Kieran Daly/LONDON
UK ACCIDENT investigators are asking the European Joint Aviation Authorities whether it was aware of "shortcomings" in the Airbus A340's fuel and flight-management systems when the type was certificated.
The move follows its investigation of an incident in which an A340 crew suffered fuel mis-readings, as well as two separate flight-management-guidance envelope computer (FMGEC) software problems.
The second of these problems, which could not be reproduced, but which was recorded by the built-in test equipment, resulted in the loss of both pilots' map displays.
The Virgin Atlantic aircraft, being operated on the Tokyo-London Heathrow service on 19 September, 1994, landed safely from a hand-flown surveillance-radar approach after the crew had declared a fuel emergency. It was eventually shut down with 4.5t of fuel remaining.
Airbus says that all the problems have been solved and modifications are under way to the global A340 fleet. The fuel-indication issue has been tackled with the addition of five extra sensors in each inner tank and a software upgrade.
The FMGEC issues have also been addressed. The first which in very limited circumstances, can cause an autopilot turn in the wrong direction, when the current heading is 180°, had already been fixed on most aircraft at the time.
The map-display problem is a long-standing issue on the A320 as well as on the A340. Airbus has been successful, in reducing its incidence, but is still working on the problem.
In its report, the UK Air Accidents Investigation Branch (AAIB) notes that aircraft are bound to suffer "minor teething troubles" after service entry.
It says that some will be discovered before service entry, but still allow certification, while others "...will inevitably require corrective action before the aircraft is fit for service and the certification authority will have to make that judgement".
Following the A340 investigation, it says, it has "...written to the JAA to ascertain whether the certification committee were aware of some of the more significant shortcomings of the A340's fuel and flight-management systems before the type certificate was granted".
The AAIB refuses to explain the reason for its action and the JAA was not immediately available to comment on the report.
Source: Flight International
