North Sea oil rigs and now also search and rescue operations in Norway won’t be allowed to use the Airbus H225 “Super Puma” helicopters any time soon. They were all grounded indefinitely during the night after investigators found signs of metal fatigue in the gears of a Super Puma that crashed in Norway earlier this spring.
Norway’s accident investigations board (Havari- kommisjonen) issued an immediate safety alert to the Euopean Aviation Safety Agency (EASA) on Wednesday, “We’re releasing information about what we think can be a sign of fatigue fracture in the gears,” William J Bertheussen, director of the accidents commission for transport, told newspaper Aftenposten Wednesday evening.
Later during the night came news that the Norwegian aviation authority (Luftfartstilsynet) had decided not only to extend the current grounding of all Super Puma helicopters used for passenger transport but also removed an exemption for search and rescue operations. The order was made on the basis of the latest discoveries made during the investigation into the crash of a Super Puma near Bergen on April 29. All 11 oil industry workers returning to the mainland from an offshore Statoil rig plus the helicopter’s two pilots were killed.
Warning system ‘not good enough’
Witnesses to the crash could quickly report that the helicopter’s rotary blades had separated from the aircraft itself, sending it within seconds into a catastrophic plunge down to the rocky islands at Turøy.
“We have at any rate made an important discovery in one of the three scenarios we’re working with as a possible cause of the accident,” Bertheussen told Aftenposten. His agency thus urged EASA to take immediate steps to ensure safety of all the same type of helicopters, because it can’t be ruled out that the same types of fatigue fracture found during metallurgical examinations can be found in other helicopters of the same type.
Aftenposten reported that the commission also wrote that the Super Puma’s warning systems for this type of fatigue fracture were not good enough.
The helicopter’s gearbox has been at the heart of the investigation all along, but it’s been difficult to recover all relevant parts of the wreckage at the crash site. The new metallurgical probes of parts recovered have been carried out by QinetiQ, described as a partly state-owned British defense contractor.
The gearbox is critical and dealt in several modules, according to Kåre Halvorsen of the commission. “We have found a fatigue fracture in the last level before power (from the motor) is transfered to the rotor,” he told Aftenposten. the part involved is called the “second-stage planet gear.” Aviation officials stressed, meanwhile, that the investigation would continue and that no final cause of the fatal crash in April had yet been determined.
The groundings of all Super Pumas may come as a relief to some offshore workers who have complained about them in the past and no longer wanted to fly in them, but it’s raised challenges for operations on the Norwegian Continental Shelf. Super Pumas have also been used for emergency preparedness and Statoil, for example, announced it was mobilizing “the necessary resources” to satisfy preparedness requirements without the use of the type of Airbus helicopter now grounded.
They’ve been used on the Oseberg Field Center, the Statfjord B platform and at the Sola airport in Stavanger, the main base for helicopter traffic to North Sea rigs. The groundings are also affecting operations in the British sector of the North Sea.