Sikorsky grounds S-92 after UK incident

Manufacturer issues safety alert on helicopter model to leave aircraft out of action in North Sea

Helicopter manufacturer Sikorsky has grounded all flights of its S-92 aircraft following an incident at a UK platform last month.

Operators have been instructed to carry out immediate checks on the tail rotors of the helicopters after Sikorsky issued a safety alert.

The alert service bulletin issued in the early hours of Tuesday was made "to define additional interim inspection requirements for the S-92 tail rotor pitch change shaft," a statement from Sikorsky sent to Upstream read.

Major North Sea operators CHC Helicopters and Bristow have grounded their flights in line with the request, Norway’s major offshore union Industri Energi (IE) stated in a release.

S92 Gouge mark: apparently left on the Franklin helideck after a recent helicopter landing

This means that all North Sea helicopter traffic is effectively grounded as a ban remains in place on flights of Airbus-manufactured Super Pumas EC225LP and AS332L2 off Norway and the UK following a fatal accident last year, although it has been lifted by the European Aviation Safety Agency.

A total of 39 flights had been either delayed or cancelled as a result of the inspections, though a flight to Ekofisk had taken off from Stavanger airport at 12:19 CET, according to air traffic website

The alert service bulletin issued by Sikorsky stated an inspection was required of the tail rotor pitch change shaft bearing assembly “for ratcheting, binding or rough turning”.

If this component fails the inspection, it must be replaced by the manufacturer, according to the bulletin obtained by Upstream.

The document further stated that “compliance is essential” and the checks must be carried out within 30 days of the bulletin being issued, and within 10 flight hours if the assembly was manufactured, repaired or overhauled after 2 November last year.

Sikorsky's statement continued: "Safety is our top priority, and Sikorsky is working closely with our customer and investigative authorities to determine the root cause of the loss of tail rotor authority in the 28 December installation landing." 

The "additional interim inspection requirements" referred to by the company include "an off-aircraft check of the PCS bearing". This check must be done before the next flight, "with some leeway for getting back to base," it added.

A spokesman for Aberdeen International Airport said: “We are aware of a safety alert that has been issued for all S-92 helicopters and are anticipating a potential impact on helicopter operations over the next few days until essential maintenance has been carried out. We will support the operators as much as possible through this disruption.”

The move follows the 28 December incident in which a CHC-operated Sikorsky S-92 chopper developed a technical fault when coming in to land on the normally unmanned West Franklin wellhead platform as it was shuttling workers from Total’s Elgin facility.

Those on board the aircraft – two crew and nine passengers – were uninjured but it left significant gouge marks on the platform’s helideck when one of its wheels came into contact with the facility.

Pictures that have emerged online show the helicopter on the Franklin platform, with apparent damage to the helideck.

The Air Accidents Investigation Branch is now investigating the incident.

IE union official Henrik Fjeldsbo said the grounding “has come at the worst time” for the North Sea industry given Super Pumas are also out of action, adding “there is no helicopter traffic at the moment”.

He said flights would be mobilised as each aircraft is checked and cleared for operations.

Fjeldsbo stated though this “has nothing do with the S-92 not being a safe helicopter, but it gives security that operators are grounding their aircraft on their own initiative until thorough checks are carried out”.

Meanwhile, a CHC-operated helicopter was stalled at Statoil's Kvitebjorn platform off Norway on Tuesday after it developed an oil leak, news site reported.

Mechanics from the flight operator had to be flown out to the installation in a search-and-rescue helicopter to carry out repairs to the stranded aircraft, which was due to ferry passengers from the facility to land when the leak was discovered.

Tests were to be carried out on the chopper before it flew to Bergen airport with pilots and mechanics onboard, according to a Statoil spokesman.