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FAA Aviation Mechanic - Powerplant (AMP) study materials
FAA Aviation Mechanic - Powerplant (AMP) study resources

FAA Aviation Mechanic - Powerplant (AMP) practice questions

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Question 1Reciprocating Engines

In what order does a four-stroke-cycle reciprocating engine complete its operating events?

  1. Intake, power, compression, exhaust
  2. Intake, compression, power, exhaust Correct answer.
  3. Compression, intake, power, exhaust
  4. Power, intake, compression, exhaust

Explanation

Each cylinder of a four-stroke engine completes one power cycle in four piston strokes: intake draws in the charge, compression raises its pressure and temperature, power converts combustion energy into work, and exhaust expels the burned gases. One complete cycle requires two crankshaft revolutions.

Question 2Reciprocating Engines

Why must a clearance be maintained between the valve stem and its actuating mechanism?

  1. Allows lubricating oil to drain from the rocker box back to the crankcase
  2. Holds the valve closed against the spring at high cylinder pressures
  3. Provides room for the valve train parts to expand as the engine warms Correct answer.
  4. Prevents the valve from rotating in its guide during engine operation

Explanation

Valve train components lengthen as they reach operating temperature. The specified clearance absorbs that expansion so the valve can still seat fully; if clearance is lost, the valve may be held partly open and burn.

Question 3Reciprocating Engines

Compression ratio, as applied to a reciprocating engine cylinder, is defined as which of the following?

  1. The ratio of the cylinder bore diameter to the length of the piston stroke
  2. The ratio of the total intake valve area to the total exhaust valve area
  3. The ratio of manifold pressure to standard sea level atmospheric pressure
  4. The ratio of the cylinder volume at BDC to the volume at TDC Correct answer.

Explanation

Compression ratio compares the volume above the piston at bottom dead center with the volume remaining at top dead center. A higher ratio yields higher compression pressure and greater thermal efficiency, but requires higher-octane fuel.

Question 4Reciprocating Engines

What is the primary purpose of the counterweights attached to a crankshaft?

  1. To offset the weight of the pistons and connecting rods Correct answer.
  2. To increase the rotational inertia of the crankshaft at low engine speeds
  3. To help throw lubricating oil onto the cylinder walls and pistons
  4. To provide a mounting surface for the propeller mounting flange

Explanation

Counterweights oppose the centrifugal loads created by the crankshaft throws, connecting rods, and pistons. Balancing these forces reduces vibration and bending loads on the crankshaft and main bearings.

Question 5Reciprocating Engines

In a typical aircraft reciprocating engine cylinder, which valve is made larger and why?

  1. Both valves are the same size in a given cylinder
  2. The exhaust valve, to speed the removal of burned gases
  3. The intake valve, to improve the cylinder's ability to take in a full charge Correct answer.
  4. The exhaust valve, because it must pass a larger volume of hot gas

Explanation

The intake valve is normally larger than the exhaust valve so the incoming fuel-air charge can enter with minimum restriction, improving volumetric efficiency. Exhaust gases leave under pressure and do not require as large an opening.

Question 6Reciprocating Engines

What is the function of the oil control ring on an aircraft piston?

  1. Seal combustion gases against leakage past the piston into the crankcase
  2. Retain the wrist pin in the piston bosses during engine operation
  3. Keep the piston centered in the cylinder bore through the full stroke
  4. Control the amount of oil left on the cylinder wall Correct answer.

Explanation

The oil control ring scrapes surplus oil from the cylinder wall and returns it through holes in the ring groove to the crankcase. This limits the amount of oil that reaches the combustion chamber and is burned.

Question 7Reciprocating Engines

Which operating condition is most likely to produce detonation in a reciprocating engine?

  1. Using fuel with an octane rating higher than the engine requires
  2. Operating with low oil temperature and high oil pressure
  3. High manifold pressure, lean mixture, and hot cylinders Correct answer.
  4. Cruising at low power with a rich mixture and cool cylinders

Explanation

Detonation occurs when the unburned portion of the charge ignites spontaneously from heat and pressure ahead of the normal flame front. High manifold pressure, a lean mixture, and high cylinder temperatures all raise peak pressure and temperature and promote this condition.

Question 8Reciprocating Engines

Which condition is a common cause of preignition?

  1. An excessively rich mixture during climb at high altitude
  2. A fuel with an octane rating higher than the engine requires
  3. A glowing carbon deposit or overheated spark plug electrode Correct answer.
  4. Ignition timing that is excessively retarded at cruise power

Explanation

Preignition occurs when the charge is ignited before the spark by a hot spot in the cylinder, such as glowing carbon, an overheated spark plug, or a overheated exhaust valve. The charge burns while the piston is still approaching top dead center, causing severe temperature and pressure rise.

Question 9Reciprocating Engines

During a differential compression test, air is heard escaping through the crankcase breather. This indicates leakage past which component?

