Reciprocating Engines

gewodoji's version from 2016-10-30 03:55

Section 1

Question Answer
Which statement is true regarding bearings used in high-powered reciprocating aircraft engines?There is less rolling friction when ball bearings are employed
Excessive valve clearance results in the valves openinglate and closing early
Backfiring through the carburetor generally results from the use ofan excessively lean mixture
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 conditionmay be a result of abnormal plain type bearing wear and is cause for further investigation
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 100-hour inspection.1 and 3
The horsepower developed in the cylinders of a reciprocating engine is known as theindicated horsepower
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
A characteristic of dyna-focal engine mounts as applied to aircraft reciprocating engines is that theshock mounts point toward the engine center of gravity.
What is an advantage of using metallic-sodium filled exhaust valves in aircraft reciprocating engines?Reduced valve operating temperatures
(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.neither No. 1 nor No. 2 is true
One of the best indicators of reciprocating engine combustion chamber problems isspark plug condition

Section 2

Question Answer
If an engine with a stroke of 6 inches is operated at 2,000 RPM, the piston movement within the cylinder will beat maximum velocity 90° after TDC
An engine misses in both the right and left positions of the magneto switch. The quickest method for locating the trouble is tocheck for one or more cold cylinders
What does valve overlap promote?Better scavenging and cooling characteristics
During overhaul, reciprocating engine exhaust valves are checked for stretchwith a contour or radius gauge
Which of the following would most likely cause a reciprocating engine to backfire through the induction system at low RPM operation?Lean mixture
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 bya dead cylinder
What is the purpose of a power check on a reciprocating engine?To determine satisfactory performance
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
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
The primary concern in establishing the firing order for an opposed engine is toprovide for balance and eliminate vibration to the greatest extent possible

Section 3

Question Answer
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
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
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
Valve clearance changes on opposed-type engines using hydraulic lifters are accomplished bypush rod replacement
Before attempting to start a radial engine that has been shut down for more than 30 minutesturn the propeller by hand three to four revolutions in the normal direction of rotation to check for liquid lock
On which strokes are both valves on a four-stroke cycle reciprocating aircraft engine open?Exhaust and intake
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
Which of the following is a characteristic of a thrust bearing used in most radial engines?Deep-groove ball
What is the purpose of the safety circlet installed on some valve stems?To prevent valves from falling into the combustion chamber
The five events of a four-stroke cycle engine in the order of their occurrence areintake, compression, ignition, power, exhaust

Section 4

Question Answer
Increased water vapor (higher relative humidity) in the incoming air to a reciprocating engine will normally result in which of the following?Increased power output due to increased volumetric efficiency
If the crankshaft runout readings on the dial indicator are plus .002 inch and minus .003 inch, the runout is.005
Which condition would be the least likely to be caused by failed or failing engine bearings?Low oil temperatures
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
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
If the oil pressure gauge fluctuates over a wide range from zero to normal operating pressure, the most likely cause islow oil supply
Grinding the valves of a reciprocating engine to a feather edge is likely to result inpreignition and burned valves
If the oil pressure of a cold engine is higher than at normal operating temperatures, theengine's lubrication system is probably operating normally
When will small induction system air leaks have the most noticeable effect on engine operation?at low RPM
Direct mechanical push-pull carburetor heat control linkages should normally be adjusted so that the stop located on the diverter valve will be contactedbefore the stop at the control lever is reached in both HOT and COLD positions.

Section 5

Question Answer
If fuel/air ratio is proper and ignition timing is correct, the combustion process should be completedjust after top center at the beginning of the power stroke
Which bearing is least likely to be a roller or ball bearing?Master rod bearing (radial engine)
Which of the following will be caused by excessive valve clearance of a cylinder on a reciprocating aircraft engine?Reduced valve overlap period
The operating temperature valve clearance of a radial engine as compared to cold valve clearance isgreater
The actual power delivered to the propeller of an aircraft engine is calledbrake horsepower
A nine-cylinder engine with a bore of 5.5 inches and a stroke of 6 inches will have a total piston displacement of1,283 cubic inches
The floating control thermostat, used on some reciprocating engine installations, helps regulate oil temperature bycontrolling air flow through the oil cooler
Excessive valve clearances will cause the duration of valve opening todecrease for both intake and exhaust valves
Which of the following conditions would most likely lead to detonation?Use of fuel with too low an octane rating
During the inspection of an engine control system in which push-pull control rods are used, the threaded rod ends shouldbe checked for the amount of thread engagement by means of the inspection holes

Section 6

Question Answer
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°
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 an engine cylinder is to be removed, at what position in the cylinder should the piston be?Halfway between top and bottom dead center
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
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
Compression ratio is the ratio between thecylinder volume with piston at bottom dead center and at top dead center
A hissing sound from the exhaust stacks when the propeller is being pulled through manually indicatesexhaust valve blow-by
Master rod bearings are generally what type?Plain
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 could cause excessive pressure buildup in the crankcase of a reciprocating engine?Plugged crankcase breather
An unsupercharged aircraft reciprocating engine, operated at full throttle from sea level, to 10,000 feet, provided the RPM is unchanged, willlose power due to the reduced density of the air drawn into the cylinders
(1) Cast iron piston rings may be used in chrome-plated cylinders.(2) Chrome-plated rings may be used in plain steel cylinders.both No. 1 and No. 2 are tue
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

Section 7

Question Answer
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
Reduced air density at high altitude has a decided effect on carburetion, resulting in a reduction of engine power byexcessively enriching the fuel/air mixture
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 cylindershave relatively thin walls and may be nitrided
Why does the smoothness of operation of an engine increase with a greater number of cylinders?The power impulses are spaced closer together
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
An increase in manifold pressure with a constant RPM will cause the bearing load in an engine toincrease
When cleaning aluminum and magnesium engine parts, it is inadvisable to soak them in solutions containing soap becausesome of the soap will become impregnated in the surface of the material and subsequently cause oil contamination foaming
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
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
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

Section 8

Section 9

Section 10