AOPA Pilot Magazine

Who is allowed to perform maintenance on a certificated aircraft? The FAA rule that answers that question is 14 CFR 43.3—Persons authorized to perform maintenance, preventive maintenance, rebuilding, and alterations. This rule authorizes repair stations, A&P mechanics, repairmen working for a repair station, air carriers, Part 135 operators, and aircraft manufacturers to perform maintenance. The rule also allows pilot-rated aircraft owners to perform preventive maintenance on an aircraft that they own. What if someone who is not an A&P—say, a maintenance-involved aircraft owner—wants to do something that goes beyond preventive maintenance—say a repair or alteration or component overhaul or replacement? Or what if an aspiring aircraft mechanic wants to go to work as an apprentice at a aircraft maintenance facility in order to gain the 30 months of practical experience required to qualify to take the knowledge and practical tests to become an A&P? Well, 14 CFR 43.3 addresses that, too. Specifically, paragraph (d) of 43.3 says: 43.3(d) – A person working under the supervision of a holder of a mechanic or repairman certificate may perform the maintenance, preventive maintenance, and alterations that his supervisor is authorized to perform, if the supervisor personally observes the work being done to the […]

Rethinking the business model for maintenance of GA aircraft. For more than a decade, my primary care physician was Dr. F. She was a wonderful doctor with a deep understanding of internal medicine and superb people skills who cared deeply for her patients. I felt fortunate to have her as my doc. But over the years, her reputation spread, and her practice grew larger. The lead time for scheduling an appointment to see her became uncomfortably long. Visits to her office became an ordeal involving lengthy delays in her always-packed waiting room, after which  I would get to see the doctor for 5-10 minutes if I was lucky. Then in October 2010, Dr. F died in the crash of a Beechcraft A36 Bonanza while on a humanitarian mission in Mexico. She was a member of The Flying Samaritans, a public benefit flying organization that operated free medical clinics at 17 locations in remote areas of Baja California. My doc regularly volunteered to participate in these clinics. (Decades earlier when I lived in Southern California, I was an active pilot for The Flying Sams.) That morning, the Bonanza took off from Ensenada headed for San Quintin. Aboard were Dr. F, another […]

The Perils of Trying to Fix a Problem You Haven’t Seen For Yourself The phrase “trust but verify” was made famous by U.S. President Ronald Reagan in December 1987 after the signing of the Intermediate-Range Nuclear Forces (INF) Treaty with Mikhail Gorbachev. The phrase comes from a rhyming Russian proverb, “доверяй, но проверяй” (romanized as “doveryay, no proveryay”). More than three decades later, U.S. Secretary of State Mike Pompeo paraphrased the proverb when speaking about U.S.-China relations as “distrust and verify”—likely closer to the Russian proverb’s true meaning. This proverb—particularly the Pompeo version—is just as applicable to aircraft maintenance as it is to arms control. Far too often in my experience, A&P mechanics attack an aircraft with tools in an attempt to fix an issue based solely on a squawk by a pilot or aircraft owner without actually verifying for themselves that the description is accurate. The result is often a lot of wasted effort, unnecessary expense and downtime, and frustration for all involved parties. Let me illustrate what I mean with a couple of real-world examples… Cessna 310 Volt-Amp Meter Years ago when I served as the twin Cessna tech rep for the Cessna Pilots Association, I received a […]

The big boys don’t do them—why must we? Given today’s acute shortage of GA mechanics and the difficulty owners are having getting their airplanes on shop schedules, I’ve been receiving an increasing number of inquiries about the need for annual inspections from frustrated aircraft owners. “Why is it necessary to have my airplane completely torn apart every 12 months?” one owner asked. “I’ve only flown about 40 hours since the last annual inspection.” “Wouldn’t it help solve the mechanic shortage if the FAA would let non-commercial operators like me do inspections every 18 or 24 months?” another owner asked. Those are great questions. I’ve long thought that the rule requiring small GA airplanes to receive a complete inspection every 12 calendar months didn’t make a lot of sense. Larger airplanes aren’t required to do it that way, so why are we? There are certainly parts of our small GA airplanes that need to be inspected frequently. For piston aircraft, that includes pretty much everything forward of the firewall. I’m talking about all that stuff that’s constantly trying to cook and vibrate itself to death.  Inspecting that stuff once a year might not be often enough. I would probably also include […]

