Pilot Debrief

BEECH V35 near New Haven, CT — 2011-09-18

Final reportERA11IA521
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Date
2011-09-18
Location
New Haven, CT, USA
Airport
HVN
Aircraft
BEECH V35
Registration
N275BM
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

The in-flight fatigue failure of the engine’s crankshaft, which resulted in the separation of the forward portion of the crankshaft and the propeller.

NTSB narrative

During the climb after takeoff, as the airplane approached 6,000 feet mean sea level, the crankshaft fractured, and the airplane experienced a total loss of engine power. The forward portion of the crankshaft, with the propeller attached, departed the engine. The pilot declared an emergency and returned to the departure airport where he performed a forced landing on a runway. The airplane sustained minor nose gear damage when it overran the runway. Examination of the crankshaft revealed that it was fractured across the No. 4 main journal. Metallurgical examination revealed cracks that initiated on the bearing surface near an oil transfer tube and propagated in fatigue. At the time of the incident, the engine had been operated for about 910 total hours, about 500 hours of which had occurred since maintenance, which was performed about 2 1/2 years before the incident and included the reinstallation of the Nos. 2 and 4 cylinders. The crankcase adjacent to the fractured portion of the crankshaft showed significant fretting on the mating surfaces, possibly due to incorrect torque applied during the previous cylinder repair; however, the investigation could not determine the relevance of that repair, if any, due to the time that had elapsed since the repair was completed.

Analysis

Primary failure mode
Mechanical failure

NTSB coding

  • Powerplant sys/comp malf/fail · Enroute-climb to cruise

Evidence available

  • Photos
  • 11 docket documents
View NTSB final reportView NTSB docket

Docket documents11

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