OAKLAND, CA, USA
N731HP
CESSNA P210N
SHORTLY AFTER DEPARTING A LOCAL AIRPORT THE AIRPLANE SUSTAINED A TOTAL LOSS OF POWER AND SUBSEQUENTLY CRASHED IN A RESIDENTIAL SECTION. THE PILOT RECENTLY PURCHASED THE AIRPLANE. DURING THE THE PRE-BUY INSPECTION AT A MIDWEST FACILITY, THE OIL FILTER CHECK AND THE OIL ANALYSIS REVEALED THE PRESENCE OF METAL PARTICLES. THE BROKER ADVISED THE PILOT NOT TO FLY THE AIRPLANE UNTIL THE ENGINE WAS OVERHAULED OR EXCHANGED. THE PILOT SETTLED FOR A PRICE REDUCTION, PURCHASED THE AIRPLANE, AND RETURNED IT TO NORTHERN CALIFORNIA. THE PILOT CONTINUED TO FLY THE AIRPLANE AND ACCRUED 22.9 HOURS AT THE TIME OF THE ACCIDENT. THE POST ACCIDENT ENGINE EXAMINATION DISCLOSED THE CRANKSHAFT FAILED IN FATIGUE AT THE NO. 2 JOURNAL WHERE IT EXITS THE NO. 2 MAIN BEARING. METALLURGICAL EXAMINATION REVEALED THE FATIGUE INITIATED DUE TO IMPROPER TORQUE OF THE THRU-BOLTS. THE AIRFRAME AND ENGINE HAD ACCRUED 937.4 TOTAL HOURS. THE ENGINE WAS OVERHAULED DUE TO A PROPELLER STRIKE WHEN IT HAD ACCRUED 522.5 HOURS.
History of the Flight On April 30, 1993, at 1730 hours Pacific daylight time, a Cessna P210N, N731HP, collided with a chain link fence and a storage shed during a forced landing in a residential neighborhood in Oakland, California. The pilot was conducting a visual flight rules personal flight to Haigh Field (O37), Orland, California. The airplane, recently purchased by the pilot, was destroyed. The certificated private pilot, the sole occupant, received serious injuries. Visual meteorological conditions prevailed. The flight originated at Hayward Airport, Hayward, California, at 1725 hours. A line service employee reported that on April 30, 1993, between 1600 and 1615 hours, he observed the pilot and an unidentified person performing maintenance in the accident airplane's engine accessory section. The pilot approached him and borrowed a screwdriver. At 1700 hours, the line service employee observed the pilot at the controls of the airplane and a mechanic hand-propping the engine. The mechanic who hand-propped the airplane told Inspector Stopponi that he had previously diagnosed the problem the pilot had with the starter, but the pilot did not want him to fix it. On the evening of the accident, he observed the pilot working on the airplane with the cowling open. He subsequently hand-propped the engine. The pilot ran the engine between seven (7) and ten (10) minutes before taxiing for takeoff. The pilot told Mr. Jules Stopponi, Aviation Safety Inspector, Federal Aviation Administration (FAA), Oakland Flight Standards District Office, that shortly after departing Hayward, the local controller instructed him to turn right to avoid the airport radar service area (ARSA). When he began the turn, he heard a loud bang and noticed the RPM gauge drop to about 500 RPM and an increase of engine noise. He turned the airplane toward Oakland and informed the Hayward local controller that he was experiencing an engine problem. He then contacted the Oakland local controller and advised him of the engine problem. Later, he told the local controller that he was not able to negotiate the airport. Crew Information The pilot holds a private pilot certificate with airplane single engine, multiengine, and instrument - airplane ratings. He also holds a third-class medical certificate which was issued on February 3, 1992; the certificate contained a "MUST WEAR LENSES FOR DISTANT - POSSESS GLASSES FOR NEAR VISION" limitation endorsement. The pilot did not submit the required Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2. The flight hours reflected on page 3 of this report were obtained from excerpts of the pilot's computerized flight log. The flight log showed that between February 25, 1993, and March 30, 1993, the pilot flew the accident airplane 22.9 hours. Between February 4, 1993, and March 30, 1993, the pilot had logged 45.3 hours in the accident airplane make and model. As of March 30, 1993, the computerized flight log showed the pilot had accrued 1,673 total flight hours. Other pilot logbook records indicate that the pilot satisfactorily completed the biennial flight review (BFR) as required by current federal air regulations on February 14, 1992. The BFR was flown in a Cessna 210 airplane. Aircraft Information Documents obtained during the investigation reveal the pilot purchased and registered the airplane to Humboldt Leasing Group, Oakland, California, on March 5, 1993. The aircraft maintenance records were recovered. Examination of the records, together with the recording tachometer, reveal the airframe and engine accrued 937.4 total flight hours at the time of the accident. Lubbock Aero, Lubbock, Texas, performed the last annual/100-hour inspection on the accident airplane and engine on April 24, 1992; the airplane and engine had accrued 873.5 hours at the time of the inspection. On February 16, 1988, the airframe was damaged due to a forced landing and