What happened
On 8 December 2000, an ATR 72-202, registration G-BXYV, was performing a public transport flight from Newcastle to Stansted. The aircraft was carrying 26 passengers and 4 crew members. During the taxi-out phase of the flight, the crew noticed what appeared to be a disconnect in the elevator pitch mechanism. This was immediately followed by the failure of the green system hydraulic pump, which is responsible for powering the brakes and landing gear.
Following these malfunctions, the aircraft was returned to the stand for inspection. There were no fatalities and no injuries reported during the incident.
The investigation
Investigators examined the green system hydraulic pump and its electrical supply. They discovered that the electrical supply loom (reference 2P) had been chafing against the right elevator control cable between fuselage frames 2/8 and 29. The abrasion had worn through the insulation of the hydraulic pump power supply cables, causing the conductors to short-circuit against the elevator control cable.
This short circuit tripped the circuit breaker for the hydraulic pump. The resulting heat from the electrical arcing caused thermal damage to the elevator control cable, leading it to break. The heat also ignited a small fire in a nearby insulation blanket, though this fire extinguished itself without spreading to other systems.
Further inspection of the wiring installation revealed that while most of the loom was securely held by clips, a specific 'p' clip at frame 28 was too large to hold the loom securely where the wiring changed direction. This allowed the electrical cables to move into contact with the control cable.