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.
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
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.
Recognizing 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?