NTSB Identification: ANC89IA099.
The docket is stored on NTSB microfiche number 39213.
Incident occurred Tuesday, June 20, 1989 in PALMER, AK
Probable Cause Approval Date: 08/26/1992
Aircraft: DE HAVILLAND DHC-3, registration: N41755
Injuries: 2 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

THE AIRPLANE PITCHED ABRUPTLY NOSE DOWN FOLLOWING AN INFLIGHT FAILURE OF THE HORIZONTAL STABILIZER'S TRIM ACTUATOR JACK SCREW. THE CREW WAS ABLE TO MAINTAIN CONTROL OF THE AIRPLANE AND MAKE A SUCCESSFUL LANDING BY EXERTING A LARGE AMOUNT OF BACK PRESSURE ON THE CONTROL WHEEL AND ADDING NEARLY FULL ENGINE POWER. AN EXAMINATION OF THE ACTUATOR REVEALED AN INADEQUATE AMOUNT OF LUBRICATING GREASE AND EXCESSIVE PART WEAR.

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

INADEQUATE LUBRICATION WHICH RESULTED IN THE FAILURE OF THE HORIZONTAL STABILIZER'S TRIM ACTUATOR.

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