PP Reciprocating Engines

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

The outer race of a single-row, self-aligning ball bearing will always have a radius equal to the radius of the balls.
There is less rolling friction when ball bearings are used than when roller bearings are employed.
Crankshaft bearings are generally of the ball-type due to their ability to withstand extreme loads without overheating.

A condition that can occur in radial engines but is unlikely to occur in horizontally opposed engines is

oil-fouled spark plug.
valve overlap.
hydraulic lock.

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

Excessive oil consumption.
High oil temperatures.
Low oil temperatures.

What is the principal advantage of using propeller reduction gears?

To enable the propeller RPM to be increased without an accompanying increase in engine RPM.
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.
To enable the engine RPM to be increased with an accompanying increase in propeller RPM.

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

Full throttle operations, low cylinder head temperatures, and high carburetor air temperatures.
Low cylinder head temperatures, improper valve timing, and sharp bends in the induction system.
Improper valve timing, sharp bends in the induction system, and high carburetor air temperatures.

Which of the following is a characteristic of a thrust-bearing used in most radial engines?

Tapered roller.
Double-row ball.
Deep-groove ball.

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

Rocker arm bearing (overhead valve engine).
Master rod bearing (radial engine).
Crankshaft main bearing (radial engine).

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

greater.
less.
the same.

A nine-cylinder engine with a bore of 5.5 inches and a stroke of 6 inches will have a total piston displacement of

740 cubic inches.
1,425 cubic inches.
1,283 cubic inches.

The five events of a four-stroke cycle engine in the order of their occurrence are

intake, ignition, compression, power, and exhaust.
intake, compression, power, ignition,, and exhaust.
intake, compression, ignition, power, and exhaust.

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.
keep power impulses on adjacent cylinders as far apart as possible in order to obtain the greatest mechanical efficiency.
keep the power impulses on adjacent cylinders as close as possible in order to obtain the greatest mechanical efficiency.

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

20 to 30 degrees before top center at the end of the compression stroke.
when the exhaust valve opens at the end of the power stroke.
just after top center at the beginning of the power stroke.

Grinding the valves of a reciprocating engine to a feather edge is likely to result in

normal operation and long life.
excessive valve clearance.
preignition and burned valves.

Which statement is correct regarding engine crankshafts?

Moveable counterweights serve to reduce the dynamic vibrations in an aircraft reciprocating engine.
Moveable counterweights serve to reduce the torsional vibrations in an aircraft reciprocating engine.
Moveable counterweights are designed to resonate at the natural frequency of the crankshaft.

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

Power and exhaust.
Intake and compresssin.
Exhaust and intake.

Which type of bearings are generally used for connecting rods and cam shafts?

Plain.
Roller.
Ball.

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

friction horsepower.
brake horsepower.
indicated horsepower.

Cam-ground pistons are installed in some aircraft engines to

provide a better fit at operating temperatures.
act as a compensating feature so that a compensated magneto is not required.
equalize the wear on all pistons.

Using the following information, determine how many degrees the crankshaft will rotate with both the intake and exhaust valves sealed.

Intake opens 15 degrees BTDC.
Exhaust opens 70 degrees BBDC.
Intake closes 45 degrees ABDC.
Exhaust closes 10 degrees ATDC.

290 degrrees
245 degrees.
25 degrees.

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

provide a straight cylinder bore at operating temperatures.
flex the rings slightly during operation and reduce the possibility of the rings sticking in the grooves.
increase the compression pressure for starting purposes.

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?

During normal operation.
When the lifters become deflated.
As a result of carbon and sludge becoming trapped in the lifter and restricting its motion.

What tool is generally used to measure the crankshaft rotation in degrees?

Dial indication.
Timing disk.
Prop Protractor.

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 around TDC.
consistent during the entire 360 degrees of crankshaft travel.
at maximum velocity 90 degrees after TDC.

If the intake valve is opened too early in the cycle of operation of a four-stroke cycle engine, it may result in

improper scavenging of exhaust gases.
engine kickback.
backfiring into the induction system.

Some cylinder barrels are hardened by

nitriding.
honing.
quenching.

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

The intake valve closes on the compression stroke.
The exhaust valve opens on the exhaust stroke.
The intake valve closes on the intake stroke.

On which part of the cylinder walls of a normally operating engine will the greatest amount of wear occur?

