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| Date: | Tuesday 19 July 2022 |
| Time: | 22:00 |
| Type: |  Zenair STOL CH 701 |
| Owner/operator: | Private |
| Registration: | N8787G |
| MSN: | 7-6684 |
| Year of manufacture: | 2011 |
| Total airframe hrs: | 70 hours |
| Engine model: | Jabiru 3300A |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Other fatalities: | 0 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Bothell, WA -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Tacoma Narrows Airport, WA (TIW/KTIW) |
| Everett-Snohomish County Airport, WA (PAE/KPAE) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
On July 19, 2022, about 2200 Pacific daylight time, a Zenith CH-701, N8787G, sustained substantial damage when it was involved in an accident near Bothell, Washington. The pilot and passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
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.
Accident investigation:
 |
|
Sources:
NTSB WPR22LA263
https://data.ntsb.gov/Docket?ProjectID=105537
Location
Images:
Photo: NTSB
Media:
An experimental aircraft crashed on 228th south of 45th Ave tonight near Canyon Park around 10:20 PM. Details are limited at this time. Two patients are being treated and transported. Expect emergency crews on scene for some time. No PIO on scene. pic.twitter.com/zj0HX1CPRw
— Snohomish Regional Fire & Rescue (@SnoRegionalFire) July 20, 2022
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 20-Jul-2022 07:02 | harro | Added |
| 23-Jul-2022 05:40 | Anon. | Updated [Embed code, Narrative, ] |
| 30-Jul-2022 16:49 | AgOps | Updated [Operator, Nature, ] |
| 11-Aug-2022 21:33 | Captain Adam | Updated [Time, Phase, Departure airport, Destination airport, Source, Narrative, ] |
| 20-Jul-2024 09:18 | ASN Update Bot | Updated [Time, Operator, Other fatalities, Source, Narrative, Accident report, ] |
| 29-Jul-2024 16:21 | Captain Adam | Updated [Time, Aircraft type, Operator, Source, Narrative, Photo, ] |
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