The PT6 engine uses 14 simplex or duplex fuel nozzles to introduce fuel into the combustion chamber. The metered fuel from the fuel control unit is supplied to the fuel nozzles through the flow divider and the primary and secondary manifolds.
The most important preventative maintenance item on the PT6 engine is fuel nozzle service. Poor fuel nozzle spray patterns can have an adverse impact on the performance of the engine and cause burning, cracking and erosion of the hot section components.
Pratt & Whitney Canada publishes a service interval for the cleaning and function checking of the PT6 fuel nozzles. The frequency of the fuel nozzle service can vary based on the condition of the fuel nozzles and the experience of a particular operator. If the fuel nozzle tips show excessive streaking or other defects when serviced it would be prudent to service the fuel nozzles more frequently ...more about PT6 Fuel Nozzles