By Paul Adams
BBC News diplomatic correspondent
The Chinook is a remarkable helicopter, hugely respected for its durability and ability to operate in extreme temperatures.
The Chinooks' procurement cost is likely to exceed half a billion pounds
It is one of the most important aircraft flown by the military.
But mention the Chinook Mark 3 (Mk3) to anyone in the defence community and heads are usually buried in hands.
What Edward Leigh, chairman of the Commons public accounts committee, calls "a gold standard cock-up" is a well-known and embarrassing saga of botched procurement, followed by protracted efforts to set things right.
In 1995, the Ministry of Defence ordered 14 Chinook Mk2a helicopters from Boeing, eight of which were modified to the more advanced Mk3 model to meet a long-standing demand for machines suitable for special operations.
Only after the eight were delivered in 2001, at a cost of £259m, did it emerge that there were problems with the avionics software and the helicopters fell short of the UK's military airworthiness standards.
As a result, they have never flown operationally.
This was simply bad project management by the Ministry of Defence, described by the public accounts committee in a 2004 report as "one of the worst examples of equipment procurement" it had seen. You will not find anyone in the MoD who tries to defend it.
The MoD spent three years trying to figure out what to do with the helicopters, finally coming up with a "fix to field" project designed to iron out the problems and get the Chinooks flying.
The first helicopter was designed to enter service this year, but this date slipped to 2011-12, with a predicted cost of £215m.
But then circumstances changed. British troop numbers in Afghanistan's troubled Helmand Province doubled between 2006 and 2007, and the increased use of roadside bombs by the Taleban meant that troops needed to fly in and out of operations.
The MoD thought long and hard about how to address the problem.
New rotor blades were fitted to Sea King helicopters, six Danish Air Force Merlins were bought and are being converted, and the number of flying hours of the existing Chinook fleet has been increased.
But efforts to buy more Chinooks failed due to a global shortage. And so, last year, a decision was taken to "revert" the Mk3s to Mk2/2a standard, as the best way of making them available.
This will add another £112m to a total procurement cost expected to exceed half a billion pounds and the National Audit Office says the work is proceeding well.
In the meantime, a temporary fix to make some of the existing Mk2s suitable for special operations threw up problems of its own.
The so-called night enhancement package involved bolting navigation units, thermal imagers and moving map displays into the cockpits, reducing normal visibility for the pilots and raising significant safety issues among senior staff at Joint Helicopter Command.
The MoD has recently earmarked funds to deal with these problems.
At the end of this long and painful story, the military will have more badly needed Chinooks and some of them, eventually, will have the required special operations capability.
But it is all happening much later than expected and at greater cost.