lube

In addition to reducing friction between moving parts, an engine lubricant accomplishes all five of the items listed in the alternatives for this question. It cools, seals, cleans, prevents corrosion, and serves as a cushion between parts where impact loads are involved.

8420. In addition to lubricating (reducing friction between moving parts), engine oil performs what functions? 1. Cools. 2. Seals. 3. Cleans. 4. Prevents corrosion. 5. Cushions impact (shock) loads. A— 1, 2, 3, 4. B— 1, 2, 3, 4, 5. C— 1, 3, 4.

An engine lubricating oil should have a high flash point so that the vapors it gives off can withstand the high temperatures encountered within the engine. The other alternatives listed with this question are characteristics an oil should not have.

8421. Which of these characteristics is desirable in turbine engine oil? A— Low flash point. B— High flash point. C— High volatility.

The viscosity of a liquid is a measure of its ability to flow at a specific temperature. This can be thought of as its resistance to flow.

8422. The viscosity of a liquid is a measure of its A—resistance to flow. B—rate of change of internal friction with change in temperature. C—weight, or density.

the operating load, the rotational speed (the operating speed of the bearing) and the operating temperatures are the most important considerations in determining the proper grade of oil to use in an aircraft engine.

8424. Which of the following factors helps determine the proper grade of oil to use in a particular engine? A— Adequate lubrication in various attitudes of flight. B— Positive introduction of oil to the bearings. C— Operating speeds of bearings.

Specific gravity is the ratio of the weight of a definite volume of the material being measured to an equal volume of pure water (distilled water) at its maximum density (at 4°C).

8425. Specific gravity is a comparison of the weight of a substance to the weight of an equal volume of A— oil at a specific temperature. B— distilled water at a specific temperature. C— mercury at a specific temperature.

Temperature has a greater effect than any of the other choices given here on the viscosity of a lubricating oil.

8426. Which of the following has the greatest effect on the viscosity of lubricating oil? A— Temperature. B— Engine RPM. C— System pressure.

Mineral-based lubricating oils have a much greater chemical stability than do vegetable-based lubricants.

8427. What advantage do mineral base lubricants have over vegetable oil base lubricants when used in aircraft engines? A— Cooling ability. B— Chemical stability. C— Friction resistance.

the most satisfactory lubricants for aircraft engines have either a mineral base or a synthetic base.

8428. The recommended aircraft engine lubricants are A— animal, mineral, or synthetic based. B— mineral or synthetic based. C— vegetable, mineral, or synthetic based.

Some spur gears, and hypoid-type gearing having high tooth pressures and high rubbing velocities, require the use of extreme-pressure (EP) lubricants.

8429. High tooth pressures and high rubbing velocities, such as occur with spur-type gears, require the use of A— an EP lubricant. B— straight mineral oil. C— metallic ash detergent oil.

Some engine manufacturers recommend that new or freshly overhauled engines be operated with straight mineral oil for the first fifty hours or at least until oil consumption stabilizes. After this, AD oil can be used.

8431. What type of oil do most engine manufacturers recommend for new reciprocating engine break-in? A— Ashless-dispersant oil. B— Straight mineral oil. C— Semi-synthetic oil.

After a reciprocating engine is adequately broken in with straight mineral oil, it is recommended that ashlessdispersant (AD) oil be used. AD oil has better lubricating characteristics than straight mineral oil and it is not so likely to form carbon deposits on the engine parts.

8432. What type of oil do most engine manufacturers recommend after new reciprocating engine break-in? A— Metallic-ash detergent oil. B— Ashless-dispersant oil. C— Straight mineral oil.

the oil pumps used in turbojet engine lubrication systems are of the positive displacement type. They may be either the vane type, spur gear type, or the gerotor type.

8433. The type of oil pumps most commonly used on turbine engines are classified as A— positive displacement . B— variable displacement. C— constant speed.

The mixture control of the carburetor or fuel injection system installed on a reciprocating engine should be set in the FULL RICH position for takeoff and high power operation. This mixture provides more fuel than is needed for optimum performance, and the additional fuel is used for engine cooling.

8434. As a general rule, the mixture setting on a reciprocating engine operating at or near takeoff power that provides the best cooling is A— FULL RICH. B— LEAN. C— FULL LEAN.

the oil-temperature control valve sensing unit is located at the inlet to the oil cooler. Hot oil is routed through the core of the cooler, and cold oil is routed around the outside of the core.

8489. Where is the oil of a dry sump reciprocating engine exposed to the temperature control valve sensing unit? A— Oil cooler inlet. B— Engine outlet. C— Engine inlet.

Cooling fins on an air-cooled aircraft engine are located on the cylinder head, the cylinder barrel and the inside of the piston heads.

8820. Where are cooling fins usually located on air-cooled engines? A— Exhaust side of the cylinder head, inside the pistons, and connecting rods . B— Cylinder head, cylinder walls, and inside the piston. C— Cylinder head, cylinder barrel, and inside the piston.

