Q: Because of medical problems, my IO-720 has not run in six months. While always hangared, the hangar is sometimes damp. The question is what to do in re-starting? Do we open it up and clean, or change the oil often?
A: Larry, first of all, we certainly hope all of your medical issues are behind you and you can get back in the air with that outstanding Lycoming IO-720-powered aircraft of yours.
I don’t think you’ve got much of an issue here with your aircraft sitting idle for about six months, however there are some suggestions that I might offer.
Not knowing what type of climate you live in, I think it would be okay for you to just do a good preflight inspection, then go fly for an hour or so.
I’d suggest flying for at least an hour at 65% to 75% power while monitoring all the instruments, making certain they are within the recommended limits.
Upon conclusion of the flight, I’d change the oil and filter, making certain to cut open the oil filter and inspect it carefully between the pleats for any indication of contaminants.
If all appears to be okay, I’d service the engine with the proper amount of oil, install a new oil filter and go fly again.
Just for peace of mind, I’d probably do another oil and filter change in about 10 hours.
Remember, the two least expensive things you can put in your engine are fuel and oil, so why not check the oil filter again within 10 hours.
I believe this simple approach should be good enough, but if there are any indications of something not to your liking, please check further.
If you have access to a borescope, you may want to take a look in all of the cylinders for any indication of corrosion. Slight corrosion normally isn’t a problem and can usually be healed by continuing to fly the aircraft on a regular basis.
If more serious or deeper corrosion is noted, this can lead to excessive piston ring wear, resulting in metal contamination of the engine (not good!). If deeper corrosion is noted, then removal of the worse case cylinder would be recommended. Depending on what is found, further inspection may be required.