FAA Aviation Mechanic Powerplant (AMP)Engine InspectionMedium
During a borescope inspection of a turbine engine, a technician observes localized hot spots and small burn-through areas on the combustion liner, concentrated near one fuel nozzle location. What is the most likely cause of this damage?
- AA malfunctioning fuel nozzle producing an uneven or misdirected spray pattern
- BExcessive compressor bleed air cooling that liner section
- CNormal thermal cycling that occurs uniformly around the entire liner
- DForeign object damage from ingested ice
Show answer & explanationAnswer & explanation
Correct answer: A. A malfunctioning fuel nozzle producing an uneven or misdirected spray pattern
Localized hot spots and burn-through concentrated near a specific fuel nozzle strongly suggest that nozzle is producing an improper (streaking or misdirected) spray pattern, causing localized flame impingement on the liner. Uniform thermal cycling, cooling air, and ice ingestion would not create a localized pattern tied to one nozzle position.
Why the other options are wrong
- B. Excess cooling air would reduce, not cause, hot spots.
- C. Normal thermal cycling produces even wear, not a localized hot spot at one nozzle.
- D. Ice ingestion typically causes broader FOD patterns, not a single localized hot spot tied to a nozzle.
Combustion Liner Hot Spot
A localized area of overheating or burn-through on a turbine combustor liner, usually caused by an uneven fuel spray pattern from a malfunctioning nozzle.
- Found during borescope inspection of the combustion section
- Concentrated near one nozzle indicates a nozzle spray defect
- Left unrepaired, can lead to liner cracking or distortion
- Requires nozzle inspection/replacement and liner assessment
Memory trick: One hot spot, one bad nozzle — find the culprit spraying crooked.