate them beyond TBO?” RCM researchers refer to this as “the Resnikoff Conundrum” (after mathematician H.L. Resnikoff).

To me, it looks an awful lot like the same circular argument that was used for decades to justify arbitrarily euthanizing airline pilots at age 60, despite the fact that aeromedical experts were unanimous that this policy made no sense whatsoever. Think about it…

Roots of Reliability-Centered Maintenance

Tuesday, February 11th, 2014

Last month, I discussed the pioneering WWII-era work of the eminent British scientist C.H. Waddington, who discovered that the scheduled preventive maintenance (PM) being performed on RAF B-24 bombers was actually doing more harm than good, and that drastically cutting back on such PM resulted in spectacular improvement in dispatch reliability of those aircraft. Two decades later, a pair of brilliant American engineers at United Airlines—Stan Nowlan and Howard Heap—independently rediscovered the utter wrongheadedness of traditional scheduled PM, and took things to the next level by formulating a rigorous engineering methodology for creating an optimal maintenance program to maximize safety and dispatch reliability while minimizing cost and downtime. Their approach became known as “Reliability-Centered Maintenance” (RCM), and revolutionized the way maintenance is done in the airline industry, military aviation, high-end bizjets, space flight, and numerous non-aviation applications from nuclear power plants to auto factories.

RCM wear-out curve

The traditional approach to PM assumes that most components start out reliable, and then at some point start becoming unreliable as they age

The “useful life” fallacy

Nowlan and Heap showed the fallacy of two fundamental principles underlying traditional scheduled PM:

  • Components start off being reliable, but their reliability deteriorates with age.
  • The useful life of components can be established statistically, so components can be retired or overhauled before they fail.

It turns out that both of these principles are wrong. To quote Nowlan and Heap:

“One of the underlying assumptions of maintenance theory has always been that there is a fundamental cause-and-effect relationship between scheduled maintenance and operating reliability. This assumption was based on the intuitive belief that because mechanical parts wear out, the reliability of any equipment is directly related to operating age. It therefore followed that the more frequently equipment was overhauled, the better protected it was against the likelihood of failure. The only problem was in determining what age limit was necessary to assure reliable operation. “In the case of aircraft it was also commonly assumed that all reliability problems were directly related to operating safety. Over the years, however, it was found that many types of failures could not be prevented no matter how intensive the maintenance activities. [Aircraft] designers were able to cope with this problem, not by preventing failures, but by preventing such failures from affecting safety. In most aircraft essential functions are protected by redundancy features which ensure that, in the event of a failure, the necessary function will still be available from some other source.

RCM six curves

RCM researchers found that only 2% of aircraft components have failures that are predominantly age-related (curve B), and that 68% have failures that are primarily infant mortality (curve F).

“Despite the time-honored belief that reliability was directly related to the intervals between scheduled overhauls, searching studies based on actuarial analysis of failure data suggested that the traditional hard-time policies were, apart from their expense, ineffective in controlling failure rates. This was not because the intervals were not short enough, and surely not because the tear down inspections were not sufficiently thorough. Rather, it was because, contrary to expectations, for many items the likelihood of failure did not in fact increase with increasing age. Consequently a maintenance policy based exclusively on some maximum operating age would, no matter what the age limit, have little or no effect on the failure rate.”

[F. Stanley Nowlan and Howard F. Heap, “Reliability-Centered Maintenance” 1978, DoD Report Number AD-A066579.]

Winning the war by picking our battles

FMEAAnother traditional maintenance fallacy was the intuitive notion that aircraft component failures are dangerous and need to be prevented through PM. A major focus of RCM was to identify the ways that various components fail, and then evaluate the frequency and consequences of those failures. This is known as “Failure Modes and Effects Analysis” (FMEA). Researchers found that while certain failure modes have serious consequences that can compromise safety (e.g., a cracked wing spar), the overwhelming majority of component failures have no safety impact and have consequences that are quite acceptable (e.g., a failed #2 comm radio or #3 hydraulic pump). Under the RCM philosophy, it makes no sense whatsoever to perform PM on components whose failure has acceptable consequences; the optimal maintenance approach for such components is simply to leave them alone, wait until they fail, and then replace or repair them when they do. This strategy is known as “run to failure” and is a major tenet of RCM.

