WPR22LA263 · Zenith CH701
Zenith CH701 · Accident: loss of engine power (total) en route
From Tacoma Narrows Airport (TIW) to Seattle Paine Field International Airport (PAE)
Event
- NTSB case
- WPR22LA263
- 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
- Event fatalities
- Unknown
- 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
Zenith CH701
- Aircraft type
- Zenith CH701
- 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
- N8787G
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Tacoma Narrows Airport (TIW), Tacoma, WATo Seattle Paine Field International Airport (PAE), Everett, WA
- Aircraft age
- About 11 years (built 2011)
- 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
- En route
- 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
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported the takeoff and en route portions of the flight were uneventful. While descending to the traffic pattern altitude at the destination airport, the engine lost power and the propeller stopped. The pilot made an emergency landing on a vacant road, colliding with powerlines. A postaccident examination of the engine revealed that the flywheel screws had separated due to fatigue, resulting in an engine failure. Examination of the screws showed multiple fatigue cracks and wear consistent with low-stress bending fatigue. Maintenance records revealed that the engine had been installed in another airplane that was involved in an accident where the propeller was damaged. According to the engine manufacturer, abrupt propeller stoppage can produce a spike of torque along the crankshaft, overloading the flywheel screws and causing failure. There was no evidence that the screws were replaced after that accident.
Probable cause
A loss of engine power due to the fatigue failure of the engine’s flywheel screws that were likely overloaded when the engine was involved in a previous accident.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR22LA263
- Event ID
- 20220720105537
- Case number
- WPR22LA263
- 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: local date, investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2022-07-20.
- API snapshot SHA-256: a98bb04eed1da75a9cb092b2e4788db60d84788bce0e62c3cdde3e753ae86233; retrieved 2026-09-16T15:29:24.398Z.