Helicopter safety study may help New Zealand

Press, 6 January 1987, Page 27

Helicopter safety study may help New Zealand

PA Wellington New Zealand civil aviation authorities were closely monitoring British and American studies aimed at eliminating helicopter accidents, said a spokesman. Britain’s helicopter industry and the Civil Aviation Authority will spend more than $3.6 million during the next three years on helicopter safety research. The sum includes $1.5 million allocated by the British Government six days after the North Sea crash of a Boeing Chinook which killed 45 oil rig workers and crew.

Most of the money will be spent on new designs for helicopters to make them more capable of absorbing energy at impact, new restraints for passengers, and new computerised onboard systems for detecting changes in vibration that forewarn a mechanical failure such as the transmission metal fatigue that brought down the Chinook. New Zealanders use helicopters in tough terrain for work the designers never dreamed of — such as deer recovery and topdressing — and the toll has been high. The oldest helicopter in

the country is only 12 years old, the average age is about five years, and one lasted only five days before being wrecked.

The Civil Aviation Division’s chief airworthiness engineer, Mr Ernie Labett, said the findings of the new studies would be closely followed. “We’ll be waiting to see what the manufacturing countries do about this,” he said.

“A helicopter is a very mechanical device, unlike an aeroplane that is a structural device. That means helicopters are more prone to mechanical failure than planes,” he said.

Already New Zealand engineers checked helicopter oil sumps for metal particles that signalled a failure, but the electronic fatigue monitoring system would be a significant step forward in safety, even if it could be applied only to larger machines, he said.

Last June America’s Federal Aviation Administration published a report that called for greater structural integrity for helicopters.

It showed that in the five most common accidents, most could have been more survivable had

passengers been better restrained, and had helicopter fuselage and seats been better designed to absorb impact energy. The worst case is a vertical collision with the ground and the administration may move demand that manufacturers’ designs give greater strength to the fuselage and prevent the overhead blades, rotor, head, and transmission from crashing through the cabin. Many a New Zealand helicopter has crashlanded safely only to roll over and disintegrate. The British electronic vibration monitoring gear may prevent most mechanical failures, but the design of the fuselage could save others, Mr Labett said. The fragility of helicopters was demonstrated at an air show at Masterton last year when a low speed contact with the ground caused a Hughes 500 to flip and destroy itself. “They can roll over very easily. All aircraft are fragile — they wouldn’t be in the air if they weren’t,” Mr Labett said.

“Always a compromise is reached. If you wanted something totally safe it wouldn’t get in the

air.” New Zealand lacked the technology and budgets to undertake its own research and had to follow the lead of manufacturing countries such as Britain and the United States. Mr Labett was particularly interested in developments in improving what he sees as the weakest link in the helicopter — the transmission between the engine and the rotor blades. “Things will happen in helicopter gearboxes. We are already analysing and monitoring the level of vibration in big jet engines. If you get a sudden change it often means a problem is about to occur. It is an aid to safety. “But again, we’d be dependent on the manufacturers to tell us what is an acceptable level of vibration. We can expect more vibration monitoring over the next few years,” Mr Labett said.

“Things will happen in helicopter gearboxes. We are already analysing and monitoring the level of vibration in big jet engines. If you get a sudden change it often means a problem is about to occur. It is an aid to safety. “But again, we’d be dependent on the manufacturers to tell us what is an acceptable level of vibration. We can expect more vibration monitoring over the next few years,” Mr Labett said. The British research will also examine the human factor.

Helicopters are noisier and vibrate more than fixed wing planes and the research is likely to recommend better headgear for pilots and shorter working hours.