Near the center of the cylinder where piston velocity is greatest.
Near the top of the cylinder.
Wear is normally evenly distributed.

During overhaul, reciprocating engine exhaust valves are checked for stretch

with a suitable inside spring caliper.
with a contour or radius gauge.
by placing the valve on a surface plate and measuring its length with a vernier height gauge.

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

When the piston has reached top dead center of the intake stroke.
Shortly before the piston reaches the top of the compression stroke.
When the piston reaches top dead center on the compression stroke.

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

707 degrees.
373 degrees.
347 degrees.

What is the purpose of the safety circlet installed on some valve stems?

To hold the valve guide in position.
To hold the valve spring retaining washer in position.
To prevent valves from falling into the combustion chamber.

Valve overlap is defined as the number of degrees of crankshaft travel

during which both valves are off their seats.
between the closing of the intake valve and the opening of the exhaust valve.
during which both valves are on their seats.

The valve clearance of an engine using hydraulic lifters, when the lifters are completely flat, or empty, should not exceed

0.00 inch.
a specified amount above zero.
a specified amount below zero.

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

intake stroke.
power stroke.
compression stroke.

Which of the following are factors in establishing the maximum compression ratio limitations of an aircraft engine?

Design limitations of the engine, the degree of supercharging, and spark plug reach.
Detonation characteristics of the fuel, design limitations of the engine, and spark plug reach.
Detonation characteristics of the fuel, design limitations of the engine, and the degree of supercharging.

Full-floating piston pins are those which allow motion between the pin and

the piston.
both the piston and the large end of the connecting rod.
both the piston and the small end of the connecting rod.

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

permit the best possible change of fuel/air mixture into the cylinders.
gain more thorough exhaust gas scavenging.
obtain the best volumetric efficiency and lower cylinder operating temperatures.

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 early and close early.
The valves will open late and close early.
The valves will open early and close late.

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

To equalize side pressure on the valve stem.
To eliminate valve spring vibration or surging.
To help equalize valve face loading.

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

solvent degreasers are much more effective.
water-mixed degreaser residues may cause engine oil contamination in the overhauled engine.
water-mixed degreaser’s cause corrosion.

Why does the smoothness of operation of an engine increase with a greater number of cylinders?

The power impulses are spaced closer together.
The power impulses are spaced further apart.
The engine has large counterbalance weights.

Compression ratio is the ratio between the

piston travel on the compression stroke and on the intake stroke.
combustion chamber pressure on the combustion stroke and on the exhaust stroke.
cylinder volume with piston at bottom dead center and at top dead center.

If the crankshaft turnout readings on the dial indicator are plus .002 inch and minus .003 inch, the runout is

.005 inch.
plus .001 inch.
minus .001 inch.

(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,

only 1 is true.
neither 1 nor 2 is true.
both 1 and 2 are true.

How is proper end-gap clearance on new piston rings assured during the overhaul of an engine?

By accurately measuring and matching the outside diameter of the rings with the inside diameter of the cylinders.
By using rings specified by the engine manufacturer.
By placing the rings in the cylinder and measuring the end gap with a feeler gauge.

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?

10:7.
10:1.
7:1.

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.
the soap can chemically alter the metals causing them to become more susceptible to corrosion.
the parts can be destroyed by dissimilar metal electrolytic action if they are placed together in the solution for more than a few minutes.

What is the purpose of a power check on a reciprocating engine?

To check magneto drop.
To determine satisfactory performance.
To determine if the fuel/air mixture is adequate.

What will be the likely result if the piston ring gaps happen to be aligned when performing a differential pressure compression check on a cyclinder?

Little or no effect.
The rings will not be seated.
A worn or defective ring(s) indication.

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

Reduced valve overlap period.
Intake and exhaust valves will open early and close late.
A power increase by shortening the exhaust event.

The floating control thermostat, used on some reciprocating engine installations, helps regulate oil temperature by

controlling oil flow through the oil cooler.
recirculating hot oil back through the sump.
controlling air flow through the oil cooler.

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.
Manifold pressure lower at idle RPM than at static RPM.
Lower than normal manifold pressure for any given RPM.

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

Magnetic timing check.
Cylinder compression check.
Valve clearance check.

After spark plugs from an opposed engine have been serviced, in what position should they be reinstalled?

