Query: Which office reported that the helicopters were being stored, rather than used?
Context: The MoD has been criticised for an ongoing fiasco, having spent £240m on eight Chinook HC3 helicopters which only started to enter service in 2010, years after they were ordered in 1995 and delivered in 2001. A National Audit Office report reveals that the helicopters have been stored in air conditioned hangars in Britain since their 2001[why?] delivery, while troops in Afghanistan have been forced to rely on helicopters which are flying with safety faults. By the time the Chinooks are airworthy, the total cost of the project could be as much as £500m.