RAF Chinook helicopters which are operating in Afghanistan are to get a £408m upgrade, the Ministry of Defence has announced.
The work will include fitting a more powerful engine to help the aircraft fly in the country's harsh conditions.
It aims to allow the 38-strong fleet to fly further without refuelling and go for longer without servicing.
In July there were criticisms over the availability of helicopters for troops in Afghanistan.
The aircraft will be fitted with more powerful Honeywell engines in a contract costing £128m, and more advanced digitised cockpits to be fitted by Thales in a contract that will cost £280m.
The work is aimed at allowing the helicopters to operate more effectively in the high altitudes and hot summers of Afghanistan.
The RAF lost two Chinooks in 10 days in August when one crash-landed and the other was hit by enemy fire and caught fire.
Speaking at the home of the fleet, RAF Odiham, Quentin Davies, the Minister for Defence Equipment and Support, said: "The Chinook is the cornerstone of our helicopter support effort in Afghanistan.
"These improvements will increase its capability and ensure it can play an even more valuable role in supporting our forces and Nato coalition allies in tackling insurgency in Afghanistan.
"Upgrading the Chinook is part of a series of improvements to our battlefield helicopter force and is powerful evidence of our commitment and determination to give our forces the very best equipment."
Upgrade will cost £408m
Glass digital cockpits make operations easier in low light conditions
RAF has 38 Chinooks in three squadrons
Able to carry up to 55 troops or 10 tonnes of freight
Several of the eight Mark 3 Chinooks which have not been in service since deliverery in 2001 because they were fitted with the wrong software would now be operating by Christmas, the minister said.
He said it was a "disgraceful story" but blamed the previous Conservative government for signing the contract.
Chinook pilot Flight Lieutenant Dan Padbury, from 27 Squadron, said the new engines were working well.
"It's early days but the new 714 engines have already performed as anticipated and will certainly increase our operational capability," he said.
"Having flown a Chinook fitted with the new engines, I noticed a marked improvement in performance."
Questions have been raised about the number and availability of UK military helicopters deployed in Afghanistan - with some commentators blaming the government for not providing enough.
It has also been argued that the UK could reduce its casualty rate if more soldiers were ferried to operations by air, rather than riskier land routes.