Accident Convair CV-580 C-GFHH,

ASN Wikibase Occurrence # 323421

Date:	Wednesday 27 September 2000
Time:	15:38
Type:	Convair CV-580
Owner/operator:	Hydro-Quebec
Registration:	C-GFHH
MSN:	109
Year of manufacture:	1953
Total airframe hrs:	78438 hours
Engine model:	Allison 501-D13
Fatalities:	Fatalities: 0 / Occupants: 22
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	La Grande-LG-4 airstrip, QC - Canada
Phase:	Landing
Nature:	Passenger - Non-Scheduled/charter/Air Taxi
Departure airport:	La Grande-LG-3 airstrip, QC
Destination airport:	La Grande-LG-4 airstrip, QC (YAH/CYAH)
Investigating agency:	TSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Around 07:30 EDT Convair CV-580 C-GFHH departed Montreal for flight Ampères 180 to fly Hydro-Quebec employees to La Grande-LG-3 airstrip, QU and La Grande-LG-4 airstrip, QU. When taxiing at Montreal-Dorval Airport, the captain found it harder than usual to turn the nose gear steering wheel to the left. However, by turning the wheel harder and intermittently and using differential braking, he was able to steer the aircraft on the ground. The flight crew therefore decided to continue the flight. On the approach to LG-4, the sky was obscured at 800 feet, visibility was 1 mile in light snow showers, and surface wind was from the west at 5 to 7 knots. Landing on runway 09 would decrease the flight time, and the maximum allowable tailwind on landing specified in the Flight Manual would not be exceeded, so the flight crew elected to make a downwind landing on runway 09. The aircraft touched down approximately 800 feet beyond the runway threshold. As soon as the nose wheel touched down, the captain set the propellers to reverse pitch. Shortly afterward, the aircraft started to drift to the right. The captain tried to correct by braking and applying full left rudder while setting the propellers to reverse pitch asymmetrically, but the aircraft continued its course and exited the south side of runway 09. The aircraft exited the runway at approximately 50 knots and went down a slope to a point about seven feet below the level of the runway surface. The aircraft continued for 350 feet over very soft and rocky ground before coming to rest. The aircraft was evacuated on the right side because the no. 1 engine kept running, despite efforts to shut it down.

FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS
- The steering control valve lever was not reassembled in accordance with the specifications and the drawings in the overhaul manual and the maintenance manual: the lever was assembled with two washers instead of one, and the circumference of the bushing was 0.0005 inch greater than the circumference of the hole in the lever. These two deficiencies created additional resistance that impeded the pivoting of the aircraft steering wheel.
- The nylon locknuts were reinstalled during the repair of the steering control valve, contrary to the recommendation that they be used only once. The locknuts then came loose in service, creating play in the parts of the valve.
- Incorrect interpretation of the problem and the influence of previous experience using the nose-gear steering wheel led the crew to make the flight despite their concern about the aircraft's nose-gear steering system.

FINDINGS AS TO RISK

- The maintenance personnel of [company] used the (incomplete) maintenance manual instead of the overhaul manual to overhaul and repair the steering control valve, contributing to the incorrect reassembly of the valve.
- The steering control valve lever was not fitted with a grease fitting, and the outside of the bushing was not grooved to allow adequate lubrication, thereby risking corrosion and seizure of the bushing inside the lever.
- The limited experience and the lack of formal training of the maintenance personnel concerning the repair and the overhaul on the steering control valve might have contributed to the incorrect reassembly of the steering control valve.
- The pilot flying cut the electrical power, as required by the hard landing procedure. The left engine could therefore not be shut down, causing a risk of injury when the passengers evacuated.
- The pilot flying cut the electrical power after the aircraft exited the runway, as required by the hard landing procedure. The electrical power required to operate the public address and alarm systems was thereby lost, and the evacuation could not be ordered promptly.
- The evacuation slide automatic deployment system was inadvertently deactivated,which could have delayed the evacuation and compromised passenger safety.

- After separating from the engine, the left propeller blades entered the fuselage and damaged an unoccupied seat.

OTHER FINDINGS

- The numerous changes in ownership of the Convair type certificate and the lack of technical support from the current holder caused maintenance problems for Convair operators and approved maintenance organizations (AMOs), particularly for recently established AMOs.

Accident investigation: