How to Maintain Your Engine

By Bill Middlebrook

(Bill Middlebrook is President and CEO of Penn Yan Aero. He is the third generation Middlebrook to own and operate the 65-year-old independent aircraft engine facility. Bill is an expert and authority on Lycoming and Continental aircraft engines.)

If you take care of your engine, your engine will take care of you. Here’s what you need to do and why:

First, take a look at your engine and its surroundings under the cowl. Is it clean? If not, clean it up so that you can properly evaluate what you have. Is there evidence of leaking oil or carbon deposits from leaking exhaust gaskets?  Are there blue stains around fuel components or intake pipes?  Are there any noticeable cracks? Does the baffle seal look worn or is it pliable and sealing correctly? Is there any loose hardware or loose components? Are there any frayed cables or wires? Make a list of issues and concerns. Whether you do the service, or not, this will help you keep track of who is responsible to resolve issues.

Next, check your oil. Is it topped up? Is it clean or dirty? Do you know what type of oil is in the engine and when it and your oil filter were last changed? Your oil and filter should be changed every 25 to 30 hours. This is especially true for in-frequent recreational flying where moisture and gas can accumulate in the engine’s crankcase, diluting your oil, and introducing corrosive chemicals to your engine’s internal parts. Engines that are stretched to 100 hours between oil and filter changes will usually see premature failure of some component. And that failure will cost you in terms of performance, safety, and money. Imagine a marginal pilot on a bad day with a component failure.

Penn Yan Aero recommends an oil filter on every engine. If your engine utilizes a metal filter screen, as opposed to a spin-on type oil filter, then you need to go get a remote oil filter adapter. Airwolf makes a good one (Penn Yan Aero sells them). Oil filters are excellent insurance and have saved more than one engine over the years. As space allows, use the largest filter available. 

Temperature, dirt, and moisture will dramatically shorten an engine’s life. Temperature effects engine life and how much moisture accumulates in your engine. An engine that runs too warm produces less power and breaks down the oil sooner than a cooler running engine.  Conversely, an engine that runs too cool can allow moisture to build up inside the engine and it will stay there. This will eventually lead to camshaft and lifter degradation and possibly cylinder barrel corrosion if you have steel barreled cylinders. You want your engine to run at between 180 and 210 degrees F. High operating temperatures caused by lack of airflow or excessive leaning will shorten cylinder life as well. Rapid heating and cooling by closing the throttle to descend, inadequate warm up and so on will also shorten cylinder life by causing excessive wear and cracking. Fly your bird as often as you can, at least once a week, for at least an hour at a time. This will allow the moisture to boil out of the engine. Pulling the aircraft out of the hangar and running it for a few minutes at a time is the worst thing you can do. All this will accomplish is to create a virtual rain forest inside your engine.

Prolonged lack of use can cause severe corrosion due to moisture and acid build-up in the engine oil. Dirt can be kept out of your engine by maintaining a high quality and properly installed air filter and airframe induction system. Prolonged use of carburetor heat should be avoided (unless necessary) as it introduces unfiltered air into the engine. Keep your air filter and engine clean. 

Proper preventative maintenance, regular oil and filter changes as outlined, and careful operation will pay handsomely in terms of safety, better performance, longer engine life, and reduced repair costs. Please take note of this. I’m an expert and have seen more engines than almost anyone else. I know what happens and I speak the truth! A properly maintained engine is obvious and contributes to the overall value of your aircraft.

Next, close up the cowl, get in, and start your aircraft. How does your engine start? How’s your engine feel? How’s it sound? How’s it idle? How’s it run up through the RPM range? If your engine pops, stumbles or is hard starting, you probably have a problem and you need to add the symptom to your list to chase down. Are there any disconcerting vibrations? If there are, even if they’ve been there forever, add them to your list. Not all engines have been overhauled by Penn Yan Aero and run smoothly, and both Lycoming and Continental engines have idiosyncrasies on a model by model basis, but overall, they are outstanding engines and should provide safe and satisfactory performance. It’s a good idea to talk with fellow pilots who are flying the same engine as you to learn the inherent traits associated with your model engine. Knowledge is power and knowing about your engine’s characteristics ahead of time can save you cash and sanity. 

Check and become familiar with your logbook. Determine when your engine was manufactured. Has your engine ever been repaired, overhauled, rebuilt, or replaced? How many hours are on your plane? How many on your engine? What are the details behind the annuals? Check to see what service has been performed and at what intervals. Have there been any repairs made? Have there been any Manufacturer’s Service Bulletins (SBs) or Airworthiness Directives (ADs) issued? Have they been complied with? Make it a point to ask your mechanic about compliance with SBs and ADs. Sometimes they get missed or are misunderstood. Legally, it’s the owner of the aircraft that is responsible for seeing that proper maintenance is carried out. Ask questions and get educated. Knowing what’s been done in terms of history and operation of your engine will help prevent surprises and promote a long and healthy engine life. 

Now, take a look at your list. Talk with your mechanic and review the list. Determine who is responsible for each item. It’s your job to be vigilant and educated on your aircraft. It will save you time and money and maybe your life and the lives of others. Double-check and make sure that all items on your list have been resolved. Understanding your engine, making sure of its maintenance, and knowing its operation is all part of being a good pilot. You’ll never regret being informed and having confidence in you equipment. Enjoying safe, smart flying is what it’s all about!