Piper PA-31-310 N1009S

Summary

On 21 August 2011 at about 22:45 local time, a Piper PA-31-310 registered N1009S was involved in an accident near Cabazon, California, United States. 3 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

21 August 2011 at 22:45

Classification

Accident

Location

Cabazon, California, United States

Nearest airport

Banning Municipal Airport (BNG)

Coordinates

33.9119, -116.8789

Aircraft

Piper PA-31-310

Registration

N1009S

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Banning → Banning

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR11LA401

Nobody was injured.

A total loss of left engine power due to the failure of the aft crankshaft counterweight retaining washer for reasons that could not be determined during postaccident examinations.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot reported that, while in cruise flight about 20 miles from the departure airport, he heard a loud bang come from the left engine and then saw oil gushing out of it, followed by a loss of engine power. The pilot feathered the propeller and attempted to return to the airport. When he realized that the airplane could not maintain altitude, he made a forced landing on uneven, vegetated desert terrain, which resulted in substantial damage to the airplane. A visual examination of the left engine revealed that the engine crankcase had fractured above the Nos. 5 and 6 cylinders. The postaccident teardown examination of the engine revealed that the aft crankshaft counterweight was partially separated from the crankshaft. The trailing edge roller pin, retaining washer, and part of the retaining snap ring were found displaced from the counterweight and were subsequently located in the oil sump. The retaining washer was fragmented into multiple pieces, which allowed the roller pin to move within its respective slot with the retaining snap ring still installed. As the roller pin became partially extracted from the counterweight, it contacted a connecting rod, which resulted in a catastrophic failure of the engine. Removal of the remaining portion of the snap ring revealed that it was installed correctly. The reason for the failure of the retaining washer could not be determined.

Quoted verbatim from the NTSB record.