Magazine Articles

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 […]

Dealing with mechanicals away from home base. Every aircraft owner dreads a mechanical breakdown while away from home on a trip. In the five and a half decades that I have owned an aircraft—I bought my first plane in 1968 and have always flown lots of long trips—I’ve been the victim of such mechanicals more times than I have fingers. From firsthand experience, I can tell you that these events are emotionally charged. You’re typically stuck somewhere you don’t want to be and at the mercy of strangers you don’t know whether or not to trust. It’s usually frustrating, frightening and exasperating. It always puzzled me that there was no nationwide or worldwide breakdown assistance program for GA owners and pilots, something analogous to what AAA provides for motorists. So, in 2016 my company launched one—SavvyBreakdown—and today we have thousands of GA airplanes enrolled in the program. We operate a toll-free hotline that connects pilots-in-distress with one of our seasoned A&P/IA account managers on a 24/7/365 basis, and we deal with every possible sort of away-from-home problem you can imagine—hundreds of them every year. Let me tell you about a half-dozen real-life breakdown incidents and how we dealt with them… […]

Optimal flying in a world of expensive avgas.  With fuel prices at all-time highs, it’s more important than ever for pilots of GA airplanes to fly in a fuel-efficient fashion. I am especially sensitive to this issue because I fly a piston twin that guzzles 30 GPH and suffer post-traumatic stress each time I refuel.  So, how can we get the best bang for our avgas buck? Well, it turns out that there are a bunch of things that contribute to fuel-efficient flying. A good place to start is our choice of airspeed. There are a number of contenders for the title of “most fuel-efficient airspeed.” The most obvious candidate is the airspeed at which drag is minimized, often referred to as “best L/D” and often found in the POH as “best glide speed.” For my Cessna 310, best L/D is 111 KIAS at max gross and lower at lighter weights. For a Cirrus SR22, it’s 92 KIAS, and for a Cessna 172 it’s 65 KIAS. This is the airspeed that will get you from point A to point B using the least amount of fuel, and the airspeed that will provide the greatest possible range starting with a given […]

The best maintenance shops often warrant the closest owner oversight.  I’m frequently asked by aircraft owners to recommend good maintenance shops in a particular area, and my company maintains a large database of maintenance resources to facilitate such referrals. Our team of more than 20 A&P/IA account managers keep close track of their experiences working with hundreds of shops, and we do our best to steer our clients to the ones with which we’ve had the best outcomes and—perhaps more importantly—away from those that were not so good. Often I find myself telling a client, “this is an outstanding shop that does thorough inspections and excellent work, but be prepared for a big bill unless you keep them on a short leash.” I do not mean this as a criticism of the shop. It simply reflects the reality that the best shops tend to do very thorough inspections and uncompromisingly meticulous repairs, and generally tend to have a perfectionist approach to maintenance. These are exactly the attributes we want the shop to have, but the result can be serious sticker shock unless the owner actively throttles the shop back by explicitly directing them to perform only the work desired nothing […]

Out-of-control annual inspections are painful—and avoidable. I received a heart-wrenching email from the owner of a Southern California flight school—I’ll call him Chuck—who operates 10 airplanes, mostly Cessna 172s and Piper Archers and Arrows, with a Seneca twin and a Cessna 140 taildragger thrown in for good measure. With a fleet like that, Chuck has a lot of experience with airplane maintenance and annual inspections, so he’s not the sort of person you’d expect to get into deep maintenance kimchee, but sadly that’s exactly what happened. Chuck wanted to expand his business to provide air tours, so he purchased a 1957 Twin Beech E18S with for $160,000 with the help of a bank loan and spent another $40,000 to upgrade the avionics. Then it came time for the first annual inspection on Chuck’s watch. His regular mechanics didn’t have any Beech 18 experience, so Chuck decided to fly the airplane some 350 nm to a specialty shop in Northern California that was well-known and apparently well-respected in the Beech 18 community. Chuck told the shop’s owner that he would be using the Twin Beech for an air tour operation, and wanted to make sure it was safe and airworthy. Chuck’s […]

