Challenger 300 nosewheel steering failure, Iqaluit 2011

Final reportRunway excursion

The short version

N818RC landed at Iqaluit after more than five hours at 41,000 ft in air at about -60°C. When the nosewheel touched the runway, the steering turned the wheel to the right on its own and held it there. Full left rudder, left brake and left tiller did not stop the swing, and the jet ran off the right side of runway 35 into the snow.

What happened

  1. The flight leaves Long Beach for Milan with a fuel stop at Iqaluit: 5 hours 36 minutes at 41,000 ft, outside air about -60°C.

  2. On final, the first officer flies the ILS/DME to runway 35 on autopilot. Vref is 114 kt. The autopilot is disconnected, and the aircraft crosses the threshold at about 118 kt.

  3. Soft touchdown on the left main gear, about 10 ft right of the centreline.

  4. The nosewheel touches the runway and thrust reversers are selected. The heading starts to swing right, and about 2 seconds after the nosewheel touches, a master caution comes on.

  5. The crew apply full left rudder, left control wheel, left brake and left tiller. The heading swings 16 degrees right and lateral acceleration reaches 0.3 g.

  6. Brake pressure recorded, 2 seconds before the aircraft leaves the runway.

  7. About 12 seconds after touchdown, the aircraft leaves the right side of the runway 4,300 ft from the threshold, at less than 60 kt.

  8. It stops in packed snow about 100 ft from the runway edge, after 400 ft over frozen ground. Snow reaches the top of the nosewheel and half the height of the main wheels.

Times are as the report gives them, which it labels Eastern Daylight Time (UTC minus 4).

The report found no sign that the runway or the weather, other than the cold, played a role. At 2100 Iqaluit had wind 080 degrees true at 4 kt, 10 statute miles in light snow and -29°C. The runway was 90% bare and dry and 10% ice. The flight service specialist gave wind 120 degrees magnetic at 3 kt for the landing. There was no fire and no evacuation. The crew did not notice any EICAS messages before shutdown. The CVR circuit breaker was not pulled afterwards, so the recording was lost.1

Skid marks showed the nosewheel pointing away from the direction of travel. The aircraft was pulled out of the snow on 16 March. On 20 March, after an 11-hour cold soak outside, the investigators switched the nosewheel steering on with the torque link disconnected. With no command from the cockpit, the steering collar moved about 15 degrees right and EICAS showed a steering failure. Later cold tests could not repeat this.1

Why it happened

  1. The report found three causes and contributing factors. On touchdown the nosewheel veered right, and the crew could not control the uncommanded veer. The electro-hydraulic servo valve did not respond to steering commands. The steering control unit then commanded the steering selector valve to close. That valve did not close. With it open, the system could not go to free castering, and the nosewheel stayed pointing right. The servo valve likely failed because of contamination, internal corrosion and exposure to cold.1

  2. The landing gear maker's analysis of the steering control unit memory found that the two failures could have come within milliseconds of each other. In a normal steering failure the nosewheel castors freely and the crew can steer with differential braking. This aircraft had two earlier steering failures, in Singapore in January 2010 and at Washington Dulles in January 2011. Both times it castored as designed. This time the open selector valve kept the servo valve pressurised, so free castering was not possible. According to the landing gear maker, this prevented any possible crew reaction to counter the veer.

  3. The selector valve vendor found gross particle contamination from the aircraft's hydraulic system. It was the direct cause of the valve's intermittent operation and likely the reason it did not release pressure. The source of the contamination was not found. The servo valve showed corrosion on its magnets, scratches and fluid contamination.

  4. The selector valve had been repaired after an earlier failure on another aircraft and was not inspected by the vendor before it was fitted to N818RC. Apart from an operational test at 2,400 hours, neither valve had a time limit or a specific inspection.

  5. Certification tests of both valves used hydraulic fluid cleaner than the class 9 cleanliness the Challenger 300 requirements specify. The effect of dirtier fluid on the steering was not known.

  6. Bombardier's records showed 13 servo valves returned in 2011 after steering failures, with contamination, low insulation resistance and signs of moisture.

The TSB made no recommendations. Bombardier tested whether moisture and contaminated fluid affect the two valves. It was preparing a service bulletin for a one-time check of the servo valve motor and for sealant around its connector and bolts. It also introduced a servo valve with an o-ring seal between connector and cap to keep moisture out.1

What a crew can take from it

  1. The nosewheel touchdown is a moment to be ready on the controls. The swing started once the nosewheel touched, with a master caution about 2 seconds later, and the aircraft was off the runway about 12 seconds after the mains touched. Brief the steering failure for a long cold-soaked flight into a cold field, and have the pilot not flying watching the centreline as the nose comes down.

  2. Know what a normal steering failure looks like, so you can tell it from this one. In the two earlier events on this aircraft the nosewheel went to free castering, and differential braking was still available to steer. Here the selector valve stayed open and the wheel was held to the right. Full left rudder, left brake and left tiller did not stop the veer. Know the steering failure indications and what your QRH asks for.

  3. Cold soak counts. The report found that the long exposure to -60°C at altitude and the cold at Iqaluit, together with the contamination, most likely played a role. If a system acts up on a cold-soaked aircraft, report it, even when it works again once warm.

  4. Read the history of the system. N818RC had two earlier nosewheel steering failures in the 14 months before this event. When the tech log shows repeat faults on one system, brief that failure before the flight.

  5. Protect the recorders after the event. The CVR breaker was not pulled and the recording was lost. Make the CVR circuit breaker part of your after-incident flow, as your operator's procedure says.

Study it on the course

Sources

  1. Transportation Safety Board of Canada. Aviation Investigation Report A11Q0052, Runway excursion, Tri Marine Management Company LLC, Bombardier BD100-1A10, N818RC, Iqaluit, Nunavut, 12 March 2011 (PDF). Released 8 January 2014.
  2. Government of Canada Publications, archived PDF of the report (TU3-5/11-0052).

Last updated 22 October 2026

For study only. Always use the approved AFM, QRH and operator procedures.