ASN Wikibase Occurrence # 181073
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| Date: | Friday 16 July 2004 |
| Time: | 10:33 |
| Type: |  Beechcraft A45 Mentor |
| Owner/operator: | Private |
| Registration: | N134BH |
| MSN: | G-791 |
| Total airframe hrs: | 4553 hours |
| Engine model: | Continental IO-520-B2 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | near LaGrange, GA -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | McMinnville, TN (KRNC) |
| New Smyrna Bch, FL (KEVB) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot stated that, while in cruise flight at 7,500 feet, the engine vibrated severely, and the propeller separated. The airplane collided with trees during emergency landing, and the propeller was not located. Examination of the engine revealed the crankshaft was fractured forward of the alternator drive gear. Examination of the fracture surface at the crankshaft separation revealed features consistent with fatigue fracture under torsional loading. Blue tinting was visible near the middle of the No. 4 main journal. Several ladder cracks were observed on the No. 4 main journal surface adjacent to the blue-tinted region. A large crack in the No. 4 main journal surface continued forward through the alternator drive gear and to the exposed fatigue fracture at the crankshaft separation. Scanning Electron Microscope examination of the crack revealed crack arrest lines and marks emanated from an area at the journal surface; the fracture surface within the origin area displayed an appearance consistent with an overstress fracture. Hardness testing of the material revealed no evidence of anomaly. According to the maintenance logs, the Continental IO-520-B2 engine received a field major overhaul on October 10, 1974. The engine received a top overhaul on July 1, 2002, at an hour meter reading of 1000.0. The hour meter reading on the airplane at the accident site was 1053.7. According to Teledyne Continental Service Information Letter SIL98-9A, the recommended time between overhaul (TBO) periods for the IO-520-B series engine is 1700 operating hours or 12 years, whichever occurs first.
Probable Cause: The maintenance personnel under-torquing of the crankcase throughbolts during top overhaul, which resulted in crankcase fretting, and the subsequent fatigue failure of the crankshaft at the No. 4 main journal. A factor was the lack of suitable terrain for forced landing.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040719X01005&key=1
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N134BH
ex.USAF/55-234.
History of this aircraft
Other occurrences involving this aircraft
| 10 April 2001 | N340JB | Private | Claxton, GA | |
w/o |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 06-Nov-2015 20:33 | Noro | Added |
| 28-Jun-2016 19:03 | TB | Updated [Operator, Other fatalities, Location, Phase, Damage] |
| 21-Dec-2016 19:30 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 07-Dec-2017 18:12 | ASN Update Bot | Updated [Operator, Departure airport, Destination airport, Source, Narrative] |
| 08-Feb-2022 14:02 | A.J.Scholten | Updated [Cn, Source] |
Corrections or additions? ... Edit this accident description
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