Next in firing order to the one from which they were removed.
Swapped bottom to top.
Next in firing order to the one from which they were removed and swapped bottom to top.

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 on compression stroke.
The piston was on exhaust stroke.
The piston was positioned past top dead center.

Excessive vale clearance results in the valves opening

late and closing early.
early and closing late.
late and closing late.

During routine inspection of a reciprocating engine, a deposit of small, bright, metallic particles which do not cliing 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.
is probably a result of ring and cylinder wall wear and is cause for engine removal and/or overhaul.
is normal in engines utilizing plain type bearings and aluminum pistons and is not cause for alarm.

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

shock mounts eliminate the torsional flexing of the powerplant.
engine attaches to the shock mounts at the engine’s center of gravity.
shock mounts point toward the engine’s center of gravity.

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

it is an indication of normal engine wear unless the particles are nonferrous.
the cause should be identified and corrected before the aircraft is released for flight.
it is an indication of normal engine wear unless the deposit exceeds a specified amount.

If the oil pressure gauge fluctuates over a wide range from zero to normal operating pressure, the most likely cause is

low oil supply.
broken or weak pressure relief valve spring.
air lock in the scavenge pump intake.

What special procedure must be followed when adjusting the valves of an engine equipped with a floating cam ring?

Adjust valves when the engine is hot,
Adjust all exhaust valves before intake valves.
Eliminate cam bearing clearance when making valve adjustment.

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 warmup.
The further decrease in valve clearance that occurs as engine temperatures increase will cause damage to the valve operating mechanism.
The valves will remain closed for longer periods than specified by the engine manufacturer.

Excessive valve clearances will cause the duration of valve opening to

increase for both intake and exhaust valves.
decrease for both intake and exhaust valves.
decrease for intake valves and increase for exhaust valves.

What does valve overlap promote?

Lower intake manifold pressure and temperatures.
A backflow of gases across the cylinder.
Better scavenging and cooling characteristics.

At what speed must a crankshaft turn if each cylinder of a four-stroke cycle engine is to be fired 200 times a minute?

800 RPM.
1,600 RPM.
400 RPM.

Engine crankshaft runout is usually checked

during an annual inspection.
during engine overhaul and after a “prop strike” or sudden engine stoppage.
after a “prop strike” or sudden engine stoppage and during an annual inspection.

Before attempting to start a radial engine that has been shut down for more than 30 minutes

turn the propeller by hand three or four evolutions in the opposite direction of normal rotation to check for liquid lock.
turn the ignition switch on before energizing the starter.
turn the propeller by hand three to four revolutions in the normal direction of rotation to check for liquid lock.

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

check for one or more cold cylinders.
perform a compression check.
check each spark plug.

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

a cracked exhaust stack.
exhaust valve blow-by.
worn piston rings.

If the oil pressure of a cold engine is higher than at normal operating temperatures, the

oil system relief valve should be readjusted.
engine’s lubrication system is probably operating normally.
oil dilution system should be turned on immediately.

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.
sheared oil pump shaft.
clogged oil cooler annular jacket.

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

A mixture leaner than a rich best-power mixture of .085.
A mixture richer than a full-rich mixture of .087?
A mixture leaner than a manual lean mixture of .060.

If an engine cylinder is to be removed, at what position in the cylinder should the piston be?

Bottom dead center.
Top dead center.
Halfway between top and bottom dead center.

The horsepower developed in the cylinders of a reciprocating engine is known as the

shaft horsepower.
indicated horsepower.
brake horsepower.

Engine operating flexibility is the ability of the engine to

deliver maximum horsepower at a specific altitude.
meet exacting requirements of efficiency and low weight per horsepower ratio.
run smoothly and give the desired performance at all speeds.

Standard aircraft cylinder oversizes 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 more limited cooling capacity.
have relatively thin walls and may be nitrided.
operate at high temperatures.

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

increase in manifold pressure.
bump in propeller RPM.
drop in torque meter pressure indication.

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

several spark plugs fouled on different cylinders.
a leak in the intake manifold.
a dead cylinder.

What is the best indication of worn valve guides?

High oil consumption.
Low compression.
Low oil pressure.

By use of a differential pressure compression tester, it is determined that cylinder 3 of a nine-cylinder radial engine will not hold pressure after the crankshaft has been rotated 260 degrees from top dead center compression stroke cylinder 1. How can this indication usually be interpreted?

