ASN Wikibase Occurrence # 285068
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| Date: | Monday 9 April 2007 |
| Time: | 12:30 LT |
| Type: |  Beechcraft 35 |
| Owner/operator: | Private |
| Registration: | N460B |
| MSN: | D-1477 |
| Year of manufacture: | 1948 |
| Total airframe hrs: | 4275 hours |
| Engine model: | Continental E185 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Topeka, Kansas -
 United States of America
|
| Phase: | Unknown |
| Nature: | Private |
| Departure airport: | Topeka-Philip Billard Airport, KS (TOP/KTOP) |
| Kansas City-Charles B. Wheeler Downtown Airport, MO (MKC/KMKC) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
According to the pilot, shortly after departing runway 18 she heard what "sounded like a loud backfire, a single bang," and then the engine lost power. The pilot selected a nearby field and performed a forced landing. During the landing the nose gear collapsed resulting in substantial damage. An examination of the engine revealed that the crankshaft gear separated from the crankshaft and was loose inside the accessory case. The upper portions of five of the six screws used to secure the gear to the crankshaft were found in the accessory case. Metallurgical examination of the fracture surface revealed signatures consistent with fatigue fractures. One screw was sectioned and tested for hardness with the results of 29, 30, 30, and 31 Rockwell C Harness (HRC). According to TCM, the drawing specifies an H5 fastener with a hardness requirement of 32 through 37 HRC. In addition, the head of the screw had a diameter of .40 inches or less. The TCM drawing specifies a diameter of .44 inches. According to TCM, this could have resulted in inadequate torque for this installation. An examination of the airplane flight controls and engine controls revealed no anomalies.
Probable Cause: The use of unapproved bolts to mount the crankshaft and gear together, causing fatigue and failure of those mounting bolts, resulting in the subsequent loss of engine power. Factors contributing to the accident were the separation of the crankshaft gear, and the lack of suitable terrain for a forced landing.
Accident investigation:
 |
|
Sources:
NTSB DEN07LA083
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 01-Oct-2022 17:21 | ASN Update Bot | Added |
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