Pilot Debrief

PIPER PA 28-161 near New Orleans, LA — 2014-08-22

Final reportCEN14LA449
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Date
2014-08-22
Location
New Orleans, LA, USA
Airport
NEW
Aircraft
PIPER PA 28-161
Registration
N8440N
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Descent

Probable cause

The in-flight fatigue failure of the crankshaft gear retaining bolt, which resulted in a total loss of engine power. Contributing to the accident were the pilot/owner’s failure to maintain the airplane in accordance with an airworthiness directive following a propeller strike and the improper installation of the lockplate.

NTSB narrative

The pilot/owner reported that, while on final approach to the destination airport, the engine experienced a total loss of power. The pilot was unable to restart the engine, and the airplane was unable to glide to the runway, so the pilot subsequently ditched the airplane into a lake. The pilot evacuated the airplane and swam to shore; the airplane sank into the lake but was subsequently recovered. A postaccident examination of the engine's crankshaft gear, retaining bolt, and lockplate revealed that the retaining bolt had fractured; the fracture surfaces and the fine ratchet marks in the initiation area were consistent with fatigue crack propagation. Defined fretting wear scars were noted partially around the circumference of the bolt through-hole. The lockplate exhibited areas of fretting wear and polishing wear scars. The lockplate's retention tab was in the "open" position and did not exhibit typical mechanical deformation associated with bending to the "closed" position, which indicates that the lockplate was not installed properly. The engine manufacturer had issued a service bulletin (SB) that outlined additional maintenance actions that should be taken if an engine experienced a propeller strike. Subsequently, the Federal Aviation Administration issued an airworthiness directive (AD) that made compliance with the SB mandatory. During the course of the investigation, the pilot reported that the engine had experienced a propeller strike days before the accident flight. He stated that he was unaware of the AD, so it was not accomplished after the propeller strike. It is likely that the crankshaft gear retaining bolt tension was loosened when the propeller strike occurred and that the improperly installed lockplate allowed the bolt to lose its clamping force. The loose bolt became fatigued and subsequently failed during the accident flight.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot failed to comply with AD after a propeller strike before the flight.

NTSB coding

Evidence available

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

Docket documents11

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