Why is fuel nozzle and spray pattern inspection critical in overhaul and what defects are sought?

• A. Surface color and chrome finish.
• B. Clogging, uneven spray, corrosion, wear, and misalignment.
• C. Bolt torque only.
• D. Gas turbine blade height.

Answer: (B)

Focusing on the spray pattern and condition of fuel nozzles is essential because the nozzle controls how fuel is atomized and distributed in the combustor. If the spray is blocked or restricted, fuel flow changes and the overall mixture becomes unpredictable. Clogging reduces or unevenly distributes fuel, which can cause some areas to run rich and others lean, hurting efficiency and increasing emissions. Uneven spray means the combustor doesn’t see a uniform fuel-air mix, leading to hot spots, higher turbine temperatures, and potential damage over time. Corrosion indicates degradation of the nozzle passages, which can create leaks, deteriorate flow, or cause unpredictable spray. Wear alters the size and shape of orifices and passages, shifting flow rates and spray characteristics. Misalignment of the nozzle or its spray pattern means fuel may impinge on incorrect combustor regions, again causing thermal and emission inefficiencies.

Other options miss the functional focus: surface color and chrome finish are cosmetic and don’t reflect internal spray performance; bolt torque is about mounting hardware, not the spray quality; gas turbine blade height has no bearing on nozzle spray behavior.