The amount of air that can flow through the cylinder fins is determined by the air-pressure differential between the top of the engine and the space below the engine. On most high-powered horizontally opposed engines, this pressure differential can be controlled with cowl flaps.

8821. How do cowl flaps aid in cooling a horizontally opposed aircraft engine? A— Recirculates air through the engine cylinders . B— Directs air through the engine cylinders. C— Controls the amount of air flowing around the cylinders.

Cowl flaps should be kept fully open when the engine is run on the ground. In flight, the cowl flaps are closed as there is enough ram air flowing through the engine for adequate cooling.

8822. The position of the cowl flaps during normal cruise f light conditions is A— closed. B— open. C— one half open.

mall cracks in a cylinder baffle that have just started can be stop-drilled to prevent them from growing.

8823. Generally, a small crack just started in a cylinder baffle A—requires repair by reinforcing, such as installation of a doubler over the area. B—requires no action unless it grows or is branched into two cracks. C—may be stop drilled.

Baffles and a cowling arrangement are used to force cooling air between the fins of an air-cooled cylinder for better cooling.

8824. Which of the following assists in removing heat from the metal walls and fins of an air-cooled cylinder assembly? A— An intercooler system. B— A baffle and cowl arrangement. C— An engine induction system.

For ground operation of an aircraft reciprocating engine, the cowl flaps should be fully open.

8825. During ground operation of an engine, the cowl f laps should be in what position? A— Fully closed. B— Fully open. C— Opened according to ambient conditions.

When any electric motor fails to operate, the first thing to check is its circuit breaker.

8827. During an operational check of an electrically powered aircraft engine cowl flap system, the motor fails to operate. Which of the following is the first to be checked? A— Flap actuator motor circuit breaker. B— Flap actuator control switch. C— Flap actuator motor.

If too much cooling-fin area is broken off of a cylinder, that particular area in the cylinder will not be properly cooled and it will develop a hot spot.

8829. Which of the following defects would likely cause a hot spot on a reciprocating engine cylinder? A— Too much cooling fin area broken off. B— A cracked cylinder baffle. C— Cowling air seal leakage.

The area around the exhaust valve port on the cylinder head of an air-cooled aircraft engine cylinder has the greatest fin area per square inch.

8830. What part of an air-cooled cylinder assembly has the greatest fin area per square inch? A— Cylinder barrel. B— Rear of the cylinder head. C— Exhaust valve port.

Helicopters cool their reciprocating engines with a fan mounted on the engine. This fan pulls air through the fins on the cylinders.

8831. Reciprocating engines used in helicopters are cooled by A— the downdraft from the main rotor. B— a fan mounted on the engine. C— blast tubes on either side of the engine mount.

The primary purpose of the oil-to-fuel heat exchanger is to remove heat from the engine lubricating oil (to cool the oil). A secondary purpose of the oil-to-fuel heat exchanger is to raise the temperature of the fuel to prevent water in the fuel from precipitating out and freezing on the fuel f ilters.

What is the primary purpose of the oil-to-fuel heat exchanger? A— Cool the fuel. B— Cool the oil. C— De-aerate the oil.

Approximately 45% of the heat energy in the fuel burned in an aircraft engine is carried out the exhaust with the exhaust gases. Another 20% is dissipated through the cylinder heads and walls, and about 5% is removed by the oil system. Only about 30% is converted into useful power.

8832. The greatest portion of heat generated by combustion in a typical aircraft reciprocating engine is A— converted into useful power. B— carried out with the exhaust gases. C— dissipated through the cylinder walls and heads.

A broken cooling fin on a cylinder head can be repaired by filing the edges to a smooth contour. This type of repair can be made only if the amount of fin area remaining after the repair is completed is within the limits allowed by the engine manufacturer.

8833. A broken cooling fin on a cylinder head A— is cause for rejection of the head. B— may be filed to smooth contours if damage and/or repair limits are not exceeded. C— should be left alone.

If an engine is overheated from excessive taxiing or improper ground operation, it should be cooled down by operating it at idle RPM for a while before it is shut down.

8834. An engine becomes overheated due to excessive taxiing or improper ground runup. Prior to shutdown, operation must continue until cylinders have cooled, by running engine at A— low RPM with oil dilution system activated. B— idle RPM. C— high RPM with mixture control in rich position.

Cylinder head temperature is normally measured by a thermocouple-type system.

8835. Cylinder head temperatures are measured by means of an indicator and a A— resistance bulb sensing device. B— wheatstone bridge sensing device. C— thermocouple sensing device.

An excessively lean mixture will cause a high cylinder head temperature because some of the mixture will be burning when it passes out of the cylinder around the exhaust valve.

8836. High cylinder head temperatures are likely to result from A— a very lean mixture at high power settings. B— fouled spark plugs. C— a very rich mixture at high power settings.

Intercoolers are used with large turbosuperchargers to cool the air that has been heated by compression before it enters the carburetor.

