Pilot Debrief

BEECH F33A near Wilder, ID — 2022-08-21

Final reportWPR22LA314
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Date
2022-08-21
Location
Wilder, ID, USA
Airport
50S
Aircraft
BEECH F33A
Registration
N4133S
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Initial climb

Probable cause

Catastrophic engine failure during the initial climb due to an incorrectly installed crankshaft counterweight retaining ring.

NTSB narrative

The airplane sustained a catastrophic engine failure shortly after takeoff due to a separated crankshaft counterweight. The pilot performed a forced landing, during which the airplane sustained substantial damage. The engine had been overhauled about 14 years and 950 flight hours before the accident. Examination of the remaining counterweights revealed that, during that overhaul, some of their retaining pins had been installed back to front. According to the engine manufacturer, such installation has been known to cause failure of the counterweights and the catastrophic damage observed. The correct installation is documented in the engine maintenance manual and reiterated in a service bulletin that was published 5 years before the engine was overhauled.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Proper installation of engine counterweights and retaining rings during maintenance.

NTSB coding

Evidence available

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

Docket documents8

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