Operators of 747-8s told to fix reverser logic flaw

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Boeing 747-8 operators will need to replace software on the type to correct a logic fault which could result in thrust reversers failing to stow during a rejected landing.

The logic can prevent the reversers from stowing on the General Electric GEnx-powered 747-8 and -8F if the aircraft reverts to “air” mode during a bounced landing.

If this situation occurs, says a US FAA airworthiness directive, it is possible for a hydraulic isolation valve to close before full stowage of the thrust reversers.

Without hydraulic pressure to the automatic stowing system, aerodynamic loads could push the thrust reversers back to their deployed position – creating the potential for inadequate climb performance.

Operators are being instructed, by the directive, to remove the “defective” electronic engine control software and install an improved version.