Jeppesen Text Guide 01 - Reciprocating Engines

B

Which statement is true regarding bearings used in high-powered reciprocating aircraft engines?
A. The outer race of a single-row, self-aligning ball bearing will always have a radius equal to the radius of the balls.
B. There is less rolling friction when ball bearings are used than when roller bearings are employed.
C. Crankshaft bearings are generally of the ball-type due to their ability to withstand extreme loads without overheating.

B

What is the principal advantage of using propeller reduction gears?
A. To enable the propeller RPM to be increased without an accompanying increase in engine RPM.
B. 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.
C. To enable the engine RPM to be increased with an accompanying increase in propeller RPM.

C

Which of the following will decrease volumetric efficiency in a reciprocating engine?
1. Full throttle operation.
2. Low cylinder head temperatures.
3. Improper valve timing.
4. Sharp bends in the induction system.
5. High carburetor air temperatures.
A. 2, 4, and 5.
B. 1,2, 3, and 4.
C. 3, 4, and 5.

C

Which of the following is a characteristic of a thrust bearing used in most radial engines?
A. Tapered roller.
B. Double-row ball.
C. Deep-groove ball.

B

Which bearing is least likely to be a roller or ball bearing?
A. Rocker arm bearing (overhead valve engine).
B. Master rod bearing (radial engine).
C. Crankshaft main bearing (radial engine).

A

The operating temperature valve clearance of a radial engine as compared to cold valve clearance is
A. - greater.
B. - less.
C. the same.

C

A nine-cylinder engine with a bore of 5.5 inches and a stroke of 6 inches will have a total piston displacement of
A. 740 cubic inches.
B. 1,425 cubic inches.
C. 1,283 cubic inches.

C

The five events of a four-stroke cycle engine in the order of their occurrence are
A. intake, ignition, compression, power, exhaust.
B. intake, power, compression, ignition, exhaust.
C. intake, compression, ignition, power, exhaust.

A

The primary concern in establishing the firing order for an opposed engine is to
A. provide for balance and eliminate vibration to the greatest extent possible.
B. keep power impulses on adjacent cylinders as far apart as possible in order to obtain the greatest mechanical efficiency.
C. keep the power impulses on adjacent cylinders as close as possible in order to obtain the greatest mechanical efficiency.

C

If fuel/air ratio is proper and ignition timing is correct, the combustion process should be completed
A. 20 to 30 degrees before top center at the end of the compression stroke.
B. when the exhaust valve opens at the end of the power stroke.
C. just after top center at the beginning of the power stroke.

A

Which statement is correct regarding engine crankshafts?
A. Moveable counterweights serve to reduce the torsional vibrations in an aircraft reciprocating engine.
B. Moveable counterweights serve to reduce the dynamic vibrations in an aircraft reciprocating engine.
C. Moveable counterweights are designed to resonate at the natural frequency of the crankshaft.

C

On which strokes are both valves on a four-stroke cycle reciprocating engine open?
A. Power and exhaust.
B. Intake and compression.
C. Exhaust and intake.

A

Master rod bearings are generally what type?
A. Plain.
B. Roller.
C. Ball.

B

The actual power delivered to the propeller of an aircraft engine is called
A. friction horsepower.
B. brake horsepower.
C. indicated horsepower.

A

Cam-ground pistons are installed in some aircraft engines to
A. provide a better fit at operating temperatures.
B. act as a compensating feature so that a compensated magneto is not required.
C. equalize the wear on all pistons.

B

Using the following information, 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.
A. 290°.
B. 245°.
C. 25°.

A

Some aircraft engine manufacturers equip their product with choked or taper-ground cylinders in order to
A. provide a straight cylinder bore at operating temperatures.
B. flex the rings slightly during operation and reduce the possibility of the rings sticking in the
grooves.
C. increase the compression pressure for starting purposes.

A

An aircraft reciprocating engine using hydraulic valve lifters is observed to have no clearance in its valve-operating mechanism after the minimum inlet oil and cylinder head temperatures for takeoff have been reached. When can this condition be expected?
A. During normal operation.
B. When the lifters become deflated.
C. As a result of carbon and sludge becoming trapped in the lifter and restricting its motion.

C

If an engine with a stroke of 6 inches is operated at 2,000 RPM, the piston movement within the cylinder will be
A. at maximum velocity around TDC.
B. constant during the entire 360° of crankshaft travel.
C. at maximum velocity 90° after TDC.

A

Some cylinder barrels are hardened by
A. nitriding.
B. shot peening.
C. tempering.

