Articles List


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 […]

The Tale of Two Prebuys

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 […]

Minimally Invasive

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. […]

Savvy’s Borescope Initiative

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 […]

Monitor-Specific FAQs

Concerning E.I. UBG-16, MGL and GRT monitors How do I upload data from a UBG-16? Files that come from a UBG-16 do not contain “heading names” for each of the columns in the file (each column represents a data series, such as EGT1). As such, if you were to upload such a file to SavvyAviation, […]

Choosing and Upgrading Your Engine Monitor

Aircraft owners often ask us for advice about what kind of engine monitor equipment we recommend installing in their airplanes. Owners who already have engine monitors installed often seek advice about upgrading them with additional capabilities or replacing them with newer, more advanced equipment. Engine monitor technology has been a fast moving target. More and […]

In-Flight Diagnostics

The best way to diagnose an engine problem is usually in the air. Note to reader: The procedures discussed in this article for gathering flight test data are described more fully in the “Flight Test Profiles” document found under the “Learn More” or “Help” menu items. Pease refer to that document when performing the flight […]

Controlling the Combustion Event

Each time you change mixture, RPM or MP, it affects combustion timing. Understanding how is your best defense against harming your engine by doing something dumb. My last few columns focused on the physics of the combustion event in Otto-cycle engines. I’m sure this was fascinating to the two or three of you who are […]

Detonation and Pre-Ignition

Often confused and misunderstood, these two abnormal combustion phenomena are as different as night and day. Although we often hear people describe what goes on inside the cylinders of an Otto-cycle engine as being an explosion – i.e., a violent, nearly-instantaneous event – it’s not. The air-fuel charge does not explode when ignited by the […]

Understanding CHT and EGT

These two key measurements can tell us a lot about what’s going on inside our cylinders. My column last month talked about the fact that our piston aircraft engines convert only about one-third of the energy contained in avgas into useful energy to the propeller. About half the fuel’s energy goes out the exhaust pipe, […]

Interpreting Your Engine Monitor

The modern probe-per-cylinder digital engine monitor is a marvelous tool for keeping tabs on your engine’s health and troubleshooting its maladies. Here are some tips for figuring out what those bars and digits mean. This is embarrassing, but I might as well come clean: Up until 2003, I was still flying my Cessna T310R with […]

Ending the War on Jugs

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 […]

Unleaded Avgas—Cure or Curse?

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 […]

Time & Materials

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 […]

Deadly Switches

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 […]

Miracle in Sioux Falls

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 […]

Fortunate Catch

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 […]

Legal interpretations

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 […]

Unbelievable Compression

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 […]

Here to Help?

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 […]

Mechanic Crisis

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 […]

Booted Out of an Annual

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 […]

Ethics of Misdiagnosis

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 […]

A Matter of Trust

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 […]

Obsessed with EGT

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 […]

System Awareness

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 […]

When Data Doesn’t Look Right

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 […]

Real-Life Breakdowns

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 […]

What Price Speed? 

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.  […]

On a Short Leash 

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 […]

Disastrous Annual

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 […]

TBO 5000!

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 […]

What we have here is a Failure to Rotate

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 […]

Tulip Fever?

“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 […]

Grading on the Curve

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 […]

Spring-Loaded to Teardown

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 […]

Cylinder Rescue

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,” […]

Balky Alternator

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 […]


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 […]

Hot Heads

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 […]

Machine Learning

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 […]

A Mechanic’s Liability

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 […]


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 […]

The Great Beyond (TBO)

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 […]

What Plane Should I Buy?

Thoughts on finding a good purchase candidate An extraordinary number of GA airplanes were bought and sold in 2020. I imagine this was somehow related to the pandemic, although I’m not sure exactly how. What I do know is that my company had been averaging about 10 prebuys per month in 2019, but by the […]

Annual Deadlock

What happens when an owner and an IA can’t agree? By Mike Busch Sam is a pilot, engineer and serial entrepreneur who lives near Washington DC. About 10 years ago, he bought a 1966 Cessna 182J Skylane that is based and maintained in nearby Maryland. It’s been a pretty economical airplane to operate and maintain. […]

How Risky is Maintenance?

An FAA review of 10 years of NTSB data tries to quantify the risk. I’ve been known preach about the virtues of maintenance minimalism—a.k.a. “if it ain’t broke, don’t fix it”—and the risk of maintenance-induced failures—a.k.a. “MIFs.” But just how risky is maintenance? How often to MIFs occur? How serious are the consequences when they […]

How Mags Fail

Preventing and dealing with magneto-ignition system failure. Both the FARs and their predecessor CARs require that certificated spark-ignition recip-rocating aircraft engines—the kind most of us fly behind—have fully redundant dual ignition systems: PART 33—AIRWORTHINESS STANDARDS: AIRCRAFT ENGINESSubpart C—Design and Construction; Reciprocating Aircraft Engines§ 33.37   Ignition system. Each spark ignition engine must have a dual […]

 How Mags Work

The spark plugs in most piston aircraft engines are still powered by 120-year-old technology. My airplane’s piston engines utilize a magneto ignition system. If you’re flying a certificated airplane, chances are good that yours does, too. The fact that we’re still stuck with these superannuated mechanical black boxes is a testament to just how hard […]

It’s Baffling

Rigid baffles and flexible baffle seals are critical in keeping your engine cool. The Cessna T210 owner was clearly frustrated with his new engine installation: “I recently had my engine rebuilt and had a new baffle kit installed. The CHTs for cylinders #5 and #6 are always 20ºF to 30ºF hotter than the rest. During […]

Good Eyes! Great Catch!

Maintenance-induced problems are common, and it often an experienced pair of eyes to diagnose them. Elko Regional Airport (KEKO) is located in northeast Nevada at an elevation of 5,000 feet above sea level, and is known for its competitive avgas prices. It’s pretty much in the middle of nowhere…but if you happen to be flying […]

Your Engine’s Lifeblood

There’s a lot more to piston aircraft engine oil than you might think When it comes to piston aircraft engines, the role of engine oil is complicated. It lubricates moving parts to reduce friction and wear, but that’s only one of six key functions it performs, and perhaps not even the most important one. The […]

The Looming Mechanic Shortage

What if your airplane breaks and there’s no one to fix it? Being a dyed-in-the-wool technology freak, I drive a Tesla Model 3. It has been a superbly reliable vehicle that doesn’t require maintenance very often. But when it does, I take my Tesla to the nearest Tesla dealership, where it is worked on by […]

Fresh Annual

Why it’s no substitute for a proper independent prebuy. Every month I receive hundreds of emails from aircraft owners seeking advice or assistance. For the most part, I genuinely enjoy these interactions and the opportunity to help fellow aircraft owners.  Occasionally, however, I run into something that I find deeply disturbing. That was the case […]

Why Valves Stick…

…and how you can avoid engine damage and power loss if you know the answer. If you fly behind a Continental or Lycoming, each of your engine’s cylinders has two valves, intake and exhaust. The valves open and close by sliding in and out through close-tolerance tubes called valve guides that are press-fit into the […]

Justice Denied?

When it comes to GA crashes, the NTSB doesn’t always get it right, nor does the jury In December of 2012, a father and his son arrived at the airport to pick up the father’s Cessna 421C cabin-class piston twin, which had been in the maintenance shop for months receiving a new paint job and […]

Predictive Maintenance

Condition-based maintenance meets big data and artificial intelligence For the past 20 years, I’ve been preaching the gospel of Reliability-Centered Maintenance (RCM), the then-revolutionary philosophy of maintenance developed in the 1960s at United Airlines by aeronautical engineer Stanley Nowlan and mathermatician Howard Heap. RCM was almost universally adopted by the airlines in the 1970s, by […]

Hot Seat

Is it legal to install uncertified equipment in a certificated aircraft? I receive and answer hundreds of emails each week from aircraft owners, pilots and mechanics who have maintenance-related questions. One I received several weeks ago seems worth sharing: Mike, I need your help. I am a member of flying club, and during the recent […]

Risky Business

Why it’s nearly impossible to install a cylinder properly when the engine is on the airplane. Cylinder replacement is a highly invasive and risky procedure with a long history of causing catastrophic in-flight engine failures that cause airplanes to fall out of the sky. I have been personally involved with at least a half-dozen of […]

Shear Joints

When using fasteners loaded in shear, things can get interesting. Last month, I wrote about joints involving threaded fasteners loaded in tension—that is, along the bolt’s longitudinal axis. Such “tension joints” are used to fasten connecting rods to crankshafts, cylinders to crankcases, and even occasionally wings to fuselages (notably in Beechcraft airplanes). I emphasized the […]

Tense Bolts

When using threaded fasteners in tension, it’s all about the preload. Threaded fasteners are ubiquitous in aviation. Look at any GA aircraft and you’ll find hundreds of them if not thousands. They attach wings to the fuselage, cylinders to the crankcase, connecting rods to the crankshaft, and instruments and avionics to the panel. They hold […]

Hostage Situation

Don’t fall victim to an overzealous mechanic. Mark is the owner of a beautiful Cessna 185 Skywagon based in the San Francisco Bay area. Awhile back, Mark and his wife travelled to Minden, Nevada in this airplane to visit with Mark’s mother-in-law who was ill. A few days later, they returned to the airport intending […]


Thoughts about being temporarily booted out of my hangar. From the time I first acquired my Cessna 310 in 1987, it has been hangered at Santa Maria Public Airport. Initially, I kept it in a large community hangar. Then in 2003, after a long wait on the airport hangar list, I was able to secure […]

What is Preventive Maintenance?

What may you do to your aircraft without A&P involvement? More than you might think. The FAA defines who may perform maintenance on certificated aircraft in FAR 43.3. This rule lists all the usual certificated suspects: mechanics, repair stations, air carriers, repairmen employed by a repair station or air carrier, and (under certain conditions) aircraft, […]

FAA’s Safety Continuum

The Friendlies are remarkably friendly to Part 91 folks Aircraft owners and pilots love to bash the FAA. We grumble and whine about all the labyrinthine regulations and requirements the Agency burdens us with, and how much it increases our complexity and cost of flying. I’m occasionally guilty of this myself—witness my “Double Standard?” column […]

Double Standard?

Why aren’t A&Ps trained as well as pilots are? I never really wanted to become an A&P. All I really wanted was to be able to maintain my own airplane without adult supervision.  Heck, I’d been doing virtually all the maintenance of my 1979 Cessna Turbo 310 myself for about 10 years. The various A&Ps […]

I Wanna Sue!

When things go awry in the sky, litigation isn’t necessarily the best remedy. My email inbox contained a message with the subject “Legal Question – Advice Needed.” That didn’t surprise me because although I’m not a lawyer, I do regularly participate in aviation litigation—mostly arising from air crashes—as an expert witness and consultant, mainly in […]

A Matter of Policy

Understanding aircraft insurance If you own an aircraft, you probably have aircraft insurance. Whether it’s the right amount of the right coverages is worth exploring. Here’s what I’ve learned in my 50+ years of aircraft ownership plus extensive discussions with veteran industry insiders who have forgotten more than I’ll ever know on the subject. Anatomy […]

Rush to Judgment

Before doing something expensive or invasive, slow down “My Cirrus SR22’s oil pressure has been slowly decreasing,” reported Oliver, one of my company’s managed maintenance clients. “At full power the pressure used to be 41-43 PSI, but over the past three months it has dropped to 36-39, and half the time I get a low […]

Preheating: Whys and Hows

Not preheating a cold engine is a effective way to damage it Preheating is important. A single cold start without proper preheating can produce more wear on your engine in less than a minute than 500 hours of normal cruise operation  I’m often asked how cold it has to be before preheating is necessary. There’s […]

Powerplant Resurrection

Reviving an engine that has been inactive for months or years Piston aircraft engines hate to sit unflown. During lengthy periods of disuse, the protective oil film strips off critical surfaces like cylinder walls, cam lobes and tappet faces, exposing them to risk of corrosion pitting. Then afterwards, when the engine is finally “dry started” […]

Errors of Distraction

When mechanics get interrupted, bad things can happen I was recently contacted by the owner of a Cessna Hawk XP (R172K)—I’ll call him “Sam”—who seemed rather shaken by a recent series of events. He told me he was a student pilot with solo flight privileges and ready to make his first solo cross-country flight in […]

Breaking Good

Taking the complexity out of cylinder break-in From time to time, every piston aircraft owner faces the question of how best to break-in new cylinders. Sometimes this involves just one or two newly-replaced cylinders, other times all cylinders have been replaced simultaneously (“top overhaul”), and yet other times the entire engine has been major overhauled […]

Just Inspect It, Please

Mechanics should never make repairs without owner approval The co-owner of a Beechcraft Bonanza emailed me that his airplane had been inspected and maintained by a trusted mechanic at his home field in California until this year, when the mechanic retired. Forced to use another shop for this year’s annual inspection, the owner and his […]

Post-Maintenance Checklist

What to do when you pick up your aircraft from the shop My company employs 14 A&P mechanics, 11 of whom are very seasoned IAs with decades of GA maintenance experience. The other day, one of them was asked by a client what he should look for during the preflight immediately following an annual inspection. […]

Operating Oversquare

The myriad benefits of high manifold pressure and low RPM I bought my first airplane at age 24 shortly after I relocated from New York to California. It was a brand new 1968 Cessna 182 Skylane that I picked up at the Cessna delivery center in Wichita, and flew home to California. In preparation for […]

Turbo Failures

They can be deadly if the pilot hasn’t been taught what to do The release of my book Mike Busch on Engines prompted lots of reader correspondence. One particularly interesting email came from the owner of a 2007 Cessna Turbo Stationair (T210H)—I’ll call him Chuck—based in Aspen, Colorado: I am terrified of the turbocharger. There […]

Piston Powerplant Progress

It has been a lot like watching paint dry I recently completed work on my second book, a 500-page monster titled Mike Busch on Engines (available on Amazon). It was a yearlong effort that involved reviewing hundreds of my past articles about piston aircraft engines, deciding which were still relevant, organizing them into a coherent […]

Fire in the Hole

Spark plugs start the fire going, and need some TLC We all know what aircraft spark plugs do: They accept high-voltage pulses from a magneto or electronic ignition unit and produce an electric spark inside the cylinder’s combustion chamber to ignite the air/fuel mixture and initiate a flame front. They do this about 20 times […]

An IA’s Dilemma

“Autographing a lie” is the worst FAR violation a mechanic can commit By Mike Busch | A&P/IA An IA is an experienced A&P mechanic who—by virtue of having earned an Inspection Authorization—is empowered by the FAA to make aircraft airworthiness determinations in connection with annual inspections and major repairs and alterations. This is a weighty […]

The Bottom End

What’s inside your engine’s crankcase? Reciprocating aircraft engines come in a variety of different cylinder arrangements—radial, inline, V, and opposed—but most engines used in piston general aviation are horizontally opposed four- and six-cylinder engines. These engines have two banks of cylinders—left and right—directly opposite each other, with a single crankshaft between them. The crankshaft is […]

Where Fuel and Air Meet

Basics of piston aircraft engine fuel metering systems If you fly a piston aircraft, chances are it has a spark-ignition (SI) engines that burns gasoline. There also exist compression-ignition (CI) engines—also called diesels—that burn kerosene, but in today’s GA fleet they’re still few and far between. While CI engines spray liquid fuel at high pressure […]

Planes and Cars

Some thought-provoking comparisons I received a thought-provoking email from AOPA PILOT reader Nate Bissonette of St. Paul, Minnesota that started me thinking about differences between automobiles and GA airplanes. According to data from the U.S. Department of Transportation, the average American driver puts in 13,474 miles behind the wheel each year. Males drive more than […]

Making Metal Behave

How we coax metal aircraft parts into doing what must be done Metal is neat stuff. It’s strong, hard, and tough. It’s easy to form, work, shape and machine. It’s fireproof and can stand up to high temperatures. But these properties aren’t unique to metal.  Ordinary cotton fiber actually has higher tensile strength than the […]

Where’s the Smoking Gun?

When aircraft problems occur, we always want an explanation but don’t always get one I receive thousands of emails from aircraft owners each year, but this one was unusual. It was nearly 3,000 words long—twice the length of this article. The 7,500-hour CFI who wrote it clearly needed to “vent” about something that scared the […]

GA Engine Summit 2017

Industry and the FAA meet to discuss GA piston engine issues In mid-September 2017, I was invited to participate in a two-day “GA Engine Summit” meeting in Burlington, Massachusetts—about 30 minutes’ drive northwest of Boston. This meeting was a long-awaited sequel to the first GA Engine Summit that took place in December 2015, which I […]

Grand Theft Propeller?

Can a mechanic hold an aircraft hostage? Or just part of it? The mechanic who phoned me sounded agitated. He explained that he’d been an A&P for quite a while, but had earned his IA recently and was relatively new to the business of doing annual inspections. An owner had brought a 1950s-vintage Piper PA-22 […]

The Disaster That Didn’t Happen

Thanks to teamwork, tens of thousands of aircraft owners dodged a devastating bullet As I write this, the aviation blogosphere and Twitterverse are abuzz over the near-disaster at San Francisco International Airport, when an arriving Air Canada A320 on a night visual approach to runway 28R came scant seconds—and less than 100 feet—from touching down […]

By The Book?

