Coast Guard Tragedy: Five rescue choppers had safety checks in January

The Irish Coast Guard’s five search and rescue helicopters, operated by CHC Ireland, were grounded for a time earlier this year following an advisory from the aircraft manufacturer issued after an incident in the North Sea.

Coast Guard Tragedy: Five rescue choppers had safety checks in January

It was part of a worldwide grounding for safety checks after a Sikorsky S-92A experienced a technical fault when it was coming in to land.

It left “significant gouge marks” on the deck of the platform.

The helicopter, which was operating from Aberdeen in Scotland, spun upon landing on the Total West Franklin rig, damaging the helideck and the aircraft’s landing gear.

CHC said the flight crew reported “unexpected control responses” on final approach and executed an emergency landing.

All operators of the Sikorsky S-92A helicopter worldwide were advised to ground their aircraft early in January until precautionary maintenance and inspections of the tail rotor could be undertaken.

Sikorsky issued the worldwide air service bulletin’ following the incident.

CHC Ireland and the Irish Coast Guard immediately began the process of inspecting all its aircraft, but requested that they stagger the process to ensure continuity of service.

This was approved and all five aircraft were grounded for the precautionary checks on a staggered basis in early January to ensure there was emergency cover available.

Each of the checks took about four hours to complete and afterwards, the aircraft were returned to service.

A month before the incident on the North Sea, the US Federal Aviation Administration (FAA) issued an emergency airworthiness directive (AD) to all owners and operators of Sikorsky S-92 helicopters to look for possible problems with tail rotor control.

It was prompted by a report of an operator losing tail rotor control while in a hover.

The emergency directive was issued on November 18, with the FAA stating: “The actions in this Emergency AD are intended to detect a binding bearing, prevent loss of TR [tail rotor] control, and possible loss of control of the helicopter.

“A preliminary investigation determined that binding in the tail rotor pitch change shaft assembly double row angular contact bearing resulted in reduced tail rotor control.

“This Emergency AD was prompted by a report of an operator losing tail rotor control while in a hover. A preliminary investigation determined that binding in the TR pitch change shaft assembly double row angular contact bearing resulted in reduced TR control.

"The investigation also found signs of excessive heat, which is an indicator of a binding bearing.”

CHC Ireland operates search and rescue services under contract to the Department of Transport and Irish Coast Guard from bases at Dublin, Waterford, Sligo, and Shannon.

As part of a 10-year, €500m deal, which was signed in July 2010, CHC agreed to replace its ageing fleet of S61N Sikorsky helicopters with the new S-92A series.

The S-92A helicopter was introduced into the Coast Guard in 2012 and over the following year, the entire fleet of older S6-1N aircraft were replaced in a phased process.

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