Powerplant Systems & Maintenance Flashcards
7 cards from real Airframe Mechanic Certification 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 & Maintenance flashcards as text
What is the purpose of a fuel-air ratio enrichment system (or power enrichment valve) in a carburetor?
Answer: Enrich the mixture at full throttle to prevent detonation and provide cooling
The power enrichment system richens the mixture at high power settings to prevent detonation and provide additional cooling through excess fuel.
What color is Jet-A turbine fuel, and what is its approximate flash point?
Answer: Colorless to straw-colored, approximately 100°F (38°C)
Jet-A is colorless to straw-colored with a minimum flash point of approximately 100°F (38°C), making it less volatile than avgas.
What is the primary cause of hot section deterioration in a turbine engine?
Answer: Thermal cycling and oxidation from extreme combustion temperatures
Combustion temperatures far exceeding blade material limits cause oxidation, thermal fatigue cracking, and erosion in the turbine hot section.
In a constant-speed propeller system, if the propeller control is moved to the INCREASE RPM position, the governor:
Answer: Releases oil from the propeller dome allowing springs/counterweights to decrease pitch
Moving toward higher RPM causes the governor to port oil away from the propeller piston, allowing centrifugal twisting moment or springs to decrease blade pitch and increase RPM.
A turbine engine hung start is defined as:
Answer: An engine that lights off but does not accelerate to idle RPM
A hung start occurs when the engine ignites and sustains combustion but fails to accelerate to self-sustaining idle speed, requiring an abort.
Which condition would cause high oil temperature and low oil pressure simultaneously in a reciprocating engine?
Answer: Low oil quantity
Low oil quantity means less oil is available to absorb heat and maintain pressure, causing both high temperature and low pressure simultaneously.
When checking ignition timing on a reciprocating engine using a timing light, the timing mark should align at:
Answer: The manufacturer-specified number of degrees Before Top Dead Center (BTDC)
Ignition timing is set to the manufacturer-specified degrees BTDC to allow combustion to reach peak pressure just after TDC for optimal power.