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What is an Aircraft Fuel Nozzle?
The fuel delivery system in many modern aircraft is complicated and made up of many different components that all work together to deliver a continuous amount of fuel to the engines. Of the various elements in the delivery system, one of the most integral is the fuel nozzle. An obstruction or any other event that may damage this component could prove devastating to the fuel system as a whole and risk a flight's integrity. In this blog, we will discuss all you need to know about the critical fuel nozzle.
In a fuel-injection system, the nozzle is the last unit that fuel passes on its way to the combustion chambers. After receiving fuel from the manifold, the nozzles atomize the liquid so that it can be burned most efficiently in the combustor. The design and placement of the nozzles are such that the fuel spray remains centered in the chamber. Commonly made from brass housings and stainless steel inserts, fuel nozzles are designed to withstand the various corrosive elements found in the engine casing.
Fuel nozzles can generally be defined as simplex, duplex, or airblast types, with the first two accounting for the vast majority currently in use. The simplex type, which was the first iteration of fuel-injection nozzles, features a simple design that includes a fine-mesh strainer, an insert, and a nozzle tip. While still found in certain aircraft, most systems have phased the simplex nozzle out and have replaced it with the duplex configuration. The two-stage duplex fuel nozzle offers a superior spray pattern and can deliver a steady amount of fuel even while the aircraft is at idling speeds, which its predecessor struggled with. Airblast nozzles, which can either be simplex or duplex, create an optimized spray pattern by mixing air and fuel at the nozzle's opening in accurate proportions. This design helps prevent carbon build-up, the most common cause of nozzle blockage.
While fuel nozzles should be inspected regularly, there is generally not a specific time prescribed by most manufacturers regarding removal and cleaning. The inspection should begin with a quick visual examination where one will look for any obvious signs of damage around the tip, adapter, and sheath. Additionally, one should also take note of the part number on the nozzle tip and make sure it is compatible with the adapter since there has been a recent trend of mismatching between these two components. Next, the user should carefully disassemble the nozzle and ultrasonically clean the individual parts. After the components have undergone the initial cleaning, they should be rinsed with hot water before being dried with filtered, compressed air. It is critical to avoid using unfiltered air during this step, as it increases the risk for contamination build-up in the nozzle.
After thorough inspection and cleaning have occurred, the nozzles should be tested with both high and low pressure to check for any potential abnormalities in the spray pattern. The first defect one may notice is streakiness, which occurs when the fuel quantity is unevenly distributed throughout the nozzle. With this pattern, there will be an obvious difference in color between different parts of the spray cone, with some areas being much darker than others. The inspector may also notice drooling, which can be identified by large drops of fuel dripping from the face of the nozzle. Finally, one may see a skewness defect, in which there is a generally off-centered or nonuniform spray pattern. The recognition of any of these should elicit a quick and thorough examination.
If you are looking for a great deal on new or replacement fuel nozzle components, there is no better alternative to ASAP Aero Supplies. As a leading parts distributor for the civil and defense aviation industries, we help customers secure cost savings and unbeatable lead times on an inventory of over 2 billion products. Additionally, with our streamlined instant RFQ service and team of industry experts available 24/7x365, you will always receive a quote in 15 minutes or less. Get started on the purchasing process today to learn why many customers rely on ASAP Aero Supplies to support all of their operational requirements.
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