Cessna 150F accident near Port Townsend, Washington, September 28, 2015
On September 28, 2015 at about 8:20 pm local time, a 1965 Cessna 150F, registered N8529G, was substantially damaged in an accident during initial climb near Port Townsend, Washington (Jefferson County International airport). It was a personal flight under general aviation rules (Part 91). 2 people were seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The loss of engine power due to the mechanic's inadequate tightening of the crankshaft gear retaining bolts during an engine overhaul, which resulted in fatigue failure of the bolts and the crankshaft gear dowel pin that allowed the crankshaft gear to separate from the crankshaft.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 28, 2015 · about 8:20 pm local time
- Place
- Port Townsend, Washington · Jefferson County International · map
- Type
- Accident
- Injuries
- 2 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 150F F, built 1965 · all 150Fs on the register
- Registration
- N8529G · no longer on the register · serial 15062629
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane, flown by a commercial pilot, had just departed for a local flight when witnesses observed it overhead and heard its engine sputtering and backfiring. One witness reported that he thought he heard the engine stop completely. Another witness reported seeing the airplane go out of sight behind a stand of trees and then hearing the sound of a crash. Postaccident disassembly and examination of the engine revealed that all four crankshaft gear retaining bolts had failed in their threaded portions, which had resulted in separation of the crankshaft gear from the crankshaft. Two of the crankshaft gear retaining bolts exhibited gross plastic deformation in their shank portions, and both of these bolts exhibited fractures consistent with overstress. The other two bolts did not exhibit gross plastic deformation, and both of these bolts exhibited flat fractures and crack arrest marks consistent with fatigue fractures. Further, the crankshaft gear dowel pin was fractured, and examination of the pin revealed that it had failed due to fatigue, which could only occur if the crankshaft gear bolts were loose during engine operation. The total time on the engine since its most recent overhaul was 41.4 hours. Although the mechanic who performed the overhaul stated that he had used a calibrated torque wrench to properly torque the bolts during the overhaul process, the loose condition of the crankshaft gear retaining bolts was most likely due to the bolts not being correctly tightened during the overhaul.
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 initial climb defining event
- Loss of engine power (total) during emergency descent
- Collision with terrain or object (not controlled flight into terrain) during landing (flare/touchdown)
The NTSB's findings
- cause Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Maintenance personnel
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng rear section › Fatigue/wear/corrosion
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instrument: airplane
- Flight time: 3,000 hours in all; 2,000 in this make and model; 20 in the last 90 days; 1 in the last 30 days; 2,900 as pilot in command
- Last flight review: September 8, 2014
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 2,373.4 hours
- Last inspection: annual inspection, January 9, 2015; 18 hours since
- Maximum gross weight: 1,601 lb
- Seats: 2
- Landing gear: fixed
- Engine: Cont Motor O-200A SERIES (piston); 2,373 hours total
The flight
- Departed from: 0S9 Port Townsend WA at 8:15 pm
- Destination: BVS Burlington WA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 340° at 8 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 63°F (17°C), dew point 48°F (9°C)
- Altimeter: 30.04 inHg
- Observation at 8:15 pm from 0S9, 15 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
16 documents, released by the NTSB on October 20, 2016. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.