Batavia, OH, USA
N5664L
American Aviation Corp. (AAC) AA-1
After takeoff, about 300 feet above the ground, the engine began to run rough. The private pilot initially attempted to turn back toward the airport, but the flight instructor took control of the airplane, performed a forced landing, and struck trees. Subsequent examination of the engine by an FAA inspector revealed valve guide wear and coking of the valve stem on the number four cylinder exhaust valve. When the inspector repositioned the valve, it stuck in the open and closed positions. Review of the airplane logbooks revealed that the engine had accumulated 1,975.49 hours of operation since it was originally manufactured, approximately 33 years prior the accident. During that time frame, the engine was never overhauled. Additionally, the engine had accumulated 23 hours of operation since the last annual inspection, which was performed about 10 months prior to the accident. A service bulletin and service instruction from the engine manufacturer recommended that the valve guides be inspected at 400-hour intervals, and that the engine be overhauled in the 12th year if it did not accumulate the recommended hourly period of time between overhauls, which was 2,000 hours.
On October 28, 2001, about 1530 eastern standard time, an American Aviation Corporation AA-1, N5664L, was substantially damaged during a forced landing after takeoff from Clermont County Airport (I69), Batavia, Ohio. The certificated flight instructor and private pilot/owner were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local instructional flight conducted under 14 CFR Part 91. The private pilot stated that he had intended to complete a biannual flight review with the flight instructor. He added that no anomalies were noted during the airplane preflight, taxi, or run-up. After departing runway 22, about 300 feet above the ground, the engine lost partial power. The private pilot initiated a left turn back toward the airport. However, he was unable to maintain altitude, and the flight instructor took control of the airplane for a forced landing. The flight instructor then turned right toward a clearing, but the airplane struck trees prior to the clearing, and came to rest in a gravel field. During the forced landing, the nose gear separated, and both wings and the fuselage sustained substantial damage. A Federal Aviation Administration inspector examined the wreckage. He was able to rotate the crankshaft by hand, and verified camshaft, crankshaft, and valve train continuity. The inspector also confirmed fuel system continuity from both fuel tanks to the carburetor. When the magnetos were rotated, they produced spark at all leads. The inspector tested the cylinder compression when the engine was cold, and the readings on cylinders one through four were 75, 64, 58, and 18 respectively. Further examination of the number four cylinder exhaust valve revealed valve guide wear and coking of the valve stem. Additionally, when the inspector repositioned the valve, it stuck in the open and closed positions. The pilot reported that the engine had 1975.49 hours of operation since it was originally manufactured in 1968. During that approximately 33-year period of time, the engine was never overhauled. The recommended hourly limit before engine overhaul was 2,000 hours. Review of Lycoming Service Instruction Number 1009AQ revealed: "Engine deterioration in the form of corrosion (rust) and the drying out and hardening of composition materials such as gaskets, seals, flexible hoses and fuel pump diaphragms can occur if an engine is out of service for an extended period of time. Due to the loss of a protection oil film after an extended period of inactivity, abnormal wear on soft metal bearing surfaces can occur during engine start. Therefore, all engines that do not accumulate the hourly period of time between overhauls specified in this publication are recommended to be overhauled in the twelfth year." Additionally, Lycoming Service Bulletin Number 388B stated that all engines should be inspected at 400-hour intervals to determine exhaust valve and guide condition (except for helicopter engines, which should be inspected at 300-hour intervals). The Bulletin provided inspection instructions, and recommended allowable clearance measurements for valve stem movement. The last annual inspection was performed on December 14, 2000, and engine had 1952.49 hours of operation at that time. During the annual inspection, the compression readings on cylinders one through four were 76, 68, 75, and 70 respectively. However, those reading were taken while the engine was hot.
Malfunction of an exhaust valve. A factor was the pilot/owner's failure to comply with the engine manufacturer's service instructions.
Source: NTSB Aviation Accident Database
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