Narrative:
The aircraft was approximately 4000 feet asl when the crew selected the flaps for the approach to Prince Albert. A bang was heard from the rear of the fuselage. The aircraft commenced an uncommanded pitch-up to a near-vertical attitude, then stalled, nosed over, and began a spin to the left. The crew countered the spin but the aircraft continued to descend in a near-vertical dive. Through the application of full-up elevator and the manipulation of power settings, the pilots were able to bring the aircraft to a near-horizontal attitude. The crew extended the landing gear and issued a Mayday call, indicating that they were conducting a forced landing. The aircraft struck a knoll, tearing away the belly cargo pod and the landing gear. The aircraft bounced into the air and travelled approximately 180 metres, then contacted a barbed-wire fence and slid to a stop approximately 600 metres from the initial impact point.
FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS:
1. During flight, the horizontal stabilizer trim actuator worked free of the mounting structure, and as a result, the flight crew lost pitch control of the aircraft.
2. During replacement of the horizontal stabilizer trim actuator, the upper attachment bolts were inserted through the airframe structure but did not pass through the upper mounting lugs of the trim actuator.
3. The improperly installed bolts trapped the actuator mounting lug assemblies, suspending the weight of the actuator and giving the false impression that the bolts had been correctly installed.
4. Dual inspections, ground testing, and flight testing did not reveal the faulty attachment.
Horizontal stabilizer
Forced landing outside airport
accident date: 23-04-2003
type: Beechcraft 99A
registration: N396HA
| Status: | Final |
| Date: | Wednesday 23 April 2003 |
| Time: | 18:02 |
| Type: |  Beechcraft 99A Airliner |
| Operator: | Transwest Air |
| Registration: | C-FDYF |
| MSN: | U-110 |
| First flight: | 1969 |
| Engines: | 2 Pratt & Whitney Canada PT6A-27 |
| Crew: | Fatalities: 0 / Occupants: 2 |
| Passengers: | Fatalities: 0 / Occupants: 4 |
| Total: | Fatalities: 0 / Occupants: 6 |
| Aircraft damage: | Damaged beyond repair |
| Location: | 11 km (6.9 mls) from Prince Albert, SK ( Canada)
|
| Phase: | Approach (APR) |
| Nature: | Domestic Scheduled Passenger |
| Departure airport: | Saskatoon Airport, SK (YXE/CYXE), Canada |
| Prince Albert Airport, SK (YPA/CYPA), Canada | |
| Flightnumber: | 602 |
The aircraft was approximately 4000 feet asl when the crew selected the flaps for the approach to Prince Albert. A bang was heard from the rear of the fuselage. The aircraft commenced an uncommanded pitch-up to a near-vertical attitude, then stalled, nosed over, and began a spin to the left. The crew countered the spin but the aircraft continued to descend in a near-vertical dive. Through the application of full-up elevator and the manipulation of power settings, the pilots were able to bring the aircraft to a near-horizontal attitude. The crew extended the landing gear and issued a Mayday call, indicating that they were conducting a forced landing. The aircraft struck a knoll, tearing away the belly cargo pod and the landing gear. The aircraft bounced into the air and travelled approximately 180 metres, then contacted a barbed-wire fence and slid to a stop approximately 600 metres from the initial impact point.
Probable Cause:
FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS:
1. During flight, the horizontal stabilizer trim actuator worked free of the mounting structure, and as a result, the flight crew lost pitch control of the aircraft.
2. During replacement of the horizontal stabilizer trim actuator, the upper attachment bolts were inserted through the airframe structure but did not pass through the upper mounting lugs of the trim actuator.
3. The improperly installed bolts trapped the actuator mounting lug assemblies, suspending the weight of the actuator and giving the false impression that the bolts had been correctly installed.
4. Dual inspections, ground testing, and flight testing did not reveal the faulty attachment.
Accident investigation:
 |
|
Classification:
Wrong installation of parts Horizontal stabilizer
Forced landing outside airport
Sources:
» CBCPhotos
accident date: 23-04-2003
type: Beechcraft 99A
registration: N396HA
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Saskatoon Airport, SK to Prince Albert Airport, SK as the crow flies is 134 km (84 miles).
Distance from Saskatoon Airport, SK to Prince Albert Airport, SK as the crow flies is 134 km (84 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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