Military helicopters could face fresh cuts despite warnings that the Armed Forces already lack what they need.
The Ministry of Defence has begun a review of helicopter requirements to ensure a "balanced and affordable plan" for the future.
The "rotary wing capability study" prompted warnings from defence industry sources that a number of programmes were "extremely vulnerable".
An order for 12 new Chinooks is likely to be reduced, executives fear.
Commanders are waiting for ministers to sign off the order, cut from 22 in the Strategic Defence and Security Review last year. Maj Gen Bill Moore, master general of the ordnance and director battlespace manoeuvre, told a recent conference that the Armed Forces did not have enough heavy-lifting helicopters.
"We need to buy additional Chinook to improve our lift," he told the Royal United Services Institute. "Our lift at the moment will not allow us to do what the Government requires us to do on operations."
The helicopter review, led by Maj Gen Moore, is expected to conclude in the autumn. Its findings are likely to inform the MoD's 2011-12 financial planning round, which is widely expected to make new cuts in the Armed Forces.
Any further reduction in helicopter capability would be difficult for Dr Liam Fox, the Defence Secretary. In opposition, he frequently criticised Labour over the provision of helicopters for troops in Iraq and Afghanistan.
Kevan Jones, a Labour shadow defence minister, said: "It is ironic that such a vociferous critic of the previous government over helicopters, now in a position to do something about it, appears not to be acting on his words."
A £300 million programme to upgrade 30 Puma medium transport helicopters is also said to be under threat, despite a signed contract with penalty clauses.
Another possibility is that the new review could lead to cuts in ship-based helicopters operated by the Royal Navy.
The defence review last year promised that the number of maritime helicopters would be "aligned to the overall size of the future maritime force structure".
The Navy's surface warfare fleet is being cut from 23 to 19.
"Everything is vulnerable," said a defence industry source. "The problems in British defence procurement are so deep that they are damn near insurmountable."
The MoD said the helicopter review would consider all aspects of British military helicopters. It would "re-examine defence's helicopter requirement to deliver the Future Force 2020 vision set out in the Strategic Defence and Security Review and ensure a balanced and affordable plan," a spokesman said.