8837. The purpose of an intercooler when used with a turbocharger is to cool the A— exhaust gases before they come in contact with the turbo drive. B— turbocharger bearings. C— air entering the carburetor from the turbocharger.

Prolonged idling of an aircraft engine will normally cause spark plugs to foul by allowing foreign material to accumulate in their firing-end cavity.

8838. Prolonged idling of an engine will usually result in A— excessive cylinder head temperatures. B— increased oil consumption. C— foreign material buildup on spark plugs.

The most widely used method of conducting heat away from the cylinder barrel of an air-cooled engine is by machining fins directly on the outside of the barrel.

8839. The most common method and generally the best conduction of heat from the inside of a cylinder barrel to the cooling air is accomplished by A— machining fins directly on the outside of the barrel. B— shrinking on a jacket or muff of aluminum cooling f ins around a steel cylinder sleeve. C— machining fins directly on the outside of the barrel and shrinking on a jacket or muff of aluminum cooling fins around a steel cylinder sleeve (on different areas of the barrel).

blast tube is used on an air-cooled engine to direct a stream of cooling air to some engine accessory, such as a magneto or a generator.

8840. What is the function of a blast tube as found on aircraft engines? A— A means of cooling the engine by utilizing the propeller backwash. B— A tube used to load a cartridge starter. C— A device to cool an engine accessory.

Part-throttle operation lowers the volumetric efficiency of a reciprocating engine. It does not allow a full charge of fuel and air to be drawn into the cylinder as the piston moves down on the intake stroke.

8842. Which of the following results in a decrease in volumetric efficiency? A— Cylinder head temperature too low. B— Part-throttle operation. C— Short intake pipes of large diameter.

the undersides of pistons are frequently finned to provide a greater area for oil to absorb heat from the piston heads.

8843. The undersides of pistons are frequently finned. The principal reason is to A— provide sludge chambers and sediment traps. B— provide for greater heat transfer to the engine oil. C— support ring grooves and piston pins.

Many large aircraft reciprocating engines have a compensating oil pressure relief valve that allows the oil pressure for cold oil to be considerably higher than it allows for warm oil. This higher pressure allows the thicker, higher viscosity oil to be forced through the engine bearings. The plunger of the oil-pressure relief valve is held down by two springs when the oil is cold. However, when the oil warms up, a thermostatic valve opens and allows oil pressure to remove the force of one of the springs. For normal operation, only one spring holds the pressure relief valve on its seat.

457. Some larger reciprocating engines use a compensating oil pressure relief valve to A— provide a high engine oil pressure when the oil is cold and automatically lower the oil pressure when the oil warms up. B— compensate for changes in atmospheric pressure that accompany altitude changes. C— automatically keep oil pressure nearly the same whether the oil is warm or cold.

Statement (1) is true. The augmenter system draws additional air over the engine for cooling. Statement (2) is also true. Augmenter tubes open into the lower rear of the aircraft engine cowling. Exhaust gases f lowing through the tube create a low pressure inside the cowling that draws air from above the engine through the cooling fins.

828. (1) Some aircraft exhaust systems include an augmenter system to draw additional air over the engine for cooling. (2) Augmenter systems are used to create a low pressure area at the lower rear of the aircraft engine cowling. Regarding the above statements, A— only No. 1 is true. B— both No. 1 and No. 2 are true. C— only No. 2 is true.

if an oil recommended for low-temperature operation is used in an engine when it is operating in high-temperature conditions, the oil will have a lower viscosity than should be used in the engine. Therefore, the oil pressure will be lower than recommended.

8411. What will be the result of operating an engine in extremely high temperatures using a lubricant recommended by the manufacturer for a much lower temperature? A— The oil pressure will be higher than normal. B— The oil temperature and oil pressure will be higher than normal. C— The oil pressure will be lower than normal.

Statement (1) is not true. The lubricating requirements of a turbine engine are quite different from those of a reciprocating engine. Therefore, the types of oil used in the two engines are different. Statement (2) is true because most of the lubricating oils used in turbine engines have a synthetic base.

8412. (1) Gas turbine and reciprocating engine oils can be mixed or used interchangeably. (2) Most gas turbine engine oils are synthetic. Regarding the above statements, A— only No. 2 is true. B— both No. 1 and No. 2 are true. C— neither No. 1 nor No. 2 is true.

An oil separator is used with a "wet"-type engine-driven vacuum pump. Wet-type vacuum pumps are lubricated by oil flowing through the pump and it is discharged with the air that leaves the pump. An oil separator in the discharge line separates the oil from the air. The air is discharged overboard or used in the deicer boots and the oil is returned to the engine crankcase.

8413. An oil separator is generally associated with which of the following? A— Engine-driven oil pressure pump. B— Engine-driven vacuum pump. C— Cuno oil filter.

The method of determining the viscosity of an oil described here is the procedure used to find the Seconds Saybolt Universal (SSU) viscosity of the oil. The SSU viscosity is usually converted into SAE viscosity which is more familiar to A&P mechanics.