Recently, a client with an older Cessna 182 Skylane reported that his nose landing gear strut was leaking fluid and repeatedly going flat. Inspection revealed that the original chrome strut piston had become badly pitted and was tearing up the nose strut seals. The owner’s shop checked the Textron Aviation parts system and found that they had one replacement strut piston in stock, and clearly, they were extremely proud of it. The price: $9,200. That’s nearly 10% of the fair market value of the whole airplane. Yikes! Salvage yards like BAS Parts Sales, Dawson Aircraft Parts and Salvage, Texas Air Salvage, Air Salvage of Dallas and Preferred Air Parts sometimes offer these strut pistons in as-removed condition for $2,500 to $3,500, but we couldn’t find one in stock at any of them. We even checked on eBay, but no joy. So, we concluded the best bet might be to find a shop capable and approved to re-chrome the pitted strut. As I’m writing this, we’re checking with Delta Strut in Stockton, California who specializes in Beechcraft landing gear repair but sometimes will work on Cessna and Piper struts. Fingers crossed. Although the cost of a new replacement nose strut piston […]

My company manages a lot of prebuys. At any given point in time, we typically have a dozen of them in progress. We’ve managed thousands of them over the years, and seen the good, the bad, and the ugly. Most of the time, the aircraft turn out to be in decent shape and the outcome is a successful purchase by our client, often after some last-minute price negotiations based on prebuy findings of airworthiness discrepancies that we think the seller should pay to correct. Once in a while, however, the prebuy uncovers problems serious enough that we advise our client to walk away and find another purchase candidate. We always try to arrange for the prebuy examination to be done by a shop or mechanic highly experienced with the particular make and model involved, and who is truly independent. By independent I mean that the selected shop or mechanic has no prior exposure to the aircraft being examined, and no prior relationship with the seller or (if applicable) the seller’s broker. This is the only way we can have confidence that the prebuy findings will be thorough, honest and unbiased. Let me tell you about two of these prebuys. One […]

What we can learn from medicine about fixing things without taking them apart. A longtime friend who was suffering from extreme fatigue and shortness of breath. She was diagnosed with congestive heart failure caused by aortic valve stenosis, and she required an aortic valve replacement. This was a very big deal that required open-heart surgery. It involved cracking her chest, placing her on a heart-lung machine, stopping her heart, cutting into her aorta, surgically removing the defective valve, suturing a replacement valve (harvested from a pig) in its place, suturing her aorta, restarting her heart, and closing up her chest. Afterward, she spent a week in the hospital and more than two months recovering at home. That occurred about 15 years ago. Now, the replacement valve is starting to give out, and she needs another valve replacement. This time, remarkably, the valve will be replaced without opening her chest or stopping her heart.  Nowadays, most aortic valve replacements are done using a technique called transcatheter aortic valve replacement or TAVR. A small incision will be made in her groin, and a guide wire will be passed up through the femoral artery into the aorta, and through the aortic valve using […]

Teaching owners (and mechanics) how to do borescope inspections right In my last column (“Ending the War on Jugs,” AOPA Pilot March 2024 issue), I talked at length about why we should use the borescope—not the compression tester—as the gold standard for assessing cylinder condition. Borescopes are now inexpensive (under $300) and capable of breathtaking image quality. These new borescopes let us diagnose cylinder issues accurately and often early enough that the problem can be remediated using modern minimally invasive techniques—lapping leaking valves in place, and freeing stuck rings with a simple solvent flush—thereby eliminating the need to incur the cost and risk of cylinder removal. But there’s a problem: Very, very few A&Ps know how to do a proper borescope inspection of cylinders. There’s little or no training on this subject in A&P school, and no relevant questions on the A&P knowledge tests. There’s nothing in any maintenance manual or service bulletin from aircraft or engine manufacturers that provides any guidance on this subject.  Interestingly, Continental has “required” that a borescope inspection be done any time a compression test is performed, but they offer not a syllable of guidance on how to do one! What’s wrong with this picture? […]

