ASN Wikibase Occurrence # 298148
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| Date: | Monday 31 July 2017 |
| Time: | 11:30 LT |
| Type: |  Cessna 172S |
| Owner/operator: | |
| Registration: | N957TA |
| MSN: | 172S9057 |
| Year of manufacture: | 2002 |
| Total airframe hrs: | 5539 hours |
| Engine model: | Lycoming IO-360-L2R |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Seattle, Washington -
 United States of America
|
| Phase: | En route |
| Nature: | Training |
| Departure airport: | Seattle-Boeing Field International Airport, WA (BFI/KBFI) |
| Seattle-Boeing Field International Airport, WA (BFI/KBFI) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During an instructional flight, the engine started running rough and, shortly after the oil pressure light illuminated, subsequently quit. The pilot elected to ditch the airplane in the water close to the shoreline.
An onsite examination of the engine revealed that the top bolt of the right magneto was loose and had backed off, which allowed the magneto to become partially separated, leaving a 3/8-inch gap at the top of the magneto where it mounted to the case, which allowed oil to exit the engine. Metal shavings were observed throughout the engine.
A review of the maintenance records indicated that the magnetos were removed and overhauled about 9 months before the accident during a 500-hour inspection, which was 420.5 hours of flight time before the accident. The airplane had accumulated about 22 hours of flight time since its last annual inspection, and the loose magneto bolt should have been able to be identified at that time.
Probable Cause: The total loss of engine power due to oil starvation as a result of the loose right magneto, which allowed oil to escape and the engine to seize. Contributing to the accident was inadequate maintenance, which failed to identify the loose magneto bolt.
Accident investigation:
 |
|
Sources:
NTSB WPR17LA176
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 15-Oct-2022 13:41 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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