A

Which statement is correct regarding a four-stroke cycle aircraft engine?
A. The intake valve closes on the compression stroke.
B. The exhaust valve opens on the exhaust stroke.
C. The intake valve closes on the intake stroke.

B

When is the fuel/air mixture ignited in a conventional reciprocating engine?
A. When the piston has reached top dead center of
the intake stroke.
B. Shortly before the piston reaches the top of the compression stroke.
C. When the piston reaches top dead center on the compression stroke.

B

Ignition occurs at 28° BTDC on a certain four-stroke cycle engine, and the intake valve opens at 15° BTDC. How many degrees of crankshaft travel after ignition does the intake valve open? (Consider one cylinder only.) :
A. 707.
B. 373.
C. 347.

C

What is the purpose of the safety circlet installed on some valve stems?
A. To hold the valve guide in position.
B. To hold the valve spring retaining washer in position.
C. To prevent valves from falling into the combustion chamber.

A

Valve overlap is defined as the number of degrees of crankshaft travel
A. during which both valves are off their seats.
B. between the closing of the intake valve and the opening of the exhaust valve.
C. during which both valves are on their seats.

B

The valve clearance of an engine using hydraulic lifters, when the lifters are completely flat, or empty, should not exceed
A. specified amount below zero.
B. a specified amount above zero.
C. 0.00 inch.

C

If the exhaust valve of a four-stroke cycle engine is closed and the intake valve is just closed, the piston is on the
A. intake stroke.
B. power stroke.
C. compression stroke.

C

How many of the following are factors in establishing the maximum compression ratio limitations of an aircraft engine?
1. Detonation characteristics of the fuel used.
2. Design limitations of the engine.
3. Degree of supercharging.
4. Spark plug reach.
A. Four.
B. Two.
C. Three.

C

Full-floating piston pins are those which allow motion between the pin and
A. the piston.
B. both the piston and the large end of the connecting rod.
C. both the piston and the small end of the connecting rod.

C

The primary purpose in setting proper valve timing and overlap is to
A. permit the best possible charge of fuel/air mixture into the cylinders.
B. gain more thorough exhaust gas scavenging.
C. obtain the best volumetric efficiency and lower cylinder operating temperatures.

B

If the hot clearance is used to set the valves when the engine is cold, what will occur during operation of the engine?
A. The valves will open early and close early.
B. The valves will open late and close early.
C. The valves will open early and close late.

B

The purpose of two or more valve springs in aircraft engines is to
A. equalize side pressure on the valve stems.
B. eliminate valve spring surge.
C. equalize valve face loading.

A

Why does the smoothness of operation of an engine increase with a greater number of cylinders?
A. The power impulses are spaced closer together.
B. The power impulses are spaced farther apart.
C. The engine has larger counterbalance weights.

C

Compression ratio is the ratio between the
A. piston travel on the compression stroke and on the intake stroke.
B. combustion chamber pressure on the combustion stroke and on the exhaust stroke.
C. cylinder volume with piston at bottom dead center and at top dead center.

C

How is proper end-gap clearance on new piston rings assured during the overhaul of an engine?
A. By accurately measuring and matching the outside diameter of the rings with the inside diameter of the cylinders.
B. By using rings specified by the engine manufacturer.
C. By placing the rings in the cylinder and measuring the end-gap with a feeler gauge.

C

The volume of a cylinder equals 70 cubic inches when the piston is at bottom center. When the piston is at the top of the cylinder, the volume equals 10 cubic inches. What is the compression ratio?
A. 1:7
B. 7:10.
C. 7:1.

C

What will be the likely result if the piston ring gaps happen to be aligned when performing a differential-pressure compression check on a cylinder?
A. Little or no effect.
B. The rings will not be seated.
C. A worn or defective ring(s) indication.

C

What special procedure must be followed when adjusting the valves of an engine equipped with a floating cam ring?
A. Adjust valves when the engine is hot.
B. Adjust all exhaust valves before intake valves.
C. Eliminate cam bearing clearance when making valve adjustment.

C

What does valve overlap promote?
A. Lower intake manifold pressure and temperatures.
B. A backflow of gases across the cylinder.
C. Better scavenging and cooling characteristics.

C

At what speed must a crankshaft turn if each cylinder of a four-stroke cycle engine is to be fired 200 times a minute?
A. 800 RPM.
B. 1,600 RPM.
C. 400 RPM.

B

The horsepower developed in the cylinders of a reciprocating engine is known as the
A. shaft horsepower.
B. indicated horsepower.
C. brake horsepower.

A

When does valve overlap occur in the operation of an aircraft reciprocating engine?
A. At the end of the exhaust stroke and the beginning of the intake stroke.
B. At the end of the power stroke and the beginning of the exhaust stroke.
C. At the end of the compression stroke and the beginning of the power stroke.

B

What is an advantage of using metallic-sodium filled exhaust valves in aircraft reciprocating engines?
A. Increased strength and resistance to cracking.
B. Reduced valve operating temperatures.
C. Greater resistance to deterioration at high valve temperatures.

C

Valve clearance changes on opposed-type engines using hydraulic lifters are accomplished by
A. rocker arm adjustment.
B. rocker arm replacement.
C. push rod replacement.

C

An increase in manifold pressure with a constant RPM will cause the bearing load in an engine to
A. decrease.
B. remain relatively constant.
C. increase.

A

Reduced air density at high altitude has a decided effect on carburetion, resulting in a reduction of engine power by
A. excessively enriching the air/fuel mixture.
B. excessively leaning the air/fuel mixture.
C. reducing fuel vaporization.

C

An unsupercharged aircraft reciprocating engine, operated at full throttle from sea level to 10,000 feet, provided the RPM is unchanged, will
A. lose power due to the reduced volume of air drawn into the cylinders.
B. produce constant power due to the same volume of air drawn into the cylinders.
C. lose power due to the reduced density of the air drawn into the cylinders.

B

Which of these conditions will cause an engine to have an increased tendency to detonate?
1. High manifold pressure.
2. High intake air temperature.
3. Engine overheated.
4. Late ignition timing.
A. 1,4.
B. 1,2,3.
C. 1,2,3,4.

A

What could cause excessive pressure buildup in the crankcase of a reciprocating engine?
A. Plugged crankcase breather.
B. Improper warm-up operation.
C. An excessive quantity of oil.

C

Excessive valve clearance in a piston engine
A. increases valve overlap.
B. increases valve opening time.
C. decreases valve overlap.

A

You are performing a 100-hour inspection on an R985-22 aircraft engine. What does the "985" indicate?

A. The total piston displacement of the engine.

B. The pistons will pump a maximum of 985 cubic inches of air per crankshaft revolution.

C. The total piston displacement of one cylinder.

B

How is the oil collected by the piston oil ring returned to the crankcase?
A. Down vertical slots cut in the piston wall between the piston oil ring groove and the piston skirt.
B. Through holes drilled in the piston oil ring groove.
C. Through holes drilled in the piston pin recess.

C

Oil accumulation in the cylinders of an inverted in-line engine and in the lower cylinders of a radial engine is normally reduced or prevented by
A. reversed oil control rings.
B. routing the valve-operating mechanism lubricating oil to a separate scavenger pump.
C. extended cylinder skirts.

A

Where are sludge chambers, when used in aircraft engine lubrication systems, usually located?
A. In the crankshaft throws.
B. Adjacent to the scavenger pumps.
C. In the oil storage tank.

C

Excessive oil is prevented from accumulating on the cylinder walls of a reciprocating engine by
A. the design shape of the piston skirt.
B. internal engine pressure bleeding past the ring
grooves.
C. oil control rings on the pistons.

C

The valve assemblies of opposed reciprocating engines are lubricated by means of a
A. gravity feed system.
B. splash and spray system.
C. pressure system.

B

How are the piston pins of most aircraft engines lubricated?
A. By pressure oil through a drilled passageway in the heavy web portion of the connecting rod.
B. By oil which is sprayed or thrown by the master or connecting rods.
C. By the action of the oil control ring and the series of holes drilled in the ring groove directing oil to the pin and piston pin boss.

C

Which of the following bearing types must be continuously lubricated by pressure oil?
A. Ball.
B. Roller.
C. Plain.

B

Which of the following results in a decrease in volumetric efficiency?
A. Cylinder head temperature too low.
B. Part-throttle operation.
C. Short intake pipes of large diameter.

B

The undersides of pistons are frequently finned. The principal reason is to
A. provide sludge chambers and sediment traps.
B. provide for greater heat transfer to the engine oil.
C. support ring grooves and piston pins.

B

Increased engine heat will cause volumetric efficiency to
A. remain the same.
B. decrease.
C. increase.

C

Sodium-filled valves are advantageous to an aviation engine because they
A. are lighter.
B. dampen valve impact shocks.
C. dissipate heat well.