KNOXVILLE, TN, USA
N185Y
BEECH J-35
SHORTLY AFTER TAKEOFF, THE PILOT REPORTED A SEVERE VIBRATION IN THE AIRPLANE, FOLLOWED BY A COMPLETE LOSS OF ENGINE POWER. AN EMERGENCY LANDING WAS ATTEMPTED TO RUNWAY 24R AT MCGHEE TYSON AIRPORT, BUT THE AIRPLANE CRASHED A MILE SHORT OF THE RUNWAY. EXAMINATION OF THE ENGINE ASSEMBLY REVEALED THAT NUMBER 1 & 2 CYLINDERS HAD SEPARATED FROM THE ENGINE CASE. THE EXAMINATION ALSO DISCLOSED THAT THE CYLINDER HOLD DOWN STUDS WERE DAMAGED AND THE THREADS WERE BATTERED. THERE WAS AN ACCUMULATION OF METALLIC DUST ASSOCIATED WITH FRETTING ADJACENT TO THE CYLINDER FLANGE AND ENGINE CASE. SEVERAL HOLD DOWN NUTS WERE NOT RECOVERED FOR EXAMINATION. THE ENGINE MAINTENANCE LOG SHOWED THAT THE NUMBER 1 CYLINDER WAS REMOVED AND INSTALLED IN ACCORDANCE WITH CURRENT SERVICE INSTRUCTIONS 314 HOURS PRIOR TO THIS ACCIDENT. SUBSEQUENT TO THIS ACCIDENT CONTINENTAL MOTORS ISSUED A SERVICE BULLETIN INCREASING THE HOLD DOWN TORQUE NUT VALUES FROM 710 INCH POUND TO 810 INCH POUNDS, AND CHANGED EXISTING SIX POINT HOLD DOWN NUTS TO TWELVE POINT NUTS.
THE MANUFACTURER'S FAILURE TO PROVIDE ADEQUATE TORQUE INFORMATION WHICH RESULTED IN THE LOSS OF TORQUE ON THE CYLINDER HOLD DOWN NUTS AND THE COMPLETE LOSS OF ENGINE POWER.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
