The UK has signed a £1 billion ($1.65 billion) contract to acquire an additional 14 Boeing CH-47 Chinook transport helicopters, with the move to expand the Royal Air Force's fleet of the type to 60 aircraft by late 2015.
Boeing is due to deliver its first Chinook HC6s to the RAF in 2013 for trials, with the remainder to be handed over by late 2015, the Ministry of Defence said.
Available for deployment from early 2015, the new batch will be fully operational by early 2017, it added.
"These additional helicopters will significantly enhance our existing heavy lift helicopter capability," said defence secretary Dr Liam Fox, who announced the contract signature during a visit to RAF Odiham in Hampshire on 22 August.
Also included is an initial five-year package of support activities, the MoD said.
In operational use for almost 30 years, the RAF's Chinooks are expected to remain in service until at least 2040.
© Craig Hoyle/Flightglobal
The UK's current Chinook inventory includes 38 HC2/2As and eight extended-range HC3 aircraft, all of which are to be upgraded to an enhanced HC4 configuration.
Its 14 new-build examples, which include replacements for two aircraft lost during non-fatal accidents in Afghanistan, will feature a high level of commonality.
One significant enhancement to be included with the Chinook HC6 will be the addition of a digital automatic flight control system, which will enhance operational safety in reduced-visibility, such as during "brown-out" while landing in dusty conditions. Other features will include a forward-looking infrared sensor, rescue hoist and defensive systems, said Boeing.
Read our special report on the UK's 30 years of Chinook operations