NTSB Identification: LAX91LA260.
The docket is stored on NTSB microfiche number 44942.
Accident occurred Sunday, June 16, 1991 in SONITA, AZ
Probable Cause Approval Date: 05/07/1993
Aircraft: PIPER PA-22-135, registration: N1429C
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.

DURING CRUISE FLIGHT, THE AIRPLANE'S ENGINE BEGAN TO RUN ROUGH. THE PILOT EXECUTED EMERGENCY PROCEDURES TO TRY TO REGAIN ADEQUATE POWER. THE POWER WAS NOT RESTORED AND THE AIRCRAFT COULD NOT MAINTAIN LEVEL FLIGHT. THE PILOT EXECUTED A FORCED LANDING TO A FIELD. DURING THE LANDING ROLL, THE AIRCRAFT COLLIDED WITH A DITCH, TRAVELED ABOUT 20 YARDS, AND NOSED OVER. EXAMINATION OF THE AIRCRAFT'S ENGINE REVEALED THAT A PISTON RING IN THE NUMBER 3 CYLINDER WAS BROKEN WHICH ALLOWED BLOW BY IN THE CYLINDER. THE PILOT SAID THAT HE HAD VAPOR LOCK. HE TOLD AN FAA SAFETY INSPECTOR THAT HE HAD USED AUTOMOBILE GAS FOR THE FLIGHT AND THE GAS WAS TRANSPORTED USING 'OLD CANS' FROM HIS FATHER'S HOUSE. NO EVIDENCE WAS FOUND TO INDICATE THAT THE AIRCRAFT'S ENGINE HAD VAPOR LOCK.

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

A LOSS OF ENGINE POWER DUE TO A BROKEN PISTON RING IN THE NUMBER 3 CYLINDER, WHICH RESULTED IN THE AIRCRAFT'S INABILITY TO MAINTAIN LEVEL FLIGHT.

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