The lives of UK troops have been put at greater risk owing to an eight-year hold-up in getting eight Chinook helicopters into service, say MPs.
The transport helicopters have remained grounded since delivery in 2001 because of cockpit computer system problems.
The Commons public accounts committee also said the decision to add night vision equipment to RAF Chinooks Mk2s had been linked to two crashes.
The Ministry of Defence (MoD) said the MPs' report contained "nothing new".
"The department has repeatedly acknowledged the problems with the initial procurement and we have changed the way we do business since these helicopters were bought," a spokesman said.
The Mark 3 Chinooks were ordered from Boeing in 1995, with a modified cockpit computer system in order to reduce costs.
But the aircraft have never been able to fly because the MoD failed to secure access to key software source code.
It announced last year that the helicopters would be downgraded to Mark 2 models, for use in Afghanistan in 2010.
The cost of the programme has spiralled from £259m to more than £422m.
Committee chairman Edward Leigh said that the Chinook Mark 3 programme had been "hamstrung from the start" with "bad decision-making to the point of irresponsibility".
He said: "The consequences have included a shortage of helicopter support in Afghanistan, thereby heightening the risk to the lives of British troops."
Defence minister Quentin Davies said the fourth report on the Mark 3 programme offered "nothing new".
He added: "We have fundamentally changed our methods of doing business, but this episode will remain a salutary example to us all.
"I am sure that given the problems that existed with this contract, the decision to convert these eight aircraft to a support helicopter role was the right one."
He said the conversion of the Mark 3s could see the Chinook fleet in Afghanistan increase 25% by 2010, two years earlier than expected.
The MoD also highlighted a 60% increase in helicopter numbers and flying hours in Afghanistan over the last two years.
'Short-term fixes'
The committee also reported that the addition of "bolt-on" night vision equipment to Mark 2 Chinooks had been linked to two crashes.
The package was fitted to the Mark 2s to compensate for the grounded Mark 3s.
An earlier National Audit Office report said the "bolt-on" night vision enhancement could reduce pilots' normal visibility.
The committee said the MoD "should examine whether its acceptance of the risks associated with short-term fixes like the night enhancement package is consistent with the priority accorded to identifying funding for long-term solutions, the duty of care it has to personnel and the principles underpinning its approach to airworthiness."
The MoD played down the significance of the crashes, likening them to "bending the fender on the car when you parked it".
The MPs' report also disclosed that Chinooks were now being used for basic pilot training because flight simulators had not been modified.
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Published: 2009/03/05 07:43:06 GMT