Hundreds of aviation jobs are set to be created in St Athan over the next 18 months.
Up to 350 maintenance, repair and overhaul jobs are coming to the Defence Aviation Repair Agency.
The news will be a boost to Dara, which was set to shed 500 jobs after it lost Harrier jet repair contracts earlier this year.
It is thought the move could come from two of the world's biggest aviation companies, ATC Lasham and TES Aviation. ATC Lasham said it was to use the 100,000 sq ft 'Twin Peaks' building, which has the capacity to house up to four Boeing 737 or two Boeing 757/767 aircraft at the same time. The news was set to be confirmed today by Assembly Economic Development Minister Andrew Davies, at Europe's biggest maintenance, repair and overhaul conference, in Berlin.
He said: 'It is excellent news and although there is still more to be done, these investments underwrite the confidence we have always had that St Athan would be an attractive proposition for the civil aerospace market.'
The availability of high-skilled labour is understood to have been a key factor behind the jobs' creation.
More than 20,000 workers are employed in more than 150 companies in the aerospace industry in Wales.
The move comes as Wales & West Utilities announced it is to create a new pounds 50m headquarters in South Wales.
The company, which has two offices in Cardiff employing 250 people, took the decision on the location after being advised by the Cardiff Bay officers of property agents Knight Frank.
A new 35,000 square foot office development will be created at Celtic Springs Business Park, in Newport.
Wales & West also has offices in Exeter and Bristol, which may relocate to Wales once the new HQ is built.