Incident Summary
During the initial climb after takeoff, at an altitude of approximately 300 feet, both the pilot and a passenger recording the departure on a video camera heard an unusual noise. Described as a metallic tapping sound, its frequency varied with engine revolutions per minute (RPM). The pilot elected to land on the remaining runway. However, the airplane overran the runway threshold and subsequently collided with a security fence.
Investigation Findings
A post-crash examination of the airplane and a separate test run of the engine failed to replicate or explain the sounds captured on the passenger's video tape. Further analysis of the audio recording by personnel from an FAA-approved engine repair station concluded that the noise was of a metallic 'tappet' type. During a subsequent disassembly of the engine, a sticking exhaust valve was discovered in the number two cylinder. The valve exhibited evidence of high temperatures and oil burning residue on its springs.
Maintenance History
Textron Lycoming has addressed the potential for exhaust valve sticking in Service Bulletin Number 388A, dated April 14, 1978, which recommends compliance at 1,000 hours of operation. Additionally, Lycoming Service Letter L197A, dated January 19, 1988, provides recommendations to avoid valve sticking, and Lycoming Service Instructions 1425A, also dated January 19, 1988, suggests maintenance procedures to reduce the likelihood of such sticking. No record of compliance with these service documents was found during the investigation.