Must manufacturer’s maintenance guidance be followed? Have you ever had your mechanic tell you something like this: “It has been six years since your propeller was last overhauled, so we’re going to have to overhaul it this year as required by Hartzell.” “Your magnetos are past due; Continental requires that they be overhauled every four […]

Back In The Game

The first flight after maintenance is special. My client wanted to buy a Bonanza A36, and narrowed his search to two promising candidates. One had recently suffered a “forgot to remove the tow bar” prop strike, necessitating an engine teardown inspection and prop overhaul, but the seller was very upbeat, suggesting that his misfortune actually […]

Traveling Toolkit

What “stuff” do you carry in your airplane? It’s a well-known fact: Most mechanical problems occur between Friday night and Sunday afternoon when you’re hundreds of miles from home base. The difference between a minor annoyance and a major travel disruption can hinge on whether you brought along the “stuff” necessary to get back in […]

Outside the Box

Compared to Lycocontisauruses, the Rotax 912 is delightfully different.  The past 20 years may well have yielded more outside-the-box ideas than any other comparable period in history. The iPod redefined the music industry in 2001. Facebook, YouTube and Twitter (2004–2006) redefined how we interact. The iPhone (2007) not only redefined “cell phone” but changed our […]

Borescope Ascendancy

Time to topple the venerable compression test? The differential compression check has been a mainstay of piston aircraft engine maintenance for the last 80 years. Like anything else in aviation that’s been around for a long time, various Old Wives’ Tales (OWTs) have evolved about the procedure, passed on from journeyman mechanic to apprentice, and […]

Field Approvals

Do you really need the FAA’s blessing to modify your aircraft? A Bonanza owner wanted to power his portable GPS and his iPad simultaneously in flight, so he asked his avionics shop to install an extra cigar lighter socket on the panel. He was told that doing so would require preparing an FAA Form 337 […]

Buy…or Walk Away?

Thoughts about when to purchase and when to pass. Who among us hasn’t spent hours looking at Trade-A-Plane or Aircraft Shopper Online looking for that perfect low time airplane with a fresh engine overhaul, new paint and interior, great avionics, and a bargain price? Dream on! Common sense says if you find one, there’s probably […]

Actionable Intelligence From Big Data

Comparing individual aircraft to others of their ilk. Last month, I described some interesting studies my colleagues and I have been doing with “big data” collected from digital engine monitors aboard more than 7,000 airplanes over more than a million flights. We demonstrated empirically that significantly more flights are flown with headwinds than with tailwinds, […]

General Aviation and Big Data – Part 1

Analyzing data from a million GA flights can yield interesting results. Pilots have long suspected that when it comes to headwinds and tailwinds, the deck is stacked against them.  I think the late Bob Blodget, Senior Editor of FLYING Magazine, captured how most pilots feel about this when he wrote that “we all come to […]

Buyer Beware

If a plane is listed for sale cheap, there’s always a reason. “Hey Mike, this is Danny in Louisiana,” read the email. Danny is one of my clients who used to own a Cirrus SR22 and now flies a Cessna 182 Katmai STOL conversion. “Would you look at this 1965 Cessna 310I on eBay and […]

Stuck in Reykjavik

When the pilot of a round-the-world flight found himself AOG in Iceland with electrical issues, remote diagnosis saved the day. Ademilola “Lola” Odujinrin has a passion for aviation. He’s 37 years old, resides in Nigeria with his wife and two school-age children, and was first bitten by the flying bug at age 7 when his […]

Whoa! This Isn’t an Inspection!

A&Ps are trained to find things wrong with your aircraft. But there’s a time and place for that, and it comes once a year. It was the week before AirVenture 2016. Normally, I would never perform any maintenance on my trusty Cessna 310 immediately before departing on an important trip, for fear I might break […]

Differential Diagnosis

Fixing is usually the easiest part of aircraft maintenance. Figuring out what’s wrong is usually the hardest part.  By Mike Busch | A&P/IA A funny thing happened on my way to Milwaukee… It was 2013 and I was flying my trusty 1979 Cessna T310R to speak at the annual national convention of the Flying Physicians […]

Whom Should You Trust?

Before following expert advice, choose your expert with care.  We aviators are of necessity a trusting lot. We constantly trust other people with our lives, our safety, and our financial wellbeing. We trust nameless and faceless air traffic controllers to keep us from hitting anything. We trust our A&P to keep our aircraft safe to […]

What Does “Airworthy” Mean?

The definition of this ubiquitous term depends on the context.  A bit over two years ago, a fellow I’ll call “Bob” bought a 10-year-old Cirrus SR22 from another fellow I’ll call “Sam.” Prior to the purchase, Bob had a very thorough pre-buy performed by an independent A&P/IA, who gave the airplane a clean bill of […]

Is Repair a Lost Art?

Aircraft parts are expensive, so we really should be repairing rather than replacing them whenever possible.  When the co-owner of a 1976 Cessna 172M emailed me, she had just come from talking to her mechanic and was clearly in a state of sticker shock: “Where can I locate a used battery box for my Skyhawk […]

A Mechanic’s Signature

What do you do if a mechanic working on your airplane tells you, “I can’t sign it off”? Dick is the maintenance officer of an 80-member flying club in northern New Jersey. The club operates several aircraft including a 2011 Cessna Skyhawk SP powered by a Lycoming IO-360-L2A engine. The engine has now reached 2,400 […]

LSAs: Who’s Guarding the Henhouse?

The new crop of factory-built LSAs are impressive and exciting, but the maintenance regulations for them are…ah…different I recently returned from the U.S. Sport Aviation Expo in Sebring, Florida, the foremost aviation event devoted to light sport, homebuilt, and ultralight aircraft. I was a first-timer at this event, having been invited by the show organizers […]

Inaugural GA Engine Summit

FAA’s Engine & Propeller Directorate meets with GA to improve how ADs are dealt with. Early last December, I had the privilege of attending a two-day meeting at the offices of the FAA’s Engine & Propeller Directorate (EPD) in Burlington, Mass., about 30 minutes’ drive northwest of Boston. The meeting was billed as the first […]

Fear and Balderdash

Maintenance decisions need to be fact- and evidence-based. The current owner of the vintage J-model Bonanza emailed me for advice. He’d purchased the airplane just four months earlier with a fresh annual inspection, and was already stressing out about what to do about his engine at the next annual eight months hence. According to the […]

Watch Your Language!