This Skyhawk’s Lycoming had a 2,000-hour TBO, but it lasted a bit longer—3,000 hours longer to be exact. What follows is true, though the names have been changed… It was 2011 and Unruly Flyers had a problem. This 14-member Midwest flying dlub’s only aircraft—a 1997 Cessna 172R—had a Lycoming IO-360 engine that was rapidly approaching its 2,000-hour TBO, forcing the club to decide. Overhaul would put Unruly Flyers on the ground for at least three months. Replacment with a Lycoming rebuilt might shorten the downtime but increase the cost. Unruly’s board was struggling with this decision, and decided to coax the club’s former maintenance officer Zachary “Whit” Wittington to come out of retirement. Whit wasn’t an A&P, but he’d been flying GA for more than two decades and had proven himself to be exceptionally maintenance-savvy.  Whit agreed to reassume his former role, and at the next Unruly board meeting (pun intended) asked all the right questions: Q: Are we having problems with the engine? A: No. Q: Why are we thinking about overhauling or replacing it? A: It’s at TBO. Q: Are we required to do anything at TBO? A: Guess not. Q: Why not continue it in service? A: […]

Is the conventional wisdom wrong about why exhaust valves burn? Piston aircraft engines have an awful lot of moving parts. Way too many, if you ask me. The thought of thousands of separate metal parts reciprocating, rotating, wiggling, wobbling, and rubbing against one another thousands of times a minute ought to make you nervous—it sure does me. It’s something I try hard not to think about while airborne, maintly because I fly a lot better when not distracted. Of those thousands of moving parts, two kinds are the most worrisome: the ones most likely to blindside you with a costly, premature, unbudgeted-for engine overhaul or replacement, and the ones most likely to make you fall out of the sky (or at least soil your undies). The biggest offender in the safety-of-wallet category is the camshaft—and for Lycomings, the cam followers a.k.a. tappets—which prepresents by far the leading cause of premature engine teardowns. (Especially if you don’t count prop strikes, which you really shouldn’t since the prop isn’t part of the engine.) In the safety-of-flight category, hands-down the most-wanted villains are exhaust valves. Exhaust valves can ruin you day in at least two different ways: they can stick or they can […]

“You snooze, you lose” or “caveat emptor”? The market for used GA airplanes is crazy right now. In the five decades I’ve been paying attention to such things, I’ve never seen anything like it. Other GA industry veterans I’ve spoken with all tell me the same thing. There’s an airplane buying spree going on, apparently driven by pent-up demand and historically low interest rates, and prices have been going through the roof.  How crazy? Well, I’m looking at a listing for a very low-time 2021 Cirrus SR22-G6-GTS with an asking price of $1.25 million. Seriously? Cirrus’s 2021 factory price list shows a price of $886,800 for this airplane brand new, which strikes me as awfully pricey for a four-seat single-engine piston airplane. Why would anyone pay a $363,200 premium for a slightly used SR22? Perhaps because the slightly used one is available today and a new 2022 model from the factory has an 8-month wait time. Buyers have itchy trigger fingers at present, and just don’t want to wait. All this somehow reminds me of the Dutch “tulip fever” of the 1630s (admittedly slightly before my time). It was a textbook bubble then and strikes me as unsustainable now. You […]

You can learn a lot from your airplane’s report card Jack owns a 2016 Cirrus SR22 with a Garmin Perspective glass cockpit—basically a G1000 on steroids. His MFD records tons of data on an SD card—CHTs, EGTs, oil pressure and temperature, MAP, RPM, fuel flow, altitude, TAS, electrical bus voltages and current, even GPS coordinates—and Jack regularly uploads this data to my company’s SavvyAnalysis platform. Once uploaded, Jack’s data is automatically scanned by a sophisticated machine-learning algorithm for evidence of failing exhaust valves. Whenever Jack requests it, selected flights are scrutinized by Savvy’s team of professional data analysts who prepare a comprehensive report on the health of Jack’s engine and the appropriateness of his powerplant management procedures. In addition, Jack receives regular “report cards” that graphically shows how his SR22 stacks up when compared to a “cohort” of more than 1,500 other normally aspirated Cirrus SR22s that followed by SavvyAnalysis. Jack’s report cards display numerous parameters related to performance, efficiency, longevity and health of his aircraft and its engine, and essentially “grades them on the curve” to show Jack how his aircraft is stacking up when compared to the other aircraft in his cohort. How Am I Doing? In late […]

