NTSB Identification: CHI90GA273.
The docket is stored on NTSB microfiche number 42794.
Incident occurred Sunday, September 23, 1990 in CAPE GIRARDEAU, MO
Probable Cause Approval Date: 12/14/1992
Aircraft: PIPER PA-3O, registration: N752CF
Injuries: 1 Uninjured.

: NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this public aircraft accident report.

THE PILOT STATES HE OBTAINED NO GEAR MOVEMENT ON SELECTING GEAR DOWN. WHEN THE SWITCH WAS RECYCLED, THE LANDING GEAR EXTENDED BUT THE GEAR DOWN INDICATOR DID NOT ILLUMINATE. TOWER REPORTED THE GEAR APPEARED TO BE DOWN. THE PILOT THEN USED MANUAL EXTENSION TO LOWER THE GEAR AND REPORTS HE OBTAINED A DOWN LOCKED LIGHT. THE LANDING GEAR RETRACTED DURING LANDING ROLLOUT. EXAMINATION REVEALED EXCESSIVE PLAY IN THE LEFT AND RIGHT MAIN GEAR LINKAGE. THE LEFT MAIN GEAR EXTENDED BUT WOULD NOT ACHIEVE OVER-CENTER IN THE DOWN POSITION USING MANUAL EXTENSION. A WIRE TO THE LEFT GEAR DOWN SWITCH WAS BROKEN WITHIN ITS INSULATION; IN AN AREA WHERE THE WIRE FLEXES AS THE GEAR CYCLES. LATER PRODUCTION AIRPLANES INCLUDE A LANDING GEAR DOWN SAFETY DEVICE TO MECHANICALLY LOCK THE GEAR DOWN WHEN EXTENDED MANUALLY. THE DEVICE MAY BE FITTED TO EARLIER AIRPLANES, AND ITS AVAILABILITY WAS ANNOUNCED IN 1973 IN A SERVICE SPARES LETTER.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

EXCESSIVE PLAY IN THE LANDING GEAR EXTENSION LINKAGE. A FACTOR IN THE INCIDENT WAS UNRELIABILITY OF THE GEAR INDICATING SYSTEM.

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