COLUSA, CA, USA
N5723B
CESSNA 182
THE AIRPLANE SUSTAINED A TOTAL LOSS OF POWER WHEN THE PILOT WAS DESCENDING TO A LOWER ALTITUDE DURING A NIGHT VFR FLIGHT. THE AIRPLANE'S ALTITUDE WAS INSUFFICIENT TO MAKE THE CLOSEST AIRPORT. THE PILOT TURNED ON THE LANDING LIGHTS AND ELECTED TO LAND IN AN OPEN FIELD. THE PILOT OBSERVED SOME POWER LINES CROSS HIS FINAL APPROACH PATH. HE ATTEMPTED TO MANEUVER BENEATH THE POWER LINES, BUT WAS UNSUCCESSFUL. THE AIRPLANE CLIPPED THE LINES AND CRASHED. THE ENGINE EXAMINATION DISCLOSED THAT THE LAST MAINTENANCE FACILITY TO OVERHAUL THE ENGINE FAILED TO NITRIDE AND HARDEN THE CAM GEARS AS REQUIRED. THE CAM AND CRANKSHAFT GEARS FAILED IN FATIGUE.
On November 13, 1993, at 1930 hours Pacific standard time, a Cessna C-182, N5723B, clipped a power line and collided with a ditch while executing an emergency landing near Colusa, California. The emergency landing was precipitated by a total loss of engine power. The pilot was conducting a visual flight rules personal flight to Redding, California. The airplane, operated by the pilot/co-owner, was substantially damaged. The certificated private pilot and two passengers were not injured. Night visual meteorological conditions prevailed. The flight originated at Los Banos, California, at 1730 hours. The pilot stated that about one minute after changing cruise altitude from 8,500 feet mean sea level (msl) to 6,500 feet msl, the engine slowly lost rpm until the engine quit. The pilot said that he used carburetor heat when he reduced the throttle during the descent. The pilot noted in the Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2, that he was receiving visual flight rules flight following from Oakland Air Route Traffic Control Center when he experienced the loss of power. The local controller provided him with a "...bearing, distance and radio frequency..." of the Colusa County Airport. The pilot said that the airplane's altitude was insufficient to make the airport. He then used his landing light to select a landing area. While on final approach to the landing area, the pilot saw power lines and turned the airplane to avoid a collision. The airplane clipped the wires and came to rest in a ditch. Mr. Peter Wilhelmson, Aviation Safety Inspector, Federal Aviation Administration (FAA), Sacramento [California] Flight Standards District Office, supervised the engine examination. Inspector Wilhelmson said that the engine was prepared for a post accident run on November 18, 1993. A mechanic at Faith Aircraft Salvage, Sacramento, California, attempted to conduct an engine operational test. According to Inspector Wilhelmson, the mechanic attempted to run the engine, but was unsuccessful. The external examination revealed that the numbers 1,4,5, and 6 cylinders had no compression, but the numbers 2 and 3 cylinders had compression. Inspector Wilhelmson instructed Faith Salvage personnel to send the engine to Chuck's Aircraft Service, San Carlos, California, for further disassembly and internal analysis. Inspector Wilhelmson said that he did not observe any physical damage to the engine or the accessories. When the mechanic removed the oil sump, Inspector Wilhelmson found two cam gear teeth. Five gear teeth were missing from the cam gear as viewed from the rear and going counterclockwise. The teeth were cleanly broken off at the tooth root. The five remaining teeth were found ground away at different degrees of severity, continuing counterclockwise. Additionally, the crankshaft gear teeth were found stripped/damaged to the same level of severity. The cam gear, crankshaft gear, and various pieces of gear teeth were examined at the National Transportation Safety Board Materials Laboratory, Washington, D.C. The metallurgist reported that the cam gear teeth failed in fatigue. The examination also showed several notches above the gear teeth flanks. A detailed optical examination of the portion of the tooth of the flanks showed multiple grinding marks. According to a representative of Teledyne Continental Motors (TCM), the gear is specified to have a quenched and tempered microstructure with a core hardness of HRC 28 to 32. The gear must also have a nitrided case with a minimum surface hardness of 69 HR30-N. The metallurgist reported that the gear contained no evidence of a hardened layer on the surface of the gear, including the teeth roots. A microhardness traverse test conducted by the metallurgist showed a relatively uniform hardness from the surface toward the interior. The hardness results are consistent with a component that did not contain a hardened surface layer. Safety Board investigators did not recover the airplane's engine logbook. The pilot reported that the engine had accrued 560 flight hours since its last major overhaul. He also said the last annual inspection was performed on July 7, 1993; the airplane/engine accrued 66 flight hours since the annual inspection.
was the poor major overhaul conducted by maintenance personnel by failing to properly service the cam shaft. The camshaft gears fatigue which led to its ultimate failure, the dark night conditions, and the power lines were factors in this accident.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
