When are borescope inspections or overhauls typically performed on an APU?

When are borescope inspections or overhauls typically performed on an APU?

• A. Only during initial manufacture.
• B. After every flight.
• C. As required by maintenance schedule or condition.
• D. Never.

Answer: (C)

Borescope inspections and potential overhauls are driven by a maintenance plan that combines scheduled intervals with condition-based checks. Using a borescope lets technicians peek inside the APU to look for wear, cracks, pitting, deposits, or other damage on hard-to-reach parts like turbines and compressors without taking the unit apart. The decision to inspect or overhaul is made when the schedule calls for it or when the inspection findings, performance data, or abnormal symptoms indicate deterioration or risk. This approach keeps the APU reliable and prevents surprises in operation. Why not every flight? Inspecting after every flight would be impractical and unnecessary, given that many wear processes accumulate over hours or cycles and can be detected at planned maintenance intervals or when condition indicators arise. The options of only at initial manufacture or never are not aligned with standard maintenance practice; APUs require ongoing evaluation to ensure safety and reliability.

Borescope inspections and potential overhauls are driven by a maintenance plan that combines scheduled intervals with condition-based checks. Using a borescope lets technicians peek inside the APU to look for wear, cracks, pitting, deposits, or other damage on hard-to-reach parts like turbines and compressors without taking the unit apart. The decision to inspect or overhaul is made when the schedule calls for it or when the inspection findings, performance data, or abnormal symptoms indicate deterioration or risk. This approach keeps the APU reliable and prevents surprises in operation.

Why not every flight? Inspecting after every flight would be impractical and unnecessary, given that many wear processes accumulate over hours or cycles and can be detected at planned maintenance intervals or when condition indicators arise. The options of only at initial manufacture or never are not aligned with standard maintenance practice; APUs require ongoing evaluation to ensure safety and reliability.