Gas Turbine Engines: Components, Inspection, Systems, and Maintenance Practice Test

Coast-down checks focus on mechanical integrity as the rotor slows and components cool. The most informative signal here is unusual rubbing, scraping, or bearing noises. Such sounds point to contact between the rotor and bearings, lubrication problems, bearing wear, or looseness. These issues can indicate lubrication starvation, misalignment, or degraded bearings that could lead to more serious failures if not addressed.

Exhaust color is a running-condition indicator; once the engine is shut down there’s no combustion, so exhaust color isn’t a meaningful sign during coast-down. Pressure pulsations in the fuel line occur during fuel metering and operation, not during post-shutdown deceleration. Turbine blade drift is a concern, but it’s not the primary cue sought in coast-down inspections; blade movement issues are typically evaluated through other targeted inspections rather than a routine coast-down check.