That British Airways 747 close-call at Jo’burg – FAA takes action

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The incident at Johannesburg last month in which a British Airways crew very nicely avoided a potentially catastrophic situation on take-off has resulted in an airworthiness directive on the Boeing 747-400.

The AD finally confirms precisely what happened. Prior to V1 a thrust-reverser amber warning was generated and a few seconds later, after V1, a second warning was received. (It’s not specified, but I think the warnings must have been either both outboards or both inboards because of how the logic works.)

The flap control unit (FCU) is designed to to retract the [updated] inner and central leading-edge flaps when the reversers are deployed in order to avoid “impingement of efflux air” from the reversers (ie FOD damage). It worked as advertised, but of course the aircraft was taking off not landing and the warnings were spurious. Result: aircraft rotates (at hot ‘n’ high Jo’burg remember) with no only outboard leading-edge flaps. The AD confirms that the crew experienced pre-stall buffet and stick-shaker activation.

Once the aircraft lifted off, the air/ground logic system re-commanded extension of the L/E flaps after five seconds, and the deployment took 10-15 seconds during which there was more buffet and stick-shaker before it climbed away, and the crew dumped fuel before returning to land for tea and medals.

What the FAA’s AD does is to mandate a Boeing service bulletin which has already been issued which “describes procedures for modifying certain thrust-reverser control system wiring to the FCU in the P414 and P415 panels. The modification includes re-routing and re-terminating one wire for each engine and replacing the wire if necessary.”

It affects only aircraft with Rolls-Royce engines. Ho hum….

The FAA adds without comment: “In addition, one operator reported 12 single-engine REV indications during take-off over the past three years, leading to seven rejected take-offs. The incident described above was the first known simultaneous two-engine event.”

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