NTSB Identification: SEA92IA136.
The docket is stored on NTSB microfiche number 47688.
Nonscheduled 14 CFR operation of TIMEAIR INC.
Incident occurred Sunday, June 21, 1992 in PORTLAND, OR
Probable Cause Approval Date: 06/30/1993
Aircraft: FOKKER F.28 MK 1000, registration: CGTAH
Injuries: 53 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.

WHILE CRUISING AT FLIGHT LEVEL 290, THE FOKKER F.28 MK 1000 EXPERIENCED AN UNCOMMANDED CLIMB OF APPROXIMATELY 3000 FEET. FULL FORWARD PRESSURE ON THE CONTROL COLUMN DID NOT ARREST THE CLIMB, AND THE ATTEMPTED USE OF THE ALTERNATE STABILIZER TRIM SWITCH RESULTED IN REPEATED POPPING OF THE CIRCUIT BREAKER. THE PILOT REGAINED PITCH CONTROL OF THE AIRCRAFT BY MOVING PASSENGERS FORWARD IN THE CABIN, AND BY ENLISTING THE PHYSICAL ASSISTANCE OF ONE FLIGHT ATTENDANT. BY ADJUSTING FLAP AND POWER SETTINGS A SUCCESSFUL LANDING WAS ULTIMATELY ACCOMPLISHED. THE INVESTIGATION REVEALED THAT THE ROD END BEARING ON THE STABILIZER SERVO SPOOL VALVE HAD BEEN OVERTORQUED, CAUSING THE FAILURE OF THE SPOOL, RESULTING IN A SLOW NOSE UP STABILIZER RUNAWAY.

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

THE PARTIAL FAILURE OF THE HORIZONTAL STABILIZER TRIM DRIVE SYSTEM, THE RESTRICTED MOVEMENT OF THE STABILIZER, AND THE OVERTORQUE OF A SYSTEM COMPONENT.

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