Pilot Debrief

Piper PA24 near South Boston, VA — 2020-05-26

Final reportERA20LA195
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Date
2020-05-26
Location
South Boston, VA, USA
Airport
W78
Aircraft
Piper PA24
Registration
N5948P
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

The powerplant mechanic’s failure to properly affix the engine crankshaft gear lockplate during overhaul, resulting in a total loss of engine power.

NTSB narrative

During a personal flight the private pilot proceeded to the destination airport and entered the airport traffic pattern for a planned full-stop landing. While on a close-in downwind leg of the airport traffic pattern the engine experienced a sudden and total loss of engine power. The pilot turned toward the approach end of the runway and attempted to restore engine power but was unsuccessful. The airplane impacted an obstruction light and touched down in tall grass on airport property before coming to rest upright. Postaccident examination of the engine revealed the crankshaft gear attachment bolt was loose, the lockplate was fractured, and the alignment dowel was sheared. The intact portion of the fractured lockplate was similar to an un-bent exemplar lockplate; therefore, it is likely the mechanic who overhauled the engine about 253 hours and 8 years earlier did not bend the lockplate against the flat of the crankshaft gear attachment bolt head. The crankshaft gear drives two idler gears in the accessory gearbox, which drive the camshaft, engine driven fuel pump, vacuum pump and the magneto drive couplings. The failure of the crankshaft gear to rotate would result in a loss of engine power.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Ensuring proper installation of the crankshaft gear attachment bolt during overhaul.

NTSB coding

Evidence available

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

Docket documents6

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