On June 22, 1992, a Fokker F.28 MK 1000 (registration CGTAH) operated by Timeair Inc. was involved in an aviation accident near Portland, OR. Investigators recorded the probable cause as: 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. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
While cruising at FL290, a Fokker F.28 Mk 1000 experienced an uncommanded climb of about 3000 feet. The pilot regained pitch control by moving passengers forward and with flight attendant assistance, then landed successfully.
Incident Description
During cruise at Flight Level 290, a Fokker F.28 Mk 1000 aircraft experienced an uncommanded climb of approximately 3000 feet. Applying full forward pressure on the control column did not arrest the climb. The flight crew attempted to use the alternate stabilizer trim switch, but this repeatedly caused the associated circuit breaker to pop.
To regain pitch control, the pilot moved passengers forward in the cabin and enlisted the physical assistance of one flight attendant. By adjusting flap and power settings, the crew was ultimately able to accomplish a successful landing.
Investigation Findings
The investigation revealed that the rod end bearing on the stabilizer servo spool valve had been overtorqued. This overtorquing caused the failure of the spool, which resulted in a slow nose-up stabilizer runaway.
Outcome
The aircraft landed successfully. No further details about injuries or damage were specified in the investigation report.
Probable cause
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.