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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.
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A condition that can occur in radial engines but is unlikely to occur in horizontally opposed engines is
Hydraulic Lock
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Which condition would be the least likely to be caused by failed or failing engine bearings?
Low Oil Temperatures
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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.
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Which of the following will decrease volumetric efficiency in a reciprocating engine?
3. Improper valve timing.
4. Sharp bends in the induction system.
5. High carburetor air temperatures.
3, 4, and 5
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Which of the following is a characteristic of a thrust bearing used in most radial engines?
Deep-groove ball
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Which bearing is least likely to be a roller or ball bearing?
Master Rod Bearing (Radial Engine)
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The operating temperature valve clearance of a radial engine as compared to cold valve clearance is
Greater
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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.
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The five events of a four-stroke cycle engine in the order of their occurrence are
Intake, Compression, Ignition, Power, Exhaust
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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.
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If fuel/air ratio is proper and ignition timing is correct, the combustion process should be completed
Just after top center at the beggining of the power strike.
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Grinding the valves of a reciprocating engine to a feather edge is likely to result in
Preignition and burned valves.
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Which statement is correct regarding engine crankshafts?
Moveable counterweights serve to reduce the torsional vibrations in an aircraft reciprocating engine.
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On which strokes are both valves on a four-stroke cycle reciprocating aircraft engine open?
Exhaust and intake.
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Master rod bearings are generally what type?
Plain.
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The actual power delivered to the propeller of an aircraft engine is called
Brake horsepower.
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Cam-ground pistons are installed in some aircraft engines to
Provide a better fit at operating temperatures.
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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 Degrees
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Some aircraft engine manufacturers equip their product with choked or taper-ground cylinders in order to
Provide a straight cylinder bore at operating temperatures.
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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
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What tool is generally used to measure the crankshaft rotation in degrees?
Timing disk
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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 degrees after TDC.
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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.
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Some cylinder barrels are hardened by
Nitriding
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Which statement is correct regarding a four-stroke cycle aircraft engine?
The intake valve closes on the compression stroke.
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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
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During overhaul, reciprocating engine exhaust valves are checked for stretch
With a contour or radius gauge
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When is the fuel/air mixture ignited in a conventional reciprocating engine?
Shortly before the piston reaches the top of the compression stroke.
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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 Degrees
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What is the purpose of the safety circlet installed on some valve stems?
To prevent valves from falling into the combustion chamber.
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Valve overlap is defined as the number of degrees of crankshaft travel
During which both valves are off their seats.
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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.
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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
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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
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Full-floating piston pins are those which allow motion between the pin and
Both the piston and small end of the connecting rod.
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The primary purpose in setting proper valve timing and overlap is to
Obtain the best volumetric efficiency and lower cylinder operating temperatures.
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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.
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The purpose of two or more valve springs in aircraft engines is to
Eliminate Valve Spring Surge
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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.
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Why does the smoothness of operation of an engine increase with a greater number of cylinders?
The power impulses are spaced closer together.
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Compression ratio is the ratio between the
Cylinder volume with piston at bottom dead center and at top dead center.
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If the crankshaft runout readings on the dial indicator are plus .002 inch and minus .003 inch, the runout is
.005 Inch
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(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
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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.
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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
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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.
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What is the purpose of a power check on a reciprocating engine?
To determine satisfactory performance.
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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.
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Which of the following will be caused by excessive valve clearance of a cylinder on a reciprocating aircraft engine?
Reduced valve overlap period.
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The floating control thermostat, used on some reciprocating engine installations, helps regulate oil temperature by
Controlling air flow through the oil cooler.
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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.
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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
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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 and swapped bottom to top.
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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 top dead center.
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Excessive valve clearance results in the valves opening
late and closing early.
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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.
-
A characteristic of dyna-focal engine mounts as applied to aircraft reciprocating engines is that the
Shock mount pivots toward the engine's center of gravity.
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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.
-
If the oil pressure gauge fluctuates over a wide range from zero to normal operating pressure, the most likely cause is
Low Oil Supply
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What special procedure must be followed when adjusting the valves of an engine equipped with a floating cam ring?
Eliminate cam bearing clearance when making valve adjustment.
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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.
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Excessive valve clearances will cause the duration of valve opening to
Decrease for both Intake and Exhaust Valves
-
What does valve overlap promote?
Better scavenging and cool characteristics.
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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
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Engine crankshaft runout is usually checked
1. during engine overhaul.
3. after a 'prop strike' or sudden engine stoppage.
1 and 3
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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.
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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.
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A hissing sound from the exhaust stacks when the propeller is being pulled through manually indicates
Exhaust valve blow-by
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If the oil pressure of a cold engine is higher than at normal operating temperatures, the
Engine's lubrication system is probably operating normally.
-
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 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.
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If an engine cylinder is to be removed, at what position in the cylinder should the piston be?
Top Dead Center
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The horsepower developed in the cylinders of a reciprocating engine is known as the
Indicated Horsepower
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Engine operating flexibility is the ability of the engine to
run smoothly and give the desired performance at all speeds.
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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 relatively thin walls and may be nitrided.
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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 RPM
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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
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What is the best indication of worn valve guides?
High oil consumption
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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.
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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.
-
Valve clearance changes on opposed-type engines using hydraulic lifters are accomplished by
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.
-
An increase in manifold pressure with a constant RPM will cause the bearing load in an engine to
Increase
-
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.
-
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.
-
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.
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(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,
Niether No.1 nor No.2 is true.
-
Which of the following engine servicing operations generally requires engine pre-oiling prior to starting the engine?
Engine Installation
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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 inspection holes.
-
Which of the following conditions would most likely lead to detonation?
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 density of the air drawn into the cylinders.
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Which of the following would most likely cause a reciprocating engine to backfire through the induction system at low RPM operation?
Lean Mixture.
-
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.
-
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.
-
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.
-
Backfiring through the carburetor generally results from the use of
An excessively lean mixture.
-
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.
1, 2, 3
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When will small induction system air leaks have the most noticeable effect on engine operation?
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 force before the RPM is reduced with the propeller control.
-
One of the best indicators of reciprocating engine combustion chamber problems is
Spark Plug Condition
-
What could cause excessive pressure buildup in the crankcase of a reciprocating engine?
Plugged Crankcase Breather
-
Excessive valve clearance in a piston engine
Decreases Valve Overlap
-
To what altitude will a turbo charged engine maintain sea level pressure?
Critical Altitude
-
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
-
One cause of afterfiring in an aircraft engine is
An excessively rich mixture.
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