AMS 274 FINAL EXAM WITH 280 QUESTIONS AND WELL ELABORATED ANSWERS JUST RELEASED THIS YEAR

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AMS 274 FINAL EXAM WITH 280 QUESTIONS AND
WELL ELABORATED ANSWERS JUST RELEASED THIS
YEAR

QUESTION: Typical air flow in a pneumatic starter: - ANSWER✔✔Air flows into the starter -->
Stator vanes (designed to choke in order to prevent overspeed) --> Turbine




QUESTION: What was Whittle famous for? - ANSWER✔✔Invented the jet engine




QUESTION: What are the 4 types of gas turbines and typical aircraft they are found on: -
ANSWER✔✔1. Turbojet (supersonic)

2. Turbofan (large commercial)

3. Turboprop (larger GA)

4. Turboshaft (helicopters)




QUESTION: What is the Brayton Cyle? - ANSWER✔✔thermodynamic cycle that explains how
gas turbine engines run




QUESTION: Bernoulli's principle: - ANSWER✔✔As the velocity of a fluid increases, the pressure
exerted by the fluid decreases (convergent ducts: velocity increases and pressure
decreases/divergent ducts: velocity decreases and pressure increases)

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QUESTION: What company produced the first gas turbine engine in the U.S.? -
ANSWER✔✔General Electric




QUESTION: In a split-spool/dual-spool/twin-spool turbine, what drives what? - ANSWER✔✔The
low-speed turbine drives the first compressor

The high speed turbine drives the second compressor




QUESTION: What is typically found in a turboshaft engine? - ANSWER✔✔A power turbine




QUESTION: What is the low bypass, medium bypass, and high bypass general engine ratios? -
ANSWER✔✔Low: 1:1

Medium: 2:1 to 3:1

High: 4:1 to 9:1




QUESTION: What is another name for an impeller? - ANSWER✔✔A centrifugal compressor




QUESTION: What does Fn stand for? - ANSWER✔✔Thrust net




QUESTION: What does Fg stand for? - ANSWER✔✔Static thrust (gross thrust)

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QUESTION: How do you calculate bypass ratio? - ANSWER✔✔airflow of the fan/airflow of the
core




QUESTION: What do inlet guide vanes do, and are they part of the compressor? -
ANSWER✔✔Stationary airfoils which proceed the 1st stage compressor rotor blades and are
used to direct air into the blades at the optimal angle (No, they are not part of the compressor)




QUESTION: What are the 4 types of jets? - ANSWER✔✔1. Rocket (operate outside of the
atmosphere)

2. Turbo jet

3. Ram jet

4. Pulse jet




QUESTION: What is the purpose of the diffuser? - ANSWER✔✔Provides additional space where
air coming from the compressor (outlet of the compressor) can spread out = velocity decreases
and pressure increases (diverging duct)




QUESTION: If the anti-ice air valve is open what happens to EGT? - ANSWER✔✔EGT increases
(tachometer and EPR also shift)

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QUESTION: How do you calculate EPR? - ANSWER✔✔Turbine discharge/Compressor inlet
pressure




QUESTION: What are the most common type of thermocouples used? -
ANSWER✔✔Chromel/Alumel (CA)




QUESTION: What do the older style APUs have in them? - ANSWER✔✔Governors




QUESTION: What is the typical gear down ratio for pneumatic starters? - ANSWER✔✔25:1




QUESTION: What is the starting sequence for turbine engines? - ANSWER✔✔Starter --> Ignition
--> Fuel




QUESTION: you hear a clicking noise from the pneumatic starter it indicates: - ANSWER✔✔The
pawls re-engaging (normal)




QUESTION: What is known as the highest point of pressure in the engine? - ANSWER✔✔At the
rear of the diffuser