The second Garda helicopter cost twice the amount envisaged and took four years to get into service after the contracts were signed, according to the Comptroller and Auditor General.
Both Garda helicopters are unable to fly at night in rural areas because of concerns over pilots' expertise, Mr John Purcell told the Dáil Public Accounts Committee. This was in spite of the fact that they were specifically acquired for use outside Dublin.
Committee chairman Mr John Perry described the situation as "mind-boggling" and "grossly inefficient" and claimed the Garda aircraft are only operating at half the promised level of operational ability.
One helicopter had flown an average of only two hours a day in 2000, and the other was in the air for only one hour and 20 minutes daily, he said.
A surveillance aircraft was also grounded for long periods because of concerns over the weight of equipment on board.
The unit started operations in 1997, with the Air Corps providing air support to the Garda. Its first helicopter cost £5.66 million, over £3 million more than originally estimated, according to Mr Purcell. Maintenance costs had also doubled.
Fianna Fáil TD Mr John McGuinness blamed the "comedy of errors" on a "turf war" between the Air Corps and the Garda.
It was "an appalling way of doing business". "Instead of availing of expertise available overseas you spent most of the time arguing among yourselves," he said.
After night flights were suspended, Air Corps personnel said an auto pilot was essential for safety on the Garda helicopter, while the Garda said it was unnecessary and would add extra weight.
This and other problems led to lengthy delays in the delivery of the craft.
The secretary general of the Department of Justice, Mr Tim Dalton, said Garda helicopters needed a greater level of piloting expertise because they follow moving targets such as suspect cars on the ground. This had not been fully appreciated at first.
One of the reasons the helicopter cost more than expected was because a twin-engine model was chosen for safety reasons, instead of the single-engine model originally recommended.
He acknowledged there had been "tensions and misunderstandings" between the Air Corps and the Garda at first but insisted things had "settled down" since.
By November, the Air Corps would have the necessary expertise for night flights, he said.
Later, the committee heard that the Criminal Assets Bureau has collected €75 million in seized property and tax settlements since it was set up in 1996.
Those under investigation by CAB have been assessed for a total of €61 million, of which €56 million has been collected, Mr Dalton told the committee.