A normal indication.
Exhaust valve blow-by.
A damaged exhaust valve or insufficient exhaust valve clearance.

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.
At the end of the power stroke and the beginning of the exhaust stroke.
At the end of the compression stroke and the beginning of the power stroke.

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

Increased strength and resistance to cracking.
Reduced valve operating temperatures.
Greater resistance to deterioration at high valve temperature.

Valve clearance changes on opposed-type engine using hydraulic filters are accomplished by

rocker arm adjustment.
rocker arm replacement.
push rod replacement.

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.
Excessive engine oil pressure.
Thermal shock of cylinders.

An increase in manifold pressure with a constant RPM will cause the bearing load in an engine to

decrease.
remain relatively constant.
increase.

Direct mechanical push-pull carburetor head control linkages should normally be adjusted so that the stop located on the diverter valve will be contacted

before the stop at the control level is reached in both HOT and COLD positions.
before the stop at the control level is reached in the HOT position and after the stop at the control level is reached in the COLD position.
after the stop at the control level is reached in both HOT and COLD positions.

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.
excessively leaning the fuel/air mixture.
reducing fuel vaporization.

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.
Increased power output due to increased volumetric efficiency.
A leaning effect on engines which use nonautomatic carburetors.

(1) Preignition 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,

only 1 is true.
both 1 and 2 are true.
neither 1 nor 2 is true.

Which of the following engine servicing operations generally requires engine pre-oiling prior to starting the engine?

Engine oil and filter change.
Engine installation.
Replacement of oil lines.

During the inspection of an engine control system in which push-pull control rods are used, the threaded rod ends should

ensure that the safety wire passes through the hole in shank of the rod-end.
be checked for thread engagement of at least two threads but not more than four threads.
be checked for the amount of thread engagement by means of the inspection holes.

Which of the following conditions would most likely lead to detonation?

Late ignition timing.
Use of fuel with too high an octane rating.
Use of fuel with too low an octane rating.

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 volume of air drawn into the cylinders.
produce constant power due to the same volume of air drawn into the cylinders.
lose power due to the reduced density of the air drawn into the cylinders.

Which of the following would most likely cause a reciprocating engine to backfire through the induction system at low RPM operation?

Idle mixture too rich.
Clogged derichment valve.
Lean mixture.

How may it be determined that a reciprocating engine with a dry sump is pre-oiled sufficiently?

The engine oil pressure gauge will indicate normal oil pressure.
Oil will flow from the engine return line or indicator port.
When the quantity of oil specified by the manufacturer has been pumped into the engine.

What is the basic operational sequence for reducing the power output of an engine equipped with a constant-speed propeller?

Reduce the RPM, then the manifold pressure.
Reduce the manifold pressure, then retard the throttle to obtain the correct RPM.
Reduce the manifold pressure, then the RPM.

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.
A rich mixture is faster burning than a normal mixture.
The mixture ratio which gives maximum economy may also be designated as best power mixture.

Backfiring through the carburetor generally results from the use of

an excessively lean mixture.,
excessively atomized fuel.
an excessively rich mixture.

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

Late ignition timing.
High manifold pressure or high intake air temperature.
Late ignition timing and an overheated engine.

When will small induction system air leaks have the most noticeable effect on engine operation?

At high RPM.
At maximum continuous and takeoff power settings.
At low RPM.

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

One of the best indicators of reciprocating engine combustion chamber problems is

excessive engine vibration.
starting difficulties.
spark plug condition.

What could cause excessive pressure buildup in the crankcase of a reciprocating engine?

Plugged crankcase breather.
Improper warmup operation.
An excessive quantity of oil.

Excessive valve clearance in a piston engine

increases valve overlap.
increases valve opening time.
decreases valve overlap.

To what altitude will a turbo charged engine maintain sea level pressure?

Critical altitude.
Service ceiling.
Pressure altitude.

If air is heard coming from the crankcase breather or oil filter during a differential compression check, what is this an indication of?

Exchaust valve leakage.
Intake valve leakage.
Piston ring leakage.

One cause of after firing in an aircraft engine is

sticking intake valves.
an excessively lean mixture.
an excessively rich mixture.

PP Reciprocating Engines

Jon K

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