Powerplant Systems & Engine Overhaul Flashcards
7 cards from real ACS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Powerplant Systems & Engine Overhaul flashcards as text
What is the significance of 'oil consumption trend monitoring' in turbine engine health management?
Answer: A sudden increase in oil consumption can indicate bearing failure or internal seal deterioration
Sudden increases in oil consumption are an early warning of bearing wear, internal seal failure, or other internal engine degradation before catastrophic failure occurs.
During cylinder inspection, a technician finds a barrel that is worn 0.010 inch over the maximum specified diameter. What is the correct action?
Answer: Chrome plate or replace the cylinder; it cannot be returned to service at this dimension
A cylinder worn beyond the manufacturer's maximum allowable diameter must be chrome plated to restore dimensions or replaced; operating beyond limits is not airworthy.
What is the purpose of 'borescope inspection' of turbine engine components?
Answer: Visually inspect hot section components for cracks, erosion, and FOD damage without engine disassembly
Borescope inspection allows visual examination of turbine blades, combustion liners, and other internal hot section parts through access ports without requiring engine removal or disassembly.
What is the function of an engine 'breather' or crankcase vent in a reciprocating aircraft engine?
Answer: Vent crankcase pressure and blow-by gases overboard to prevent pressure buildup and oil leaks
The crankcase breather vents combustion blow-by gases that pass the piston rings into the crankcase, preventing pressure buildup that would force oil out of seals and gaskets.
When performing a differential compression test, a reading of 72/80 is obtained. What does this indicate?
Answer: Minor leakage within acceptable limits; the cylinder passes with 90% retention
72/80 means 72 psi is retained versus the 80 psi input, representing 90% retention; most manufacturers accept cylinders retaining 75–80% or better, so this reading is typically within limits.
What hazard does 'hydraulic lock' present to a reciprocating engine during start?
Answer: Liquid accumulation in a lower cylinder can prevent the piston from reaching TDC, potentially bending a connecting rod
Hydraulic lock occurs when oil or unburned fuel accumulates in a lower cylinder; liquids are incompressible, so if the piston tries to compress liquid it can bend or break the connecting rod.
In a turbine engine, what does the term 'compressor stall' refer to?
Answer: A disruption in the smooth airflow through the compressor, causing momentary flow reversal and loss of compression
A compressor stall is an aerodynamic disruption where the angle of attack on compressor blades exceeds the stall angle, causing local flow separation and potentially violent pressure oscillations.