Pilot Debrief

BEECH V35 near Rutledge, TN — 2023-09-02

Final reportERA23LA361
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Date
2023-09-02
Location
Rutledge, TN, USA
Aircraft
BEECH V35
Registration
N5431U
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Climb

Probable cause

A total loss of engine power due to the fatigue failure of a retaining circlip in one of the No. 2 crankshaft cheek counterweights, which resulted in liberation of the counterweight.

NTSB narrative

The pilot reported that he was about 15 minutes into the cross-country flight when the engine made a “loud bang,” began to run rough, and eventually seized. Unable to glide to an open field, the pilot conducted a forced landing into trees. He and his passenger were not injured; however, the airplane was substantially damaged. Examination revealed several holes in the engine case, and one of the No. 2 crankshaft cheek counterweights was missing. Further examination revealed two of the counterweight retaining circlips were fractured. Examination of the fractured circlips revealed that one of the circlip legs failed from fatigue crack propagation. The engine had been disassembled and the crankshaft inspected due to a propeller strike about 130 operating hours before the accident.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have returned to the departure airport after engine started running rough.

NTSB coding

Evidence available

  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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