Questions and Answers - Aircraft Reciprocating Engine (Part 1) | Aircraft Systems

Questions and Answers - Aircraft Reciprocating Engine (Part 1)

Multiple Choices Questions

1. 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.

2. A condition that can occur in radial engines but is unlikely to occur in horizontally opposed engines is
a. valve overlap.
b. zero valve clearance.
c. hydraulic lock.

3. Which condition would be the least likely to be caused by failed or failing engine bearings?
a. Excessive oil consumption.
b. High oil temperatures.
c. Low oil temperatures.

4. 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.


5. 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. l, 2,3 and 4.
c. 3, 4 and 5.

6. 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.

7. 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).

8. The operating temperature valve clearance of a radial engine as compared to cold valve clearance is
a. greater.
b. less.
c. the same.

9. 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.

10. 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.

11. 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.

12. If fuel/air ratio is proper and ignition timing is correct, the combustion process should be completed
a. 20 to 30' 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.

13. Grinding the valves of a reciprocating engine to a feather edge is likely to result in
a. normal operation and long life.
b. excessive valve clearance.
c. preignition and burned valves.

14. 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.

15. 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.

16. Master rod bearings are generally what type?
a. Plain.
b. Roller.
c. Ball.

17. The actual power delivered to the propeller of an aircraft engine is called
a. friction horsepower.
b. brake horsepower.
c. indicated horsepower.

18. 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.

19. 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. 2900
b. 2450
c. 250

20. 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.


21. An aircraft reciprocating engine using hydraulic valve lifters i s 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.

22. What tool i s generally used to measure the crankshaft rotation in degrees?
a. Dial indicator.
b. Timing disk.
c. Prop protractor.

23. 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.

24. If the intake valve is opened too early in the cycle of operation of a four-stroke cycle engine, it may result in
a. improper scavenging of exhaust gases.
b. engine kickback.
c. backfiring into the induction system.

25. Some cylinder barrels are hardened by
a. nitriding.
b. shot peening.
c. tempering.

26. 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.

27. On which part of the cylinder walls of a normally operating engine will the greatest amount of wear occur?
a. Near the center of the cylinder where piston velocity is greatest.
b. Near the top of the cylinder.
c. Wear is normally evenly distributed.

28. During overhaul, reciprocating engine exhaust valves are checked for stretch
a. with a suitable inside spring caliper.
b. with a contour or radius gauge.
c. by placing the valve on a surface plate and measuring its length with a vernier height gauge.

29. When is the fuellair 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.

30. Ignition occurs at 28" BTDC on a certain four-stroke cycle engine, and the intake valve opens at 15O BTDC. How many degrees of crankshaft travel after ignition does the intake valve open? (Consider one cylinder only.)
a. 7070
b. 3730
c. 3740

31. 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.

32. 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.

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

34. 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.

35. 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.

36. 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.

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

38. 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.

39. 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.


40. 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
a. solvent degreasers are much more effective.
b. water-mixed degreaser residues may cause engine oil contamination in the overhauled engine.
c. water-mixed degreasers cause corrosion.

41. 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.

42. 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.

43. If the crankshaft runout readings on the dial indicator are plus .002 inch and minus .003 inch, the runout is
a. 005 inch.
b. plus .001 inch.
c. minus .001 inch.

44. (I) Cast iron piston rings may be used in chromeplated cylinders.
      (2) Chrome-plated rings may be used in plain steel cylinders.

Regarding the above statements,
a. only No. 1 is true.
b. neither No. 1 nor No.2 is true.
c. both No. 1 and No.2 are true.

45. 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.

46. The volume of a cylinder equals 70 cubic inches when thegiston 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.

47. When cleaning aluminum and magnesium engine parts, it is inadvisable to soak them in solutions containing soap because
a. some of the soap will become impregnated in the surface of the material and subsequently cause engine oil contamination and foaming.
b. the soap can chemically alter the metals causing them to become more susceptible to corrosion.
c. the parts can be destroyed by dissimilar metal electrolytic action if they are placed together in the solution for more than a few minutes.

48. What is the purpose of a power check on a reciprocating engine?
a. To check magneto drop.
b. To determine satisfactory performance.
c. To determine if the fuel/air mixture is adequate.

49. 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.

50. Which of the following will be caused by excessive valve clearance of a cylinder on a reciprocating aircraft engine?
a. Reduced valve overlap period.
b. Intake and exhaust valves will open early and close late.
c. A power increase by shortening the exhaust event.

51. The floating control thermostat, used on some reciprocating engine installations, helps regulate oil temperature by
a. controlling oil flow through the oil cooler.
b. recirculating hot oil back through the sump.
c. controlling air flow through the oil cooler.

52. Which of the following would indicate a general weak-engine condition when operated with a fixed-pitch propeller or test club?
a. Lower than normal static RPM, full throttle operation.
b. Manifold pressure lower at idle RPM than at static RPM.
c. Lower than normal manifold pressure for any given RPM.

53. What is required by 14 CFR Part 43 appendix D when performing an annual/100-hour inspection on a reciprocating engine aircraft?
a. Magneto timing check.
b. Cylinder compression check.
c. Valve clearance check.

54. After spark plugs from an opposed engine have been serviced, in what position should they be reinstalled?
a. Next in firing order to the one from which they were removed.
b. Swapped bottom to top.
c. Next in firing order to the one from which they were removed and swapped bottom to top.

55. 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?
a. The piston was on compression stroke.
b. The piston was on exhaust stroke
c. The piston was positioned past top dead center.



SUPPORTING LESSONS
General Requirements
Types of Engines
Reciprocating Engines
Crankshafts
Connecting Rods
Pistons
Piston Rings
Cylinders
Firing Order
Valves
Valve Operating Mechanism
Bearings
Propeller Reduction Gearing and Propeller Shafts
Reciprocating Engine Operating Principles
Operating Cycles
Reciprocating Engine Power

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