What happened
On 27 September 2000, a Convair 340 (580), registration C-GFHH, was performing an instrument flight from La Grande 3 to La Grande 4, Quebec. During the landing on Runway 09, the aircraft touched down approximately 800 feet beyond the threshold. Upon touchdown, the pilot engaged reverse pitch on the propellers, at which point the aircraft began to drift to the right. Despite the pilot's attempts to correct the course using braking and rudder input, the aircraft exited the south side of the runway at approximately 50 knots.
The aircraft traveled 350 feet across soft, rocky terrain before coming to a stop. During the excursion, the landing gear collapsed, causing the propellers to strike the ground and separate from the engines. The left engine continued to run for approximately 15 minutes after the stop, despite the crew's attempts to shut it down using the emergency fuel cut-off handles. The crew initiated an evacuation via the right-side window exits to avoid the running engine. Five persons sustained minor injuries, and while the aircraft suffered substantial damage, no fire occurred.
The investigation
The TSB examined the aircraft's steering system and the maintenance history of the nose-gear assembly. Investigators discovered that the steering control valve lever had been incorrectly reassembled during a previous overhaul. Specifically, the assembly included an extra washer and a bushing that did not meet proper clearance specifications, which created significant resistance when the pilot attempted to turn the steering wheel.
Furthermore, the investigation looked into the crew's decision to continue the flight despite noticing difficulty steering the aircraft during taxiing at a previous stop. The investigation also reviewed the engine shutdown procedures and the impact of the pilot's decision to cut electrical power following the hard landing, which rendered the public address and alarm systems inoperable.
Findings
- The incorrect reassembly of the steering control valve lever, involving an extra washer and improper bushing clearance, was the primary cause of the steering resistance.
- The reuse of nylon locknuts during maintenance led to excessive play in the valve components.
- The flight crew's decision to proceed with the flight despite known steering difficulties contributed to the occurrence.
- Maintenance errors, including the use of an incomplete maintenance manual instead of an overhaul manual, contributed to the improper repair of the steering system.
- The loss of electrical power, while following hard-landing procedures, prevented the use of the public address system to order the evacuation and hindered the ability to shut down the engine via electrical switches.