ASN Wikibase Occurrence # 297292
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Thursday 16 May 2002 |
| Time: | 09:20 LT |
| Type: |  Cessna 170B |
| Owner/operator: | Private |
| Registration: | N4669C |
| MSN: | 25613 |
| Total airframe hrs: | 1262 hours |
| Engine model: | Lycoming O-360-A1A |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | North Pole, Alaska -
 United States of America
|
| Phase: | Unknown |
| Nature: | Private |
| Departure airport: | Fairbanks International Airport, AK (FAI/PAFA) |
| North Pole, AK (95Z) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The right main landing gear leg separated from the airplane while landing on a gravel airstrip, which resulted in substantial damage to the airframe. The main landing gear had recently been rebuilt, and this was the second landing since the work was completed. The gear leg had been secured to the airplane with an AN7-20A bolt and an MS21044C stainless steel nut. The bolt, which remained attached to the separated gear leg was bent and the threads were damaged. The MS21044C nut had fractured, and was found in the right main landing gear bulkhead assembly. Examination of the nut determined it fractured due to circumferential overstress tension. The airplane manufacturer's parts catalog specifies a AN365-720C steel nut to secure the main landing gear legs. The military standard, under which the original AN365 nut was manufactured, requires any substitute nut to be of like material, plating, and thread size, and specifically excludes the substitution of the MS21044C nut in lieu of the AN365-720C nut. The proper substitute for the AN365-720C is the MS21044N, which is an all steel nut. However, the rated tensile strength of the AN365, MS21044C and MS21044N series nuts are all 125 ksi. Examination of the bolt revealed sheared threads adjacent to the bolt grip, indicating that the nut was intact on the bolt when the bolt/nut combination was loaded to failure. The bending deformation of the bolt indicated a side load was present during the failure. This side load could have resulted from a hard landing with the airplane moving sideways or improper reinstallation of the landing gear may have allowed normal landings to introduce side loads.
Probable Cause: The separation of the right main landing gear from the airplane during landing. A factor associated with the accident is the unapproved hardware used to attach the main landing gear.
Accident investigation:
 |
|
Sources:
NTSB ANC02LA034
History of this aircraft
Other occurrences involving this aircraft
| 29 August 2001 | N4669C | Private | 0 | FAIRBANKS, Alaska | |
sub |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 14-Oct-2022 16:50 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation