THE Air Force's fleet of F-111 strike/reconnaissance aircraft returned to duty during Exercise Pitch Black after a short-circuit in one aircraft led to the fleet being suspended from flying in late June.

Just after midday on July 23, the first F-111 (tail number A8-109) roared through a blue Queensland sky while a gathered media contingent watched from below.

"It's good we've started flying again," said Group Captain Geoff Brown, Commanding Officer of No. 82 Wing. "With this exercise happening it's important that the F-111s are flying as part of the strike package. Primarily this exercise is about strike operations and this is what the aircraft is designed for."

F-111 aircraft might also take part in key exercises with the United States Air Force as part of Red Flag 02 later this year.

The Air Force has completed an initial investigation of an incident involving an F-111 at Darwin.

The primary cause was found to be a short circuit in a wiring loom.

Chief Engineering Officer at RAAF Base Amberley Wing Commander Mel Benfer said the aircraft was flying in to land when a "loud bang" was heard.

On closer investigation, maintenance crew found that there was some damage in the fuel tanks as a result of a contained explosion within. The wires within the fuel pumps that led to the explosion were inspected and replaced.

"From a structural perspective it showed that the aircraft is very strong and it shows that 30 years ago when they designed the aircraft that the design was extremely good to contain such an explosion," WGCDR Benfer said.

He said at this stage the Air Force had identified a planned withdrawal date for the F-111 in the 2015 time frame.

"With the way we manage the aircraft and the support we get from DSTO and industry and Defence I believe we can still support that 2015 figure," he said.

GPCAPT Brown said the Air force had lost a little bit of time in operational training, but it had "pulled forward all the planned maintenance on the aircraft before our next big exercise".

"The aircraft involved [in the incident at Darwin] was still flying OK because of the spare fuel tank with sufficient fuel to safely land the aircraft," he said.

Repairs to the affected aircraft are ongoing, while the balance of the fleet has also been inspected.

The F-111 remains a formidable capability for the Australian Defence Force and provides a major deterrent in Australia's area of operations.

A range of maintenance, support and development mechanisms are in place to keep the F-111 operational until the planned withdrawal date.

By CPL Mark Eaton