A maintenance revolution…

Jet airliner

The 747, DC-10 and L-1011 were the first airliners that had RCM-based maintenance programs.

As a direct result of this research, airline maintenance practices changed radically. RCM-inspired maintenance programs were developed for the Boeing 747, Douglas DC-10 and Lockheed L-1011, and for all subsequent airliners. The contrast with the traditional (pre-RCM) maintenance programs for the Boeing 707 and 727 and Douglas DC-8 was astonishing. The vast majority of component TBOs and life-limits were abandoned in favor of an on-condition approach based on monitoring the actual condition of engines and other components and keeping them in service until their condition demonstrably deteriorated to an unacceptable degree. For example, DC-8 had 339 components with TBOs or life limits, whereas the DC-10 had only seven—and none of them were engines. (Research showed clearly that overhauling engines at a specific TBO didn’t make them safer, and actually did the opposite.) In addition, the amount of scheduled maintenance was drastically reduced. For example, the DC-8 maintenance program required 4,000,000 labor hours of major structural inspections during the aircraft’s first 20,000 hours in service, while the 747 maintenance program called for only 66,000 labor hours, a reduction of nearly two orders of magnitude.

Greybeard AMTs.

Owner-flown GA, particularly piston GA, is the only remaining segment of aviation that does things the bad old-fashioned way.

Of course, these changes saved the airlines a king’s ransom in reduced maintenance costs and scheduled downtime. At the same time, the airplanes had far fewer maintenance squawks and much better dispatch reliability. (This was the same phenomenon that the RAF experienced during WWII when they followed Waddington’s advice to slash scheduled PM.)

…that hasnt yet reached piston GA

Today, there’s only one segment of aviation that has NOT adopted the enlightened RCM approach to maintenance, and still does scheduled PM the bad old-fashioned way. Sadly, that segment is owner-flown GA—particularly piston GA—at the bottom of the aviation food chain where a lot of us hang out. I’ll offer some thoughts about that next month.

Freedoms of the Air

Friday, February 7th, 2014
Bonnie, Laura, Camille ready for lift off

Bonnie, Laura, Camille ready for lift off

Recently I got the chance to talk with a good friend and Ambassador for General Aviation, Mike Jesch.  Mike is an American Airlines Captain, pilot for Angel Flight, LightHawk, and Cessnas to OSH, FAAST speaker, CFII, board member of Fullerton Pilots Association, you get the drift.

He and his family are hosting some foreign exchange students from the Agricultural University of Beijing, China, for a two week US holiday. Mike secretly hoped that it would work out to take the kids for a short ride in his Cessna 182, and indeed was a question he asked of the exchange program coordinator: Would it be okay to take the kids for an airplane ride? He was very relieved to receive an affirmative answer. The three girls, Bonnie, Camille, and Laura, were all very enthusiastic about this idea.

The day dawned clear and bright, and as they approached the airport and the airplanes came into view, he could see the excitement level increase on each of the girls’ faces.  He recalls, “When I opened the hangar door revealing my 1977 Cessna 182Q, the excitement reached a fever pitch. I walked them around the airplane, explaining my preflight inspection procedure, sampled the fuel, checked the oil, then showed them the cabin interior and gave them my passenger briefing. I reassured them that, at any point, if any of them were nervous, or scared, just let me know, and I’d land the airplane as soon as possible. They were still eager and willing, so we saddled up and started off.” As he lifted off the runway at Fullerton, CA [KFUL] and announced “…And, we’re flying!”, the pitch of their voices went up further still, and the smiles stretched from ear to ear! ”  The plan was to fly around the LA area, showing them the downtown area, Dodger Stadium, Griffith Park, the Hollywood sign, Malibu, Santa Monica, through the Mini Route down to Redondo Beach, around the Palos Verdes Peninsula, the Port of Los Angeles and Long Beach, the Queen Mary, and back to Fullerton. From shortly after takeoff, their noses were pressed to the windows, and excited chatter passed back and forth, each pointing out one sight or another, and cameras clicking away.

