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27th of September 2000, Blog #550

A Convair 340 (580) was being operated on a non-scheduled passenger flight for a Canadian electricity company, flying staff to different bays in the James Bay Region (between Ontario and Quebec, Canada). When the aircraft taxied out for its first flight of seven that day, the crew had difficulties switching the nosewheel steering but were able to control the aircraft using differential braking. The situation was acceptable to the crew, but during the day, when on the ground, the problem persisted.

The aircraft at its final position (Source; baaa-acro.com © Michel Hébert)

On approach for the 4 th landing of the day at La Grande 4 (LG-4) the weather was observed as follows;

  • Clouds - overcast at 800 feet

  • Visibility - 1 statute mile

  • Wind - Westerly wind 5 to 7 knots

  • Precipitation - light snow

LG-4 has a runway 09-27, and as it would save flight time and the tailwind would be within the 'Prop-jet Convair Flight Manual' the crew elected to land on runway 09. The approach to 09 was uneventful, the aircraft was properly configured and a stabiles approach was flown to the touchdown, which occurred 800 feet past the runway threshold. After the nose wheel had touched down the propellers were set to reverse pitch, As the aircraft started to decelerate it started to drift to the right. The crew attempted to correct this by differential braking, full left rudder and asymmetrical reverse pitch on the propellers. This did not have the desired effect and the aircraft exited the runway at a speed of approximately 50 knots, and a course 25º of the runway centerline. The aircraft went down a slope and continued over soft and rocky ground before coming to a stop 7 feet below the runway surface and 350 feet from the runway.

The aircraft at its final position (Source; baaa-acro.com © Michel Hébert)


Before the aircraft came to a stop the captain pulled the emergency handles (E-handles) for the engines, this cuts the fuel supply to shut the engines down. The lefthand E-handle could not be pulled all the way out. The captain instructed the co-pilot to initiate the evacuation of the aircraft. As the copilot went to the cabin he heard a strange noise that he could not identify. When the first passenger evacuated from the left overwing exit it became apparent the left engine was still running. The passenger was ordered back in the cabin for his safety and to evacuate from a different exit. The co-pilot informed the captain that the engine was still running, who then returned to the cockpit in an attempt to shut the engine down, using the normal and emergency mode, but both were unsuccessful. All occupants left the aircraft via the right overwing exit and walked back to the runway. five of the passengers received minor injuries. The aircraft sustained substantial damage, there was no post-accident fire. As the aircraft exited the runway, the landing gear dug into the soft ground, causing the propellers to contact the ground. The propellers, with their reduction gear assemblies, separated from the engines. After separating from the engine, the left propeller blades entered the fuselage and damaged an unoccupied seat. The landing gear of the aircraft collapsed rearward. The left engine overheated and stopped from a lack of oil about 15 minutes after the occurrence.

The aircraft at its final position (Source; baaa-acro.com © Michel Hébert)

The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing transportation safety, after the investigation their report was published on the 12th of February 2002. in the report the following findings as to causes and contributing factors were presented;

  1. The nose wheel steering control valve lever had not been reassembled after maintenance, this caused the additional resistance felt by the crew.

  2. The nylon locknuts were reinstalled during the repair of the steering control valve, contrary to the recommendation that they can be used only once. The locknuts then came loose in service, creating play in the parts of the valve.

  3. 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.

Additional findings as to a risk and other findings were also presented in the report, they can be found in the investigation report, as well as the safety action taken by the operator, by clicking on the .pdf file below.

Convair Nose wheel steering failure 27-sept-2000
.pdf
Download PDF • 383KB

Close up of the aircraft damage at its final position (Source; baaa-acro.com © Michel Hébert)



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