received extensive repairs; the airframe and engine had accrued 522.5 hours at the time. The engine was disassembled and overhauled by a properly certificated aircraft mechanic with an inspection authorization certificate. Inspector Stopponi reported that Mr. Mike Ammerman, co-owner, Midwest Aircraft Services, Inc., Newton, Kansas, told him during a telephone interview conducted on May 17, 1993, that his company was hired to perform a pre-buy inspection on the accident airplane. In the course of the inspection, an oil sample was sent to Aviation Oil Analysis for analysis. In the interim, Midwest Aircraft Services, Inc., mechanics cut open the oil filter element and found metal particle contaminates. The airplane was flown for five hours and the mechanics rechecked the filter. The filter element contained more metal particle contaminates. Mr. Ammerman advised the pilot that his company's position was that the airplane should not be flown until the engine was overhauled or exchanged with a remanufactured engine. Mr. Jack Fiden, General Manager, Yingling Aircraft, Wichita, Kansas, told Inspector Stopponi in a telephone interview conducted on May 18, 1993, that his company was brokering the airplane for an estate. During the purchase negotiations between the pilot and Yingling Aircraft, it was agreed that an impartial third party should perform a pre-buy inspection. When the engine integrity became suspect, the trustee for the estate authorized a significant price reduction and the pilot purchased the aircraft. Mr. Fiden stated that he felt that the airplane was such a flight risk he would not authorize his company pilots to return the airplane to his facility. The pilot flew the airplane to California. On April 19, 1993, the pilot contacted a fixed based operator and arranged for an annual inspection to be performed by the company. On April 26, 1993, the pilot again called the company to confirm the proposed annual inspection work and reported that the engine was experiencing starter problems. On April 29, 1993, the pilot called the fixed based operator and was told that the company was going out of business and would not be able to perform the annual inspection or correct the starter problem. The pilot ultimately contacted Mr. David Sos, Herfi Aircraft, Orland, California, and arranged for Herfi Aircraft to perform an annual inspection and exchange a gyroscopic instrument. The pilot was scheduled to bring the airplane to Herfi Aircraft on April 30, 1993. On April 30, 1993, the pilot called Mr. Sos and advised him that he would depart Hayward and arrive at Orland between 1700 and 1800 hours. The pilot never arrived. Wreckage and Impact Information Inspector Stopponi conducted the on-scene investigation and subsequent engine examination. During the on-scene phase of the investigation he observed that the propeller did not exhibit any damage consistent with power being produced at the time of impact. He was unable to establish continuity of the engine gear and valve train assembly. He later determined the engine crankshaft was broken. On May 13, 1993, Inspector Stopponi supervised the disassembly examination of the engine at Concord Airport, Hangar A5. During the disassembly, the thru- and cylinder head bolts required minimal effort to loosen them. The examination revealed the crankshaft failed at the number 2 journal where it exits the number 2 main bearing. Visual examination disclosed that the fracture surface initiated at the radius between the journal and the number 3 short cheek. This area displayed high temperature distress and contact with other metal objects. The number 2 main bearing saddle was flattened and one of its main bearing halves was missing. Fretting was observed at the main bearing saddle surface on the nos. 1 thru 4 cylinders on both crankcase halves. Tests and Research The fractured section of the crankshaft was metallurgically examined by Anamet Laboratories, Inc., Hayward, California. The metallurgist concluded: "It appears that the failure of the crankshaft was not due to a defect or deficiency of the part itself but, by inference, to circumstances of installation, operation or maintenance. It is suggested that the loose crankcase tie-bolts and fretting noted in the crankcase at the number 2 main bearing indicate an inadequate preload. As a result, the crush or compressive load on the bearings could be altered permitting rotation of the bearings, inadequate clearance for lubrication or abrasion and metal transfer. Further conclusions are not possible since an evaluation of the assembly or installation conditions is beyond the scope of this investigation."
the pilot's poor decision to continue flying the airplane with a known deficiency and the poorly performed major overhaul of the engine. The failed crankshaft due to fatigue are factors in this accident.
Source: NTSB Aviation Accident Database
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