When it comes to PT6, there are two main types of Fuel Nozzles; the Simplex and the Duplex.
With Simplex fuel nozzles, you have two different nozzles; primary and secondary. Each nozzle has a single orifice. Simplex nozzles are typically set up as either all primary (in some engines), or in a ratio of 7 to 7 or 10 to 4 primary to secondary. The configuration depends on the engine model and the configuration status of the engine.
Upon start up, fuel is distributed only to the primary nozzles. At a given N1, the secondary nozzles kick in. With Duplex nozzles, fuel is introduced in a similar way as with a Simplex nozzle system. The Simplex system works in two stages with primary spray upon start up and secondary kicking in as the engine spools up.
The difference is that in a Duplex nozzle system, all of the nozzles are identical. Each one has two passages and two concentric ports, located in the tip that spray fuel. The primary and secondary are, in effect, within each nozzle. Simplex are 3 nozzles – Primary, Secondary and Inlet, and the Duplex nozzles also have an inlet.
The most important thing to remember is to always consult the manufacturer’s maintenance manual, overhaul manual, operator’s manual, etc… As with all properly maintained Pratt & Whitney Canada PT6 engines, there are many inspections and maintenance events that need to be performed, and at regularly scheduled intervals. This, therefore; helps to ensure the continued safe operation of the engines. All inspections and maintenance sessions are equally as important as the next, however; you should always pay extra close attention to the fuel nozzle inspections. These can have a profound effect on the health and longevity of your engines.
If you would like more information about PT6 Fuel Nozzles or any other accessories, contact us and we’ll be pleased to help.