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I Don’t Fly Enough

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

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

Take 2017 for example:

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

My 8,500 nm trip during Fall 2017.

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

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

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

I didn’t fly enough

Months I didn't fly

Months I didn’t fly my airplane during 2017.

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

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

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

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

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

Defenses

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

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

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

Care to join me?

Mike Busch is arguably the best-known A&P/IA in general aviation, honored by the FAA in 2008 as National Aviation Maintenance Technician of the Year. Mike is a 8,000-hour pilot and CFI, an aircraft owner for 50 years, a prolific aviation author, co-founder of AVweb, and presently heads a team of world-class GA maintenance experts at Savvy Aviation. Mike writes a monthly Savvy Maintenance column in AOPA PILOT magazine, and his book Manifesto: A Revolutionary Approach to General Aviation Maintenance is available from Amazon.com in paperback and Kindle versions (112 pages). His second book titled Mike Busch on Engines was released on May 15, 2018, and is available from Amazon.com in paperback and Kindle versions. (508 pages).

13 Comments

  1. Hey Mike, what do you think about engine pre-oilers? Do you think these help to mitigate periods of non-use for the engines. I have a pair on my Beech Duke and use them religiously, hoping to prevent the issues you outlined as I also sometimes go long stretches between flights.

    • Pre-oilers don’t help much with Lycomings because of their high-mounted camshaft. It’s really impossible to get oil to the cam lobes and lifter faces without spinning the crankshaft…unless the engine had been modified with STC’d Ney nozzles.

      Pre-oilers help a bit more with Continentals because they have a low-mounted camshaft, so oil forced into the main bearings fall onto the camshaft even if the engine is t running.

  2. Hi Mike!
    Years ago my mechanic recommended I add Marvelous Mystery oil to my fuel in my C-172 180Hp. Do you prefer Cam Guard over MMO? Is it bad/ or a waste to use both?

    • MMO can help with sticking lifters and perhaps with sticking valves, but it does nothing to inhibit corrosion. CamGuard is the best anti-corrosion additive I’ve come across.

      • I also use areoshell w100. Just changed 2 mos ago. How do you recommend starting CamGuard into my maintenance routine?

        • You can add CamGuard at any time. The proper amount is 5% of the oil volume (e.g., add one pint of Camguard to 10 quarts of oil). Add it again at each oil change. If you burn a lot of oil, add a bit each time you add a quart of make-up oil.

  3. Absolutely agree with you Mike. Unfortunately personal time scarcity often is the bane of frequent use of an airplane. My Cheetah basically sat for two years, outside, in the northeast, with only about 40 hours on a factory rebuilt engine. It distressed me knowing what was happening. At that point I decided to sell it rather than let it deteriorate further. Every now and then I miss having it, but free time just got in the way.

  4. When high-utilization passenger 727s and DC9s were converted to low-utilization cargo service in the 1980s, their JT8D engines began to corrode internally and a couple came apart internally when fatigue cracks initiated in corrosion pits in steel compressor discs. The solution included plating of steel disks and more frequent shop visits. If you can’t fly your airplane every two weeks or so, it would be advisable to at least start the engine(s) and run it up to perform pre-takeoff checks. Also exercise constant speed props. If you just don’t have time to do that, and can’t get someone to do it for you, please consider selling the airplane and renting airplanes, and/or joining a flying club.

    • Hi John,
      When dealing with infrequently flown engines, the start, run-up and shutdown method may actually do more harm than just leaving the engine to sit.
      When running, we are converting fuel into CO2, some unburnt hydrocarbons and LOTS of water. When an engine is run for only a brief time, this water is not allowed to evaporate out of the engine oil.
      When the oil is allowed to sit with the water and the byproducts of combustion, the pH of the oil decreases. It is this acidic oil-water combo that really starts the internal corrosion.

      Apart from frequent flights, the best defense is frequent oil changes (to restore the oil’s acid neutralizers) and to use an engine dehumidifier as Mike suggested.

      • Thanks Drew. Good information for piston engines, and maybe also for jets. After further reflection, I’m not sure my comparison was valid. The jets in my example sat for long periods of time after shutdown causing internal condensation, but they were operated just about every day and they did corrode internally. Their intakes are much larger than that of piston engines, thus allowing more space for condensation even when intakes and exhaust were covered. Maybe not a good example. Great discussion. Hopefully helpful to owner/pilots with very low utilization.

  5. Hi Mike,
    What is you thoughts on Camguard in turbo engines, in particular the Continental TSIO-360?
    Thanks.

  6. Mike,

    What are your thoughts on keeping engine heaters like Tanis plugged in continuously? I live in Florida where the temps have been between 30 and 70 degrees. I keep my plane in the hangar and I keep it plugged in but on those warmer days, the engine is pretty darned warm. Can that hurt it?

  7. William Blatter

    January 24, 2018 at 8:10 am

    Hi, Mike. As a follow-up to Scott Morrison’s question below, I too keep the block heaters running continuously whenever the planes sit idle in the hangar. It is my belief that this practice is beneficial in that it inhibits the temperature gyrations giving rise to condensation inside the engine. Am I correct? What are your thoughts on this practice?

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