NTSB Identification: SEA96LA140.
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Nonscheduled 14 CFR
Accident occurred Tuesday, July 02, 1996 in JACKSON, WY
Probable Cause Approval Date: 08/25/1997
Aircraft: Piper PA-31, registration: N27518
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.
During a normal landing, the aircraft's nose gear collapsed. The pilots stated that three green indicator lights were observed during the final landing checklist. In postaccident troubleshooting, an instrument panel mounting screw which was too long was discovered. This screw was obstructing the movement of the landing gear selector handle to a full down position, allowing it to return prematurely to neutral (which removes hydraulic pressure from the gear system.) The nose gear was thus not hydraulically moved over center and was unlocked, even though the nose gear indicated down and locked in this configuration. Per the aircraft service manual, the nose gear linkage incorporates a downlock spring, and both gear linkage overcenter travel and gear down limit switch position are adjustable. It was not determined whether, or when, these items were checked or adjusted before the accident. After the proper screw was installed in the instrument panel, the gear operated properly in retraction tests.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: An improper screw installation by an unknown individual into the instrument panel, which restricted movement of the gear handle resulting in premature disengagement of the normal landing gear extension system. A factor was one or more improperly adjusted nose gear system components, which resulted in an unlocked nose gear that falsely indicated down and locked. Full narrative available
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