The families of the helicopter pilot, co-pilot and winchman who died while on a search and rescue mission in 2017 are facing significant legal bills arising out of a Department of Transport review of the accident, RTÉ Investigates has learned.

Pilot Dara Fitzpatrick, co-pilot Mark Duffy and winchman Ciarán Smith along with winch operator Paul Ormsby lost their lives when their search and rescue helicopter R116 crashed into Blackrock Island off the coast of Mayo in March 2017.

The families hired legal teams to represent the interests of the deceased crew during hearings of a Review Board, which was established last year by then-Transport Minister Shane Ross.

The Board was tasked with re-examining certain conclusions and findings of an Air Accident Investigation Unit (AAIU) draft report on the accident that had been challenged by helicopter operator CHC Ireland.

Fearful that attempts could be made during the review to attach blame for the accident to any of the deceased crew, the families of Ms Fitzpatrick, Mr Duffy and Mr Smith hired legal counsel to represent the deceased trio at the Review Board hearings.

Helicopter R116 crashed into Blackrock Island off the coast of Mayo in March 2017

The Department of Transport strongly opposed applications to the Review Board by the families' legal teams to have their costs covered, angering several family members of the deceased.

"They lost their lives in public service," one relative told RTÉ Investigates.

"We were dragged into the Review process that we didn't have anything to do with. It was CHC that brought the review. I would have expected the Minister to be defending us."

CHC is a US-based company that is hired by the State to operate the country's helicopter search and rescue service.

RTÉ Investigates understands that the families' final legal costs have not yet been calculated, but legal sources said that the fees for such a lengthy inquiry dealing with such a highly technical subject could run into hundreds of thousands of euro.

Responding to a question about why the representatives of Minister Eamon Ryan argued against paying the legal costs of the families and why the Department had not agreed to pay those costs, the Department of Transport hinted at the possibility of a rethink.

In a statement, it said: "Legal advice was sought on the issue of awarding costs to the families who were represented at the Review Board hearings.

"While it was determined that the Review Board does not have the jurisdiction to award costs to any party appearing before it, the Minister has now asked officials to consider this matter further."

Taoiseach Micheál Martin told the Dáil on Wednesday, following the initial report about the potential legal costs, that he "will inquire into" the matter.

"It was an appalling, terrible tragedy", the Taoiseach said, adding that it "caused enormous grief for the families".

"It is important that families don't get dragged into a situation where they have exorbitant legal bills arising from a situation not in their control," he said.

Mr Martin added that he has not seen Minister Ryan's remarks on this, and said he will get a briefing from him.

The Taoiseach was responding to Sinn Féin leader Mary Lou MacDonald, who said it is "scandalous" the Government decided not to pay the legal costs.

In a ruling seen by RTÉ Investigates, the Review Board, which was chaired by its sole member, barrister Patrick McCann, acknowledged the contribution made by the families' lawyers to the board's workings and also acknowledged that they had little choice but to hire lawyers.

Referring to the family of pilot Dara Fitzpatrick, Mr McCann wrote: "Given the volume of documentation, its complexity, applicable legal rules, the nuanced factual matters meant, it would have been difficult if not impossible for the Commander's family to represent its own interest and the late Commander's interests without legal representation."

Pilot Dara Fitzpatrick, co-pilot Mark Duffy, winch operator Paul Ormsby and winchman Ciarán Smith lost their lives

However, the Department of Transport argued successfully at the Review Board that it was not obliged to cover the families' legal costs and that the Review Board "did not have an implied power to award costs".

Its position, according to the ruling, was informed by advice from the Attorney General that the Review Board did not have the power to make an award of costs to any party or against any other party.

The law governing air accident investigations allows any person or organisation to seek a re-examination of "any findings and conclusions" that appear to "reflect adversely" on their reputation.

However, while the Air Accident Investigation Unit (AAIU) has carried out around 1,000 investigations, this was the first time that one of its reports has been sent for re-examination by a Review Board.

The 333-page AAIU draft report took more than two years to compile and was completed in late 2019. Publication, which was delayed until the Review Board completed its work, is expected shortly, once the AAIU has incorporated changes recommended by the Review Board.

AAIU inquiries are protected by highly restrictive legislation that makes it a criminal offence to reveal details prior to official publication of an air accident investigation report.

After the Rescue 116 accident, safety issues at helicopter operator CHC were raised by RTÉ's Prime Time. It also emerged that Blackrock Island was not included in a database designed to warn the crew they were in danger of hitting land.