week 4

17- What is the purpose of the density controller in a turbocharger system? A- Limits the maximum manifold pressure that can be produced at other than full throttle conditions. *B- Limits the maximum manifold pressure that can be produced by the turbocharger at full throttle. C- Maintains constant air velocity at the carburetor inlet.

Expl- A density controller is designed to limit the manifold pressure below the turbocharger's critical altitude. It regulates bleed oil only at the full-throttle position.

27- Reciprocating engine exhaust system designs commonly used to provide for ease of installation and/or allow for expansion and contraction, may include the use of 1. spring loaded ball/flexible joints. 2. slip joints. 3. bellows. 4. flexible metal tubing. A- 1, 2, 3, and/or 4. B- 1, 2, and/or 4. *C- 1, 2, and/or 3.

Expl- A reciprocating engine exhaust system is made in sections so that it can expand and contract with changes in temperature without cracking. The various sections of the exhaust system for a normally aspirated engine use slip joints to allow component movement. Turbocharged engines cannot tolerate the small leakage allowed by slip joints, and the sections of the exhaust system are joined with bellows and/or spring-loaded ball joints.

24- The purpose of a sonic venturi on a turbocharged engine is to *A- limit the amount of air that can flow from the turbocharger into the cabin for pressurization. B- increase the amount of air that can flow from the turbocharger into the cabin for pressurization. C- increase the velocity of the fuel/air charge.

Expl- A sonic venturi in a turbocharger installation acts as a flow limiter. When the air passing through the venturi reaches a speed of Mach 1, a shock wave forms that slows down all air passing through it. This limits the amount of air that can enter the pressurization system.

25- What is used to drive a supercharger? A- Exhaust gases. *B- Gear train from the crankshaft. C- Belt drive through a pulley arrangement.

Expl- A supercharger is an air compressor that increases the amount of air an internal combustion engine can take into its induction system. There are two types of superchargers: gear driven and those driven by a turbine powered by the exhaust gases. In modern terminology, a compressor driven by a gear train from the crankshaft is called a supercharger and one driven by the exhaust gases is called a turbosupercharger, or more simply, a turbocharger.

45- How may reciprocating engine exhaust system leaks be detected? A- An exhaust trail aft of the tailpipe on the airplane exterior. B- Fluctuating manifold pressure indication. *C- Signs of exhaust soot inside cowling and on adjacent components.

Expl- An exhaust-system leak in a reciprocating-engine exhaust system can be detected by the presence of exhaust-gas soot collecting inside the cowling and nacelle areas.

3- An increase in manifold pressure when carburetor heat is applied indicates *A- ice was forming in the carburetor. B- mixture was too lean. C- overheating of cylinder heads.

Expl- An increase in manifold pressure after carburetor heat is applied indicates that ice has been forming inside the carburetor and the heat has melted it.

44- What could be a result of undetected exhaust system leaks in a reciprocating engine powered airplane? *A- Pilot/passenger incapacitation caused by carbon monoxide entering the cabin. B- A rough-running engine with increased fuel consumption. C- Too low exhaust back pressure resulting in the desired power settings not being attained.

Expl- Any exhaust-system leak should be regarded as a severe hazard. Depending upon the location and type of leak, it can result in carbon monoxide (CO) poisoning of the crew and passengers, or it can cause an engine compartment fire.

41- Augmenter tubes are part of which reciprocating engine system? A- Induction. *B- Exhaust. C- Fuel.

Expl- Augmenter tubes used on reciprocating engines are part of the exhaust system. Exhaust gases flowing through these venturi-like tubes create a low pressure and increase the flow of cooling air across the engine.

33- On an aircraft that utilizes an exhaust heat exchanger as a source of cabin heat, how should the exhaust system be inspected? A- X-rayed to detect any cracks. B- Hydrostatically tested. *C- With the heater air shroud removed.

Expl- Because of the possibility of carbon monoxide getting into the cabin through a leaking exhaust system, all of the heater muffs must be removed from the exhaust system on a maintenance inspection. With the heater muffs removed, the entire exhaust system is carefully inspected.

35- How do the turbines which are driven by the exhaust gases of a turbo-compound engine contribute to total engine power output? *A- By driving the crankshaft through suitable couplings. B- By driving the supercharger, thus relieving the engine of the supercharging load. C- By converting the latent heat energy of the exhaust gases into thrust by collecting and accelerating them.

Expl- Blowdown, or velocity, turbines used as power recovery turbines on turbocompound engines, extract energy from the exhaust gases and deliver it to the crankshaft through a fluid coupling.

16- Boost manifold pressure is generally considered to be any manifold pressure above A- 14.7 inches Hg. B- 50 inches Hg. *C- 30 inches Hg.

Expl- Boost manifold pressure is normally considered to be any pressure above existing ambient pressure. This is generally thought of as pressure above 30 inches of mercury, absolute.

13- Bootstrapping of a turbocharged engine is indicated by A- an overboost condition of the engine on takeoff. *B- a transient increase in engine power. C- a maximum increase in manifold pressure.

Expl- Bootstrapping is a transient increase in engine power that causes the turbocharger to speed up, which in turn causes the engine to produce more power. Bootstrapping is indicated by a continual drift in the manifold pressure indication.

31- What type of nuts are used to hold an exhaust system to the cylinders? *A- Brass or heat-resistant nuts. B- High-temperature fiber self-locking nuts. C- High-temperature aluminum self-locking nuts.

Expl- Brass or special high-temperature locknuts are used to hold an exhaust system to the cylinders of a reciprocating engine.

5- Carburetor icing on an engine equipped with a constant-speed propeller can be detected by A- a decrease in power output with no change in manifold pressure or RPM. B- an increase in manifold pressure with a constant RPM. *C- a decrease in manifold pressure with a constant RPM.

Expl- Carburetor ice can be detected in an engine equipped with a constant-speed propeller by a drop in manifold pressure as the ice restricts the airflow into the engine. The constant-speed propeller will hold the engine RPM constant.

7- Carburetor icing may be eliminated by which of the following methods? A- Alcohol spray and electrically heated induction duct. B- Ethylene glycol spray and heated induction air. *C- Alcohol spray and heated induction air.

Expl- Carburetor ice is prevented by heating the induction air, either by routing it around the exhaust, or by picking it up in some warm portion of the engine nacelle. Impact ice is prevented from forming on the carburetor by the use of an alcohol spray.

2- Carburetor icing is most severe at *A- air temperatures between 30 and 40°F. B- high altitudes. C- low engine temperatures.

Expl- Carburetor icing is most severe when the air temperature is between 30° and 40°F and the relative humidity is high. Enough heat is required to change liquid fuel into fuel vapor to drop the temperature of the air, condense out any moisture in the air and freeze it inside the carburetor.

34- How should ceramic-coated exhaust components be cleaned? A- With alkali. *B- By degreasing. C- By mechanical means.

Expl- Ceramic-coated exhaust system components should be cleaned by degreasing only. Ceramic-coated parts should never be cleaned by sandblasting them or by cleaning them with alkali cleaners.

4- Into what part of a reciprocating engine induction system is deicing alcohol normally injected? A- The supercharger or impeller section. *B- The airstream ahead of the carburetor. C- The low-pressure area ahead of the throttle valve.

Expl- Deicing alcohol is normally sprayed into the induction system of a reciprocating engine from a spray ring located at the air inlet of the carburetor.

40- All of the following are recommended markers for reciprocating engine exhaust systems except A- India ink. lead pencil. C- Prussian blue.

Expl- Do not mark on any exhaust system component with a lead pencil. The graphite in the lead can make a distinct change in the molecular structure of the exhaust system material when it is heated, and it can cause the material to crack.

43- What is the purpose of an exhaust outlet guard on a small reciprocating engine? *A- To prevent dislodged muffler baffles from obstructing the muffler outlet. B- To reduce spark exit. C- To shield adjacent components from excessive heat.

Expl- Engine power loss and excessive back pressure caused by exhaust-outlet blockage may be averted by the installation of an exhaust-outlet guard, as is described in AC 43.13-1B, Figures 8-21a and 8-21b.

26- Why is high nickel chromium steel used in many exhaust systems? A- High heat conductivity and flexibility. *B- Corrosion resistance and low expansion coefficient. C- Corrosion resistance and high heat conductivity.

Expl- High nickel-chromium steel is used in exhaust systems because of its high corrosion resistance and its low coefficient of expansion.

14- Which of the following would be a factor in the failure of an engine to develop full power at takeoff? *A- Improper adjustment of carburetor heat valve control linkage. B- Excessively rich setting on the idle mixture adjustment. C- Failure of the economizer valve to remain closed at takeoff throttle setting.

Expl- Improper adjustment of the carburetor heat valve control linkage could prevent the engine from developing full takeoff power. The density of any heated air taken into the carburetor is so low that it will not furnish enough oxygen to allow the engine to develop full power.

36- How should corrosion-resistant steel parts such as exhaust collectors be blast cleaned? A- Use steel grit which has not previously been used on soft iron. B- Use super fine granite grit. *C- Use sand which has not previously been used on iron or steel.

