New Method Saves Time When Detecting Leaks On Aircraft-fkzww

UnCategorized Tracing leaks in an aircraft fuel system is a time-consuming procedure for which there has so far been a shortage of good methods. One problem is that it is more or less impossible to estimate how long it will take to identify and repair the leaks. Now there is a solution that dramatically reduces the time required for leak detection. It uses diluted hydrogen as a tracer gas and can be used both in aircraft maintenance and manufacture. The equipment has been certified according to the EU ATEX directive and fulfils the requirements for use in explosive environments such as aircraft fuel systems. In a time of ever keener .petition and efficiency demands, .bined with an ageing aircraft fleet, it is be.ing more and more important to minimise the time an aircraft spends on the ground. It is a known fact that leaking fuel systems are a major contributor to maintenance and repair time and costs. An American Air Force report on the maintenance of the KC135 tanker – an old 1950s warhorse – can serve as an example. Between 1998 and 2002, an average of 120 fuel leaks was repaired, taking 3245 man-hours and costing over 41 million US dollars every month. The problem with fuel leaks is especially severe with military aircraft since they are subjected to extra high stress. In addition, leaks occur more easily in some types of aircraft because of their design. The age of an aircraft is naturally also a significant factor in terms of its tendency to leak. The fuel tanks of some older aircraft have a primer that cannot withstand the aviation fuel in use today, so they are more prone to corrosion. "Fuel leaks are a thorough nuisance, since it’s incredibly difficult to estimate how long it will take to repair them", says Matthias Block, sales manager at Alcatel Hochvakuum GmbH in Germany which numbers EADS among its customers. With today’s methods, tracing a leak is pure detective work and this applies to aircraft in service and in production. Fuel leaks in aircraft in service are usually identified and categorised by fuel stains on the outside of the aircraft. When a leak has been identified, the meticulous and often time-consuming work of tracing its origin begins. Leaking fuel can travel long distances through channels that form under the sealing .pound when it ages or is subjected to stresses. In addition, there is often more than one leak. Before tracing a leak the fuel tank needs to be drained and ventilated to eliminate the risk of explosion. After refilling the repaired tank it is not un.mon to discover new leaks and to have to repeat the entire procedure. A .mon method to locate leaks is to pressurise the leak from the outside and trace it on the inside with soap spray. Other options are to use various dye penetrants or fluorescent paint and UV light. Talcum powder may be used, for example, to test fuel bladders. Sometimes tracer gas is used for leak locating. One .mon tracer gas is helium. A drawback of that method is that it is easy to get a too high background level of helium in enclosed spaces. In many cases this makes it impossible to locate leaks. The test area must be thoroughly ventilated before leak locating can be resumed. However, leak locating with tracer gas is still the simplest approach. Adixen Sensistor has now developed an Ex-classified solution for leak locating with hydrogen tracer gas, which does not require time-consuming ventilation. The Extrima leak detector uses diluted hydrogen as a tracer gas and is intrinsically safe, meaning that it fulfils the Ex requirements for use in the majority of explosive environments. Extrima is classified EEx ia IIC T3 and satisfies the requirements for use in Ex-classified zone 0. In practice, this means that the equipment is safe to use in a fuel tank, for example, even if the tank has not been fully drained and ventilated. Extrima has been certified according to ATEX (Atmospheres Explosive), the EU directive for equipment and work in explosive environments. The most .mon leaks occur around screws and rivets. When using hydrogen for leak detection, there is a choice of two approaches; locating the leak from the outside or the inside. To enable leak locating to be done by a sole operator, Adixen Sensistor has developed special "injection pads". Without these, another person is needed to supply the tracer gas manually. The pads are placed at the locations on the outside of the skin that have shown indications of leakage. They need to be applied for 30-60 minutes prior to applying tracer gas pressure. This can be done while the tank is draining. Via the injection pads, hydrogen tracer gas is injected at a slight positive pressure of up to 0.5 bars or 7 psi. The pads ensure a constant and measurable pressure. The operator can then access the fuel tank and locate leaks on the inside with a hand probe. The other method, which is .mon in the manufacture of new aircraft, involves filling the tank with tracer gas and locating leaks on the outside. In this instance, a pressure of only a few psi is needed, equivalent to a few hundred millibars. When filling the tank with gas, strict pressure control is essential, since even relatively moderate pressures can damage the tank. The equipment, named Extrima, is in the form of a small (5 kilos / 11 lbs) detector and hand probe which can easily be taken into the tank. "Our specialist’s first impression of Extrima was that leak detection could be done very close to the leak, which makes it far easier to trace it. It could definitely save a lot of time", says Oliver Graf, project manager at Lufthansa Engineering and Operational Services, where the new method was demonstrated. "We are looking forward to use Extrima to locate fuel leak entries easier and faster", adds Oliver Paris, senior supervisor at Lufthansa Technik. The tracer gas consists of 5 percent hydrogen in nitrogen and is non-explosive, renewable and environment-friendly. Gas suppliers often call it forming gas. A .mon problem in leak detection with tracer gases is a too high background. However, this is negligible with forming gas, since it has a high dilution rate and therefore disperses rapidly. Leak locating with hydrogen tracer gas is a method that has existed for more than two decades. Adixen Sensistor originally developed it for the tele.s sector, where it is used to detect leaks in telephone cables. It is also used in the automotive, process, packaging and refrigeration industries, among others. In the aviation industry, the hydrogen method has begun to be used for leak testing of oxygen systems, cooling systems and fuel systems, for example. Extrima was developed in response to direct requests from aviation customers who had previously used the hydrogen method, but without ATEX-certified equipment. ‘The first customer contacted us two or three years ago", explains Mattias Block, who sees great potential for the method. Initial tests done with Extrima shows that major time savings can be made during leak detection and when checking repaired leaks. Since the equipment is intrinsically safe, leak detection can be done even with some fuel still in the tank. "Tests done on .bat aircraft points to time savings of more than 50 percent .pared with earlier methods", says Dave Morris, sales manager at Alcatel Vacuum Products in the USA: "There is a huge application base for this method both on the military and the civil side, and both for maintenance and manufacturing. Because of its reliability when it .es to finding every leak, it is faster and less re-testing is needed." About the Author: 相关的主题文章: