Understanding Your Engine
by Bill Middlebrook
Flying is a lifestyle and flying Lycoming and Continental engines is part of the life. Whether you do the service, or you trust the service to an FBO or mechanic, you need to know and understand your engine. Happy, safe flying starts with a well maintained engine.
First, make a disciplined, visual inspection of your engine and its surroundings under the cowl. Is it clean? If not, make note of where and the type of dirt. Is there evidence of leaking oil? Are there 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? Check your oil. Is it topped up? Is it clean or dirty? Do you know when it was last changed? Do you know what type of oil is in the engine and when it’s due to be changed? Make a list of these items, issues, and concerns. This will be important in understanding who is responsible to chase them down so that they are resolved and are no longer issues.
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. 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 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.
Oil and filter changes should be accomplished every 25 to 30 hours. Engines that are stretched to 100 hours will usually see premature failure of some component. Don’t have an oil filter? Get one! Add it to your list. There are many options for adding oil filters to both Lycoming and Continental engines. Oil filters are excellent insurance and have saved more than one engine over the years. 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 filter, we recommend that a remote filter adapter be installed. As space allows, use the largest filter available. The cost of an oil filter is considerably less expensive than an engine overhaul. We recommend that you change your oil and filter every 25 to 30 hours.
Proper preventative maintenance, regular oil and filter changes as outlined, and careful operation will pay handsomely with a longer engine life and reduced repair costs.
Next, close up the cowl, get in, and start your engine. 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? Although these engines are dated in terms of design, they typically run very well. 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. Knowledge is power and knowing about your engine’s characteristics ahead of time can save you cash and sanity.
Check 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 hours are 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 or Airworthiness Directives issued? Have they been complied with? Again this goes back to the mechanic as it’s his or her job to make sure this is accomplished during annual inspections, 100 hour inspections, etc. Or is it? Problem is, sometimes they get missed or misunderstood. And the fact is, legally it’s the owner of the aircraft that is actually 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. A well maintained aircraft will have a short list. If you have more than a half dozen items on your list, it’s a good thing that we’re doing this. Your aircraft needs you. Determine who is responsible for each item. What items are things your mechanic should be checking? Is he or she? Talk with him or her and review the list. Are you comfortable with your mechanics abilities? Let your mechanic handle the items he’s trained to handle. But know what you have and know what your mechanic is checking and fixing. 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. Divide up your list and double check that all items have been resolved. Bring your equipment up to spec and make sure that it is maintained.
Understanding your engine, making sure of its maintenance, and knowing its operation is all part of the flying lifestyle and 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.
Bill Middlebrook is an expert and authority on Lycoming and Continental aircraft engines. He is President and CEO of Penn Yan Aero. He is the third generation Middlebrook to own and operate the independent aircraft engine facility.