The next day, Mike got a call from one of the other host parents of two freshman boys. Apparently, the girls had been communicating with their friends! The boys had expressed an interest in also going for an airplane ride.  So, on that night, after dinner, he drove all the kids back over to the airport.  He said, “The boys  were amazed when they saw the airplane for the first time.”  The usual pre-flight inspection and briefing ensued, and they were off.  Kelvin and Owen (joined by Mike’s daughter, Karen) were audibly excited, too, as they defied gravity and launched into the night sky. Astounded by the beauty of all the lights of the LA area, they were instantly transfixed. Mike negotiated a transition through the Los Alamitos Army Air Base to the shoreline, then turned right to fly over the port of Long Beach and Los Angeles. Spectacularly lit up at night, the boys appreciated the sight of the world’s largest port complex, where most of the goods imported from China arrive and are unloaded and shipped all over the country.

Image

Owen ,Camille, Karen, Bonnie, Mike, Laura and Kelvin

Mike reflected on the differences between general aviation in the United States versus China.  “All the kids were absolutely amazed that a private citizen such as myself could own an airplane, go and visit it at any time, take it up in the air whenever I want, even flying directly over the top of a local military base and weapons depot and the largest port complex in the world, at night, all without a mountain of paperwork and permission from the authorities. In all of China, there are not more than a couple hundred airplanes in private hands, yet here at my home base Fullerton Airport alone, we have over 200 airplanes. And we have hundreds of airports across this country that have even more.” He pondered this difference between our countries, and says he gained a new appreciation for the freedoms of the air that we enjoy in this country. Certainly we have issues to deal with, perhaps chief among them cost and regulation, but in spite of all the issues, the system of aviation we have here is still pretty darned good, and worth protecting. Worth celebrating. Worth using. And perhaps most importantly, worth sharing it, especially with those who live in a place where this is not possible. “I harbor no illusions that these young Chinese students will themselves have the opportunity to become pilots, or to own airplanes. But maybe, just maybe, they’ll have a conversation with some friends, perhaps even future leaders in China, and tell them about the time – you won’t believe this! – when they got to fly in a small private airplane in California, on a clear and beautiful winter evening” he says.

Why I Don’t Talk About “General Aviation” Anymore

Thursday, January 23rd, 2014

Back in the 1950′s, Cessna Aircraft produced this gem… “Wings for Doubting Thomas

This little documentary clearly spelled out the value proposition for Private Aviation 2 generations ago.

I rarely talk about “General Aviation.”

Like most people who read this blog, I’m much more interested in, “Private Aviation.”

You might think quickly that it’s the same, thing, but it’s not. General aviation is broadly defined as as all aviation except for military and airlines. That’s great, but I’m not a, “General Aviation enthusiast.” Frankly I don’t care much about, “General Aviation.” I don’t fly biz jets, cargo, fly much for hire, (Though I have the certificate for, it’s just not a big part of my life these days.) spray crops, perform in air shows, whatever…

While I may aspire to sit in the back of a something with turbines, drinking Cristal… It does not inspire me. I’d rather be up front flying the jet.

Private aviation is the part of civil aviation that does not include flying for hire.”

“In most countries, private flights are always general aviation flights, but the opposite is not true: many general aviation flights (such as banner towing, charter, crop dusting, and others) are commercial in that the pilot is hired and paid. Many private pilots fly for their own enjoyment, or to share the joys and convenience of general aviation with friends and family.”

– Wikipedia

You see “General Aviation,” is doing just fine. Ask anyone running a jet charter business these days. Business is up, folks who choose to afford it are buying jet cards and getting to where they want to go in style, and plenty of people are making a good living helping them get there. I’m fine with all that. “General Aviation,” is not dying. It’s growing.

