Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.
Issue link: http://experimenter.epubxp.com/i/113663
Make sure that the engine you are buying is the engine you want. For instance, fuel injection is cool, but it's expensive to maintain. A 200-hp engine sounds like a way neater engine than a 180, but do you need it? True, it's an 11-percent boost on paper, but are you aware that engine nomenclature allows a few horsepower above or below the rating? Are you truly going to need those extra horsepower for which you're spending all that extra money? It's likely that a used engine will make fewer rated horses than a perfectly tuned dyno-run example of a new one, so the difference you see on paper may be very little difference in the air. Are you in a hurry? Are you on amphibious floats on a small mountain lake, or do you typically fly from a sealevel airport with a 6,000-foot runway? All that said, what can you do to make sure you're buying a decent engine? Whether you plan to use the engine right away or do some work on it, be sure you know what you're getting. Check all the numbers in the documentation against the numbers on the physical items. If you're not getting logs, then you're buying a core. Be sure the engine complies with all the airworthiness directives (ADs), and if it doesn't, get a better deal. Likewise, check the service bulletins (SBs); if the engine doesn't comply with them, that may be better for you as a bargaining chip, but that doesn't necessarily mean it's a good deal. With this information, you can determine how far the engine is from compliance and how much your minimum outlay for repair and modification should cost. When was the engine last signed off? An engine that's been sitting on a pallet or even in factory packaging may be unairworthy if it's been sitting long enough, if it wasn't preserved for storage, or if it sat in a harsh environment. And an engine that has been sitting may also no longer comply with ADs and SBs. When was the engine last flown? What was done to it, either in terms of periodic running or preservation, since then? Why was the engine taken out of service? Check also in the aircraft logbook for any record of off-ramp excursions, prop strikes or damage, gear repairs, flood damage, etc. Often, the airframe repairs that are mentioned can shed light on your engine's history. Did the same mechanic who did the airframe or prop work also service the engine? of a qualified mechanic—will go a long way toward knowing what you're buying. In other words, you gotta look inside. For knowing what to look at, Lycoming's SB 388C is a great guide. Read it before you look at your prospective engine, bring it along as a negotiating tool, and do whatever it says that's within your ability and the circumstances of the buying experience. If the engine is on a flyable airplane, go flying. Watch the gauges; how fast do the temperature and oil pressures rise? Listen and feel for vibrations. At altitude, sanely test the throttle response from idle through full power and back. Run it awhile at cruise settings. Have a friend watch the exhaust during startup and running. He can listen, too—a lot of sounds are audible on the outside that are lost in the usual cacophony of the cockpit, particularly if you're wearing a headset. What kind of smoke does the engine produce and when? There's smoke in many colors. Black (or dark grey) smoke comes from a rich mixture; it's often seen on takeoff when the engine's running full rich. It should go away when the mixture is properly managed. Blue (or white) smoke is usually oil. A puff of blue at startup or after a negative-g maneuver (or a big bump) is okay; continuous smoking usually comes from wear. Valve guides, stem seals, or the piston rings are the likeliest culprits, and those are problems that must be fixed. Any smoking should prompt a look at the logs. Do the fuel and oil consumption numbers make sense? Next, look for the obvious. If the engine is still on the airplane, you can learn more. Does the prop look good, or—watch out—is the prop new? Are there telltale marks, burns, drips, cooked-oil stains, or dents in the cowl or baffling? Are all the pieces of "cooling tin" intact and properly fastened? Is the carburetor dripping gasoline, or does it Is the engine already in an E-AB? Any gaps in the history are suspect; and logs for E-ABs range from perfect to…well, not so good. What props has the engine turned? Check to see that the props were compatible with the engine model. Beyond the Paper Trail What this paper chase won't tell you, though, is how much your likely (or ultimate) cost will be. Your inspection—and that Photography courtesy Penn Yan Aero Damaged camshafs usually mean damaged lifers, too. Tis means a teardown is needed, where you likely will fnd other parts that also will need replacement. EAA Experimenter 37