A batch of eight high-tech British Chinook mk3 military helicopters have been out of service for eight years due to a software problem.
According to The Times newspaper, the problem occured when officials tried to save money by installing their own avionics software rather than using Boeing's original software for the helicopters.
The Ministry of Defence has since denied that it had been trying to save money, but admitted the error.
A National Audit Office report last year found that British officials had failed to ask for the software access code when they ordered the helicopters. Boeing then refused to provide the code, citing intellectual property rights.
The Chinooks were handed over to the army in 2001 at a cost of £259m.
The military has since refitted the helicopters with software used in earlier chinook models.