ASN Wikibase Occurrence # 296977
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| Date: | Friday 12 July 2002 |
| Time: | 09:20 LT |
| Type: | Monnett Moni |
| Owner/operator: | Private |
| Registration: | N9104S |
| MSN: | PJT-00048 |
| Year of manufacture: | 1998 |
| Total airframe hrs: | 151 hours |
| Engine model: | Komet KFM107E |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Laurel, MT -
 United States of America
|
| Phase: | Unknown |
| Nature: | Private |
| Departure airport: | Laurel, MT (6S8) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot of the homebuilt aircraft and installer of the wooden propeller assembly reported that during a performance test/rate of climb test with the new propeller, he smelled a wood burning smell followed by a "real bad vibration." The pilot initiated a forced landing to an open field. During the landing roll on the soft terrain, the landing gear sheared off. After the accident, the pilot noted that one of the blades of the wooden propeller was missing. The remaining blades and two hub plates were sent to the NTSB Materials Laboratory for examination. The metallurgist reported that the fretting observed on the hub plates suggested that the hub mounting bolts were not as tight as required allowing the hub to oscillate on its mounting flange. The motion in the pitch block of both blades produced the heat that charred the wood and softened the pitch block material allowing it to be displaced and imprinted with the pattern of the wood plies. The compression failure and the frictional features on the hub portion in the pitch block indicated a fatigue-like failure in wood which propagated until the remaining wood could not withstand the stresses of operation and subsequently failed in a tensile mode.
Probable Cause: Undertorqued mounting bolts which resulted in fatigue to the wooden propeller blade and subsequent in flight separation of one of the blades while in cruise flight. An improper installation of the propeller assembly and soft terrain encountered during the landing roll were factors.
Accident investigation:
 |
|
Sources:
NTSB SEA02LA130
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 14-Oct-2022 12:58 | ASN Update Bot | Added |
| 19-Sep-2023 01:44 | Ron Averes | Updated |
Corrections or additions? ... Edit this accident description
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