When requesting maintenance, the words you use can be very important. The voice on the phone identified himself as a Cessna 182 owner—let’s call him Jim—who said he was considering overhauling his O-470-R engine and could use some advice. I asked Jim why he was considering overhauling his engine, thinking maybe it was approaching TBO […]

Insurance Woes

When repairs are covered by insurance, it’s the owner’s job to keep things under control. By the time he contacted me, the aircraft owner—let’s call him Fred—was boiling mad. Fred had bought an airplane last year, and the pre-buy and subsequent annual inspection gave his new-to-him bird a clean bill of health. Yet even before […]

Blame the Hardware

When pilots screw up, plaintiff lawyers always seem to sue equipment manufacturers. In June 2014, I posted an item to the AOPA Opinion Leaders Blog titled “The Dark Side of Maintenance.” It talked about what I refer to as “maintenance-induced failures” (or “MIFs” for short). In my blog post, I gave a bunch of examples […]

Tectonic Shifts

Changing competitive landscape in piston GA aircraft and engines. By Mike Busch I just returned from EAA AirVenture 2015 in Oshkosh, where aviation firms traditionally make major announcements. This year was no exception. One of the most significant announcements to me (as an aircraft owner and maintenance professional) was the one by Continental Motors that […]

Don’t Go Overboard

Suppressing the urge to overreact to and overkill problems. The Bonanza owner encountered an engine problem 11 hours after his aircraft came out of annual. He had crossed the Sierra Nevada Mountains VFR at 12,500 feet westbound enroute to the Bay Area, and was descending through 11,000 feet when he felt a bit of engine […]

Backdoor Rulemaking?

Cessna gets caught with its hand in the FAA’s cookie jar. On February 10, 2014, the Cessna Aircraft Company did something quite unprecedented in the history of piston GA: It published a revision to the service manual for cantilever-wing Cessna 210-series airplanes that added three new pages to the manual. Those three pages constituted a […]

Discrepancy Discretion

Who decides whether or not your aircraft is airworthy? By Mike Busch My column in the May 2015 issue of EAA Sport Aviation, titled “Fix It Now…Or Fix It Later,” discussed how to deal with mechanical problems on the road. It offered some specific advice about how pilots and aircraft owners can decide whether a […]

Why I Hate Pulling Jugs

It’s riskier business than most owners or A&Ps realize. Regular readers of this column know how I feel about changing cylinders in the field. I hate it. Especially when several cylinders are changed at one time; this is risky business. Changing them all (the so-called “top overhaul”) is even riskier. In my column in the […]


Clearing up confusion about aircraft mods. You want to modify your certificated aircraft. Let’s say it’s something simple like adding an extra cigarette lighter socket to power your portable GPS or cellphone charger. Or installing an external mirror so you can verify your landing gear is down. Or tweaking your engine cooling baffles to get […]

Fix It Now…Or Fix It Later?

You’re on a trip when a mechanical arises. First you mutter the obligatory expletives, and then you must decide: Should you get the problem fixed now, or live with it until you get home? Nothing is more frustrating than dealing with mechanical problems on the road. It’s always uncomfortable when you’re far away from your […]


Oleopneumatic shock struts use hydraulic fluid, compressed gas, and darn clever engineering to improve our landings. If every one of our landings were a “greaser” and if runways never had bumps or potholes, then the landing gear on our airplanes could be dead simple. Wheel assemblies rigidly attached to the airframe would work fine, just […]

150 Year-Old Technology

Most of us are still flying (and driving) behind powerplant technology that dates from the 19th century. The original four-stroke Otto-cycle internal-combustion engine was patented in 1862 by a Frenchman named Alphonse Beau de Rochas. More scientist than engineer, de Rochas never actually built an operational engine. The first working prototype was built by a […]

The Perfect Mechanic

What to look for when choosing an A&P to work on your aircraft. Over the past 45 years, I’ve had the opportunity—and often the privilege—of  working with hundreds of aircraft mechanics. At first it was as a naïve aircraft owner having them perform inspections and repairs on my airplane. Later it was as a student […]

Silent Killer

If you think CO-related accidents are rare, think again… On January 17, 1997, a Piper Dakota departed Farmingdale, New York, on a planned two-hour VFR flight to Saranac Lake, New York. The pilot was experienced and instrument-rated; his 71-year-old mother, a low-time private pilot, occupied the right seat. Just over a half-hour into the flight, […]

Prebuy Do’s and Don’ts

If you’re buying an aircraft, here’s how to structure the prebuy.  Over the past six months, my company’s prebuy activity has gone right through the roof. We’ve been responding to 30 to 50 prebuy requests a month, perhaps four times as many as we were seeing a year ago.  I’m not quite sure what this […]

Energy and Efficiency

Why are our piston aircraft engines so @#$%*! inefficient? Our piston aircraft engines convert chemical energy into mechanical work, but they don’t do it very efficiently. It turns out that only about one-third of the energy contained in the 100LL we burn winds up getting to the propeller and doing useful work to propel us […]

Human Error

“To err is human…” but when humans make mistakes working on aircraft, bad things can happen. During the century since the Wright Brothers first flew, the predominant perpetrator in aircraft accidents has shifted dramatically from machine to human. Today, human error is responsible for about 90% of aircraft accidents and incidents. It’s not that people […]

A Mechanic’s Liability

If your mechanic seems over-cautious and self-protective in his approach to maintaining your airplane, he has good reason. Mechanics have always been subject to FAA sanctions: certificate suspension or revocation, fines, warning notices, letters of correction, and remedial training. But during the 1960s and 1970s—the heyday of piston general aviation—such enforcement actions against GA mechanics […]