But “Private Aviation” is the community that inspires me. It’s Private Aviation that’s what we’re really talking about when we fry bacon at Camp Scholler, or eat pancakes at the fly in. The ability to climb into a plane and fly myself and my friends or family someplace is like a magic power.

It’s Private Aviation that we built OpenAirplane to serve.

So you see, I don’t talk much about General Aviation. When I speak to the press about OpenAirplane. I explain that it is a marketplace for Private Aviation. I get asked all the time if OpenAirplane will let them hail a jet like they can hail a cab, or if we can help them charter a flight. My answer is always, “Not yet.” It’s just not the business we’re in right now. There are plenty of smart people working to offer charter for businesses and pleasure. That part of General Aviation is well served. I explain that we are focused on Private Aviation, because that’s where the opportunity lies today to unlock more value than anywhere else right now. General Aviation is a competitive, well served market with a healthy ecosystem. But Private Aviation hasn’t seen much innovation since Cessna commissioned that film. This is strange to me, because GPS, iPads, and composites sure have made it a lot easier. Private Aviation can create entirely new use cases for the over 5,000 airports, thousands of aircraft, and hundreds of thousands of certificates in the wallets of  pilots across the country.

Private Aviation has been in decline since the airlines we’re deregulated in 1978. The value proposition of Private Aviation has been evolving ever since. The industry and the community need to both step up to communicate the value proposition for Private Aviation to a new generation of “doubting Thomases,” updating what you see in the old documentary film above to speak to the value proposition we can offer today.

For most of us, the conversation isn’t about General Aviation, it’s about Private Aviation. Let’s call it what it is. I have no time sit back and complain. I believe we can make it better than ever.

Time for a Shakeup

Wednesday, January 22nd, 2014

Last November the Federal Air Surgeon, Fred Tilton, unilaterally declared that mandatory screening for obstructive sleep apnea (OSA) in pilots would begin “shortly.”

The initial BMI threshold would be 40, with an ominous vow that “once we have appropriately dealt with every airman examinee who has a BMI of 40 or greater, we will gradually expand the testing pool by going to lower BMI measurements until we have identified and assured treatment for every airman with OSA.”

Tilton noted that “up to 30% of individuals with a BMI less than 30 have OSA”. Between the fact that people with normal-range BMIs have been diagnosed with sleep apnea and his apparent zest for uncovering “every” airman with OSA, logic dictates that the eventual threshold would be in the mid-20s, if not lower.

The aviation community was up in arms pretty quickly, and for good reason. For one thing, the mid-20s are the upper end of the normal BMI range. It’s also worth noting that even the World Health Organization acknowledges that the BMI scale was never designed for application to individual people, but rather for statistical modeling of entire populations. BMI is based solely on weight and height, so it does not account for differing body types. Nor does it obey the law of scaling, which dictates that mass increases to the 3rd power of height.

In plain English, a bigger person will always have a higher BMI even if they are not any fatter. This penalizes tall individuals, as well as bodybuilders and athletes who are in prime physical shape by assigning them absurdly high BMI numbers. Likewise, short people are misled into thinking that they are thinner than they are.

Nevertheless, Tilton declared his intention to press on anyway, without any industry input or following established rulemaking procedures despite the fact that this scavenger hunt would break invasive new ground in aeromedical certification.

Then, even the Aviation Medical Examiners objected to the new policy, noting that “no scientific body of evidence has demonstrated that undiagnosed obesity or OSA has compromised aviation safety” and that providing long term prognoses is not part of the FAA’s job. The medical certification exists soley to “determine the likelihood of pilot incapacitation for the duration of the medical certificate.”

Without the support of the civil aviation medicine community, Tilton was literally standing alone. At that point, Congress jumped into the fray on the pilot community’s behalf and eventually forced the Air Surgeon to back down… for now.

While the battle may have been won, the war is far from over. Mark my words, this is not the last you’ll hear about this bogeyman. Tilton may be forced to consult with the aviation community or follow a rulemaking procedure of some sort, but his zeal for the topic means OSA screening will be back in one form or another.

