FAA Powerplant Written Practice Test

How are discharge nozzles in a fuel-injected reciprocating engine identified to indicate the flow range?

1. By the size of the nozzle opening

2. By an identification letter stamped on one of the hexes of the nozzle body

3. By color coding on the nozzle

4. By the material composition of the nozzle

The correct answer is: By an identification letter stamped on one of the hexes of the nozzle body

Discharge nozzles in a fuel-injected reciprocating engine are identified to indicate the flow range primarily by an identification letter stamped on one of the hexes of the nozzle body. This identification is crucial because it provides a clear and standardized way to determine the nozzle's specific flow characteristics, which can include variations in fuel delivery rates. The lettering system allows for easy identification and differentiation amongst nozzles when maintenance or replacement is necessary, helping to ensure that the correct nozzle is used for the engine's performance requirements. While size can influence the flow rate, simply looking at the size of the opening does not provide a comprehensive flow range identification. Color coding can be used in some systems but is not universally applied and may not provide the specificity needed for identifying flow ranges in conjunction with other operational details. The material composition of the nozzle also does not inform about the flow capacity; it primarily affects durability and resistance to certain fuels or operational temperatures, rather than directly indicating the flow rate.