NTSB Identification: ATL94LA150.
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Accident occurred Wednesday, August 03, 1994 in WAXHAW, NC
Probable Cause Approval Date: 02/24/1995
Aircraft: CESSNA 150J, registration: N60182
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE FLIGHT INSTRUCTOR AND HIS STUDENT WERE TAKING OFF ON A LOCAL, INSTRUCTIONAL FLIGHT. ABOUT 300 FEET AGL, DURING THE INITIAL CLIMB, THE ENGINE LOST POWER, ACCOMPANIED BY A STRONG VIBRATION. THE AIRCRAFT WAS FORCE LANDED, AND COLLIDED WITH TREES. A POST- ACCIDENT EXAMINATION OF THE ENGINE REVEALED THAT THE NUMBER 2 EXHAUST VALVE WAS STUCK OPEN. FURTHER INSPECTION SHOWED COKING AND CARBON DEPOSITS ON THE VALVE STEM AND GUIDE. AFTER CLEANING, THE VALVE STEM DIAMETER WAS MEASURED TO BE .4328'. THE ALLOWABLE RANGE IS .4335' TO .4340'. THE ENGINE HAD A HISTORY OF STICKING VALVES; THE NUMBER TWO EXHAUST VALVE WAS FREED BY MAINTENANCE PERSONNEL 5 HOURS BEFORE THE CRASH. THEY ALSO REPORTED THAT THE VALVE WAS FREED WITHOUT REMOVING THE CYLINDER OR THE VALVE.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A LOSS OF ENGINE POWER DUE TO A STUCK, AND WORN, EXHAUST VALVE, AND THE INADEQUATE INSPECTION OF THE ENGINE BY OTHER MAINTENANCE PERSONNEL. A FACTOR WAS THE TREES AT THE FORCED LANDING AREA.

Full narrative available

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