To effectively combat such overreach, we’ve got to attack the problem from its true source. In this case, the Air Surgeon’s ammunition came from National Transportation Safety Board recommendations issued in the wake of a 2008 regional airline flight which overflew its destination by 26 miles when both pilots fell asleep.

… the National Transportation Safety Board recommends that the Federal Aviation Administration:

Modify the Application for Airman Medical Certificate to elicit specific information about any previous diagnosis of obstructive sleep apnea and about the presence of specific risk factors for that disorder. (A-09-61)

Implement a program to identify pilots at high risk for obstructive sleep apnea and require that those pilots provide evidence through the medical certification process of having been appropriately evaluated and, if treatment is needed, effectively treated for that disorder before being granted unrestricted medical certification. (A-09-62)

The NTSB serves a useful purpose in assisting transportation disaster victims and investigating accidents, but when it comes to safety recommendations, the agency operates in a kind of vacuum, divorced from some of the most pressing realities of the modern general aviation world. The reason is simple: their mission statement. It calls for the Board to “independently advance transportation safety” by “determining the probable cause of the accidents and issuing safety recommendations aimed at preventing future accidents.”

While there’s nothing objectionable about their mission, note how there’s no mention of the cost these recommendations impose on those of us trying to make a go of it in the flying industry. Since it’s not part of their mission statement, it is not a factor the Board takes into account. It doesn’t even appear on their radar. The Board’s federal funding and their lack of rulemaking authority negates any such considerations. So a sleep apnea study costs thousands of dollars — so what? If it prevents one pilot from falling asleep in the cockpit in next half century, it’s well worth the decimation to an already down-and-out sector of the economy.

That’s been the logic for the NTSB since it was conceived by the Air Commerce Act in 1926. It worked well when aerospace safety was at its nadir — but that was nearly ninety years ago. As air transportation evolved during the 20th century, attempts at increasing safety have reached the point of diminishing returns and exponentially increasing cost. At some point the incessant press toward a perfect safety record will make aviating such a sclerotic activity that it will, in effect, cease.

It’s a problem for any industry, and it’s especially so for one that’s teetering on the edge of oblivion the way ours is. The good news is that this can be fixed. It’s time to shake things up at the NTSB by revising their mission statement to make cost analysis a major part of the Board’s function. They should work with stakeholders to carefully study the long-term effect each recommendation would have on the health and size of the aviation industry before they make it.

For what it’s worth, the FAA needs this mission statement adjustment just as much as the NTSB. More, in fact, because the NTSB can recommend anything it wishes, but the regulatory power to act upon those suggestions is outside their purview and rests with the Federal Aviation Administration. From medical approval to burdensome aircraft certification rules, the FAA is the hammer. We have to start somewhere, though, and the NTSB is in many ways the top of the heap, the place where these ideas get their start. It would be nice to see the industry’s lobbyists in Washington, D.C. suggest such a bill to members of Congress.

One final thought: if government’s power really does derive from the “consent of the governed”, this should be an idea even the NTSB (and FAA) can get behind. Otherwise, they may convene one day and find that there’s not much of an industry left for them to prescribe things to.

The Waddington Effect

Tuesday, January 14th, 2014
Conrad Hal (C.H.) Waddington

C.H. Waddington (1905-1975)

In 1943, a British scientist named Conrad Hal (C.H.) Waddington made a remarkable discovery about aircraft maintenance.  He was a most unlikely person to make this discovery, because he wasn’t an aeronautical engineer or an aircraft mechanic or even a pilot.  Actually, he was a gifted developmental biologist, paleontologist, geneticist, embryologist, philosopher, poet and painter who wasn’t particularly interested in aviation.  But like many other British scientists at that time, his career was interrupted by the outbreak of the Second World War and he found himself pressed into service with the Royal Air Force (RAF).

