Airbus Industrie has issued a safety bulletin ordering rewiring modifications and thorough checks of the thrust reverser systems on Pratt & Whitney JT9D-7R4 and PW4000-powered A300-600 and A310 twinjets, before reactivation of the reversers.
The move follows an incident in November when a Korean Air (KAL) A300-600, powered by PW4000s, suffered a brief, uncommanded, thrust reverser deployment in flight. The incident occurred shortly after take-off from Jakarta in Indonesia on a flight to Seoul, and caused the aircraft to roll to the left before the reverser was deactivated. The airliner returned safely to Jakarta.
Airbus responded by issuing an all-operators telex recommending the deactivation of the thrust reversers on affected aircraft. This was followed by airworthiness directives from the French and US aviation authorities.
Airbus and P&W have established that the incident was caused by a combination of faults involving a leaking air valve and the loss of an electrical signal maintaining the reverser's stowed position as its default. The corrective action involved rewiring to maintain the electrical signal, and a thorough inspection of the reverser system.
According to the manufacturer, the incident was the first of its kind on an Airbus aircraft.
Some 190 aircraft operated by over 35 airlines are affected by the airworthiness directives instructing operators to deactivate the system. Airbus believes that aircraft operations will not be adversely affected by the order.
Source: Flight International
