Aircraft Air Start Units and Their Importance

Many modern aircraft rely on external ground support equipment (GSE) for their engine starting process, allowing for the engine to be cranked and driven until the engine is capable of sustaining its own operations. The starting process for a gas turbine engine is typically conducted with the use of an Air Start Unit (ASU) that of which will typically be supplied at the aircraft stand of an airport for use while passenger boarding is near completion. To help you better understand the engine starting process, we will discuss the ASU, as well as the various accessories one may use to best take advantage of such equipment.

While an ASU is a powerful piece of equipment, it is simply an engine driven air compressor at its most basic form. As such, it functions by drawing in atmospheric air and passing it through a series of filters to remove any contaminants or harmful particles. Once the air passes through the filters, it then enters a compressor where its pressure is raised before being directed into the jet engine itself to drive the air starter motor. For the compressor of the ASU to operate, it requires power from a diesel engine and gearbox pair that ensures optimal speed control. Additionally, various air regulation and control valves are situated on the unit, allowing for excess pressure to be released as required. As ASUs may need to be transported to aircraft or around the airport, the entire assembly is generally placed in a weather-protected enclosure and installed onto a truck or cart. Lastly, a control panel will be present with various displays, gauges, and meters so that personnel can guarantee optimal starting conditions and settings.

Despite turbine engines featuring a process that allows them to be fairly self-sustaining, they require the use of an ASU to get the cycle started so that the turbine assembly can begin driving the compressor as the combustion chamber ignites fuel and air mixtures. As air is supplied to the engine by the ASU, the engine shaft will be driven with the use of a gearing mechanism. As such, the energy of the supplied compressed air is transformed into the rotational force of the motor. Once the engine is able to reach a desirable speed for self-sustaining operations, fuel combustion will begin and the ASU is removed.

In some instances, aircraft may require what is known as an air start adapter to ensure that they can conduct the engine starting process. These adapters allow for Ground-Air connections to be established in the instance that an APU faults away from base, or when other various issues occur. By having an air start adapter on hand, pilots and operators can better avoid delays that result from a failed starting or inability to use GSE. While OEM adapter components are generally the most recommended for reliability, there are various forms of third party adapter components that one may take advantage of.

If you find yourself in need of ASU equipment, an air start adapter, or other various types of GSE, let the experts at ASAP Fasteners help you fulfill all your operational needs with time and cost savings for your benefit. Owned and operated by ASAP Semiconductor, we present customers access to an inventory containing over 2 billion new, used, obsolete, and hard-to-find parts that have been sourced from leading global manufacturers that we trust. Take the time to explore our offerings as you see fit, and our team of industry experts are always ready to assist you with competitive quotes for your comparisons and customized sourcing solutions. Give us a call or email today and see how we can serve as your strategic sourcing partner for all your operational needs.


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