WPR15FA268 · Cessna 150F F
Cessna 150F F · Accident: loss of engine power (total) during initial climb
From Jefferson County International Airport (0S9) to Skagit Regional Airport (BVS)
Event
- NTSB case
- WPR15FA268
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Cessna 150F F
- Aircraft type
- Cessna 150
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N8529G
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Jefferson County International Airport (0S9), Port Townsend, WATo Skagit Regional Airport (BVS), Burlington, WA
- Aircraft age
- About 50 years (built 1965)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Initial climb
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of engine power (total)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft power plant
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR15FA268
- Event ID
- 20150928X72825
- Case number
- WPR15FA268
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: ea3b766f9a2f060148add01b98e2c58a177a5e2a6482fa4ef4a7469a18de3ef5; retrieved 2026-09-16T02:49:59.908Z.