Weak compression doesn’t always mean that the cylinder has to come off. For most of my nearly six decades as an aircraft owner and three decades as an A&P, the rule about cylinders was simple: If the compression reading was less than 60/80, the cylinder had to come off for repair or replacement, period. The mechanics who worked on my airplanes, then later mentored me about maintenance, and then still later became my professional colleagues seemed quite happy with this straightforward rule. (Mechanics are always happiest when they have clear guidance to follow.) In 1984, Continental muddied the water when they issued Service Bulletin M84-15 that substituted a “master orifice tool” in place of the traditional 60/80 go/no-go criterion. This allowed Continental cylinders to remain in service with compression readings down to the mid-40s so long as the leakage was past the rings. This guidance was based on dynamometer test cell research by Continental engineering demonstrating that an engine with all cylinders at 40/80 made exactly the same horsepower as one with all cylinders at 75/80. (Most A&Ps weren’t comfortable with this, and would still yank jugs if they measured anywhere in the 50s.) However, M84-15 also said that no […]

Does unleaded fuel really cause exhaust valve seat recession? The October 27 announcement by the University of North Dakota (UND) flight school that it was terminating its year-long test of Swift UL94 unleaded avgas and returning to 100LL came as a shock and disappointment to many in the industry, me included. The school’s Director of Maintenance, Dan Kasowski, cited evidence of “significant” exhaust valve/seat recession in some of the Lycoming-powered Piper Archers in its training fleet. Kasowski was not more specific about the amount of recession or the percentage of cylinders or aircraft affected, saying only that the data is still being collected and is being forwarded to Lycoming for analysis. The UND announcement was shocking because virtually all previous tests of FAA-approved unleaded avgas—both Swift UL94 and GAMI G100UL—seemed to indicate that the effects of operating piston aircraft engines on these fuels was all positive with no negatives. In addition, decades of experience using 91-octane premium unleaded automotive gasoline in a wide range of low-compression aircraft engines ranging from Lycoming O-320s to Continental O-470s uncovered no problems whatsoever. So the UND findings were quite unexpected, to say the least. Is this a major setback for the long-awaited transition to […]

Why is GA maintenance done on a T&M basis, which places all the risk on the aircraft owner and none on the shop? A successful surgeon put his Beechcraft Baron 58 in an Arkansas shop for a makeover. He wanted both engines overhauled, new paint and interior, and the steam gauges replaced with a modern glass panel. The shop estimated they could get all this done in about six months at a cost of about $200,000. Much to the doctor’s dismay, the work actually took two years the final bill was about $500,000.. I learned about this when a mutual friend called me to ask if there was anything I could do for the Baron owner, who was extremely upset and understandably feeling seriously ripped off. I told my friend that while I certainly felt the owner’s pain, there was really nothing I or anyone else could do to help. Like the vast majority of GA maintenance, the work was done on a time-and-materials (T&M) basis. This meant that the owner agreed to pay for all the labor expended by the shop and its subcontractors (e.g., the paint shop) on an hourly basis, and for any required parts (typically at […]

That ubiquitous key-operated ignition switch is fraught with peril On July 26, 2018, private pilot Lanny Steven Kramer of Sarasota, Florida, and his wife Fran flew to the Cleveland Regional Jetport (RZR) in Cleveland, Tennessee to run some errands, after which they returned to the airport to depart. Shortly before 5 p.m., Lanny was preflighting the Cessna 182 Skylane while Fran had opened the righthand cabin door and was preparing to climb into the right seat. Then Fran heard a noise that sounded like the plane’s engine was trying to start. She found Lanny lying on the ramp in front of the airplane. He had sustained severe head injuries and was non-responsive. The Skylane’s ignition key was in his pocket.Fran called for help, which quickly arrived. Lanny was transported to the hospital by medevac helicopter, but succumbed to his head trauma. NTSB Findings Accident investigators found that the righthand magneto of the plane’s Continental O-470 engine was “hot”—the mag’s P-lead was not grounded out by the cockpit ignition switch. They found that the switch was not in the OFF position, but rather was in an intermediate position between the OFF and RIGHT detents. In that position, the switch did not […]

