ASN Wikibase Occurrence # 353714
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| Date: | Tuesday 29 September 1998 |
| Time: | 15:54 LT |
| Type: |  Cessna 150L |
| Owner/operator: | Private |
| Registration: | N19427 |
| MSN: | 15074415 |
| Year of manufacture: | 1973 |
| Total airframe hrs: | 5306 hours |
| Engine model: | Continental O-200-A |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Bonners Ferry, ID -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Private |
| Departure airport: | (65S) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During the initial climb following a touch-and-go landing, the engine sputtered twice and the pilot-in-command initiated an emergency landing. The field of choice was obstructed with construction equipment and she chose an alternate field. She retarded the throttle to idle, lowered full flaps, and slipped the aircraft to land as expeditiously as possible; and then steered the aircraft into small trees and brush to avoid going over an embankment. Post-crash examination revealed all 3 bosses of the #3 cylinder broken, thus rendering the intake/exhaust valves permanently closed. Metallurgical examination revealed that the separation of the rocker arm shaft bosses was initiated by fatigue cracking in the boss located adjacent to the exhaust valve. Further examination revealed the presence of heavy tool marks on the bore surface of all three bosses. The heavy manual cutting of the bore surface is not authorized by the engine manufacturer and the surface created by this procedure did not meet the engine manufacturer requirements for surface finish in the bore of the bosses. A review of the aircraft's engine log revealed an overhaul 645.4 hours previous to the accident. The overhaul facility reported that all 4 cylinders were outsourced during the overhaul procedure.
Probable Cause: Improper maintenance by an outsourcing facility which resulted in a lack of identification of scoring of the interior of the #3 cylinder rocker shaft bosses. The scoring resulted in a fatigue fracture and subsequent permanent closure of both intake and exhaust valves. Contributing factors were the lack of a suitable landing site and trees.
Accident investigation:
 |
|
Sources:
NTSB SEA98LA190
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 10-Mar-2024 09:45 | ASN Update Bot | Added |
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