ASN Wikibase Occurrence # 285120
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| Date: | Sunday 25 March 2007 |
| Time: | 08:30 LT |
| Type: |  Bellanca 7ECA |
| Owner/operator: | Aviation Club Inc. |
| Registration: | N53874 |
| MSN: | 1135-76 |
| Total airframe hrs: | 2400 hours |
| Engine model: | Lycoming O-235-C1 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Wawayanda, New York -
 United States of America
|
| Phase: | Unknown |
| Nature: | Training |
| Departure airport: | Sussex Airport, NJ (KFWN) |
| Sussex Airport, NJ (KFWN) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The flight instructor and student pilot were practicing stalls when the airplane experienced a sudden, total loss of engine power. Postaccident examination of the engine revealed that the left crankcase half idler gear shaft was dislodged from its respective mounting boss. The two idler gear shaft retaining bolts were broken. The idler gear that interconnected the crankshaft and camshaft remained on the idler shaft and was observed with a "U"-shaped fracture at the gear ring area that separated two full teeth. Optical examination of the gear fracture revealed fracture face markings, including arrest lines consistent of fatigue progression, which was estimated to cover more than 95 percent of the fracture surface. Both gear shaft retaining bolts were separated near their respective heads. The bolts displayed severe circumferential wear through the threaded shanks that removed the majority of the bolt diameters. High magnification viewing of the fractures in these areas on both bolts revealed features indicative of multiple origin fatigue propagating through the remaining cross sections. The lock plate was fractured in several locations and heavily distorted. The bolt holes in the lock plate were severely elongated and enlarged over their original diameter. While it was likely that loosening of the bolts precipitated the gear failure, no conclusive evidence was uncovered to confirm that scenario. The engine's most recent annual inspection was performed about 4 months prior to the accident. At that time, the engine had been operated for 1,226 hours since it was overhauled in 1985, and 639 hours since it was disassembled and reassembled after a propeller strike during 2001.
Probable Cause: A failure of the crankshaft idler gear, which resulted in a total loss of engine power while maneuvering.
Accident investigation:
 |
|
Sources:
NTSB NYC07LA086
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 01-Oct-2022 18:00 | ASN Update Bot | Added |
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