Does your engine REALLY need to be euthanized? “I’m in trouble. Can you help?”  The owner of the vintage Mooney was obviously stressed. He identified himself as a highly experienced military pilot but a first-time aircraft owner who’d recently flown his airplane to Florida on business.  When it came time to return home, the Mooney’s Lycoming IO-360 wouldn’t start. He took it into the local shop on the field, who discovered that the left magneto’s case had cracked. Since the left magneto is the one used to start the engine in this airplane, that seemed to be the smoking gun that would explain why it wouldn’t start. The shop proposed to order a replacement magneto, and the owner approved. “Now they’re telling me the engine needs to be torn down!” he told me in a panic-laced voice. “It’s nowhere close to TBO, and I really can’t afford an overhaul right now.” “Why does the mechanic think the engine needs a teardown?” I queried, finding it hard to imagine how a bad magneto could justify something so drastic. The owner explained to me that when the A&P removed the damaged left magneto, he observed that two of the steel balls from […]

Low compression doesn’t always require cylinder removal Sam’s 1979 Piper PA-34-200T Seneca II was in the shop, and Sam was not happy. The shop had just done a compression test on the plane’s two Continental TSIO-360-EB3B engines and had given Sam some unwelcome news…  “Compression on left #4 is 35/80 and right #3 is 31/80,” Sam reported. “These engines are factory rebuilds installed in 2014, and they’ve been flying about 150-200 hours per year. The left engine had cylinder #4 replaced less than 1,100 hours ago and now needs to be replaced again. The right engine had cylinder #3 replaced only 500 hours ago and now needs to be replaced again. Apparently, I am doing something drastically wrong with these engines. It cannot be normal to have to replace NINE cylinders in 1,750 hours—two of them TWICE! What am I doing wrong?” Repetitive cylinder removals like the ones Sam experienced often trigger such guilt feelings, but the truth is that usually it’s not the fault of the owner or pilot. More likely they’re the fault of trigger-happy mechanics who were trained that low compression automatically requires removing the cylinder.  It doesn’t. What it does require is a good borescope inspection […]

Chasing down an elusive charging system gremlin Intermittent problems are the worst! They always seem to happen at the worst possible time, like when you’re in the middle of nowhere away from home base. They never seem to happen when you want them to happen, like when you’re trying to show them to your A&P so he can troubleshoot and fix them.  Case in point: Nearly 30 years ago, not long after I bought my Cessna 310. I was in the middle of a 4,000-mile cross-country that took me from California to Illinois, Kansas, Oklahoma, and back home to California. I was not an A&P at the time, simply a maintenance-involved airplane owner. (The A&P would come a decade later.) The first sign of trouble occurred as I was starting engines at Champaign, Illinois headed for Wichita. With both engines running, I noted that the amber warning light marked “ALT FAILURE: R ALT” did not go out the way it should have. I didn’t know whether this was a genuine alternator failure or just a malfunctioning idiot light, but figured I’d better try to find out.  I shut off the known good alternator (the left one) to see what would […]

How often does your propeller REALLY need to get overhauled? “Your prop is due for overhaul,” says your IA who you hired to do your annual inspection. “It’s been six years.” If your airplane has a constant-speed prop, overhauling it is going to set you back about $3,000 including removal and installation labor.  If it has deice boots, figure another $1,000. If you fly a twin like mine with two full-feathering constant-speed deiced props, well…ouch! Nowadays most props have a TBO of 2000 or 2400 hours and 60 or 72 months, whichever comes first. Doing the math, you’d have to average more than 400 hours per year for the 2000 or 2400 hours to come first. For most of us, it’s the calendar time component of the TBO that always comes up first. The average owner-flown GA airplane flies roughly 100 hours a year, which means that the prop will come “due” for overhaul after just 500 or 600 hours. If you fly less than 100 hours a year, it’s even worse. Do we really have to overhaul our props every five or six years regardless of how few hours are on them? Does it even make sense to do […]

What to do about uncomfortably high CHT For decades now, I’ve been preaching that the two keys to piston aircraft engine longevity are avoiding extended periods of disuse and managing CHT. If you allow your engine to sit unflown for weeks at a time, you risk internal corrosion—and corrosion is the number one reason that engines fail to make TBO. If you allow your CHTs to get too hot, you increase the stress on the engine’s reciprocating components (especially connecting rod bearings and bushings, piston pins, and valves), and increase the risk of catastrophic failure from destructive detonation, preignition, and head-to-barrel separation. In a perfect word, we would have sensors in each of our cylinders measuring peak combustion chamber pressure and instrumentation that would let us see this in the cockpit. This is exactly the way engines are instrumented when they run on GAMI’s engine test stand in Ada, Oklahoma—the most sophisticated piston aircraft engine test facility in the world. But it’s not practical to install this sort of instrumentation in our aircraft, so CHT is the best proxy for internal cylinder pressure (ICP) that we have. If we want to protect our engines against excessive ICP, we need to […]

