What happened
On 26 March 2014, a Bombardier CL600-2B16, registration N664D, was conducting a post-maintenance check flight at Biggin Hill Airport. The purpose of the flight was to test the functionality of the air-driven generator (ADG). During the flight, the crew intentionally took the main generators offline to simulate the conditions required for the ADG to deploy. While the test was successful, the crew failed to restore the aircraft to its normal electrical configuration before landing.
As a result of the continued emergency power configuration, several critical systems remained inoperative, including the ground spoilers, anti-skid system, nosewheel steering, and flaps. The aircraft approached the runway at a high speed of approximately 160 kt. Upon touchdown, only the left thrust reverser deployed, and the aircraft struggled to decelerate. The pilot applied maximum braking, which led to the rupture of all four main tyres and caused damage to the main wheels and brake units. Smoke was observed emanating from the tyres during the landing roll, and the aircraft was unable to taxi off the runway.
The investigation
Investigators examined the aircraft's flight data and reports from the pilot, the maintenance organisation, and air traffic control. The investigation established that the crew had not followed the recommended procedure, which explicitly states that normal electrical power must be restored before the final landing approach.
Evidence from the flight deck indicated a lack of clear communication regarding roles and responsibilities. The crew had not established a firm plan for the check flight, and there was a misunderstanding between the pilots and the maintenance engineer regarding who would monitor the procedure and who would manage the aircraft's configuration. Furthermore, the engineer noted that the crew did not refer to the Quick Reference Handbook (QRH) during the flight.
Findings
- The crew failed to restore normal electrical power prior to the landing approach.
- A lack of clear briefing resulted in a misunderstanding of roles between the pilots and the engineer.
- The crew did not utilize the Quick Reference Handbook to manage the electrical configuration.
- The decision to perform the check during a single visual circuit at a busy airfield created unnecessary time pressure and reduced crew vigilance.
- The aircraft's configuration led to the loss of the anti-skid system and ground spoilers, contributing to the high-speed landing and subsequent tyre failures.