Norwegian accident investigators think their findings from a fatal helicopter crash in 2016 should prompt new design demands for gearboxes worldwide. They believe a simple grain of sand can cause the entire rotor of a helicopter to fall off.
That’s what happened when a Super Puma helicopter carrying offshore oil rig workers from the North Sea back to the Norwegian mainland crashed on April 29, 2016, killing all 13 people on board.
The weather was good and there was no sign of human error. Rather, the gearbox housing for the helicopter’s rotary blades disengaged from the aircraft itself, sending it plunging to the rocky coastline below as it was approaching Bergen’s airport for landing.
The accidents investigation board found that small particles in the oil inside the gear wheel caused one of its teeth to crack. That caused such grave damage inside the gearbox that the rotor fell. “A helicopter consists of many individual components, each of them critical to safety,” Kåre Halvorsen of the board (Havarikommisjonen) told newspaper VG. “A helicopter has only one gearbox, and if something happens inside, it’s often fatal.”
The board’s findings, announced late last week, are thus being sent out internationally. “We’re advising EASA (the European aviation safty agency), to examine the certification of gearboxes in general,” Halvorsen said, adding that the Norwegian board thinks the safety margins on today’s gearboxes are too small.