HAVERHILL, MA, USA
N63387
Cessna 150M
In level flight at 2,000 feet, the engine began running rough with an associated vibration. The CFI took control of the airplane and the vibration became stronger. After shutting down the engine, the CFI attempted to land on an abandoned runway. The airplane impacted trees approximately 100 feet beyond the departure end of the abandoned runway. Examination of the engine logbooks and discussions with the operator disclosed that the engine was 362 hours beyond Time Between Overhaul (TBO) and automotive fuel was utilized without a Supplemental Type Certificate. Disassembly of the engine revealed the number two cylinder's exhaust valve was fractured and the cylinder was cracked. An examination of the fractured exhaust valve by the Materials Laboratory Division of the National Transportation Safety Board revealed that the 'shank area immediately adjacent to the fracture was reduced in size, and the fracture features were indicative of bending overstress separation with no indications of pre-existing cracking.'
On March 4, 1998, about 0906 eastern standard time, a Cessna 150M, N63387, was destroyed as it collided with trees during a forced landing near Haverhill, Massachusetts. The certificated flight instructor (CFI) and the student pilot 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 flight originated from the Lawrence Municipal Airport, Lawrence, Massachusetts, about 0810. The CFI reported that they had completed maneuvers in the local practice area, and climbed to 2,000 feet. He recalled that they were in cruise flight for about 2 minutes when the engine began running rough with an associated strong vibration. The CFI stated that he took control of the airplane with all engine indications normal. Unable to reach the airport and with the vibration getting worse, the CFI shutdown the engine and attempted to land at a closed airport. The flight instructor reported that they were high and fast, floated over the abandoned runway and impacted trees approximately 100 feet beyond the departure end of runway 32. The airplane came to rest in a nose down attitude, and the student and flight instructor exited the airplane through the left door. On March 5, 1998, a Federal Aviation Administration Inspector assisted in the disassembly of the engine. The number two cylinder was removed revealing a fractured exhaust valve, a piston head which contained holes, and a crack cylinder wall. Examination of the engine logbooks and discussions with the operator disclosed that the engine was 362 hours beyond Time Between Overhaul (TBO) and automotive fuel was utilized without a Supplemental Type Certificate (STC). The number two cylinder assembly with the intake valve installed, and the fractured exhaust valve were examined by the Materials Laboratory Division of the National Transportation Safety Board. The examination revealed that the valve head was heavily damaged and distorted by mechanical forces but with no indications of severe thermal distress such as channeling or burning. The shank area immediately adjacent to the fracture was reduced in size, and the fracture features were indicative of bending overstress separation with no indications of pre-existing cracking."
A loss of engine power due to a fractured number two cylinder exhaust valve and cracked cylinder. Contributing factors were the operator's allowance of the time between engine overhaul to be exceeded and the trees.
Source: NTSB Aviation Accident Database
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