DUBLIN (Reuters) - The black box from a Sikorsky S-92 helicopter that crashed in Ireland last month with four people on board has shown no signs of mechanical faults, the country’s Air Accident Investigation Unit said on Saturday.

Two months before the crash, U.S.-based Sikorsky, part of Lockheed Martin, issued a service notice saying the tail rotor and bearing assemblies of the S-92 should be checked following an incident with the tail rotor during a landing on an oil rig off Scotland on Dec. 28.

“An initial analysis has been conducted of the data... No mechanical anomalies have been identified,” the investigation unit said after an initial analysis of the aircraft’s black box.

The S-92 helicopter crashed off the coast of Ireland on March 14 during an Irish Coast Guard rescue operation, killing two people with another two missing and presumed dead.

European regulators last year grounded certain Super Puma helicopters made by rival Airbus after an accident in which the rotor head separated from the helicopter.