My hapless blunder en route to Oshkosh triggered a series of incredibly fortuitous events. It was mid-July and my annual pilgrimage to AirVenture Oshkosh was rapidly approaching. I’d finished preparing PowerPoint for the 11 different presentations I would be making. Now I started thinking about the upcoming flight. Flying from California to Wisconsin solo can get lonely, so I called my colleague Colleen Sterling and asked if she was interested in flying with me. After conferring with her husband Dave, they both accepted my invitation. Colleen and Dave are two of my favorite people. Both are very accomplished pilots—Dave’s a recently retired 787 captain—and both are A&P/IAs. They own five airplanes between them, all based at San Diego’s Gillespie Field (KSEE), and race three of them at Reno. Serious aviators!. On Friday, I flew my Cessna 310 to KSEE and stayed overnight with Colleen and Dave. We planned to launch early Saturday morning and fly at least two-thirds of the way to Oshkosh, remain overnight (RON), then depart Sunday morning to arrive at Wittman Field by noon. Northern Route Colorado looked awful on NEXRAD, so a northerly route via Salt Lake City looked prudent. Using Foreflight, I found a promising […]

A maintenance-aware owner is the last line of defense against maintenance errors Corey owns a 1978 Bonanza A36 and is quite involved in its maintenance. He does his own oil changes and other preventive maintenance. He even bought his own borescope and uses it to keep tabs on the health of his cylinders. He’s my kind of aircraft owner! His most recent borescope inspection revealed what looked to him like burned exhaust valves in the #3 and #4 cylinders. He reported this finding to his local shop, and after verifying his diagnosis a decision was made to send the better cylinder out for overhaul by an engine shop in Tulsa and to replace the worse one with a new Superior Millennium. (I’m not sure whether any consideration was given to lapping the exhaust valves in place—maybe they were too far gone for that.) The work seemed to be proceeding smoothly. Before long, the shop installed the new and overhauled cylinders and had the plane almost buttoned back up when Corey stopped by to check on their progress. Informed that the airplane was almost ready for the break-in flight, Corey went over to eyeball his newly installed jugs—and he saw red. […]

If you ask FAA lawyers what a regulation means, the answer might surprise you We’ve all studied the regs. If you’re a pilot, you’ve spent hours poring over Part 61 (pilot certification, ratings, currency) and Part 91 (operating rulese, owner responsibilities), both of which are voluminous. If you’re a mechanic, you’ve hopefully memorized Part 65 (mechanic eligibility, privileges and limitation) and Part 43 (maintenance) which are comparatively shorter but quite pithy. These regulations are written and maintained by a large team of FAA lawyers who work for the Regulations Division of the FAA Office of the Chief Counsel. If you have a question about the meaning of a rule, you can write to the Assistant Chief Counsel for Regulations (AGC-200) requesting a legal interpretation. (It’s sort of like asking the IRS for a revenue ruling.) Your request will be assigned to one of the rulemaking attorneys responsible for that particular section of the FARs, who hopefully will prepare a detailed written legal interpretation to be signed by the Assistant Chief Counsel and sent to you. Hopefully you’re not in a hurry, because the wheels of government turn slowly. Response time is generally at least several months, sometimes a lot longer. […]

How reliable and valid is the almighty compression test? Each annual inspection begins with a moment of terror when the IA removes the top spark plugs and takes a compression reading of each cylinder. We hold our breath awaiting the verdict. If the numbers are good, we exhale and relax. If not, we anticipate the sticker shock of cylinder removal and repair or replacement—and we pray that opening Pandora’s box won’t result in an even costlier verdict requiring an engine teardown or replacement. Sound familiar? Been there and done that? I certainly have.This agonizing compression testing ritual takes place hundreds of thousands of times each year. The requirement for performing a compression test at each annual and 100-hour inspection is written right into the FARs—specifically Part 43 Appendix D—so your IA has no choice about doing it. I’ve seen serious buyers walk away from an excellent airplane because they didn’t like the looks of the compression readings during the pre-buy. Yet this obsession with compression readings is so very wrong on multiple levels. Why wrong? I will explain… For one thing, the differential compression test is spectacularly unreliable. This means that you can test a cylinder multiple times and get  […]

