Accident Grumman AA1B N1638R, Saturday 15 December 1990

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Date:	Saturday 15 December 1990
Time:	11:11 LT
Type:	Grumman AA1B
Owner/operator:	Private
Registration:	N1638R
MSN:	AA1B0638
Engine model:	Lycoming O-235-L2C
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Roswell, NM - United States of America
Phase:	Initial climb
Nature:	Private
Departure airport:
Destination airport:	Alamogordo, NM
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
THE PILOT SAID THAT AFTER TAKEOFF, AT AN ALTITUDE OF APPROXIMATELY 150 FEET, THE ENGINE STARTED RUNNING ROUGH. HE SAID THAT ENGINE PERFORMANCE CONTINUED TO DETERIORATE AND HE HAD TO MAKE A FORCED LANDING. THE AIRCRAFT STRUCK THE GROUND HARD AND SUSTAINED SUBSTANTIAL DAMAGE TO THE ENGINE COWLING AND THE MAIN LANDING GEAR. SUBSEQUENT EXAMINATION OF THE ENGINE REVEALED ONE CYLINDER HAD FOULED SPARK PLUGS AND ALL CYLINDERS EXCEPT ONE HAD LOW COMPRESSION.

Probable Cause: LOW CYLINDER COMPRESSION AND FOULED SPARK PLUG.

Accident investigation: