City Jet flight WX5026 serious incident was notified to the Air Accidents Investigation Branch (AAIB) on 20-02-2007 , involving EI-CZO in which the aircraft burst all four main landing gear tyres during the landing.
Enquiries by AAIB revealed that the aircraft had overrun the landing distance available (LDA), but remained on the paved surface, and that the flight crew had reported a total failure of the aircraft’s brakes.
In light of previous overrun events involving the BAe 146 and Avro RJ series of aircraft the Chief Inspector of Air Accidents ordered an Inspectors Investigation to be carried out into this incident.
The Aircraft crossed the threshold with a speed of Vref +16 kts, made a long flare and did not deployed the speed brakes.
The following causal factors were identified:
- The incorrect determination of the approach reference speed (Vref ) as 119 kt, resulted in the aircraft landing faster than was necessary.
- The data suggested that the control columns may have been positioned forward of their customary position after touchdown, which could have contributed to a reduction of the aircraft’s weight applied to the main wheels during the first part of the landing roll.
- Despite the commander’s recollection that he moved the airbrake/lift spoiler lever to the ‘lift spoiler’ position, the lift spoilers did not deploy, although the system was determined to have been serviceable.
- The non-deployment of the lift spoiler surfaces after touchdown did not enable the timely transfer of the aircraft’s weight from the wing to the main wheels, and hence the effectiveness of the wheel brakes during the early part of the landing roll was not maximised.
- The commander’s perception of brake system failure led him to select the emergency braking system which removed the anti-skid protection.
- The lack of any positive force required to hold the lift spoiler lever at the lift spoiler activation position probably resulted in the lever moving away from the point of activation before the conditions required to satisfy the lift spoiler deployment logic could be met.