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Aviation Accident

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NTSB Identification: ERA15LA311
14 CFR Part 91: General Aviation
Accident occurred Friday, August 14, 2015 in Allentown, PA
Probable Cause Approval Date: 11/19/2015
Aircraft: THOMAS A SIMINSKI ZENITH CH 750, registration: N1750Z
Injuries: 1 Serious.

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 pilot reported that, after takeoff, the airplane’s engine lost partial power about 100 ft above ground level and that he then attempted to return to the airport. The pilot further stated that “the engine would not keep me flying and the airplane just fell into the forest.”
During the on-scene examination, the No. 1 spark plug was found missing from the cylinder head but still attached to the ignition lead. The threads were stripped out of the cylinder head. It is likely that the No. 1 spark plug was liberated from the cylinder head due to the stripped threads, which led to the partial loss of engine power.


The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
  • A partial loss of engine power due to the No. 1 spark plug being liberated from the cylinder head due to the stripped threads in the cylinder head. Contributing to the accident was the pilot’s decision to attempt to return to the airport while at a low altitude.