Waddington wound up reporting to the RAF Coastal Command, heading up a group of fellow scientists in the Coastal Command Operational Research Section.  Its job was to advise the British military on how it could more effectively combat the threat from German submarines.  In that capacity, Waddington and his colleagues developed a series of astonishing recommendations that defied military conventional wisdom of the time.

For example, the bombers used to hunt and kill U-boats were mostly painted black in order to make them difficult to see.  But Waddington’s group ran a series of experiments that proved that bombers painted white were not spotted by the U-boats until they were 20% closer, resulting in a 30% increase in successful sinkings. Waddington’s group also recommended that the depth charges dropped by the bombers be set to explode at a depth of 25 feet instead of 100 feet.  This recommendation—initially resisted strongly by RAF commanders—ultimately resulted in a sevenfold increase in the number of U-boats destroyed.

Consolidated B-24 "Liberator" bomber

Consolidated B-24 “Liberator” bomber

Waddington subsequently turned his attention to the problem of “force readiness” of the bombers.  The Coastal Command’s B-24 “Liberator” bombers were spending an inordinate amount of time in the maintenance shop instead of hunting U-boats.  In July 1943, the two British Liberator squadrons located at Ballykelly, Northern Ireland, consisted of 40 aircraft, but at any given time only about 20 were flight-ready.  The other aircraft were down for any number of reasons, but mostly undergoing or awaiting maintenance—either scheduled or unscheduled—or waiting for replacement parts.

At that time, conventional wisdom held that if more preventive maintenance were performed on each aircraft, fewer problems would arise and more incipient problems would be caught and fixed—and thus fleet readiness would surely improve. It turned out that conventional wisdom was wrong. It would take C.H. Waddington and his Operational Research team to prove just how wrong.

Waddington and his team started gathering data about the scheduled and unscheduled maintenance of these aircraft, and began crunching and analyzing the numbers.  When he plotted the number of unscheduled aircraft repairs as a function of flight time, Waddington discovered something both unexpected and significant: The number of unscheduled repairs spiked sharply right after each aircraft underwent its regular 50-hour scheduled maintenance, and then declined steadily over time until the next scheduled 50-hour maintenance, at which time they spiked up once again.

Waddington Effect graph

When Waddington examined the plot of this repair data, he concluded that the scheduled maintenance (in Waddington’s own words) “tends to INCREASE breakdowns, and this can only be because it is doing positive harm by disturbing a relatively satisfactory state of affairs. There is no sign that the rate of breakdowns is starting to increase again after 40-50 flying hours when the aircraft is coming due for its next scheduled maintenance.” In other words, the observed pattern of unscheduled repairs demonstrated that the scheduled preventive maintenance was actually doing more harm than good, and that the 50-hour preventive maintenance interval was inappropriately short.

The solution proposed by Waddington’s team—and ultimately accepted by the RAF commanders over the howls of the maintenance personnel—was to increase the time interval between scheduled maintenance cycles, and to eliminate all preventive maintenance tasks that couldn’t be demonstrably proven to be beneficial. Once these recommendations were implemented, the number of effective flying hours of the RAF Coastal Command bomber fleet increased by 60 percent!

Fast forward two decades to the 1960s, when a pair of gifted scientists who worked for United Airlines—aeronautical engineer Stanley Nowlan and mathematician Howard Heap—independently rediscovered these principles in their pioneering research on optimizing maintenance that revolutionized the way maintenance is done in air transport, military aviation, high-end bizjets and many non-aviation industrial applications.  They were almost certainly unaware of the work of C.H. Waddington and his colleagues in Britain in the 1940s because that work remained classified until 1973, when Waddington’s meticulously-kept diary of his wartime research activities was declassified and published.

Next time, I’ll discuss the fascinating work of Nowlan and Heap on what came to be known as “Reliability Centered Maintenance.” But for now, I will leave you with the major takeaway from Waddington’s research during World War II: Maintenance isn’t an inherently good thing (like exercise); it’s a necessary evil (like surgery). We have to do it from time to time, but we sure don’t want to do more than absolutely necessary to keep our aircraft safe and reliable. Doing more maintenance than necessary actually degrades safety and reliability.