A turboprop engine is a type of turbine engine used to power an aircraft propeller. A very well-known and respected turboprop engine type is the Pratt & Whitney Canada PT6. Developed by Pratt & Whitney Canada (PWC), it was designed in the late 1950’s before entering service in 1964. Many variants of the engine have been made since its inception, but the PT6A has remained the most widely-used. Not only are these engines popular among pilots, they are loved just as much by mechanics. Here are three reasons why:


The PT6A is the ideal piece of machinery for mechanics. The engine’s free-turbine modular design allows access to its hot section, power turbine, and accessory gearbox area without having to disassemble the engine. It grants mechanics the ability to perform significant operation on the engine very conveniently


Because the PT6A has been in production and use for so long, Pratt & Whitney Canada have used that time to hone in on the perfect engine. The decades of service experience and hundreds of millions of flight hours mean PWC has seen it all. Over time, they’ve run into and fixed every problem imaginable and thus a good engine has become a great engine.


The PT6A engine is the byproduct of over fifty years of engine development. PWC’s refinement over five decades, along with advances in aviation technology, have brought the PT6 engine to its summit. The PT6A is in use in nearly 200 countries and has logged almost 400 million hours of flight - more than any other engine in production.

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National Stock Numbers or NSNs, are 13-digit serial numbers assigned to all standardized items within the federal supply chain. All components that are used by the U.S Department of Defense are required to have an NSN, the purpose of which is to provide a standardized naming of components. The NSN system can be dated back to the WWII era when the military would use a specific component that had several different names depending on who supplied or manufactured the component. This made it difficult for the military to locate suppliers, or share items between the different organizational branches. An item could be in short supply in one location, but in surplus in another. To overcome this sourcing issue, the Department of Defense created the NSN system.

Also known as NATO stock numbers, NSNs are recognized by all NATO countries. The NSN can be further broken down into smaller subcategories, each providing individual information about the component. To begin, the first four digits of the NSN are known as the Federal Supply Classification Group. The FSCG determines which of the 645 subclasses an item belongs to. The FSCG is further split into the Federal Supply Group (FSG) and the Federal Supply Classification (FSC). The FSG is made up of the first two digits of the NSN which determines which of the 78 groups an item belongs to. The second 2 digits make up the FSC, which determines the subclass an item belongs to. In the aerospace industry a key federal supply group is FSG 15: Aircraft and Airframe Structural Components. The remaining 9 digits are made up of the 2-digit country identifier followed by the 7 National Item Identification Number (NIIN). The US for example, has the country identifier, 00.

At Aviation Distribution, owned and operated by ASAP Semiconductor, we stock over 2 billion new and obsolete NSNs applicable with the defense industry. Because searching through long lists of NSNs can be daunting and time consuming, we incorporated an easy-to-use search engine that allows our customers to type in the exact NSN they need. Alternatively, our customers can take their time browsing through the NSNs, which are conveniently grouped under their corresponding FSC. All of the NSNs that we supply and ship are sourced from premier industry manufacturers. At Aviation Distribution we understand the implications behind high quality assurance standards associated with mil.spec. We are an FAA AC-0056B accredited and ISO 9001:2015 distributor, as well as a trusted a PPRIS contractor.

Our team of industry experts are on hand to answer any questions that you may have. We can cross-reference NSNs with CAGE codes and part numbers, so you can avoid any costly purchasing mistakes. With a streamlined shipping and supply chain that spans across North America and Canada, we can deliver your part in no time at all. We can handle any time-sensitive AOG situations with ease. We make NSN procurement as simple as possible. Visit our website, https://www.aviationdistribution.com/, today and see for yourself.

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Cranks and crankshafts have existed since the ancient Roman Empire, in a variety of agricultural and industrial applications. With the dawn of the Industrial Revolution and the invention of the internal combustion engine, however, crankshafts became an integral and vital part of motors, without which vehicles like automobiles and aircraft could not function.

