NTSB Identification: ANC06TA009.
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Accident occurred Saturday, November 05, 2005 in Cordova, AK
Probable Cause Approval Date: 06/28/2006
Aircraft: Cessna 185, registration: N771X
Injuries: 1 Minor,2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.
A commercial certificated pilot in a tundra tire-equipped airplane from a CFR Part 135 operator, under contract to the Federal Aviation Administration (FAA) as a public use flight, was transporting FAA personnel to a navigational facility on a remote island. During the landing roll on a dirt surface runway, the lower end of the left main landing gear strut fractured at the axle bolt holes, where the axle is bolted onto the strut. The fractured end of the left gear strut dug into the ground, the airplane swerved 90 degrees to the left and nosed down, receiving structural damage to the left wingtip and the right main landing gear. The main landing gear is a spring steel strut that is shot peened during manufacture, and is bolted to the fuselage at its upper end. Photographs of the point of separation revealed a vertical fracture, oriented 90 degrees to the span of the gear strut, through the upper axle retaining bolt holes. The fractured surface of the lower end of the strut, containing the axle and brake assembly, had a rough, crystalline appearance with darkening of the metal surface along the outer edges of the strut. The fractured surface of the upper end of the strut, where it dug into the ground, had a smooth polished appearance. Periodic visual inspection of the landing gear is required by 14 CFR Part 43. Neither the manufacturer or the FAA have established service limits (hours or cycles) for the main landing gear strut. Removal of the gear strut for inspection, or the use of nondestructive inspection techniques, is not required by the manufacturer or the FAA. On March 16, 2001, the NTSB recommended that the FAA issue an airworthiness directive (AD) to require an initial and recurring inspection of Cessna main landing gear spring steel struts, using nondestructive inspection techniques. On August 31, 2001, the FAA reported to the NTSB that the current inspection criteria outlined in the Cessna Maintenance Manual are adequate to detect cracks in the main landing gear struts, and that additional airworthiness action is not warranted. On March 25, 2002, the NTSB responded by stating, in part: "The Safety Board continues to believe that a visual inspection alone will not detect cracks in the Cessna main landing gear spring struts. However, the Safety Board acknowledges that the statistical evidence does not warrant issuance of ADs at this time as called for in the Board's recommendation." In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1), the pilot indicated that the landing gear strut, Part number 0741001-5, had accrued about 9,000 hours of service. In the optional area of the report: Recommendation (How Could This Accident Have Been Prevented), the pilot wrote: "Put time life [limit] on gear legs."
The National Transportation Safety Board determines the probable cause(s) of this accident to be: A fracture and separation of the main landing gear strut during the landing roll, which resulted in a loss of control, and subsequent nose down. Factors contributing to the accident were the manufacturer's and the FAA's insufficient standards/requirements regarding inspection procedures for the main landing gear struts. Full narrative available
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