8414. The time in seconds required for exactly 60 cubic centimeters of oil to flow through an accurately calibrated orifice at a specific temperature is recorded as a measurement of the oil's A— flash point. B— specific gravity. C— viscosity.

The viscosity index of an oil is a measure of the rate of change of the viscosity of the oil with a change in its temperature.

8415. Upon what quality or characteristic of a lubricating oil is its viscosity index based? A— Its resistance to flow at a standard temperature as compared to high grade paraffin-base oil at the same temperature. B— Its rate of change in viscosity with temperature change. C— Its rate of flow through an orifice at a standard temperature.

The viscosity index of an oil is a measure of the rate of change of the viscosity with a change in its temperature. The higher the viscosity index of an oil, the less the viscosity changes as its temperature changes.

8416. Lubricating oils with high viscosity index ratings are oils A— in which the viscosity does not vary much with temperature change. B— in which the viscosity varies considerably with temperature change. C— which have high SAE numbers.

Synthetic oil used in turbine engines has two advantages over petroleum oil. It has less tendency to deposit lacquer and coke and it has less tendency to evaporate at high temperature.

8417. Compared to reciprocating engine oils, the types of oils used in turbine engines A— are required to carry and disperse a higher level of combustion by-products. B— may permit a somewhat higher level of carbon formation in the engine. C— have less tendency to produce lacquer or coke.

The oil used in reciprocating engines has a relatively high viscosity because of: 1. Large engine operating clearances due to the relatively large size of the moving parts, the different materials used and the different rates of expansion of the various materials 2. High operating temperatures 3. High bearing pressures

8418. The oil used in reciprocating engines has a relatively high viscosity due to A— the reduced ability of thin oils to maintain adequate film strength at altitude (reduced atmospheric pressure). B— the relatively high rotational speeds. C— large clearances and high operating temperatures.

An ideal engine oil is one with a low viscosity (it is thin and pours easily). The low viscosity allows it to circulate easily within the engine. It must also maintain a reasonable film strength so the lubricating film will not break down at the high operating pressures and temperatures encountered within the engine.

8419. If all other requirements can be met, what type of oil should be used to achieve theoretically perfect engine lubrication? A— The thinnest oil that will stay in place and maintain a reasonable film strength. B— An oil that combines high viscosity and low demulsibility. C— An oil that combines a low viscosity index and a high neutralization number.

The oil-temperature regulator on a dry-sump reciprocating aircraft engine controls the temperature of the oil by directing it either through the core of the cooler or around the core. The oil cooler is located between the scavenger-pump outlet and the storage tank.

8435. The engine oil temperature regulator is usually located between which of the following on a dry sump reciprocating engine? A— The engine oil supply pump and the internal lubrication system. B— The scavenger pump outlet and the oil storage tank. C— The oil storage tank and the engine oil supply pump.

The scavenger pump pumps the oil from the engine through the cooler to the oil tank. If the line between the scavenger pump and the oil cooler separates, the scavenger pump will pump all of the return oil overboard.

8436. What will happen to the return oil if the oil line between the scavenger pump and the oil cooler separates? A— Oil will accumulate in the engine. B— The return oil will be pumped overboard. C— The scavenger return line check valve will close and force the oil to bypass directly to the intake side of the pressure pump.

At cruise RPM, the engine oil pressure pump produces more flow at the pressure at which the oil-pressure relief valve is set than is needed to lubricate the engine. Some of the oil will bypass back into the inlet side of the pump through the oil pressure relief valve.

8437. At cruise RPM, some oil will flow through the relief valve of a gear-type engine oil pump. This is normal as the relief valve is set at a pressure which is A— lower than the pump inlet pressure. B— lower than the pressure pump capabilities. C— higher than pressure pump capabilities.

In a reciprocating engine lubrication system, the oil temperature bulb senses the oil temperature at a point after the oil has passed through the oil cooler. The temperature shown in the cockpit is the temperature of the oil as it enters the engine.

8439. In a reciprocating engine oil system, the temperature bulb senses oil temperature A— at a point after the oil has passed through the oil cooler. B— while the oil is in the hottest area of the engine. C— immediately before the oil enters the oil cooler.

The oil tank vent prevents the pressure in the oil tank used with a reciprocating engine rising above or falling below the ambient pressure.

8443. What prevents pressure within the lubricating oil tank from rising above or falling below ambient pressure (reciprocating engine)? A— Oil tank check valve. B— Oil pressure relief valve. C— Oil tank vent.

4 CFR §23.1557(c)(2) states "Oil filler openings must be marked at or near the filler cover with the word "Oil" and the permissible oil designations, or references to the Airplane Flight Manual (AFM) for permissible oil designations."

8447-2. Oil tank fillers on reciprocating engines are marked with the word A— "oil," and tank capacity, in accordance with 14 CFR part 45. B— "oil," type, and grade, in accordance with 14 CFR part 33. C— "oil," in accordance with 14 CFR part 23.

A magnetic chip detector warns of possible impending engine failure by indicating the presence of ferrous metal particles. If these particles are present in the oil, they will bridge the gap in the detector between the center electrode and ground electrode, completing an electrical circuit to illuminate a warning light in the cockpit.

8450. Possible failure related ferrous-metal particles in turbine engine oil cause an (electrical) indicating-type magnetic chip detector to indicate their presence by A— disturbing the magnetic lines of flux around the detector tip. B— bridging the gap between the detector center (positive) electrode and the ground electrode . C— generating a small electric current that is caused by the particles being in contact with the dissimilar metal of the detector tip.

The oil-pressure relief valve in the lubrication system of an aircraft engine is adjusted to maintain the desired system pressure. Pressure above that for which the relief valve is set, lifts the valve off its seat and bypasses the oil that caused the excess pressure back to the inlet side of the oil pump.

8453. What unit in an aircraft engine lubrication system is adjusted to maintain the desired system pressure? A— Oil pressure relief valve. B— Oil viscosity valve. C— Oil pump.

il pressure above that recommended by the engine manufacturer should be avoided because excessive oil pressure can damage oil coolers and burst oil lines. A burst oil line could cause a loss of all of the lubricating oil.

8454. Low oil pressure can be detrimental to the internal engine components. However, high oil pressure A— should be limited to the engine manufacturer's recommendations. B— has a negligible effect. C— will not occur because of pressure losses around the bearings.

Almost all aircraft engines have a pressure pump whose output exceeds the demands of the engine. A relief valve is incorporated in the pressure portion of the system to relieve excess pressure back to the inlet of the pump.

8458. In order to relieve excessive pump pressure in an engine's internal oil system, most engines are equipped with a A— vent. B— bypass valve. C— relief valve.

Engine lubricating oil absorbs as much heat as possible from all of the lubricated surfaces, but they absorb the most heat from the under side of the piston head and from the cylinder walls.

8459. What is the source of most of the heat that is absorbed by the lubricating oil in a reciprocating engine? A— Crankshaft main bearings. B— Exhaust valves. C— Pistons and cylinder walls.

The gear teeth in the accessory section of an engine are lubricated by oil that is sprayed from the accessory shaft bearings and splashed around inside the accessory case.

8460. How are the teeth of the gears in the accessory section of an engine normally lubricated? A— By splashed or sprayed oil. B— By submerging the load-bearing portions in oil. C— By surrounding the load-bearing portions with baffles or housings within which oil pressure can be maintained.

the check valve in the dry-sump lubrication system of a reciprocating engine prevents oil from the tank from seeping into the crankcase during the times when the engine is not operating.

8461. What is the purpose of the check valve generally used in a dry sump lubrication system? A— To prevent the scavenger pump from losing its prime. B— To prevent the oil from the supply tank from seeping into the crankcase during inoperative periods. C— To prevent the oil from the pressure pump from entering the scavenger system.

the mechanical efficiency of an engine (the ratio of the power delivered to the propeller shaft to the power produced in the engine) has the least effect on the oil consumption of any of the other items listed in this question. The engine RPM and the characteristics of the lubricant definitely affect the oil consumption of an aircraft engine.

8462. From the following, identify the factor that has the least effect on the oil consumption of a specific engine. A— Mechanical efficiency. B— Engine RPM. C— Lubricant characteristics.

the oil collected by the oil control ring on a piston is returned to the crankcase through holes drilled in the piston ring groove.

8463. How is the oil collected by the piston oil ring returned to the crankcase? A— Down vertical slots cut in the piston wall between the piston oil ring groove and the piston skirt. B— Through holes drilled in the piston oil ring groove. C— Through holes drilled in the piston pin recess.

The fuel line where the gasoline is directed into the lubricating oil to dilute it for cold-weather starting is connected into the lubricating system where the oil pressure is the same as it is inside the oil tank. Fuel is never fed into the oil between the pressure pump and the pressure system.

8464. Which of the following lubrication system components is never located between the pressure pump and the engine pressure system? A— Oil temperature bulb. B— Fuel line for oil dilution system. C— Check valve.

some aircraft engines are equipped with an oil dilution system that puts gasoline from the aircraft fuel tanks into the engine oil before the engine is shut down at night. The oil is thinned, or diluted, and the friction from the cold oil is greatly reduced for cold-weather starting. When the engine starts and the oil warms up, the gasoline evaporates from it.

8465. As an aid to cold-weather starting, the oil dilution system thins the oil with A— kerosene. B— alcohol. C— gasoline.

The initial oil-pressure relief valve setting for a newly overhauled engine is made in the overhaul shop. If the pressure is not correct when the engine is started, it can be adjusted.

8466. The basic oil pressure relief valve setting for a newly overhauled engine is made A— within the first 30 seconds of engine operation. B— when the oil is at a higher than normal temperature to assure high oil pressure at normal oil temperature. C— in the overhaul shop.

The oil-temperature bulb is located in the line between the oil tank and the inlet of the pressure pump on a dry-sump reciprocating engine. Oil temperature measured at this point is oil-inlet temperature.

8467. Where is the oil temperature bulb located on a dry sump reciprocating engine? A— Oil inlet line. B— Oil cooler. C— Oil outlet line.

The cylinder walls of an aircraft reciprocating engine are lubricated by oil that is either sprayed on them from the main bearing of the crankshaft or else splashed on them.

8468. Cylinder walls are usually lubricated by A— splashed or sprayed oil. B— a direct pressure system fed through the crankshaft, connecting rods, and the piston pins to the oil control ring groove in the piston. C— oil that is picked up by the oil control ring when the piston is at bottom center.

In case an oil filter element becomes completely clogged, provisions are made (usually a bypass valve) to provide oil to the bearings. If the filter clogs, the bypass valve will open and allow the pump to supply the engine with unfiltered oil. It is much better to have unfiltered oil going through the engine than for the engine to have no oil.

8469. If an oil filter element becomes completely clogged, the A— oil supply to the engine will be blocked. B— oil will be bypassed back to the oil tank hopper where larger sediments and foreign matter will settle out prior to passage through the engine. C— bypass valve will open and the oil pump will supply unfiltered oil to the engine.

Cylinders of inverted in-line engines and radial engines have skirts that extend up into the crankcase far enough to prevent oil flooding the lower cylinders. These extended skirts do not prevent oil from getting into the cylinders, but they do minimize it. Engines with cylinders extending below the center line should be pulled through by hand before they are started to be sure there is no oil in any of the lower cylinders.

8470. Oil accumulation in the cylinders of an inverted inline engine and in the lower cylinders of a radial engine is normally reduced or prevented by A— reversed oil control rings. B— routing the valve-operating mechanism lubricating oil to a separate scavenger pump. C— extended cylinder skirts.

Oil used in an aircraft engine becomes contaminated with gasoline, moisture, acids, dirt, carbon and metallic particles. Because of the accumulation of these harmful substances, the oil used in an engine should be periodically drained and replaced with fresh oil.

8471. What is the primary purpose of changing aircraft engine lubricating oils at predetermined periods? A— The oil becomes diluted with gasoline washing past the pistons into the crankcase. B— The oil becomes contaminated with moisture, acids, and finely divided suspended solid particles. C— Exposure to heat and oxygen causes a decreased ability to maintain a film under load.

Cuno filter separates contaminants from the oil by passing the oil between the disks in a stack. The thickness of the spacers between the disks determines the separation of the disks. This separation determines the minimum particle size that can be filtered out of the oil.

8472. What determines the minimum particle size which will be excluded or filtered by a cuno-type (stacked disc, edge filtration) filter? A— The disc thickness. B— The spacer thickness. C— Both the number and thickness of the discs in the assembly.

A hopper in the oil supply tank of some dry-sump engine installations reduces the time needed to warm the oil up to its operating temperature. When the oil is cold, the oil in the hopper, rather than in the entire tank, is circulated through the engine. As the oil warms up, the oil surrounding the hopper gradually feeds into the oil flowing through the engine. When it is necessary to dilute the oil, gasoline is added so it mixes with the circulating oil. This diluted oil remains in the hopper where it is the first oil used when the engine is started.

8473. What is the primary purpose of the hopper located in the oil supply tank of some dry sump engine installations? A— To reduce the time required to warm the oil to operating temperatures. B— To reduce surface aeration of the hot oil and thus reduce oxidation and the formation of sludge and varnish. C— To impart a centrifugal motion to the oil entering the tank so that the foreign particles in the oil will separate more readily.

The flow control valve in an oil cooler used on an aircraft reciprocating engine determines which of two possible paths the oil takes as it passes through the oil cooler. If the oil is hot, the valve directs it through the core of the cooler where the heat can be removed. If the oil is not hot, it is bypassed around the outside of the core of the cooler.

8474. The purpose of the flow control valve in a reciprocating engine oil system is to A— direct oil through or around the oil cooler. B— deliver cold oil to the hopper tank. C— compensate for volumetric increases due to foaming of the oil.

Sludge chambers are used inside the crankshaft throws of a reciprocating engine. Sludge is thrown by centrifugal force away from the oil passages in these chambers. It is held there until the engine is overhauled.

8475. Where are sludge chambers, when used in aircraft engine lubrication systems, usually located? A— In the crankshaft throws. B— Adjacent to the scavenger pumps. C— In the oil storage tank.

oil tanks used in dry-sump lubrication systems of aircraft reciprocating engines are vented to the engine. The engine crankcase is then vented to the outside air. This venting system prevents the heating and expansion of the oil from causing a buildup of air pressure inside the oil tank.

8476. Why is an aircraft reciprocating engine oil tank on a dry sump lubrication system equipped with a vent line? A— To prevent pressure buildup in the reciprocating engine crankcase. B— To eliminate foaming in the oil tank. C— To prevent pressure buildup in the oil tank.

Oil control rings on the pistons of a reciprocating engine control the amount of oil allowed to remain on the cylinder walls.

8477. Excessive oil is prevented from accumulating on the cylinder walls of a reciprocating engine by ' A— the design shape of the piston skirt. B— internal engine pressure bleeding past the ring grooves. C— oil control rings on the pistons.

The scavenger pump in a dry-sump aircraft-engine lubricating system has a greater capacity than the pressure pump. The oil returned to the tank by the scavenger pump has a greater volume than the oil moved by the pressure pump because it is hotter and has air trapped in it.

8479. The pumping capacity of the scavenger pump in a dry sump aircraft engine's lubrication system A— is greater than the capacity of the oil supply pump. B— is less than the capacity of the oil supply pump. C— is usually equal to the capacity of the oil supply pump in order to maintain constant oiling conditions.

When the engine oil is below its normal operating temperature, the automatic bypass valve is wide open. This wide-open valve allows the oil to completely bypass the cooler. As the oil warms up, the automatic bypass valve closes and directs the oil through the core of the cooler so it can be cooled.

8480. In which of the following situations will the oil cooler automatic bypass valve be open the greatest amount? A— Engine oil above normal operating temperature. B— Engine oil below normal operating temperature. C— Engine stopped with no oil flowing after runup.

In order to maintain a constant oil pressure as the clearances between the moving parts of an engine increase through normal wear, the output of the oil pressure pump remains relatively constant for any given RPM. But, since there is more oil flowing out through the bearings and other moving parts, less oil is returned to the inlet side of the pump by the relief valve.

8481. In order to maintain a constant oil pressure as the clearances between the moving parts of an engine increase through normal wear, the supply pump output A— increases as the resistance offered to the flow of oil increases. B— remains relatively constant (at a given RPM) with less oil being returned to the pump inlet by the relief valve . C— remains relatively constant (at a given RPM) with more oil being returned to the pump inlet by the relief valve.

The valve assemblies of opposed reciprocating engines are lubricated by the pressure system. Oil under pressure flows through the hydraulic tappet bodies and through hollow pushrods to the rocker arms where it lubricates the rocker arm bearings and the valve stems. The oil then drains back into the crankcase through either the pushrod housing or an external oil line from the rocker box to the crankcase.

8482. The valve assemblies of opposed reciprocating engines are lubricated by means of a A— gravity feed system. B— splash and spray system. C— pressure system.

14 CFR Part 33 "Airworthiness Standards for Aircraft Engines" requires that an aircraft-engine oil strainer must be constructed and installed in such a way that oil will flow through the engine at its normal rate, even though the strainer or filter element is completely blocked.

8483. What will result if an oil filter becomes completely blocked? A— Oil will flow at a reduced rate through the system. B— Oil flow to the engine will stop. C— Oil will flow at the normal rate through the system.

Piston pins in an aircraft reciprocating engine are lubricated by oil sprayed or thrown out by the master rod or connecting rod into the inside of the piston. Oil thrown up into the piston lubricates the piston pin in both the piston and in the small end of the connecting rod.

8486. How are the piston pins of most aircraft engines lubricated? A— By pressure oil through a drilled passageway in the heavy web portion of the connecting rod. B— By oil which is sprayed or thrown by the master or connecting rods. C— By the action of the oil control ring and the series of holes drilled in the ring groove directing oil to the pin and piston pin boss.

Oil supply tanks used with dry-sump engines are normally vented to the engine crankcase. The crankcase is, in turn, vented to the outside air. This method of venting provides adequate ventilation of the tank and prevents the loss of oil through the vents.

8487. The vent line connecting the oil supply tank and the engine in some dry sump engine installations permits A— pressurization of the oil supply to prevent cavitation of the oil supply pump. B— oil vapors from the engine to be condensed and drained into the oil supply tank. C— the oil tank to be vented through the normal engine vent.

The pressure relief valve in an engine lubrication system is located between the pump and the internal oil system to maintain the pressure of the oil being moved by the pump at the pressure required for the operation of the engine. Flow caused by excess pressure is dumped back into the inlet of the pump.

8488. An engine lubrication system pressure relief valve is usually located between the A— oil cooler and the scavenger pump. B— scavenger pump and the external oil system. C— pump and the internal oil system.

The oil-cooler flow control valve is normally open when the oil does not need cooling (when the oil temperature is too low). The oil passes through the open valve and around the oil cooler core. When the oil temperature becomes high enough that it needs to be cooled, this valve closes and the oil flows through the cooler core where it gives up some of its heat to the air.

8490. Under which of the following conditions is the oil cooler flow control valve open on a reciprocating engine? A— When the temperature of the oil returning from the engine is too high. B— When the temperature of the oil returning from the engine is too low. C— When the scavenger pump output volume exceeds the engine pump input volume.

the oil-pressure relief valve in a reciprocating engine relieves the oil back to the inlet side of the pressure pump.

