The Government jet has been "exceptionally reliable" over the past three years and the Cabinet decision to issue tenders for a new one "simply cannot be justified", the Labour Party spokesman on defence has said.
Mr Joe Sherlock was speaking in response to figures from the Department of Defence that show the Government's Gulfstream IV jet was available for 134 out of 135, or 99.26 per cent, of its requested missions last year.
The Department of Defence's own figures further show the jet completed 96 per cent of the missions for which it was requested in 2000 and 96.7 per cent of its requested missions in 2001.
Mr Robert Bonnier, spokesman for Gulfstream in Savannah, Georgia, where the Government's jet was built, told The Irish Times the Gulfstream fleet had a reliability of 99.7 per cent. He would not be drawn on whether the Government's Gulfstream IV was sufficiently unreliable to need replacing.
However, documents released under the Freedom of Information Act appear to indicate that in one area, at least, the jet is not in significantly different condition to standard 12-year-old Gulfstream IV jets, and that the issues causing it to break down on occasion are unavoidable.
A report for the Air Corps, by Lt Col Paul Farrell, chief airworthiness officer at Baldonnel Aerodrome, dated January 31st, outlines a briefing from Mr Eric Greene, Gulfstream's representative at Baldonnel, on apparent wiring problems.
He writes that Mr Greene told him that the wiring, as fitted, "represents standard Gulfstream wiring and installation practices".
Lt Col Farrell writes: "He stated that there is no Gulfstream inspection requirement that would have detected this deterioration prior to its presentation as a definite aircraft problem.
"He stated that there is no inspection regime or practice that can ensure such wiring loom problems will not arise."
The incident on January 17th, when the Taoiseach, Mr Ahern, had to return from Mexico on a commercial flight because the Gulfstream was unserviceable, was caused by the failure of a fuel shut-off valve.
A report on this incident to Lt Col O'Sullivan, dated January 18th, shows the aircraft did eventually leave Mexico without the need for flying new parts from Savannah to Mexico.
Mr Sherlock said yesterday that the reliability of the jet since 2000 told "a very different story to the one we have been given by the Government in their attempts to justify spending more than €50 million on a new jet".
At a time when there were cutbacks, Mr Sherlock said, "the expenditure of so much public money on what looks increasingly like a vanity project for the Taoiseach and his colleagues simply cannot be justified."