A Highly Modified Skyhawk

How does an IA deal with a situation like this? The maintenance officer of a small flying club asked if my company would be willing to manage the maintenance of the club’s 1976 Cessna 172M. The airplane had been flying about 200 hours a year, and had faced a number of maintenance challenges. After trying […]

Cylinder Work: Be Afraid

It is nearly impossible to install a cylinder properly when the engine is on the airplane. Here’s why. I suppose it comes as no surprise to readers of this column that I’m not exactly a fan of top overhauls. I never like to see any cylinder removed from any piston aircraft engine unless there’s absolutely […]

Scuzzy Skyhawk

Why a thorough, independent prebuy examination is so essential, even for a simple 172. The prospective buyer was looking for a Lycoming-powered Cessna 172 Skyhawk, and had a budget of $35,000. He searched online and found one being offered with an asking price in the high 20s, a price that left some room in his […]

Ferry Permits

If your aircraft isn’t airworthy but you need to fly it anyway, here’s how. As every pilot knows, it’s strictly against the rules to fly an unairworthy aircraft: §91.7   Civil aircraft airworthiness. (a) No person may operate a civil aircraft unless it is in an airworthy condition. (b) The pilot in command of a civil aircraft […]

Not-So-Plain Bearings

There’s a lot more to engine bearings than meets the eye. According to Miriam-Webster, a bearing is “a machine part in which another part turns.” Most aircraft have lots of them.  Wheels spin on their axles with the help of tapered roller bearings. Magnetos, alternators, generators and starter motors incorporate ball bearings to support their […]

High Oil Consumption

Don’t do anything rash until you’re sure where the oil is going. A fellow named Ted phoned me to say that his 1984 Cessna T210 was in the shop for its annual inspection, and his mechanic was suggesting a $14,000 top overhaul. “Mike, I’ve read a lot of your articles and I know you’re not […]

Mechanic, Heal Thyself

All airplanes occasionally get sick. Even mine. Every year, I take my airplane on a big summer trip around the U.S., speaking at various aviation events and culminating with a week at EAA AirVenture. This year’s trip was 50 days long—June 17th to August 5th—and covered 6,500 nautical miles, put 40 hours on the Hobbs, […]

Damage History

The term “damage history” is not well-defined. Here are some thoughts on the subject. One of my clients just had a fancy digital engine monitor installed in his airplane. During the installation, the shop hired to do the work drilled a half-inch hole in a non-structural area of the cabin sidewall to accommodate the OAT […]

FAA’s War on Jugs: An Update

Yikes! It’s far worse than I expected, and it must be stopped. By Mike Busch I must be losing my touch. When I last wrote about this subject 9 months ago—in the February 2013 issue of EAA Sport Aviation—I reported that in 2009 the FAA effectively legislated out of existence Superior Millennium-brand investment-cast cylinders (that […]

Rough Engine

Understanding the underlying causes of engine roughness is the key to eliminating it. One of the most common squawks reported by pilots and aircraft owners is a rough-running engine. If the roughness can be duplicated during a ground runup, then the mechanic might have a chance to troubleshoot it systematically.  Most of the time, however, […]

Thinking Slow

Why many career A&Ps are not great troubleshooters. I recently had a fascinating exchange with my friend and colleague Paul New. Paul is an A&P/IA and a truly extraordinary aircraft mechanic who was honored by the FAA as the National Aviation Maintenance Technician of the Year in 2007 (the year before I was so honored). […]

AOG Rescue

A mechanical problem away from home is every aircraft owner’s worst nightmare. Here’s how one owner dealt with such a nightmare…with a little help. On an otherwise-peaceful Saturday morning, I received a panicky text message from Mark, a Cessna 185 owner from the San Francisco Bay Area. Mark said that he and his wife had […]

“But My Mechanic Says…”

Aircraft owners get lots of bad advice from their A&Ps. Ever wonder where the A&Ps get it from? “I know you’re a strong proponent of the in-flight mag check,” emailed the aircraft owner, “but I have been advised against doing this by my A&P due to concerns that I could get a serious backfire that […]

Compression in Context

Few aviation maintenance tasks are so misunderstood—and so responsible for inappropriate work and expense—as the routine differential compression test. It happens every year: We put our aircraft in the shop for its annual inspection. The IA pulls out the compression test gauges and measures each cylinder while we hold our breath and pray silently until […]

The Blame Game

When “stuff happens” to your aircraft, it’s not always someone else’s fault. Regular readers of this column know that I grumble a lot about “stupid mechanic tricks” made by career A&Ps who should know better. Some have accused me of mechanic-bashing. That’s a bit harsh, but I’ll readily admit to being a hard marker when […]

The Redundancy Trap

The best way to protect against the in-flight failure of any aircraft component is to have two. Or is it? CIVIL AVIATION REGULATIONSPART 13—AIRCRAFT ENGINE AIRWORTHINESSSubpart B—Reciprocating Engines§ 13.111   Ignition system. All spark ignition engines shall be equipped with either a dual ignition system having at least two spark plugs per cylinder and two separate electrical circuits […]

A Little Dab’ll Do Ya…In

Even a seemingly trivial mistake by a well-intentioned mechanic can have dire consequences. On April 19, 2005, a 1966 Beechcraft Debonair was cruising at 8,500’ on a VFR flight from Van Nuys to San Jose, Calif., when the pilot heard a loud noise and the Continental IO-550 engine started running rough. The pilot checked the […]

Diagnostic Tales from the War Zone

Troubleshooting is best accomplished by first gathering data and then analyzing it logically. The owner of a 2005 Cessna T182 was in Key West Florida when he experienced unusual roughness immediately after engine start. The EGT and CHT on the #3 cylinder seemed unusually low at first, but the roughness seemed to clear up before he […]

Separation Anxiety

Can we prevent these catastrophic head-to-barrel separations? On February 24, 2012, the National Transportation Safety Board issued Safety Recommendation A-12-7 to FAA acting administrator Michael Huerta, expressing great concern over 29 cylinder head fatigue failures of Titan-brand cylinders manufactured by Engine Components, Inc. between 2003 and 2009 and installed on Continental IO-520, TSIO-520 and IO-550 […]

How Much is Too Much?

