Maintenance

A characteristic of dyna-focal engine mounts as applied to aircraft reciprocating engines is that the

Shock mounts point toward the engine's center of gravity.

Which condition would be the least likely to be caused by failed or failing engine bearings?

Low oil temperatures

Which statement is correct regarding engine crankshafts?

Moveable counterweights serve to reduce the torsional vibrations in an aircraft reciprocating engine.

Which bearing is least likely to be a roller or ball bearing?

Master rod bearing (radial engine)

What is the purpose of installing two or more springs on each valve in an aircraft engine?

To eliminate valve spring vibration or surging.

A hissing sound from the exhaust stacks when the propeller is being pulled through manually indicates

Exhaust valve blow-by

The operating temperature valve clearance of a radial engine as compared to cold valve clearance is

Greater

Valve clearance changes on opposed-type engines using hydraulic lifters are accomplished by

Push rod replacement

If the ignition switch is moved from BOTH to either LEFT or RIGHT during an engine ground check, normal operation is usually indicated by a slight

Drop in torque meter pressure indication.

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

Provide a straight cylinder bore at operating temperatures.

Excessive valve clearances will cause the duration of valve opening to

Decrease for both intake and exhaust valves.

When will small induction system air leaks have the

most noticeable effect on engine operation?

At low RPM.

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.

Valve overlap is defined as the number of degrees

of crankshaft travel

During which both valves are off their seats.

Which type of bearings are generally used for

connecting rods and cam shafts?

Plain

(1) Cast iron piston rings may be used in chrome-plated cylinders.

(2) Chrome-plated rings may be used in plain steel cylinders.

Regarding the above statements,

Both No. 1 and No. 2 are true.

The actual power delivered to the propeller of an

aircraft engine is called

Brake horsepower

What tool is generally used to measure the

crankshaft rotation in degrees?

Timing disk

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.)

373°

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

245°

On which strokes are both valves on a four-stroke

cycle reciprocating aircraft engine open?

Exhaust and intake

Which statement pertaining to fuel/air ratios is true?

The mixture ratio which gives the best power is richer than the mixture ratio which gives maximum economy.

the oil pressure of a cold engine is higher than at

normal operating temperatures, the

Engine's lubrication system is probably operating normally.

During the inspection of an engine control system

in which push-pull control rods are used, the

threaded rod ends should

Be checked for the amount of thread engagement by means of the inspection holes.

What is the purpose of the safety circlet installed on

some valve stems?

To prevent valves from falling into the combustion chamber.

How is proper end-gap clearance on new piston

rings assured during the overhaul of an engine?

By placing the rings in the cylinder and measuring the end-gap with a feeler gauge.

If an engine with a stroke of 6 inches is operated at

2,000 RPM, the piston movement within the

cylinder will be

At maximum velocity 90° after TDC.

The valve clearance of an engine using hydraulic

lifters, when the lifters are completely flat or empty,

should not exceed

A specified amount above zero.

Standard aircraft cylinder oversize usually range

from 0.010 inch to 0.030 inch. Oversize on

automobile engine cylinders may range up to 0.100

inch. This is because aircraft engine cylinders

Have relatively thin walls and may be nitrided.

Compression ratio is the ratio between the

Cylinder volume with piston at bottom dead center and at top dead center.

Which of the following would most likely cause a

reciprocating engine to backfire through the

induction system at low RPM operation?

Lean mixture

An increase in manifold pressure with a constant

RPM will cause the bearing load in an engine to

Increase

On which part of the cylinder walls of a normally

operating engine will the greatest amount of wear

occur?

Near the top of the cylinder.

What is the basic operational sequence for

reducing the power output of an engine equipped

with a constant- speed propeller?

Reduce the manifold pressure, then the RPM.

Increased water vapor (higher relative humidity) in

the incoming air to a reciprocating engine will

normally result in which of the following?

Decreased engine power at a constant RPM and manifold pressure.

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.

Which of the following engine servicing operations

generally requires engine pre-oiling prior to starting

the engine?

Engine installation

When cleaning aluminum and magnesium engine

parts, it is inadvisable to soak them in solutions

containing soap because

Some of the soap will become impregnated in the surface of the material and

subsequently cause engine oil contamination and foaming.

What does valve overlap promote?

Better scavenging and cooling characteristics.

What is an advantage of using metallic-sodium

filled exhaust valves in aircraft reciprocating

engines?

Reduced valve operating temperatures.

A condition that can occur in radial engines but is

unlikely to occur in horizontally opposed engines is

Hydraulic lock

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.

At what speed must a crankshaft turn if each

cylinder of a four-stroke cycle engine is to be fired

200 times a minute?

400 RPM

Some cylinder barrels are hardened by

Nitriding

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 worn or defective ring(s) indication.

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

One of the best indicators of reciprocating engine

combustion chamber problems is

Spark plug condition

As the pressure is applied during a reciprocating

engine compression check using a differential

pressure tester, what would a movement of the propeller in the direction

of engine rotation indicate?

The piston was positioned past the top dead center.

A nine-cylinder engine with a bore of 5.5 inches

and a stroke of 6 inches will have a total piston

displacement of

1,283 cubic inches

Before attempting to start a radial engine that has

been shut down for more than 30 minutes,

Turn the propeller by hand three to four revolutions in the normal direction of rotation to check for liquid lock.

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 the oil pressure gauge fluctuates over a wide

range from zero to normal operating pressure, the

most likely cause is

Low oil supply.

Grinding the valves of a reciprocating engine to a

feather edge is likely to result in

Pre-ignition and burned valves.