When it comes to maintenance problems, the FAA might be able help you but only in very limited ways. My April column, titled “Booted Out of Annual,” related a true story of a Bonanza owner who put his plane in the shop for its annual inspection, got into a disagreement with the shop’s manager, and wound up having his plane thrown out of the shop in pieces. The beleaguered owner ultimately contacted the local FSDO (against my advice) for the purpose of filing a complaint against the shop. An Airworthiness Safety Inspector (ASI) there appeared to take pity on him and helped him out of this predicament.  Shortly after this column appeared in print, I received a long, thoughtful email from a gentleman I’ll call “Fred” who was retired from the FAA after two decades working at both a FSDO and an FAA Regional Office. (I thought “Fred the Fed” had a nice ring to it.) Fred was very concerned that my April column might give AOPA PILOT readers a wrong impression about when it is and isn’t appropriate for an owner to ask the FSDO for help, and what FAA personnel are and aren’t allowed to do. Fred and […]

THERE ARE NO LONGER ENOUGH A&PS TO MAINTAIN OUR GA AIRPLANES “The annual I scheduled more than a year ago got cancelled on a five-week notice,” read a recent post to the Beechcraft Bonanza Owners Facebook group. The unhappy owner went on to say that it was going to be impossible for him to find another IA to do the annual inspection of his Bonanza, which was coming due in just five weeks. The Bonanza owner posted the cancellation notice he received from his shop’s director of maintenance. In it, the director of maintenance said he was just not able to hire, train, and retain enough A&Ps to keep up with the shop’s scheduled workload. He also cited supply chain issues that delayed completion, and not enough hangar space to accommodate aircraft that were “in limbo” awaiting needed parts or outside work. “Sometimes I just look at the shop schedule and sigh,” the director of maintenance wrote. “I have a hard time saying no, and that has led to working seven days a week for far too long. I cannot do that anymore. I need to cancel some upcoming annual appointments.” Critical A&P shortage This post by the Bonanza owner […]

This unfortunate aircraft owner was placed in an untenable position by an unreasonable maintenance manager  Sometimes truth is stranger than fiction.  I’m going to change the names—I’ll call the aircraft owner “Oliver” and the A&P/IA “Isaac” and the shop manager “Maurice—and avoid geographical references. But I swear this really happened. The story started some months ago when Oliver put his recently acquired 1960 Beech Debonair in the shop on his home airport for its 2022 annual inspection. This is his first airplane and was the first annual on his watch. He delivered the plane to the shop on a Friday. Monday morning, the shop’s young A&P/IA, Isaac, ran up the engine to heat up the oil and cylinders, then started draining the oil and performing a hot compression check. All compressions tested okay except for cylinder #6 which measured 40/80. Cylinder #6 was borescoped, and the images did not reveal any obvious issues.  Isaac cut open the oil filter and inspected it. A small amount of metal was found in the pleats, so Isaac placed the filter media in a plastic bag and overnighted it to Aviation Laboratories along with an oil sample. Meantime, the maintenance manager Maurice—who is not […]

Should you have to pay for work or parts that don’t fix the problem? “Mike, I have an ethical question for you: How should an aircraft owner determine fair compensation to a mechanic for parts and labor that were unnecessary?” The email was from a 1947 Piper PA-12 Super Cruiser owner—I’ll call him Don—who had just received an invoice from his shop and was wondering whether or not to pay it. Don explained that his Lycoming O-235-C1 engine had always started easily. That changed after the last annual inspection when his A&P told him that he should be starting the engine with the mag switch set to LEFT since only the left magneto was equipped with an impulse coupling for starting. Don had been starting the engine on BOTH for the past 20 years, and he found the engine almost impossible to start using the procedure his mechanic had prescribed. Don reported this to his A&P, who proceeded to replace the primer. There was no improvement in starting, so the A&P replaced the left magneto. Still no improvement. The A&P asked Don to check the idle mixture by performing an idle RPM rise test. Don performed the test and reported […]