A crankshaft is a shaft with one or more cranks, obviously, and in the context of an internal combustion engine is the primary shaft to which connecting rods pair it with the pistons of the engine. As the cylinders of the engine fire and push the pistons, the connecting rods transfer this motion to the crankshaft, which transmits this energy to the wheels of an automobile, the propeller of an aircraft, or whatever means of propulsion the vehicle has. Essentially, the crankshaft transforms the linear motion of the piston into a rotational motion that provides energy for the vehicle to move.

Crankshafts must endure tremendous stresses in their operation, so they must be extremely durable and well-engineered. The crankshaft is connected to the fly-wheel, the engine block, and to the pistons via their respective connecting rods. The crankshaft has a linear axis that it rotates around, with several bearing journals riding on replaceable bearings in the engine block. As the crankshaft undergoes sideways load from each cylinder in the engine, it has to be supported by several bearings, not just one at each end. Higher performance engines tend to have more main bearings than low-performance engines to provide more support to the crankshaft.

Some engines must mount counterweights for the reciprocating mass of each piston and connecting rod to maintain engine balance. These are usually cast as part of the crankshaft, but some are bolt-on pieces. These add weight, obviously, but provide a smoother-running engine and allow higher RPM levels to be achieved. In some configurations, the crankshaft contains direct links between adjacent crank pins without an intermediate main bearing. These links are called flying arms, and are sometimes used in V6 and V8 engines, and allow the engine to be designed with different angles between valves than what would otherwise be required to create an even firing interval. This arrangement reduces weight and total engine length, but also reduces the crankshaft’s rigidity.

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Modern turbofan engines are remarkably complex pieces of machinery, so tools for maintaining and repairing them must be specialized to the task. In this blogpost, we’ll break down six types of tools you should always have if you’re performing regular turbofan maintenance.

Oil pressure can be the first indicator of a mechanical issue with your engine. If there is a change in pressure, you’ll need to react by checking the pressure adjustment and cold start valve to make sure that they are both clean and functioning properly. This will require disassembling the springs and pistons, which in turn requires specific tooling, which can vary from engine to engine, so make sure you have the right set!

Tying into the first point, oil and fuel filter replacement is a scheduled and routine type of maintenance, but a vital one for engine health. Specialized tools for removing the caps and filters are a better alternative than trying to remove them by hand.

The internal piping of a turbofan engine can be extremely complex and disassembling it for visual inspection is expensive in both man-hours and money. A borescope and a set of guide tubes to thread through the engine’s ports can help you save both. If you operate a mixed fleet with different engines however, you’ll need guide tubes matching each of the various engines.

Helical inserts, or helicoils, are used to secure steel screws inside magnesium or aluminum housing. However, these screws can sometimes get stuck inside their inserts due to heat distress or corrosion, meaning that if you try to remove the screw during disassembly, the insert will be removed as well. Whenever this happens, you’ll want an insert tool kit to replace the helicoil. Helical inserts are also used in other parts of an aircraft’s fuselage, so an insert kit is useful in other maintenance applications as well.

In a turbofan engine, the seals of the accessory gearbox can eventually begin to leak. This applies to both the carbon-face seals used in newer models as well as the older neoprene seals and can be identified by oil stains in the bottom of the engine’s cowling. These stains are easy to spot during a visual inspection, and easily fixed as long as you follow the engine’s maintenance manual and use the proper tools.

If an aircraft with bladed fans is left outside without engine covers, windmilling can occur. Windmilling is the issue of the engine’s fan turning while the engine is shut down, which causes a slight degree of friction as the blades shift in their pockets. In cold-weather conditions, shrinkage between components can make this friction an even greater issue, and eventually produces titanium dust that can become a serious engine health issue. Therefore, fan blades need to be removed one by one, have lubricating grease applied to them, and then re-installed. Each step in this process requires specialized tools for the job.

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