Air Transport

British Airways has been criticised for having a culture that led some mechanics to cover up mistakes instead of reporting them.

The findings were made in a new in-depth report on the BA Boeing 777-200 that spewed fuel from an uncovered fuel tank aperture inside the left main gear wheel well as it took off from London Heathrow airport bound for Harare, Zimbabwe on 10 June 2004.

Immediately after take-off, another aircraft at the runway holding point reported a trail of smoke from the rear of the 777 and a smell of fuel vapour.

The BA crew elected to dump fuel and return, correctly deducing there was a fuel leak from the centre-wing fuel tank. They landed with minimal braking and emergency services in attendance to reduce the chance of fire induced by fuel contacting the brakes. There were no injuries to the 15 crew and 151 passengers.

The mistake that caused the incident occurred during a C check at BA's Cardiff heavy maintenance base when the centre-wing fuel tank was being checked internally.

A "purge door" - the cover for an aperture about 5cm (2in) in diameter - had been removed from the fuel tank wall which faces into the wheel well. The UK Air Accidents Investigation Branch report says the maintenance check required access to the centre fuel tank to carry out an internal structural inspection of the rear spar and to carry out a special check of the bonding of the centre tank float switches.

Purge doors allow fuel vapour to be vented before mechanics gain access to the empty tank. In this case the purge door was not replaced, and the AAIB found that the "defect job card", which would have ensured the plate's replacement, was not raised. In addition, the AAIB found that maintenance diagrams of the position of several fuel tank internal apertures were inaccurate.

The AAIB made four recommendations for improving the reporting procedures within BA maintenance, and also required that, having implemented those, the airline should safety-audit the Cardiff plant. BA says the changes have all been made.