There’s metal in your oil filter. Now what? “I’ve been a happy aircraft owner until this morning,” Frank wrote me. “My aircraft is in the shop for its annual inspection, and the mechanic just called to say that they found magnetic chips in the oil filter, and the big-bore Continental engine would have to be […]

Red Box, Red Fin

How NOT to lean your engine. At my July pilgrimage to EAA AirVenture in Oshkosh, I had the opportunity to speak to thousands of pilots and aircraft owners on a wide variety of subjects ranging from reliability-centered maintenance to TBO busting to corrosion, and to conduct a half-dozen informal hour-long Q&A sessions addressing whatever maintenance-related […]

Mini or Maxi?

Is your mechanic a minimalist or a maximalist? I’m an unabashed maintenance minimalist. I believe in doing only maintenance necessary to make an aircraft safe, reliable, and compliant with regulations. I believe that doing more maintenance than that is not only a waste of time and money, but that it also makes the airplane less […]

Flying Efficiently

In a world of $7 avgas, it’s more important than ever to get the best bang for the buck. How can we get the best fuel economy from our airplanes? Given the painful cost of avgas these days, this is a question on lots of airplane owner’s minds. That goes at least double for unfortunate […]

Cam Distress

When your engine finally needs to be overhauled, the most likely cause will be corrosion-induced distress to the cam lobes.  I recently received an email from a Skylane owner in Miami, Florida who was understandably upset after receiving bad news from his IA, and looking for a second opinion: “My 1980 Cessna 182Q went into […]


The decision whether or not to tear down an aircraft engine is among the most difficult and agonizing ones we make.  My company manages the maintenance of many hundreds of piston-powered GA airplanes, so we frequently deal with all manner of engine problems. Our biggest challenge involves diagnosing the problems and then deciding what work […]

Spark Plug Wars

We’re seeing an epidemic of Champion spark plug problems. Champion insists its plugs are fine and the problems are self-inflicted. The truth may be a bit more complicated.  By Mike Busch Premature failures of Champion-brand aviation spark plugs first showed up on my radar screen several years ago. My company manages the maintenance of nearly […]

The Decision Point

During every annual inspection, there’s a particular point in time when you and your IA need to sit down and make decisions. Regular readers of this column know how strongly I feel about aircraft owners taking charge of their maintenance and managing the mechanics and shops they hire to work on their aircraft. An owner […]

Trust But Verify

Before you approve any costly or invasive repair to your aircraft, make sure the discrepancy is real. Arguably the worst part of being an aircraft owner is the annual ordeal of putting your plane in the shop every 12 calendar months and then bracing yourself for bad news. Over the past 4 years, my company […]


A mechanical problem away from home is every aircraft owner’s worst nightmare. Here are some thoughts about how best to deal with one. As a tech rep for the three largest airplane type clubs in the world (ABS, CPA, COPA) and as the founder and CEO of the world’s largest professional maintenance management firm for […]

The Most Unforgivable Sin

Running out of fuel only happens to the other guy, right? I usually don’t write about experimental aircraft because my 45 years of aviation experience has been almost exclusively with certificated normal-category airplanes. However, I’m making an exception this month. This column was prompted by the June 16, 2001 crash of an experimental Lancair IV-P […]

How to Flunk an Annual Inspection

Under the FARs, an annual inspection is a pass-fail test. Sometimes failing is the best course of action. Of the nearly 200 rules in Part 91 of the Federal Aviation Regulations, far and away the most expensive for most aircraft owners is this one: § 91.409   Inspections. (a) …No person may operate an aircraft unless, within the […]

When to Overhaul

How do you decide when it’s time to overhaul your engine? If not at TBO, then when? Regular readers of this column know that I’m not a big fan of the idea of overhauling engines at TBO. I consider engine TBO to be a thoroughly discredited concept that has cost aircraft owners hundreds of millions […]


When are manufacturer-specified inspection, overhaul and replacement intervals mandatory for a Part 91 operator? “It has been six years since your propeller was last overhauled, so we’re going to have to overhaul it this year as required by Hartzell.” “Your magnetos are past due; TCM requires that they be overhauled every four years.” “We need […]

My $.02 On $6.00 AVGAS

My 1979 T310R is equipped with a Shadin fuel totalizer which—like my fuel gauges—is calibrated in pounds of fuel (rather than gallons). So when the price of 100LL reached $6.00 per gallon, I half-jokingly turned to a pilot friend who was flying with me in the right seat and explained that those fuel quantity and […]

Warranty Schmarranty!

You bought a $40,000 engine, and it turns out to be a lemon. That’s okay, you’re covered under warranty, right? Hmmm… On a breathtakingly beautiful spring day in April 2011, one of my clients landed his 1980 Cessna T210 at its home base—a high-altitude airport (5,000 feet MSL) surrounded by 10,000-foot mountainous terrain in all […]

Is your airplane too broken to fly?

The rules about flying with inoperative equipment are complicated, and have changed a lot. Here’s the latest. Is your airplane squawk-free? I know mine isn’t. At any given point in time, you’ll find a yellow Post-it Note on the instrument panel of my 1979 Cessna T310R listing all known squawks. Any time I notice a […]

Owner-Produced Parts

If your certificated aircraft needs a replacement part that’s ridiculously expensive or downright unobtainable, the FAA will allow you to produce one yourself.  The 1960s and 1970s were the biggest years for production of piston GA airplanes. By the peak production year of 1979, manufacturers like Beech, Cessna, Mooney, Piper, and others were pushing new […]

Battery TLC

The care and feeding of aircraft batteries. Last month, in Part 1 of this article, we discussed the construction, chemistry, types and characteristics of lead-acid aircraft batteries. This month, we’ll talk about the care and feeding of those batteries, including charging and discharging, conditioning, capacity testing, and deciding when a battery should be retired and […]

About Batteries

Sensitive and fragile compared to their automotive brethren, aircraft batteries need TLC if you don’t want to be left stranded. Aircraft batteries are the Rodney Dangerfields of general aviation. They get no respect. We let them sit unflown for weeks at a time, sometimes months. We deep-discharge them by forgetting to turn off the master […]

Is it safe? Is it airworthy?

