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Special giant covers protect Navy helicopters from worst of Mother Nature

27 February 2023
Royal Navy helicopters are ‘wearing’ hi-tech protective new covers – allowing them to scramble in minutes in the Arctic, jungle or desert.

The gigantic ‘onesies’ or cover sheets are spread over the vital parts of multi-million pound Merlin helicopters so they can operate in extreme environments, protecting key parts of the aircraft from the worst that Nature can throw at them. 

The Merlins – based at Royal Naval Air Station Yeovilton – accompany the Royal Marines wherever they deploy in the world as part of the Commando Helicopter Force, and are expected to fly in harm’s way carrying marines and their kit into action in the jungle, desert, High North or temperate climes.

This winter the helicopters are deployed to Bardufoss in Norway, deep inside the Arctic Circle where there are hangar facilities – but they are also expected to operate in the field, forward bases in the middle of nowhere, with no facilities… and no shelter from the elements if they have to spend the night or an extended period there with temperatures regularly dropping below -20 Celsius.

Given time pressures – the need to scramble at short notice – plus the cutting-edge electronics and hydraulics, and temperatures much lower than typically experienced at home in Somerset, you cannot simply wait for the Merlin to defrost as you might a car, by turning the key, putting the fans on full blast and the wipers on max to clear the frosted-up windscreen.

The efficiency of the engineers prevented both damage and delay: within minutes of being on the ground, the snow began to fall - snow which would quickly become ice once it made contact with the airframe and rotor blades.

Lieutenant Andy Duffield

Fitted in under an hour, the ‘onesies’ – the official designation is ‘Extreme Cold Weather covers’ –protect the heart of the helicopter (nose, cockpit, cabin, engine and rotors) from temperatures as low as -60 Celsius all the way up to the extreme heat of 80 Celsius.  

For commercial reasons, the composition of the giant sheaths, designed and produced by a Wrexham firm, is a secret, but they prevent icing up, or damage potentially caused by salt and sand in extreme humidity.

The covers were tested for real for the first time when the Merlins flew out to Norway. Bad weather forced three of the helicopters to divert to the small coastal airfield at Brønnøy, roughly half way between Trondheim and Bodø.

“Imagine attempting to put a cover onto a star-shaped duvet, whilst wearing oven gloves, and stood on a step-ladder in a blizzard,” said pilot Lieutenant Andy Duffield. “It took under an hour to have all three aircraft wrapped up.

“The efficiency of the engineers prevented both damage and delay: within minutes of being on the ground, the snow began to fall - snow which would quickly become ice once it made contact with the airframe and rotor blades. Ice on any airframe is problematic due to the weight it adds and changes it makes to the aerodynamics.”

Further tests were carried out with the new covers once the helicopters arrived in Bardufoss in different weather/temperature conditions.

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