Staff at a defence repairs facility in Perthshire have taken part in a national protest against proposals to sell the business.
Plans are in the pipeline to sell the agency to a Canadian firm
Demonstrations have been held at the Defence Aviation Repair Agency (DARA) at Almondbank, near Perth, and also in Hampshire.
Employees at the sites carry out helicopter maintenance for the Ministry of Defence.
There are plans to sell the agency to Canadian firm Vector Aerospace.
Ian Waddell from the Unite union said: "Trade union members at DARA Almondbank and DARA Fleetlands are incensed that the government could contemplate selling such valuable defence assets at a time when the supply of helicopters to the front line in Iraq and Afghanistan is of such critical importance.
"The ethos of delivering a product for the defence of the nation could be lost overnight and replaced by a commercial ethos where profit comes first.
"There is a huge question mark over whether the private sector is better placed to provide the service provided by loyal and committed civil servants."