Investigation Continues into August Super Puma Crash

 - October 2, 2013, 4:15 AM
On August 24 the Helicopter Safety Steering Group recommended a temporary grounding of all Super Puma flights–more than 50 percent of the capacity in the North Sea–before recommending a return to flight five days later.

The fatal crash of a CHC Scotia-operated Eurocopter AS332L2 Super Puma on August 23 off the Shetland Islands in the UK has created an outcry among passengers and is puzzling experts. Investigators have found no evidence of technical failure so far, nor have they hinted at human factors. Meanwhile, a pilot based in the North Sea noted that the helicopter seriously deviated from the expected course, two nautical miles from its destination, Sumburgh Airport.

The fifth Super Puma accident or major incident since 2009 in the UK offshore industry, the August accident has inspired a strong response among oil-and-gas workers, who use Super Pumas and other helicopters to travel to and from platforms in the North Sea. A petition and Facebook page calling for the ban of the medium-twin series in offshore flights have garnered more than 12,000 signatures and 38,000 likes, respectively. Unions have been vocal, too. “This is the second [of these incidents and accidents] resulting in fatalities. It’s unacceptable and it can’t go on,” said Unite Scottish secretary Pat Rafferty.

In 2012 two EC225s (also members of the Super Puma series) executed well publicized ditchings. After a long period of grounding in the North Sea region, and thanks to a main gearbox retrofit kit, the EC225 was cleared to fly again in July. EC225s had just started to resume North Sea operations and not all of them had been modified as of August 23. Passenger and operator sensitivity was running high when the August crash happened.

Reaction grew tenser since information was scarce in the days after the accident. The AAIB did not recover the cockpit voice/flight data recorder until August 29 because the wreckage was scattered. After hitting the water surface, the aircraft rapidly inverted and drifted to a rocky shoreline, where it was largely broken up. Four of the 16 passengers died and one of the two pilots was seriously injured.

On August 24 the Helicopter Safety Steering Group recommended a temporary grounding of all Super Puma flights–more than 50 percent of the capacity in the North Sea–before recommending a return to flight five days later.

As the UK’s Air Accidents Investigation Branch (AAIB) was gathering and assembling evidence, a technical issue was looking less likely. The branch said it appears the helicopter was “intact” with “both engines delivering power” when it struck the sea at a near level pitch attitude with a slight right bank.

However, the recorded data shows a deviation from the expected course from about 2 nm from the runway threshold. There, the aircraft was approximately 240 feet below the vertical approach profile, with a rate of descent of about 500 feet per minute and an airspeed of 68 knots. One North Sea-based pilot deemed that vertical deviation already to be “a major one,” while the aircraft was flying too slowly for such a descent rate.

The airspeed continued to reduce to less than 30 knots, and as it did so the helicopter pitched increasingly nose-up. The descent rate remained constant for a period, before increasing rapidly. Shortly thereafter, the helicopter struck the sea. The autopilot localizer and vertical speed modes were engaged for the approach.

Safety Stat Comparison Not Available

Despite several attempts with five different companies, safety committees and aviation authorities, AIN could not obtain statistics to compare the safety record of the Super Puma with that of other helicopters. A UK CAA expert suggested that attempting to compare the safety records of different helicopter types would be a perilous pursuit. He cited the preponderance of operational causes and the difficulty in obtaining reliable data on utilization by type. Nevertheless, a question looms among pilots in the North Sea: why so many Super Puma accidents in the UK and so few in Norway?

Support for Super Puma

Three stakeholders in the Eurocopter Super Puma’s predicament rallied last month in support of the aircraft. “We do not believe that the accident was caused by an airworthiness or technical problem,” the UK CAA said in a statement. Meanwhile, Eurocopter CEO Guillaume Faury asserted, “The worldwide safety records of this family are the best in industry.” However, he did not substantiate his claim with numbers. UK chancellor George Osborne flew offshore in a Bristow-operated AS332L and stated, “The helicopter link is vital for the [oil and gas] industry.” What makes this show of support unusual is the fact that it happened before the AAIB issued a special bulletin saying it had found no evidence of technical failure.