Today, 19 years ago, a BAe 146-RJ100 was scheduled to operate a scheduled flight from Glasgow (Scotland) to Birmingham. With departure scheduled for 06.50 local time, the Captain performed the external (Pre-Flight) checks without observing anything out of the ordinary. After the flight preparations were completed without any remarks the doors were closed and the aircraft headed for the runway. Onboard 94 passengers, 3 cabin crew and 2 pilots.
A BAe-146-RJ for reference, not the incident aircraft
After receiving their take-off the throttles were advanced and the aircraft started to accelerate down the runway. At about the time of the Vrotate call, a light shimmy was felt by both pilots which seemed to originate from the nose landing gear, both flight crew members mentioned that they noticed it. However, the severity was of such a low level that it did not cause any alarm with the crew.
An uneventful flight followed towards Birmingham, due to low visibility a CAT IIIB autoland was briefed and flown. The descent and approach were flown without any issues. The aircraft was configured early for the landing at runway 15, the gear was lowered at 7 miles from the runway. The autoland was completed satisfactorily and after vacating the runway a short taxi followed before the aircraft arrived on its parking stand.
Once on the stand, the dispatcher was pointing excitedly to the nose gear, followed shortly thereafter by an engineer informing the crew that one of the nosewheels was missing from the nose landing gear. Each of the nose wheels is secured on the axle by means of Wheel Retaining Nut {(1) in the drawing below} which is secured in place by two Locking Bolts {(2) in the drawing below}, these two Locking Bolts are then lock wired together to secure them. On the inside and outside of the wheel hub, a ring or spacer is used on the axle. On the outside hub a spacer {(3) in the drawing below} between the Wheel Retaining Nut and the wheel and an Abutment Ring {(4) in the drawing below} This Abutment Ring has a square edge on one side and a Chamfered Edge on the other. The chamfered edge of the Abutment Ring is to be installed so as to fit over the chamfered edge on the axle. The square edge is to face the inner bearing of the wheel. {see the drawing below).
The investigation into the loss of the nose wheel revealed that the Abutment Ring was installed incorrectly with the square edge against the axle and the chamfered edge against the inner bearing of the nosewheel. This resulted in a gap between the abutment ring and the axle abutment, see the picture below.
The conclusion of the investigation stated;
The wheel detached due to the incorrect assembly of the abutment ring on the axle. The design of the abutment ring allows it to be fitted the wrong way round and, in this circumstance, the locking bolts do not perform their locking function of the wheel retaining nut. The locking bolts can still be fitted and wire locked without it being apparent that they are not located into the slots in the axle and are, therefore, free to move with the wheel retaining nut. The incorrect assembly of the right nosewheel may not result in its detachment since the direction of rotation of the right wheel will tend to tighten the wheel retaining nut
Several safety actions were implemented by the operator to prevent re-occurrence. The full report by the Air Accident Investigation Branch can be found by clicking here..
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