Survival of the fittest

Mike Richardson meets survival systems specialist, Aero Sekur's chairman, Mark Butler to learn more about the company's work with emergency flotation and external liferaft systems. Whether it involves airborne systems, flotation and external liferaft systems, fuel tanks or even parachutes, pretty much everything Aero Sekur does is all about ensuring the survival of both pilot and passenger. The company recently announced a major emergency flotation and external liferaft systems contract for AgustaWestland's AW189 family of helicopters. Aero Sekur says its systems are designed to offer a high level of compatibility across the AgustaWestland range, with benefits including reduced costs, high modularity and shared maintenance. “This contract was hugely important to us, because we've worked with AgustaWestland from the initial concept of the helicopter to not only design a flotation liferaft system for each model of helicopter, but also offer a system that has a high degree of commonality,” begins company chairman, Mark Butler. “Instead of us working on each helicopter model on an individual basis - which would require AgustaWestland to support six different models and all that entails - we've integrated a common system that is then tailored to the individual model. This significantly reduces the cost of maintenance, the bill of material for maintenance, plus training requirements are simplified. A repair & overhaul unit can now basically deal with variations on the same theme, rather than having to instigate training programmes for each separate item.” Simplifying the process

It's by doing this that Butler feels Aero Sekur has introduced some much needed commonality into the design engineering and qualification process. “It means that each successive helicopter model's development and qualification process becomes cheaper and much quicker to complete,” he adds. “There's always an unavoidable amount of work to do during the development cycle, but for the qualification process, the customer can leverage on the information they've already acquired because the design is much simpler and they can start to use more similarity in the qualification process, which makes it much easier and simpler. It's an efficient, planned process which means it suits both the OEM and Aero Sekur very well. It means we do not need to perform any unnecessary tasks and that the customer obtains a system that is much cheaper in terms of maintenance and quicker in terms of the qualification process.” As a supplier, Aero Sekur has strived to get its OEM customers to consider and adopt these kinds of systems as early as possible in the design process. “What happens historically with our flotation and liferaft systems is that the OEM builds the helicopter, and then their designer suddenly realises that they need a flotation system,” continues Butler. “This means we have to try and re-engineer the system around an existing product and almost inevitably it ends up as a compromise - and perhaps a less than optimal design - and often very ugly too. We can provide really elegant solutions that are almost invisible  if we're contacted as early as possible in the helicopter design process. “AgustaWestland understand this concept very well. If we take the AW139 helicopter as an example, we worked with them from a very early stage and have incorporated our survival systems into the design of their helicopter. The solid covers of the survival system make it very difficult to spot that there is a flotation system - and an external liferaft system - built into this helicopter. It can be done properly and elegantly  and very aerodynamically too. AgustaWestland has fully embraced our message, and it has worked right from the beginning. We have engineers more or less permanently embedded at AgustaWestland and we're trying to get other OEM customers to do the same.” Obviously, it's not practical to simply drop the helicopter in the sea under test conditions, so Aero Sekur simulates this test by using finite element modelling (FEM) and a test frame to perform deployment of its survival systems in water. “Where we have been performing tests using existing airframes, we can purchase an existing scrap airframe and test it,” Butler explains. “Our design engineers put a lot of work into modelling systems and perform some very complex modelling solutions. When addressing a composite material for example, our designers perform this task by modelling a number of FEM grids and get them to interact. Instead of taking a rough average, we actually predict how the materials will work together. We then combine them with hydrodynamic models, so we can actually model the behaviour of a flexible structure filled with a fluid very accurately. We'll usually ask the OEM for a helicopter model so that we can perform the structural analysis on all the airframe connections. We have to ensure that our survival systems can keep the helicopter afloat – at least in a ‘sea state six' condition. “We recently tested one of our external liferaft systems by repeating underwater deployment to see whether the liferaft would still deploy if it was 2-3m beneath the surface, which it did so successfully. We don't often get to test a helicopter's hydrodynamic stability during a storm. Usually it's modelled because the hydrodynamic modelling is advanced enough that we can predict how it will react. In this case, the customer has asked us to actually validate the modelling by performing this test. It will be an interesting challenge and there are design facilities available that can simulate these kinds of conditions.” Look smart

Butler claims his company's unique selling point is that it offers the most technically advanced solutions in the marketplace. “As a company we're not necessarily the biggest in the marketplace, but we lay claim to being the number one in this area of technology,” he concludes. “We want to maintain this position by being the smartest kid on the block. This means putting a huge amount of research effort into materials and systems technology. “Our flotation systems deploy in under two seconds, which is very important because when a helicopter hits the water, it starts to sink and because it's inherently unstable, it immediately tries to rotate in the water. If it pitches by more than 30° then it will capsize. It's important that the pilot deploys the flotation system quickly so that not only will it keep the helicopter afloat, but keep it upright too.” www.aerosekur.com