powerplant

Flashcards from lecture notes on reciprocating and turbine engines.

What are the five events of a four-stroke cycle engine in order of occurrence?

The five events are intake, compression, ignition, power, and exhaust.

On which strokes are both valves on a four-stroke cycle reciprocating engine open?

Intake and Exhaust

If the exhaust valve of a four-stroke cycle engine is closed and the intake valve is just closed, the piston is on the:

Compression stroke

Which statement is correct regarding a four-stroke cycle aircraft engine?

The exhaust valve opens on the exhaust stroke.

What is the primary concern in establishing the firing order for an opposed engine?

Provide for balance and eliminate vibration to the greatest extent possible.

What is the typical firing order of a 6-cylinder Horizontally Opposed Engine?

1, 6, 2, 5, 3, 4

In a gas turbine engine, combustion occurs at a constant:

Pressure

Where is the highest gas pressure in a turbojet engine?

At the entrance of the burner section.

In the dual axial-flow or twin spool compressor system, the first stage turbine drives the:

N2 compressor

The pressure of subsonic air as it flows through a convergent nozzle:

Decreases

The Brayton cycle is known as the constant:

Pressure Cycle

The Hot Section of a gas turbine engine is consisting of:

Combustor, Turbine, Exhaust

An Air Intake of gas turbine engine has:

Intake Nose and Intake Duct

What are the two basic elements of the turbine section in a turbine engine?

Stator and Rotor

The turbine section of a jet engine:

Drives the compressor section.

What is the principal advantage of using propeller reduction gears?

To enable the engine RPM to be increased with an accompanying increase in power and allow the propeller to remain at a lower, more efficient RPM.

Which of the following will decrease volumetric efficiency in a reciprocating engine?

3, 4, and 5. [Improper valve timing, Sharp bends in the induction system, and High carburetor air temperatures]

If fuel/air ratio is proper and ignition timing is correct, the combustion process should be completed:

20 to 30 before top center at the end of the compression stroke.

The actual power delivered to the propeller of an aircraft engine is called:

Brake horsepower.

Cam-ground pistons are installed in some aircraft engines to:

provide a better fit at operating temperatures.

Determine how many degrees the crankshaft will rotate with both the intake and exhaust valves seated: Intake opens 15 BTDC. Exhaust opens 70 BBDC. Intake closes 45 ABDC. Exhaust closes 10 ATDC.

245.

Some aircraft engine manufacturers equip their product with choked or taper-ground cylinders in order to:

provide a straight cylinder bore at operating temperatures.

When is the fuel/air mixture ignited in a conventional reciprocating engine?

Shortly before the piston reaches the top of the compression stroke.

The primary purpose in setting proper valve timing and overlap is to:

permit the best possible charge of fuel/air mixture into the cylinders.

When does valve overlap occur in the operation of an aircraft reciprocating engine?

At the end of the exhaust stroke and the beginning of the intake stroke.

What is an advantage of using metallic-sodium filled exhaust valves in aircraft reciprocating engines?

Reduced valve operating temperatures.

Reduced air density at high altitude has a decided effect on carburetion, resulting in a reduction of engine power by:

excessively enriching the air/fuel mixture.

Which of these conditions will cause an engine to have an increased tendency to detonate?

1,2,3. [High manifold pressure, High intake air temperature, Engine overheated]

During overhaul, the disassembled parts of an engine are usually degreased with some form of mineral spirits solvent rather than water-mixed degreasers primarily because:

water-mixed degreaser residues may cause engine oil contamination in the overhauled engine.

What is required by 14 CFR Part 43 appendix D when performing an annual/100-hour inspection on a reciprocating engine aircraft?

Cylinder compression check.

During routine inspection of a reciprocating engine, a deposit of small, bright, metallic particles which do not cling to the magnetic drain plug is discovered in the oil sump and on the surface of the oil filter. This condition:

may be a result of abnormal plain type bearing wear and is cause for further investigation.

If metallic particles are found in the oil filter during an inspection,

the cause should be identified and corrected: before the aircraft is released for flight.

The fan rotational speed of a dual axial compressor forward fan engine is the same as the

low-pressure compressor.

An exhaust cone placed aft of the turbine in a jet engine will cause the pressure in the first part of the exhaust duct to:

increase and the velocity to decrease.

What is the function of the stator vane assembly at the discharge end of a typical axial-flow compressor?

To straighten airflow to eliminate turbulence.

What are the two functional elements in a centrifugal compressor?

Impeller and diffuser.

Some engine manufacturers of twin spool gas turbine engines identify turbine discharge pressure in their maintenance manuals as:

Pt7

What is the purpose of the diffuser section in a turbine section?

To increase pressure and reduce velocity.

A weak fuel to air mixture along with normal airflow through a turbine engine may result in:

a lean die-out.

Which of the following types of combustion sections are used in aircraft turbine engines?

Multiple-can, annular, and can-annular.

At what stage in a turbine engine are gas pressures the greatest?

Compressor outlet.

The vortex dissipators installed on some turbine- powered aircraft to prevent engine FOD utilize

a stream of engine bleed air blown toward the ground ahead of the engine.

Aircraft magneto housings are usually ventilated in order to

Provide cooling and remove corrosive gases produced by normal arcing.

Where are the hot and cold junctions located in a cylinder temperature indicating system?

The hot junction is located at the cylinder and the cold junction is located at the instrument.

An increase in manifold pressure when carburetor heat is applied indicates:

Ice was forming in the carburetor

Carburetor icing may be eliminated by which of the following method.

Alcohol spray and heated induction air

What is the first engine instrument indication of a successful start of a turbine engine?

Rise in the exhaust gas temperature.

When internally timing a magneto, the breaker points begin to open when a rotating magnet is.

Few degrees past the neutral position.

Fuel lines are kept away from sources of heat, and sharp bends and steep rises are avoided to reduce the possibility of.

VAPOR LOCK

What is the purpose of a safety gap in some magnetos?

To discharge the secondary coil's voltage if an open occurs in the secondary circuit.

Which of the following influences the operation of an automatic fuel control unit on a turbojet engine?

Burner Pressure.

The recommended aircraft engine lubricants are.

Mineral or synthetic based.

When starting an engine equipped with a carburetor air heater, in what position should the heater be placed?

Cold

What unit in an engine lubrication system is adjusted to maintain the desired system pressure?

Oil pressure relief valve.

What part of an aircraft in flight will begin to accumulate ice before any other?

Carburetor

If the ignition switch is moved from BOTH to either Left or Right during an engine ground check, normal operation is usually indicated

Slight drop in RPM.

As an aircraft engine's speed is increased, the voltage induced in the primary coil of the magneto.

Increases.

A fuel strainer or filter must be located between the:

Tank outlet and the fuel metering device.

What directly regulates the speed of a turbocharger.

Waste gate

Primary engine instrument.

Tachometer

When testing a magneto distributor block for electrical leakage, which of the following of test equipment should be used?

High-Tension harness tester.

Where should the main fuel strainer be located in the aircraft fuel system?

At the lowest point in the fuel system.

On most reciprocating multiengine aircraft automatic propeller synchronization is accomplished through the actuation of the

propeller governors

What powers the variable inlet guide vanes used on some APUs to regulate

engine pressure

Fuel boost pumps are operated:

To provide a positive flow of fuel to the engine

When a new carburetor is installed on an engine:

Engine is warmed up to normal temperatures, adjust the idle mixture, then the idle speed

If a float type carburetor becomes flooded, the condition is most likely caused by:

A leaking needle valve and seat assembly

On an aircraft that utilizes an exhaust heat exchanger as a source of cabin heat, how should the exhaust system be inspected?

With the heater air shroud removed

On a carburetor without an automatic mixture control as you ascend to altitude, the mixture will:

Be enriched

Fuel cross-feed systems are used in to:

Maintain aircraft stability

Which method is commonly used to adjust the level of a float in a float-type carburetor?

Add or remove shims under the needle-valve seat

The device that controls the ratio of the fuel/air mixture to the cylinder is called:

Mixture control

How are combustion liner walls cooled in a gas turbine engine?

By secondary air flowing through the combustion chamber

A punctured float in a float-type carburetor will cause the fuel level to:

Rise, and enrich the mixture

When is the greatest demand placed on an APU?

When supplying bleed air

If an engines equipped with a float-type carburetor and the engine runs excessively rich at full throttle, a possible cause of the trouble is a clogged:

Main air bleed

When air passes through the venturi of a carburetor, what three (3) changes occur?

Velocity increases, temperature decreases, and pressure decreases

Compared to normally aspirated engines, turbocharged engine exhaust systems operate at:

higher temperatures and higher pressures

What carburetor component actually limits the desired maximum airflow to the engine at full throttle?

Venturi

If the idling jet becomes clogged in a float-type carburetor, the:

Engine will not idle