Whether you’re affected by a shelter-in-place order, or as in some countries where pleasure flight is prohibited for the moment, there are some special considerations you might want to take—or avoid taking—for your airplane as it endures an unanticipated and longer-than-usual period of time on the ground.
Turn The Prop? This common and well-intentioned action could actually hurt your airplane. When I was a kid, there was an old-timer who would turn the props on his friends’ aircraft from time to time if they were sitting for any length of time. “Don’t want their engines to seize up,” he said, opining that by turning the prop a few blades now and then, it would move oil around the engine and keep the moving parts from sticking in place. He meant well, but it didn’t help. In fact, he was scraping any protective layers of oil from cylinder walls that may have been left at the last shutdown, when the engine had been turning fast enough to pump oil throughout its entire system. Lycoming specifically discourages such behavior, saying that pulling an engine through two or three times without starting it will have removed the protective coating from the valve train, camshaft and followers, and cylinder walls, and that starting the engine in such a condition would cause scuffing and scoring of parts, “resulting in excessive wear.”
Run It Up? Then there’s the “I’ll run it up and give it a workout on the ground” crowd. On the surface, that also seems like a fine idea to many—you’d get the engine warmed up and the oil would be circulating at a volume and pressure to properly protect the engine. What happens, though, is the combination of temperature and time isn’t enough to burn off all the condensation in the oil. In order to do a ground run long enough to really achieve this goal, you’d bake the cylinders on many engine-aircraft combinations that don’t get proper cooling airflow until you’ve reached flying speed.
Pickle it? There are proper methods for short-term storage of an aircraft engine, for pilots and aircraft owners who want to care for their airplanes in this downtime. Lycoming and Continental both have guidance on how to set their engines up for short-term storage. Continental owners will want to consult Service Information Letter 99-1; Lycoming folks will need Service Letter 180 B.
There are differences between the manufacturers’ letters, but the big steps involved are similar. Drain the old oil, install a new filter and service with the grade of oil directed by the respective engine brand’s direction in the letter. Continental directs flying for an hour; Lycoming simply says to operate long enough to get temperatures stabilized at the normal range. After shutdown, technicians are directed to remove the top spark plugs, spray the cylinders with a preservative oil, and add desiccants as needed in humid areas. Desiccant plugs in place of spark plugs can also help. A big red flag (an actual flag!) should be attached to anything used in the pickling process that is not to be used in flight.
Once “pickled,” a placard on the propeller should warn anyone against rotating it, to protect the coated surfaces.
Lycoming is clear their guidance is just that—not a firm directive and that can be adapted to individual situations depending on time to be parked and the climate where the airplane is situated. Both manufacturers also have guidance for returning engines to service after being preserved, or for extending preservation beyond the short-term timeframe.
Bug Prevention: While the engine is a big concern for most, other parts of the plane deserve some consideration as well. A good pitot cover should not need mentioning, but you might also want to come up with protection for static ports to ensure no bugs find their way into these tiny aluminum, steel, and plastic caves to make a nest. As with the desiccant bags, very vivid markings should be employed. A trip around the patch with an impaired pitot-static system is bad enough when we are sharp, it’s even worse if we’ve been out of the saddle as pilots, and compounded by embarrassment if we caused the failure ourselves.
Tires: Some museum pieces and long-term projects are parked with the tires jacked just above the ground to keep tires from going completely flat and damaging the sidewalls. But the threat of a pinched tire tube and damaged sidewall should be weighed against the possibility of your plane falling off the jacks if one jack fails or some outside force comes into play, such as an earthquake, or someone unwittingly bumping your plane.
Fuel: You’ll likely want to top off your fuel system to keep condensation in your fuel system to a minimum. And sump the daylights out of your tanks when it’s time to fly again. Fuel vents, like static ports, would be a good place to seal off and very visibly flag for safety.
Batteries? Aircraft batteries don’tt like to sit for long periods between use and charging. If your airplane has an external power plug, you may consider doing your first start from an external power source. For aircraft without a plug, owners may want to pull their battery and charge it prior to the first run after storage. There is an option some owners use for airplanes that do not fly often: A low-current charger that keeps batteries at peak voltage. These battery tenders can be used via clips removed prior to flight. Some owners install a pigtail to the battery terminals allowing a simple plug-in when the aircraft is parked. Those same owners often receive their pigtails in an envelope from their mechanics after an annual inspection, often with a scowl and a gentle reminder that equipment purchased from the local auto parts store isn’t really the sort of things that insurance companies or FAA examiners would smile upon discovering at a crash site or during a ramp check.
A word of caution, though. Electrical things left untended at a hangar have the potential to go horribly wrong when nobody is around with a fire extinguisher. Years ago, the FBO hangar at Carrollton, Georgia burned down. There were a number of versions of the story told, from a copier or air compressor that caught fire, to arson—which was the final ruling, to the heartbreak of many with airplanes in the hangar whose insurance policies did not pay off. The hangar blaze destroyed, among other aircraft, an irreplaceable antique Bücker Jungmann biplane. Those who were around when it happened, or those of us who grew up hearing the story told again and again, have a hard time leaving anything plugged in when we leave our hangars.
On a personal note, our Mooney is in a hangar where we parked it before things got ugly, and is an hour’s drive away. The hangar has an apartment attached with an elderly friend living there. His health vulnerability trumps my need to fly or put a wrench to the gray bird right now. It has sat for months throughout its life before without significant problems. Another month or so if needed won’t be the longest spell of being parked that it has ever seen. Machines, after all, are usually a lot easier to fix than people who fall ill.
Jeremy King is an A&P mechanic, an airline pilot and the proud owner of a 1965 Mooney M20C.