TULLAHOMA, TN, USA
N20001
TAYLORCRAFT F19
THE PILOT STATED THAT ABOUT 20 MINUTES AFTER TAKEOFF, WHILE MANEUVERING NEAR HIS RESIDENCE, THE AIRCRAFT ENGINE LOST POWER. HE MADE AN EMERGENCY LANDING IN A FIELD, BUT THE AIRPLANE HIT A FENCE AND ENCOUNTERED UNEVEN TERRAIN DURING THE LANDING. EXAMINATION OF THE ENGINE REVEALED THAT THE STARTER ROLLER CLUTCH, WHICH HAD BEEN INSTALLED IN THE AIRCRAFT IMMEDIATELY BEFORE THE FLIGHT, HAD SEIZED. THE ROLLER CLUTCH WAS IN PLACE, BUT THE ROLLERS WERE FOUND TO HAVE MELTED AND HAD WELDED TO THE SHAFT. SUBSEQUENTLY, ALL FOUR OF THE CRANKSHAFT GEAR CAPSCREWS HAD FAILED, RESULTING IN DISENGAGEMENT OF THE CRANKSHAFT GEAR AND SUBSEQUENT POWER LOSS. A SERVICE BULLETIN (TELEDYNE CONTINENTAL M79-10) HAD BEEN ISSUED BY THE MANUFACTURER IN JUNE OF 1979 TO PROVIDE PRESSURIZED LUBRICATION OF THE ROLLER CLUTCH STARTERS, BUT THE SERVICE BULLETIN HAD NOT BEEN ACCOMPLISHED. THE ENGINE HAD BEEN SHIPPED FROM THE FACTORY ON 5/26/78 (BEFORE THE SERVICE BULLETIN WAS ISSUED). THE STARTER INSTALLATION INSTRUCTIONS DID NOT REQUIRE THAT THE SERVICE BULLETIN BE COMPLIED WITH BEFORE INSTALLATION OF THE STARTER. THERE WAS EVIDENCE THAT THE STARTER ROLLER CLUTCH LACKED ADEQUATE LUBRICATION.
HISTORY OF FLIGHT On February 13, 1995, about 1340 central standard time, a Taylorcraft F19, N20001, collided with a fence and terrain during an emergency landing, following a loss of engine power, near Tullahoma, Tennessee. The private pilot was not injured in the accident. The aircraft was being operated under the provisions of 14 CFR Part 91 at the time. Visual meteorological conditions existed at the time, and no flight plan had been filed for the local flight. The flight departed Tullahoma, Tennessee, about 1325. The pilot stated that while maneuvering near his residence, the aircraft engine lost power. He attempted an emergency landing in a field, and hit a fence during the landing roll. The pilot stated that this was the first flight of the aircraft since the installation of a new starter. TESTS AND RESEARCH The aircraft was equipped with a Prestolite Model MZ4214 starter serial number 5J000132. Examination of the engine revealed that the starter roller clutch had seized. There was no external damage or abnormal wear to the bearing journals or the teeth on the large and small gears. The roller clutch was in place. The rollers were melted over, and had welded to the shaft. The plastic cage was melted and smeared inside the housing. Lubrication holes were in place in the shaft. The four crankshaft gear capscrews had broken off flush with the end of the crankshaft. The ends of the capscrews remained in the crankshaft. The capscrews remained lock-wired together in pairs of two. Examination of the capscrews revealed that they exhibited fatigue markings across the diameter. There were no wear indications on the capscrew flanks or under the heads of the capscrews. The threads remaining on the capscrews were intact, but showed some damage from contact with other parts. Examination of the crankcase revealed that Service Bulletin M79- 10, issued June 25, 1979 had not been complied with. The service bulletin called for a change in the crankcase and starter jack to provide pressurized lubrication to the starter roller clutch, when the roller type clutch was installed. The procedure called for drilling of the rear main bearing, the starter jack shaft, and the crankcase, in order for the oil to flow from the crankcase into the starter roller clutch. Research revealed that the engine had been shipped from the factory on May 26, 1978, prior to the issuance of Service Bulletin M79-10. The Prestolite Starter, is a roller type starter, and requires lubrication for operation. The starter kit installation instructions do not require that Service Bulletin M79-10 be accomplished prior to the installation of the starter.
A LACK OF LUBRICANT TO THE STARTER/ROLLER CLUTCH, SEIZURE OF THE STARTER, AND FAILURE OF THE FOUR CRANKSHAFT GEAR CAPSCREWS (BOLTS), WHICH RESULTED IN DISENGAGEMENT OF THE CRANKSHAFT (ACCESSORY) GEAR AND SUBSEQUENT LOSS OF ENGINE POWER.
Source: NTSB Aviation Accident Database
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