What is likely to occur if a reciprocating engine is

operated at high power settings before it is properly

warmed up?

Oil starvation of bearings and other parts.

If the intake valve is opened too early in the cycle of

operation of a four-stroke cycle engine, it may

result in

Backfiring into the induction system.

If an engine operates with a low oil pressure and a

high oil temperature, the problem may be caused

by a

Leaking oil dilution valve

Which of the following is most likely to occur if an

overhead valve engine is operated with inadequate

valve clearances?

The valves will not seat positively during

start and engine warm up.

Which of the following conditions would most likely

lead to detonation?

Use of fuel with too low an octane rating.

The floating control thermostat, used on some

reciprocating engine installations, helps regulate oil

temperature by

Controlling air flow through the oil cooler.

Direct mechanical push-pull carburetor heat control

linkages should normally be adjusted so that the

stop located on the diverter valve will be contacted

Before the stop at the control lever is

reached in both HOT and COLD positions.

To what altitude will a turbo charged engine

maintain sea level pressure?

Critical altitude

When is the fuel/air mixture ignited in a

conventional reciprocating engine?

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

Why does the smoothness of operation of an

engine increase with a greater number of

cylinders?

The power impulses are spaced closer together.

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?

7:1

(1) Pre-ignition is caused by improper ignition timing.

(2) Detonation occurs when an area of the combustion chamber becomes incandescent and ignites the fuel/air mixture in advance of normal timed ignition.

Regarding the above statements,

Neither No. 1 nor No. 2 is true.

Cam-ground pistons are installed in some aircraft

engines to

Provide a better fit at operating temperatures.

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.

Three

If air is heard coming from the crankcase breather

or oil filler during a differential compression check,

what is this an indication of?

Piston ring leakage

Which of the following is a characteristic of a thrust

bearing used in most radial engines?

Deep-groove ball

The five events of a four-stroke cycle engine in the

order of their occurrence are

Intake, compression, ignition, power, and exhaust.

Excessive valve clearance results in the valves

opening

Late and closing early.

By use of a differential pressure compression

tester, it is determined that the No. 3 cylinder of a

nine-cylinder radial engine will not hold pressure

after the crankshaft has been rotated 260° from top

dead center compression stroke No. 1 cylinder.

How can this indication usually be interpreted?

A normal indication.

What could cause excessive pressure buildup in

the crankcase of a reciprocating engine?

Improper warm-up operation.

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.

3, 4, and 5

During ground check, an engine is found to be

rough-running, the magneto drop is normal, and the

manifold pressure is higher than normal for any

given RPM. The trouble may be caused by

A dead cylinder.

Full-floating piston pins are those which allow

motion between the pin and

Both the piston and the small end of the connecting rod.

If fuel/air ratio is proper and ignition timing is

correct, the combustion process should be

completed

Just after top center at the beginning of the power stroke.

The horsepower developed in the cylinders of a

reciprocating engine is known as the

Indicated horsepower

What is the best indication of worn valve guides?

High oil consumption

During overhaul, reciprocating engine exhaust

valves are checked for stretch

With a contour or radius gauge.

Engine crankshaft runout is usually checked

1. During engine overhaul.

2. During annual inspection.

3. After a 'prop strike' or sudden engine stoppage.

4. During a 100-hour inspection.

1 and 3

Engine operating flexibility is the ability of the

engine to

Run smoothly and give the desired performance at all speeds.

Which of the following will be caused by excessive valve clearance of a cylinder on a reciprocating aircraft engine?

Reduced valve overlap period.

Which fuel/air mixture will result in the highest engine temperature (all other factors remaining constant)?

A mixture leaner than a manual lean mixture of .060

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

If an engine cylinder is to be removed, at what

position in the cylinder should the piston be?

Top dead center

What special procedure must be followed when

adjusting the values of an engine equipped with a

floating cam ring?

Eliminate cam bearing clearance when making valve adjustment.

Which statement is correct regarding a four-stroke

cycle aircraft engine?

The intake valve closes on the compression stroke.

An unsupercharged aircraft reciprocating engine,

operated at full throttle from sea level, to 10,000

feet, provided the RPM is unchanged, will

Lose power due to the reduced density of the air drawn into the cylinders.

Which of the following would indicate a general

weak-engine condition when operated with a fixed-

pitch propeller or test club?

Lower than normal static RPM, full throttle operation.

Which statement is true regarding bearings used in high-powered reciprocating aircraft engines?

There is less rolling friction when ball bearings are used than when roller bearings are employed.

An engine misses in both the right and left positions of the magneto switch. The quickest method for locating the trouble is to

Check for one or more cold cylinders.

How may it be determined that a reciprocating

engine with a dry-sump is pre-oiled sufficiently?

Oil will flow from the engine return line or indicator port.

The primary concern in establishing the firing order

for an opposed engine is to

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

To reduce the power output of an engine equipped

with a constant-speed propeller and operating near

maximum BMEP, the

Manifold pressure is reduced with the throttle control before the RPM is reduced with the propeller control.

If the hot clearance is used to set the valves when the engine is cold, what will occur during operation of the engine?

The valves will open late and close early.

The primary purpose in setting proper valve timing

and overlap is to

Obtain the best volumetric efficiency and lower cylinder operating temperatures.

If the crankshaft runout readings on the dial

indicator are plus .002 inch and minus .003 inch,

the runout is

.005 inch

Reduced air density at high altitude has a decided

effect on carburetion, resulting in a reduction of

engine power by

Excessively enriching the fuel/air mixture.