A report into how a part fell off a Tornado jet has led to concerns about a decision which saw RAF maintenance work moved from south Wales to Norfolk.
Dara at RAF St Athan had contracts to maintain Tornados and Harriers
BBC Wales's Eye on Wales programme has seen a copy of a report into an accident at RAF Marham in Norfolk.
The RAF said the accident had nothing to do with Dara's move to Marham, and that safety was always a top priority.
Vale of Glamorgan MP John Smith wants work to remain at the Defence Aviation Repair Agency (Dara) in St Athan.
Dara is a civilian arm of the Ministry of Defence (MoD) and is the biggest government-owned aerospace repair facility in Europe.
Last year, the UK government announced its plans to hand over aircraft maintenance to the RAF. Armed Forces Minister Adam Ingram said the switch would mean better value for money.
As a result, hundreds of workers at St Athan lost their jobs, despite the investment of £80m in a "super-hangar" at the site to accommodate maintenance work.
The report into the accident at RAF Marham said a fairing - a shaped covering designed to reduce drag - fell off a Tornado jet.
The report concluded there were too many inexperienced staff and also questioned the capacity of the RAF to supervise maintenance work carried out at the base.
"There has been a very, very worrying incident involving a Tornado aircraft, and it is due to a lack of experience and supervision existing on the camp now - never mind when we roll forward the entire front-line fleet of the RAF's fast jets," said Mr Smith, who has been a critic of the MoD decision from the start.
"I am very concerned that the RAF will not be able to cope with the workload and that's very worrying for the future.
"The RAF is good at fighting wars. What they are hopeless at is repairing aircraft in factories, and that's why we've got to stop this."
The MoD confirmed to Eye on Wales that the Tornado incident had happened, but said it was unconnected with the decision to move major maintenance to RAF Marham.
There was nothing to suggest, it said, that transferring repairs to one operational base would affect the RAF's high safety standards.
Brian Godsell, of the union Amicus, said the decision to switch to Norfolk was "an absolute scandal - a complete waste of money and the tax-payer will have to pick up the bill".
Eye on Wales is on BBC Radio Wales at 1800 BST on Monday.