NTSB Identification: ANC05LA001.
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Accident occurred Thursday, October 07, 2004 in Anchorage, AK
Probable Cause Approval Date: 07/07/2005
Aircraft: Piper PA-18-150, registration: N5760D
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The private pilot reported he made a hard landing on a paved runway in his tail wheel and tundra tire equipped airplane, and that the left main landing gear assembly subsequently collapsed. The airplane sustained structural damage to the left wing when it struck the runway. An inspection of the main landing gear (MLG) assembly by the NTSB investigator-in-charge and FAA certification engineers, disclosed that the MLG was not an approved component, although it had been stamped "PMA" for Primary Manufacturing Authority, indicating it was an approved part. Further research and analysis of the gear assembly revealed that it had fractured at the shock strut attachment lugs, and that the lugs were approximately one-half strength of the original factory equipment. The MLG assembly has been available for several years, and may be retro-fitted to the entire Piper Cub series airplanes. The FAA aircraft certification branch and the manufacturer are presently conducting a review of the design and have indicated that a manufacturer's Service Bulletin will be published offering a strengthened version of the MLG, and that the FAA will issue either a Special Airworthiness Information Bulletin, or an Airworthiness Directive.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The inadequate and unapproved design of the main landing gear assembly by the manufacturer, which resulted in a failure of the main landing gear during landing, and structural damage to the airplane. A factor in the accident was the pilot's misjudged flare. Full narrative available
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