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UK investigators are trying to establish the reasons why a British Airways Airbus A319 suffered a serious loss of electrical power last month shortly after departing from London Heathrow at night.

The aircraft, G-EUOB, was eight minutes into the flight to Budapest at about 19:26, and nearing FL200, when there was “an audible clunk” noise, several electrical systems ceased to operate, and the cockpit became dark.

Among the electrical systems which failed were the primary flight displays and navigation displays on both the captain’s and first officer’s instrument panels. The crew also lost the upper electronic centralised aircraft monitor (ECAM) display, the autopilot and auto-thrust, intercom and general flight-deck lighting.

An attempted ‘Mayday’ transmission was not received by air traffic controllers because the aircraft’s radio was no longer powered. The highly experienced captain maintained aircraft attitude by the external horizon and standby instruments. Investigators believe the standby horizon was probably “not powered or lighted” and in any case should have remained usable for only another five minutes.

In a special bulletin on the 22 October incident the UK Air Accidents Investigation Branch (AAIB) states that the aircraft remained in the “degraded condition” for about two minutes.

After carrying out ECAM procedures the crew managed to restore the primary flight instruments and most other capabilities, including air-ground communication, although a number of other less-important systems remained inoperative.

Following a 40min hold for further checks the aircraft was cleared to continue to Budapest, where it landed safely. There were no injuries among the 76 passengers and six crew.

Maintenance engineers reset all the affected systems and the aircraft – a four-year old example registered G-EUOB, with International Aero Engines V2500 powerplants – remained in operation for another six days with no reported electric problems.

The AAIB became aware of the event only through the crew’s mandatory occurrence report and the aircraft was then taken out of service for further inspection under AAIB supervision. Integrity checks on the electrical power system and checks on the engine pylons’ integrated drive generator feed connectors yielded nothing unusual. Before the aircraft was returned to service inspectors removed several components including the three display management computers, a generator control unit, a system data acquisition concentrator unit and a flight warning computer.

Investigators are still carrying out studies into the incident, in co-operation with Airbus and British Airways, and expect to publish a more detailed report once their work is complete.

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Maintenance engineers reset all the affected systems and the aircraft – a four-year old example registered G-EUOB, with International Aero Engines V2500 powerplants – remained in operation for another six days with no reported electric problems.

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Following a 40min hold

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'Twas a PAN call not a Mayday

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