Piper PA-31-310 accident near Cabazon, California, August 21, 2011
On August 21, 2011 at about 10:45 pm local time, a Piper PA-31-310, registered N1009S, was substantially damaged in an accident during enroute (cruise) near Cabazon, California (Banning Municipal Airport). It was an aerial observation flight under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 21, 2011 · about 10:45 pm local time
- Place
- Cabazon, California · Banning Municipal Airport · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper PA-31-310 · all PA-31-310s on the register
- Registration
- N1009S · no longer on the register · serial 31-329
- Damage
- Substantial damage
- Flight
- Aerial observation flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (total) during enroute (cruise) defining event
- Collision with terrain or object (not controlled flight into terrain) during emergency descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Failure
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 8,000 hours in all; 5,000 in this make and model
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 10,878.5 hours
- Last inspection: annual inspection, January 14, 2011
- Seats: 8
- Landing gear: retractable
- Engine 1: Lycoming TIO-540 -A2B (piston); 5,587 hours total
- Engine 2: Lycoming TI0-540 SER (piston); 0 hours total
The flight
- Departed from: BNG Banning CA
- Destination: BNG Banning CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 050° at 6 knots
- Visibility: 10 statute miles
- Sky: scat at 20,000 ft
- Temperature: 120°F (49°C), dew point 28°F (-2°C)
- Altimeter: 29.75 inHg
- Observation at 10:53 pm from PSP, 18 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.