This cutting-edge technology could revolutionize GA maintenance. The exhaust valve is the most likely component of a piston aircraft engine to fail catastrophically. When one fails, combustion ceases in the cylinder, the engine loses power and starts running rough. This usually results in a precautionary landing—on-airport if you’re lucky, off-airport if you’re not. It’s particularly serious with a four-cylinder engine, because a four runs a lot worse on three than a six does on five. Occasionally, the liberated valve fragment gets wedged into the piston crown, which can shatter the piston and cause a total power loss, sometimes with fatal results. That’s why it’s so important to detect incipient exhaust valve failures early before they can cause serious problems. The traditional way is the annual compression test, but that isn’t a very reliable method because loss-of-compression typically doesn’t occur until the valve is very sick and close to failing.  A borescope inspection is vastly better and can detect failing valves a lot earlier. AOPA publishes a great poster to help mechanics understand what to look for—Google “Anatomy of an Exhaust Valve Failure.” Unfortunately, most shops don’t do regular borescope inspections, and the ones that do typically do them only at […]

If your A&P seems over-cautious and self-protective, there’s good reason. By Mike Busch Mechanics have always been subject to FAA sanctions: certificate suspension or revocation, fines, warning notices, letters of correction, and remedial training. But enforcement actions against GA mechanics were exceedingly rare. The most common way for a mechanic to run afoul of the FAA is to “pencil whip” a logbook entry—for example, stating that some Airworthiness Directive (AD) was complied with or some other inspection or repair was performed—and then the FAA finds that the work wasn’t actually done as documented. If a mechanic is caught “autographing a lie” by the FAA, his certificates are probably toast. That said, it’s pretty easy for mechanics to avoid getting crossways with the FAA. The regulations that govern mechanics (Part 43) are far more concise and understandable than those that govern pilots and aircraft owners (Parts 91). Part 43 contains just 13 rules and they’re remarkably straightforward. Reduced to its essentials, Part 43 simply requires that a mechanic: Pretty commonsense stuff. A mechanic who makes a good-faith effort to follow these simple rules is unlikely to get hassled by the Friendlies. Civil Liability But an A&P who complies with these regs […]

When piston airplanes are fueled with Jet A, bad things can happen. On March 2, 2008, a turbonormalized Cirrus SR22 was destroyed when it crashed shortly after takeoff in Rio de Janiero, Brazil, killing all four people aboard. Shortly after the aircraft departed from runway 20, the airplane’s engine lost power, and the aircraft hit a building and exploded. Further investigation revealed that the aircraft had been refueled with Jet A instead of 100LL. On April 17, 2015, a Cessna 421B crash-landed on a highway shortly after takeoff from Lufkin, Texas, resulting in one serious and two minor injuries. According to the pilot, the aircraft seemed to perform normally during the runup, takeoff and initial climb. Passing 2,100 feet AGL, the left engine sputtered and lost all power. Within 30 seconds, the right engine also lost all power and the big cabin-class twin descended for a forced landing. The airplane landed hard, damaging the wings and fuselage and rupturing the right fuel tank, finally coming to rest in the grassy median of a highway. The smell of jer fuel was prominent at the accident scene. Investigators found that the FBO’s Jet A truck had recently had its wide duckbill-style nozzle […]

Lessons learned from geriatric engines. Time Between Overhaul (TBO) is a strange concept. The FAA, in its infinite wisdom, requires aircraft engine manufacturers to publish TBOs for their engines, but doesn’t require aircraft owners to abide by them. You are free to continue flying behind your engine as it remains airworthy.  Yet many owners and mechanics start getting nervous as they see tach time approach published TBO. Countless numbers of healthy engines are needlessly euthanized when their time-in-service approaches that consecrated number. For Part 91 operators, doing so is not an FAA requirement—it’s more like a religious belief. My Teachable Moment teach·a·ble mo·mentnoun(U.S.) an event or experience which presents a good opportunity for learning something about a particular aspect of life. [Oxford English Dictionary] My teachable moment that convinced me to stop believing in overhauling at TBO came about 30 years ago. In 1987, I purchased a Cessna 310 twin whose two TSIO-520 engines were just 100 hours shy of Continental’s published TBO of 1,400 hours. It didn’t take long for me to get there. When I did, I asked for advice from several friends who were veteran A&P/IAs. (This was long before I was an A&P myself.) Their unanimous […]