How far does your IA have to go to verify that your aircraft is airworthy? The subject line of the email got my attention: “Annual gone wrong…please help!” The author—let’s call him Morrie—identified himself as a first-time airplane owner. “I have my Citabria in for annual now,” Morrie said, “and I feel like one of your Savvy Maintenance columns is unfolding in front of me and my wallet. I had no issues with my first annual inspection last year, but I took it to a different IA this year and things seem to be unravelling.” Morrie explained that the original 115 hp Lycoming O-235 engine on his 1975 Citabria 7ECA has been replaced in 1996 with a 150 hp Lycoming O-320. That engine was overhauled in 1999, and the logbook entry made by the A&P who overhauled it stated “all ADs were complied with.” “My current IA is saying that is not good enough, and that he cannot verify the part number and serial number of the camshaft that was installed and therefore says he needs to tear down my engine!” The AD that had Morrie’s IA so concerned was a very old one—AD 63-23-02 published in 1963—that affected Lycoming […]

Don’t use exhaust gas temperature as a leaning reference I respond to at least 100 queries from aircraft owners and pilots each week. At least a dozen of those are questions or requests for advice about leaning, and most of them relate to EGT. A few common ones: Q: My POH recommends leaning to 50˚F rich of peak EGT, but your articles/webinars/books seem to say I shouldn’t do this. What’s with that? A: Back in the 1960s or 1970s when your airplane’s POH was written, engineers believed this was a good way to lean the engine. Since then, we’ve learned a lot more about the effect of mixture on the combustion event—in large part through the research efforts of George Braly at the world’s most advanced piston aircraft engine test facility he created at General Aviation Modifications, Inc. (GAMI) in Ada, Oklahoma—and we now know that 50˚F rich of peak (ROP) is very nearly the WORST possible mixture for engine longevity. I recommend against leaning to 50˚F ROP because I want your engine to live long and prosper. Q: When leaning my engine to XX˚F ROP/YY˚F LOP, should I use the first cylinder to peak, the last cylinder to peak, […]

Situational awareness requires being aware of your aircraft’s systems, too. On Saturday, August 26, 2022, a young CFI took off from Monterey, California in a Cessna 172 on a “Discovery Flight.” His passengers were a young couple, with the man occupying the left front seat and the woman seated in the back. The CFI occupied the right front seat. The airplane leveled off at 3,500 feet, at which point the CFI turned the controls over to the male passenger and started giving him basic instruction. The flight proceeded first north, then west following the coastline to Santa Cruz, did some maneuvers and airwork, then turned southeast to return to Monterey. Not long afterwards, the CFI sensed that the engine was losing power, and the tachometer confirmed this. He quickly ran through the memory items on his loss-of-power checklist: pitch to best-glide speed, mixture full rich, primer locked, carb heat on, fuel selector set to BOTH, etc. None of this helped, and the engine continued to lose power and RPM. At this point, the CFI looked at the oil pressure and temperature gauges. The oil pressure gauge read zero! The CFI advised NORCAL Approach that he had an engine emergency. Approach […]

Using AI and deep learning to detect anomalous engine monitor data Nowadays more than half of the piston GA fleet is equipped with some sort of recording digital engine monitor. Older ones tend to be fairly primitive and record just EGTs and CHTs and not much else. Modern ones have myriad sensors and capture numerous temperatures, pressures, voltages, currents, air data, attitude, acceleration, and GPS position data. A modern engine monitor with a few dozen sensors and a one-second sampling rate records more than 100,000 measurements per hour of flight. This data can have immense diagnostic value. In a perfect world, our engine monitors would analyze all this data in real time and alert us whenever something doesn’t look right. But even state-of-the-art avionics have an extremely limited ability to do this. Some engine monitors will alarm when various data values—CHTs, TIT, oil temperature and pressure, etc.—fall outside user-configurable minimum or maximum values. Others alarm only when values hit the manufacturer-specified redline (which is often way too late to save the day). Yet others offer no alarms at all. No engine monitor does what our human data analysts at Savvy Aviation are trained to do: to look for patterns in […]