We often treat the words “safe” and “airworthy” as if they were synonyms. They’re not.  On the landing roll, something didn’t feel right. The Cessna pulled strongly to the left. The pilot had to apply full right pedal and some right brake to keep it on the runway. As the pilot struggled to make the […]

Making Metal?

How to ensure that nothing is coming apart inside your crankcase.  I’d been working with a Bonanza owner in Memphis for several weeks helping him chase down a problem with his Lycoming engine. Yes, Lycoming—the aircraft was an A36 with a Machen conversion to a fire-breathing 350 hp Lycoming TIO-540-J2BD engine. The owner of this […]

The Waddington Effect

Contrary to popular belief, more maintenance isn’t necessarily better. Often it’s worse—a lesson that was learned during WWII. I’ve written at length in prior issues of EAA Sport Aviation on the subject of Reliability-Centered Maintenance (RCM), the scientific and engineering discipline of designing optimum maintenance programs to provide the highest levels of safety and reliability […]

Slippery Stuff

More about what aircraft owners should know about piston aircraft engine oil. Last month, we began our discussion of piston aircraft engine oil by discussing the types and properties of the various kinds of engine oil available, and I offered some thoughts about which oils I prefer and why. This month, I’ll continue the discussion […]

All About Oil

What aircraft owners should know about piston aircraft engine oil. This is the first of a two-part article about the lubricating oil we use in our piston aircraft engines, and we’ll be covering a lot of territory. We’ll discuss the various types of engine oil—monograde versus multigrade, mineral oil versus synthetic—and the pros and cons […]

The Mag Check

You’ve been doing mag checks since your first flight lesson, but are you doing them right? From your first days as a student pilot, you were undoubtedly taught to perform a “mag check” as part of each pre-takeoff runup. But do you know how to do it correctly, what to look for, and how to interpret […]

Return to Service

Mechanics approve an aircraft for return to service after maintenance by signing a logbook entry, but pilots actually return the aircraft to service by flying it. Never forget that on the first flight after maintenance, you’re a test pilot…so please act accordingly. For months, a client of mine had been searching for a Bonanza A36 […]

EGT Myths Debunked

Pilots still seem to have a lot of misconceptions about EGT. Let’s see if we can clear some of them up. These days, pilots of piston-powered aircraft seem to be fixated upon exhaust gas temperature (EGT). Scarcely a day goes by that I don’t receive a phone call or email or support ticket asking some […]

How To Destroy Your Engine

Destructive detonation and pre-ignition events can destroy your engine in two minutes flat. Know the symptoms, and act fast! At least once a year, I am contacted by an aircraft owner whose piston aircraft engine was destroyed or severely damaged by a destructive detonation or pre-ignition event. But lately, the pace seems to be quickening. […]

Exhaust Valve Failures – Part 2

We have the technology to prevent these failures by detecting them in the incipient phase. Last month we discussed how exhaust valves fail and why they sometimes fail prematurely. This month, we’ll shift our focus to how we can monitor exhaust valve condition, detect incipient valve problems, and deal with them before in-flight failure occurs. […]

Exhaust Valve Failures – Part 1

Exhaust valves are the most heat-stressed components in your piston aircraft engine, and the most likely to fail prior to TBO. Here’s what you need to know about them. I experienced my first in-flight exhaust valve failure about twenty years ago. The engine started running very rough (as you might expect of a six-cylinder engine […]

Work Orders and Invoices

Your maintenance shop’s paperwork can make all the difference between a good outcome and a nightmare. When he contacted me, the owner of a pristine turbonormalized A36 Bonanza seemed obviously frustrated: I manage to fly only 50 to 75 hours a year, but my annual inspections have been running between $8,000 and $12,000 every year […]

Who’s the boss?

Every pilot understands the notion of “pilot in command.” That’s because we all had some certificated flight instructor (CFI) who mercilessly pounded this essential concept into our heads throughout our pilot training. Hopefully, it stuck. As pilot-in-command (PIC), we are directly responsible for, and the final authority as to, the operation of our aircraft and […]

Is this engine airworthy?

How do we assess whether a piston aircraft engine is airworthy? Compression tests and oil consumption are only part of the story—a smaller part than most owners and mechanics think. My friend Bob Moseley is far too humble to call himself a guru, but he knows as much about piston aircraft engines as anyone I’ve […]

Reliability-Centered Maintenance (Part 3)

By Mike Busch To apply RCM principles properly to the maintenance of our piston aircraft engines, we need to analyze the failure modes and failure consequences of each major component part of those engines. Last month, we looked at the issue of catastrophic failures of piston aircraft engines, and saw that the predominant risk of […]

Reliability-Centered Maintenance (Part 2)

Last month, we examined the principles of RCM used by the airlines and military to achieve cost-effective maintenance. Now, let’s explore how RCM can be applied to our small GA aircraft, and especially to our piston aircraft engines. For three decades, the airlines and military have been using Reliability-Centered Maintenance to slash maintenance cost and […]

Reliability-Centered Maintenance (Part 1)

A strategy known as “Reliability-Centered Maintenance” has drastically reduced the cost of maintaining transport and military aircraft, while simultaneously improving dispatch reliability. Isn’t it time we applied this approach to piston GA? More than 30 years ago, in 1974, the U.S. Department of Defense commissioned United Airlines to prepare a report on the techniques used […]