ONE of the government's three ministerial jets has been put out of commission after it was deemed no longer "airworthy".

The Air Corps was told in April that the safety of the Beechcraft could no longer be guaranteed "due to the age of the airframe and its operational history".

The plane had been in service with the Air Corps for 28 years and had flown more than 16,000 hours, which in recent years involved dozens of government trips.

The Department of Defence has said it had no plans to replace the aircraft due to the "current economic environment".

It said the Ministerial Air Transport Service (Mats) would have to make do with its two existing jets, a Gulfstream IV and a Learjet 45.

A statement said: "Its [the Beechcraft's] principal role was as a twin engine pilot trainer, and it was also used as a back-up aircraft for the Mats.

"In April 2009, the Air Corps was advised by the aircraft manufacturers that due to the age of the airframe and its operational capacity, the aircraft could not be certified as airworthy.

"In the current economic environment and given the pressures on the Defence budget there are no immediate plans to seek approval for the purchase of a replacement aircraft. The Gulfstream IV and Learjet 45, which are dedicated to the Mats, remain available to facilitate government in fulfilling official engagements both at home and abroad."

Ministers' use of government jets has fallen in recent months as serious questions were raised about ministerial overseas travel expenditure during the Celtic Tiger era.

The Beechcraft was the cheapest option available to the government. Its hourly running cost was just €1,770, which compares favourably to €2,950 for the Learjet 45 and a massive €7,890 for using the Gulfstream IV.

The government still managed to amass large travel bills aboard the Beechcraft and its total cost since 2006 was €414,600. In 2006, the plane was in the air for 5,580 minutes, which had declined to 4,240 minutes by last year as government spending was reined in.

This year, just a single mission was undertaken using the Beechcraft and that involved a short hop to Belfast for the foreign affairs minister Micheál Martin.

Transporting government ministers aboard the other two government jets has cost more than €10.6m in the past four years.