Accident Piper PA-12 N4401M, Monday 8 July 1991

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Date:	Monday 8 July 1991
Time:	13:15 LT
Type:	Piper PA-12
Owner/operator:	Sky Signs, Inc.
Registration:	N4401M
MSN:	12-3341
Year of manufacture:	1947
Engine model:	Lycoming O-320
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Myrtle Beach, SC - United States of America
Phase:	En route
Nature:	Unknown
Departure airport:	Conway, SC (NONE)
Destination airport:
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
AFTER ABOUT 30 MINUTES OF OPERATION, DURING A BANNER TOW FLIGHT, THE ENGINE BEGAN TO RUN ROUGHLY. THE AIRPLANE WAS AT 300 FEET OVER THE OCEAN ADJACENT TO A PUBLIC BEACH. UNABLE TO MAINTAIN ALTITUDE THE PILOT DITCHED IN THE OCEAN TO AVOID THE CROWDED BEACH. SUBSEQUENT EXAMINATION OF THE ENGINE REVEALED THAT THE NO. 4 CYLINDER EXHAUST VALVE HAD BROKEN AT THE PISTON END. THE ENGINE HAD 1939 HOURS SINCE THE LAST OVERHAUL.

Probable Cause: THE FAILURE OF THE NUMBER 4 CYLINDER EXHAUST VALVE. FACTORS IN THE ACCIDENT WERE THE LACK OF A SUITABLE LANDING SITE AND THE WATER DITCHING.

Accident investigation: