On Friday, UK and Norwegian authorities announced their intention to clear Airbus H225LP and AS332L2 helicopters to resume flight, provided operators adhere to new modifications and maintenance guidelines. The helicopters had been grounded in both countries shortly after the fatal crash of an H225LP (EC225LP) near Turoy, Norway, in April 2016. EASA had approved the model for return to service in October 2016.
The conditions for return to flight imposed by the UK Civil Aviation Authority and the Civil Aviation Authority of Norway focus around a second-stage planet gear in the epicyclic module of the main rotor gearbox—the component faulted as a main contributor to the Turoy accident by the Accident Investigation Board of Norway (AIBN) in a preliminary report issued on April 28. Requirements for return to flight include a change in the design by removing the components that were susceptible to premature deterioration; earlier replacement of components; a design change to introduce an improved maintenance inspection method to detect any deterioration at an early stage; more frequent inspections; and a reduction in the thresholds for rejecting components based upon early signs of any deterioration.
A plan of checks, modifications and inspections needs to be undertaken before any flights take place, including all required procedures, processes, tooling and training.
On July 7 British and Norwegian authorities announced their intention to clear the Airbus H225LP and AS332L2 to resume flying, provided their operators adhere to new modifications and maintenance guidelines. The ban was expected to be lifted officially on July 14. The helicopters had been grounded virtually worldwide since June last year following the crash two months earlier of an H225LP (EC225LP) operated by CHC for Statoil near Turoy, Norway. The accident killed all 13 people on board after the main rotor hub detached from the main gearbox (MGB) in flight. Although the EASA cleared the helicopter for return to service in October last year and the FAA followed suit in December via alternate means of compliance (Amoc), the type remained grounded from commercial service in both the UK and Norway, where it was used heavily to support North Sea offshore oil operations.
The conditions for return to flight imposed by the UK Civil Aviation Authority and the Civil Aviation Authority of Norway focus on a second-stage planet gear in the epicyclic module of the main rotor gearbox, the component the Accident Investigation Board of Norway (AIBN) identified as a main contributor to the Turoy accident in a preliminary report issued on April 28 this year. The mandated inspection/replacement regimen is similar to that devised by the EASA last year.
The requirements for return to flight: change in the design by removal of the components that were susceptible to premature deterioration; earlier replacement of components; design change to introduce an improved maintenance inspection method to detect any deterioration at an early stage; more frequent inspections; and a reduction in the thresholds for rejecting components in response to early signs of deterioration. Operators must conduct checks, modifications and inspections before any flights to verify that all required procedures, processes, tooling and training have been adhered to.
Despite these new safeguards, the Super Puma faces an uncertain future for offshore missions. Statoil announced earlier this year that under no circumstances will it allow its workers to fly in Super Pumas, a stance echoed by ConocoPhillips. Industri Energi, a union representing 60,000 oil workers in Norway, reacted angrily to the proposed lifting of the flight ban there, claiming it was premature as the Norwegian AIBN has yet to conclude its investigation into the Turoy accident and has yet to determine why one of the gearbox planet gears fractured. The union maintains that lives will be at unnecessary risk until such time there is confidence a similar accident will not happen. Henrik Fjeldsbø, head of the union's helicopter committee, charged that the modifications and maintenance changes Airbus proposed are insufficient to ensure safe operations.
In particular, he noted that the existing gearbox chip detector was only 12 percent effective. “It's terrifying,” he said in a statement released by the union early last month.
In a statement released on July 7, Airbus Helicopters acknowledged that “there is still a lot of work to be done to restore confidence in the aircraft” and that the lifting of the flight ban in the UK and Norway “will not result in immediate passenger flights.” Airbus said it has taken various measures to improve Super Puma safety, among them a “design change addressing fatigue failure, improved spalling detection and greater reliability.” Specifically, the OEM said it has improved the MGB by replacing the planet gear that failed in the accident helicopter and cutting its life limit to 1,000 flight hours from 4,000; improved spalling detection by introducing a new full-flow magnetic plug to detect particles in the oil, more stringent inspection criteria and new equipment allowing for more detailed particle analysis; and implemented a new quality assurance process (for example, a new packaging system equipped with shock sensors) that better protects critical dynamic components throughout their maintenance history.