Expl- In cleaning corrosion-resistant steel parts with an abrasive blast, it is important that the abrasive not have any contamination of regular iron or steel in it. Particles of iron or steel could become embedded in the corrosion-resistant steel and would eventually lead to failure of the part.

28- One source commonly used for carburetor air heat is A- turbocharger heated air. B- alternate air heat. *C- exhaust gases.

Expl- Induction air flows over a portion of the engine exhaust system to receive heat to prevent in order to prevent the formation of carburetor ice, and to remove ice that has formed in the induction system.

42- Dislodged internal muffler baffles on a small reciprocating engine may *A- obstruct the muffler outlet and cause excessive exhaust back pressure. B- cause the engine to run excessively cool. C- cause high fuel and oil consumption.

Expl- Internal muffler failure (baffles, diffusers, etc.) can cause partial or complete engine power loss by restricting the flow of exhaust gases. This obstruction of the exhaust-gas flow causes an excessive amount of exhaust back pressure.

32- Repair of exhaust system components A- is impossible because the material cannot be identified. B- must be accomplished by the component manufacturer. *C- is not recommended to be accomplished in the field.

Expl- It is generally recommended that exhaust stacks, mufflers, tail pipes, etc., be replaced with new or reconditioned components, rather than being repaired. Because of the difficulty of repairing these components, they should not be repaired in the field, but should be repaired by a specially equipped and approved repair facility.

47- Most exhaust system failures result from thermal fatigue cracking in the areas of stress concentration. This condition is usually caused by A- the drastic temperature change which is encountered at altitude. B- improper welding techniques during manufacture. *C- the high temperatures at which the exhaust system operates.

Expl- Most exhaust system failures result from thermal fatigue cracking in the areas of stress concentration. This thermal fatigue is caused by the high temperatures at which the exhaust system operates.

8- Where would a carburetor air heater be located in a fuel injection system? A- At the air intake entrance. *B- None is required. C- Between the air intake and the venturi.

Expl- No carburetor air heater is required for a fuel-injected engine. However, most engines equipped with fuel injectors have an alternate air system in which warm air from the engine compartment can be taken into the fuel injection system if ice forms on the inlet air filter.

37- Power recovery turbines used on some reciprocating engines are driven by the A- exhaust gas pressure. B- crankshaft. *C- velocity of the exhaust gases.

Expl- Power-recovery turbines, also known as 'blowdown turbines,' are velocity turbines. PRTs are used on the Wright R-3350 Turbocompound engine to extract energy from the exhaust gases and return it to the crankshaft by means of a fluid coupling.

38- Reciprocating engine exhaust systems that have repairs or sloppy weld beads which protrude internally are unacceptable because they cause A- base metal fatigue. B- localized cracks. *C- local hot spots.

Expl- Repairs with sloppy weld beads that protrude into a reciprocating-engine exhaust system are not acceptable, because they can cause local hot spots and may restrict the flow of the exhaust gases.

30- Sodium-filled valves are advantageous to an aviation engine because they A- are lighter. B- dampen valve impact shocks. *C- dissipate heat well.

Expl- Sodium-filled valves absorb heat from inside the combustion chamber as heat is transferred into the sodium. When the sodium sloshes up into the hollow valve stem, the heat is transferred through the valve guide into the cylinder head. The heat is removed from the cylinder head by a flow of cooling air through the fins.

23- The absolute pressure controller on some small engines is designed to sense oil pressure which flows through the waste gate actuator and then through the controllers on the turbocharger system; the pressure between the turbocharger and the throttle valve is called A- turbocharger boost pressure. induction manifold pressure. *C- upper deck pressure.

Expl- The air pressure that is present between the turbocharger and the throttle valve is known as the upper-deck pressure.

19- What directly regulates the speed of a turbocharger? A- Turbine. *B- Waste gate. C- Throttle.

Expl- The amount of exhaust gas passing through the turbine in a turbocharger determines its speed, and the waste gate determines the amount of exhaust gas allowed to pass through the turbine.

22- The differential pressure controller in a turbocharger system *A- reduces bootstrapping during part-throttle operation. B- positions the waste gate valve for maximum power. C- provides a constant fuel-to-air ratio.

Expl- The differential-pressure controller reduces the undesirable condition known as bootstrapping during part-throttle operation. Bootstrapping is an indication of unregulated power changes that result in a continual drift in manifold pressure.

46- Compared to normally aspirated engines, turbocharged engine exhaust systems operate at A- similar temperatures and higher pressures. *B- higher temperatures and higher pressures. similar temperatures and pressures.

Expl- The exhaust system of a turbocharged engine operates at a much higher temperature and pressure than the exhaust system of a comparable normally aspirated engine.

