Learjet 35A runway overrun in Montréal caused by hydraulic fluid depletion

Casualties unknown • Montréal/Pierre Elliott Trudeau International Airport, Quebec, CA

A medical evacuation Learjet 35A overran the runway at Montréal/Pierre Elliott Trudeau International Airport after a hydraulic leak caused the failure of brakes, spoilers, and thrust reversers.

What happened

On the early morning of a flight from Brunswick, Georgia, to Montréal, a Learjet 35A operated by Canadian Global Air Ambulance overran Runway 06R at Montréal/Pierre Elliott Trudeau International Airport. The aircraft, registration C-GAJS, was performing a medical evacuation mission with two pilots, two flight nurses, and two passengers on board.

During the approach, the crew encountered several technical discrepancies. While the landing gear was confirmed down and locked, the flaps failed to extend to the required 40° setting, remaining at 20°. As the aircraft approached the threshold, the Enhanced Ground Proximity Warning System (EGPWS) issued "TOO LOW FLAPS" alerts. Upon touchdown, the crew discovered that the spoilers failed to deploy and the thrust reversers were inoperative. Shortly after landing, the pilot realized the brakes had also failed. The aircraft traveled approximately 8,300 feet down the runway before exiting the paved surface and coming to rest 600 feet in a grass field. The aircraft sustained damage to the fuselage and the left wing, but there were no injuries.

The investigation

The investigation focused on the hydraulic system and the maintenance and operational procedures of the crew. Investigators identified a loose "B" nut in the nose gear hydraulic line, which had caused a slow leak that depleted the hydraulic fluid level. This depletion directly impacted the functionality of the flaps, spoilers, thrust reversers, and brakes.

Technicians also examined the thrust reverser accumulator, finding the air pressure was significantly below the required manufacturer specifications, which prevented the reversers from deploying. The investigation also looked into the crew's training and the company's maintenance protocols, specifically the 15-day Service & Condition Check interval and the use of the "Through-Flight" checklist, which may have prevented the early detection of the low fluid level.

Probable cause

The primary cause of the runway overrun was a hydraulic fluid depletion resulting from a loose nut in the nose gear hydraulic line, which led to the simultaneous failure of the aircraft's braking, spoiler, and thrust reverser systems. Contributing factors included the crew's failure to recognize the loss of hydraulic pressure due to the absence of a low-pressure warning light on this specific aircraft, and the failure to use the emergency braking system.

Frequently asked questions

What happened in the 2006-11-26 Learjet 35A C-GAJS accident near Montréal/Pierre Elliott Trudeau International Airport, Quebec, CA?

A medical evacuation Learjet 35A overran the runway at Montréal/Pierre Elliott Trudeau International Airport after a hydraulic leak caused the failure of brakes, spoilers, and thrust reversers.

What aircraft was involved and where did it happen?

The accident on 2006-11-26 involved a Learjet 35A C-GAJS, operated by Canadian Global Air Ambulance, at Montréal/Pierre Elliott Trudeau International Airport, Quebec, CA.

What was the probable cause of the accident?

The primary cause of the runway overrun was a hydraulic fluid depletion resulting from a loose nut in the nose gear hydraulic line, which led to the simultaneous failure of the aircraft's braking, spoiler, and thrust reverser systems. Contributing factors included the crew's failure to recognize the loss of hydraulic…

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