8492. In a reciprocating engine, oil is directed from the pressure relief valve to the inlet side of the A— scavenger pump. B— oil temperature regulator. C— pressure pump.

If oil becomes congealed in the core of a cooler because of its low temperature, the surge protection valve in the cooler will open and allow the oil to flow around the core of the cooler through an annular jacket. The operating engine oil flowing through this jacket will warm up the oil in the core so it will liquify and return to the lubrication system.

8493. If the oil in the oil cooler core and annular jacket becomes congealed, what unit prevents damage to the cooler? A— Oil pressure relief valve. B— Airflow control valve. C— Surge protection valve.

The primary source of oil contamination, which is present under all operating conditions, is the combustion deposits due to combustion chamber blow-by and oil that has become overheated by its contact with the cylinder walls.

8494. The primary source of oil contamination in a normally operating reciprocating engine is A— metallic deposits as a result of engine wear. B— atmospheric dust and pollution. C— combustion deposits due to combustion chamber blow-by and oil migration on the cylinder walls.

If foreign material becomes caught under the relief valve, it will hold the valve off its seat and cause the oil pressure to drop.

8495. A drop in oil pressure may be caused by A— the temperature regulator sticking open. B— the bypass valve sticking open. C— foreign material under the relief valve.

The main oil filter in an aircraft engine strains the oil just after it leaves the pressure pump.

8496. The main oil filters strain the oil at which point in the system? A— Immediately after it leaves the scavenger pump. B— Immediately before it enters the pressure pump. C— Just as it leaves the pressure pump.

A check valve in an engine lubricating system prevents oil from the tank from entering the accessory case when the engine is not running.

8497. Which type valve prevents oil from entering the main accessory case when the engine is not running? A— Bypass. B— Relief. C— Check.

An oil tank must have an expansion space of not less than 10% of the tank capacity, or one-half gallon. The required expansion space for a five-gallon oil tank is one-half gallon, which is two quarts.

8498. An oil tank having a capacity of 5 gallons must have an expansion space of A— 2 quarts. B— 4 quarts. C— 5 quarts.

An expansion space is required in an engine oil tank because the oil expands (enlarges) when it gets hot and when it collects foam.

8500. Why is expansion space required in an engine oil supply tank? A— To eliminate oil foaming. B— For oil enlargement and collection of foam. C— For proper oil tank ventilation.

Friction-type bearings, which are usually called plain bearings, must be continuously lubricated by pressure oil

8502. Which of the following bearing types must be continuously lubricated by pressure oil? A— Ball. B— Roller. C— Plain.

Baffles and deflectors force the cooling air into close contact with the fins of an aircraft cylinder head and cylinder barrel. This directed flow of air aids in efficient and uniform cooling of the cylinder.

8814. The primary purpose of baffles and deflectors installed around cylinders of air-cooled aircraft engines is to A— create a low pressure area aft of the cylinders. B— force cooling air into close contact with all parts of the cylinders. C— increase the volume of air used to cool the engine.

Augmenters are venturi-shaped stainless steel tubes into which the exhaust gases from a reciprocating engine are directed. The augmenters use the venturi effect to draw an increased airflow over the engine to augment (increase) the engine cooling.

8815. What is the purpose of an augmenter used in some reciprocating engine exhaust systems? A— To reduce exhaust back pressure. B— To aid in cooling the engine. C— To assist in displacing the exhaust gases.

It is extremely important that cylinder baffles and deflectors be kept in a good state of repair. Leaking baffles or improperly oriented deflectors can cause a loss of cooling which can cause engine damage.

8816. Aircraft reciprocating engine cylinder baffles and deflectors should be repaired as required to prevent loss of A— power. B— fin area. C— cooling.

If cooling fins are cracked, the affected area may be removed and the fins contour-filed. This repair is permitted only if the finished repair leaves the amount of fin area on the cylinder that is specified by the engine manufacturer.

8817. Cracks in cooling fins that do not extend into the cylinder head may be repaired by A— filling the extremities of crack with liquid metal. B— removing affected area and contour filing within limits. C— welding and then grinding or filing to original thickness.

Anytime there is a question about what can be done to an aircraft engine, information in the engine manufacturer's service or overhaul manual must be consulted and complied with.

8818. Which of the following should a mechanic consult to determine the maximum amount of cylinder cooling fin that could be removed when cracks are found? A— AC 43.13-1A. B— Engine manufacturer's service or overhaul manual. C— Engine structure repair manual.

A bent cooling fin on a cast-aluminum cylinder head should be left alone if it has not cracked. Attempting to straighten the thin cast fin could cause it to crack.

8819. A bent cooling fin on an aluminum cylinder head A— should be sawed off and filed smooth. B— should be left alone if no crack has formed. C— should be stop drilled or a small radius filed at the point of the bend.