Since it was first launched commercially in 1996, the Airbus Helicopters (formerly Eurocopter) EC135’s distinctive twin-tailed fuselage has become a regular sight in the skies of Europe, and across the world. It has been adopted as a fast-response emergency aircraft by both police and ambulance services – sometimes, covering both roles at the same time. It can be deployed to pursue speeding cars, track escaping criminals or to land in difficult locations, from mountains to school sports fields, and whisk seriously injured patients to the nearest suitable hospital in a matter of minutes.
PMMA sheets are said to ensure that pilotes have a clear panoramic view. (photos: Evonik)
Curved protection
The front windscreen displays a multi-curved design that is intended to give pilots and crew the widest possible panoramic view. It is made of Evonik’s polymethyl methacrylate (PMMA) ‘Plexiglas’ and is manufactured to provide protection from UV rays while maximising visibility. Outstanding visibility is obviously essential for the helicopter’s pilots, who want to see where they are going, but it is important to the aircraft’s crew and function as well: observation is the reason for the aircraft to be deployed in emergency and law enforcement roles.
All the transparent glazing on the EC135 model – front, side and rear is made from PMMA.
Withstanding stress
Air rescue missions place great demands on materials. Helicopters and their glazing have to withstand extreme changes in temperature, wind and weather, as well as aggressive UV radiation. Aircraft have to be as light as is practical, without sacrificing integrity or performance. Plexiglas is half the weight of conventional mineral glass and its use for all the glazed areas on the EC135 helicopter helps to reduce fuel consumption and thus enable it to stay in the air for longer. The material is also safer than glass, according to Gottfried Hornung, Supply Chain Officer and Head of the EC135/145 Final Assembly Line at Airbus Helicopters.
“For safety reasons, glass is unsuitable,” he explained. “If an accident occurs, such as a bird strike, glass breaks into thousands of tiny pieces and impairs visibility. This risk is eliminated with Plexiglas: only the directly affected area is damaged”. Plexiglas sheets are also easy to shape and enable the company to build the characteristic spherical canopies on the EC135.
Quality control at the Evonik plant in Weiterstadt, Germany
Production and modification
Evonik produces Plexiglas at its plant in Weiterstadt, Germany, where the material is produced in a special casting process. Each sheet of the material is examined and certified to be compliant with the aviation industry’s strict standards for acrylic material, in terms of optical quality, thickness tolerance, and mechanical properties. The material is then handed over to, Josef Weiss Plastic, helicopter glazing specialists, for further processing. The plastic is heated and stretched into the desired form and each sheet is again checked for any defects, optical or physical. Per month around seven sets of finished glazing arrive at Airbus Helicopter’s German headquarters in Donauwörth.
Manufacturing of the EC 135 (video: Evonik)
More than 1,000 Plexiglas-equipped EC135 helicopter models are currently in operation worldwide. Germany’s largest automobile club, the Adac, runs one of the two biggest air rescue squads in the country, comprising a fleet of 49 helicopters. Rescue teams were called out a record number of times in 2012; helicopters were dispatched on 49.243 occasions, which adds up to 130 critical manoeuvres a day.
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