11- As manifold pressure increases in a reciprocating engine, the A- volume of air in the cylinder increases. B- weight of the fuel/air charge decreases. *C- density of air in the cylinder increases.

Expl- The manifold pressure is a measure of the absolute pressure of the air inside the induction system of a reciprocating engine. The higher the manifold pressure, the greater the density of the air being taken into the cylinders.

1- A method commonly used to prevent carburetor icing is to *A- preheat the intake air. B- mix alcohol with the fuel. C- electrically heat the venturi and throttle valve.

Expl- The most commonly used method of preventing carburetor ice is to preheat the intake air.

18- What is the purpose of the rate-of-change controller in a turbocharger system? A- Limits the maximum manifold pressure that can be produced by the turbocharger at full throttle conditions. Controls the rate at which the turbocharger discharge pressure will increase. C- Controls the position of the waste gate after the aircraft has reached its critical altitude.

Expl- The rate-of-change controller controls the rate at which the turbocharger compressor discharge pressure will increase.

29- What is the purpose of a slip joint in an exhaust collector ring? *A- It aids in alignment and absorbs expansion. B- It reduces vibration and increases cooling. C- It permits the collector ring to be installed in one piece.

Expl- The sections of an exhaust collector ring are joined together by slip joints that allow the metal to expand and contract as it is heated and cooled. Slip joints aid in alignment and absorb expansion.

6- What part of an aircraft in flight will begin to accumulate ice before any other? A- Wing leading edge. B- Propeller spinner or dome. *C- Carburetor.

Expl- The temperature drop inside the carburetor as the fuel is converted from a liquid into a vapor will cause carburetor ice to form even when there is no visible water in the air. The other types of ice mentioned in this question are atmospheric ice in which the aircraft must be flown through visible moisture. Carburetor ice can accumulate more readily than these other types.

21- What are the three basic regulating components of a sea-level boosted turbocharger system? 1. Exhaust bypass assembly. 2. Compressor assembly. 3. Pump and bearing casing. 4. Density controller. 5. Differential pressure controller. A- 2, 3, 4. *B- 1, 4, 5. C- 1, 2, 3.

Expl- The three basic regulating components in a sea-level-boosted turbocharger system are the exhaust bypass assembly, the density controller and the differential-pressure controller.

20- What is the purpose of a turbocharger system for a small reciprocating aircraft engine? A- Compresses the air to hold the cabin pressure constant after the aircraft has reached its critical altitude. B- Maintains constant air velocity in the intake manifold. *C- Compresses air to maintain manifold pressure constant from sea level to the critical altitude of the engine.

Expl- The turbocharger system used on a small aircraft compresses the air before it is taken into the induction system. The engine is able, by using this compressed air, to automatically maintain manifold pressure from sea level to its critical altitude.

10- The use of the carburetor air heater when it is not needed causes A- a very lean mixture. B- excessive increase in manifold pressure. *C- a decrease in power and possibly detonation.

Expl- The use of carburetor heat when it is not necessary will decrease the engine power because the engine will be operating with an excessively rich mixture. There will also be the possibility of detonation because of the hot charge in the cylinders.

9- During full power output of an unsupercharged engine equipped with a float-type carburetor, in which of the following areas will the highest pressure exist? A- Venturi. B- Intake manifold. *C- Carburetor air scoop.

Expl- The venturi and the intake manifold both have a pressure lower than ambient. Only the carburetor air scoop has a pressure higher than ambient pressure.

12- Which of the following statements regarding volumetric efficiency of an engine is true? A- The volumetric efficiency of an engine will remain the same regardless of the amount of throttle opening. B- It is impossible to exceed 100 percent volumetric efficiency of any engine regardless of the type of supercharger used. It is possible to exceed 100 percent volumetric efficiency of some engines by the use of superchargers of the proper type.

Expl- The volumetric efficiency of an engine is the ratio of the fuel-air charge taken into a cylinder to the charge the cylinder will hold at normal atmospheric pressure. It is possible, by supercharging, to increase volumetric efficiency to more than 100%.

39- Ball joints in reciprocating engine exhaust systems should be A- tight enough to prevent any movement. B- disassembled and the seals replaced every engine change. *C- loose enough to permit some movement.

Expl- When ball joints are used in the exhaust system of a reciprocating engine, it is essential that they be free to move in their sockets under all temperature conditions. This freedom of motion prevents failure of the engine or the exhaust system.

15- If the turbocharger waste gate is completely closed, A- none of the exhaust gases are directed through the turbine. B- the turbocharger is in the OFF position. *C- all the exhaust gases are directed through the turbine.

Expl- When the waste gate of a turbosupercharger is completely closed, all of the exhaust gases flow through the turbine.