  1. The exhaust valve is burned or warped
  2. The intake valve is leaking at its seat
  3. The spark plug is loose in its boss
  4. The piston rings are worn or broken Correct answer.

Explanation

Air that reaches the crankcase must have passed the piston rings, so flow at the breather or oil filler points to ring and cylinder wall condition. Leakage at a valve would instead be heard at the intake or exhaust opening of that cylinder.

Question 10Reciprocating Engines

What is the purpose of designing valve overlap into an aircraft engine's valve timing?

  1. Reduce cylinder head temperature at high power settings by purging residual gases
  2. Prevent detonation when manifold pressure is high and the mixture is lean
  3. Improve volumetric efficiency by using exhaust gas inertia to help fill the cylinder Correct answer.
  4. Cushion the valves so they do not slam onto their seats at high speed

Explanation

Overlap is the period near top dead center when both valves are open. The outward flow of exhaust gas helps pull the fresh charge into the cylinder, improving volumetric efficiency, especially at high power settings.

Question 11Reciprocating Engines

What is the standard firing order of a four-cylinder horizontally opposed aircraft engine?

  1. 1-2-4-3
  2. 1-3-2-4 Correct answer.
  3. 1-4-3-2
  4. 1-2-3-4

Explanation

The crankshaft throws of a four-cylinder opposed engine are arranged so that the power impulses follow 1-3-2-4. This order distributes the power strokes evenly through the 720-degree cycle and avoids firing adjacent cylinders in sequence on the same crank throw.

Question 12Reciprocating Engines

What is the function of a hydraulic valve lifter in an aircraft engine?

  1. Maintain zero valve clearance as the engine changes temperature Correct answer.
  2. Damp out valve spring surge at high engine speeds
  3. Provide a cushion between the rocker arm and the valve stem tip
  4. Limit maximum valve lift as engine speed increases

Explanation

A hydraulic lifter uses engine oil pressure to keep the valve train in constant contact with no lash. As components expand and contract with temperature, the lifter automatically takes up or releases the difference so clearance stays at zero.

Question 13Reciprocating Engines

Why is an aircraft cylinder barrel manufactured with a slight taper, or choke?

  1. Its diameter is largest at the top to allow for piston expansion
  2. Its diameter is smallest at the bottom, near the crankcase flange
  3. Its diameter is smallest at the top, where operating temperature is highest Correct answer.
  4. Its diameter is constant, with only the wall thickness varying

Explanation

The top of the barrel runs hotter and expands more than the bottom when the engine reaches operating temperature. Grinding the bore slightly smaller at the top means that, once hot, the cylinder assumes a nearly uniform diameter and the rings seal properly throughout the stroke.

Question 14Reciprocating Engines

On a turbocharged reciprocating engine, what does the waste gate control?

  1. The compressor discharge temperature entering the throttle body
  2. The fuel flow to the injector nozzles at high altitude
  3. How much exhaust gas bypasses the turbine, setting manifold pressure Correct answer.
  4. The oil pressure and flow supplied to the turbocharger bearings and seals

Explanation

The waste gate is a valve that diverts some exhaust gas around the turbine wheel. By varying the amount that reaches the turbine, it regulates compressor speed and therefore the manifold pressure delivered to the engine.

Question 15Reciprocating Engines

Valve float at high engine speed occurs because of which condition?

  1. The valve lifter pumps up and holds the valve open
  2. The rocker arm ratio increases at high engine speed
  3. Valve clearance closes up as the stem expands with heat
  4. The valve spring cannot close the valve before the cam returns Correct answer.

Explanation

At high rpm the cam lobe returns to the lifter faster than the spring can accelerate the valve closed. The valve then remains off its seat briefly, losing compression and potentially contacting the piston.

Question 16Reciprocating Engines

Which operating practice best promotes proper seating of new piston rings after cylinder work?

  1. Using the highest octane fuel available during the break-in period
  2. Cruising at low power settings for the first ten hours of operation
  3. Operating at high power settings with a rich mixture during break-in Correct answer.
  4. Idling the engine frequently to keep cylinder temperatures low

Explanation

High power settings produce the cylinder pressures needed to force the rings against the cylinder walls so they wear in and seat. The rich mixture keeps cylinder head temperatures within limits during this period.

Question 17Reciprocating Engines

How does the master rod of a radial engine differ from the other connecting rods?

  1. Transmits power to the propeller shaft through the planetary reduction gears
  2. Runs on a crankshaft main bearing journal rather than on a crankpin
  3. Carries a piston pin and rings but rides on a crankshaft main bearing
  4. Attaches directly to the crankshaft and carries the articulated rods Correct answer.

Explanation

In a radial engine the master rod is the only rod that wraps around the crankpin. The remaining cylinders use articulated (link) rods whose knuckle pins are carried on the flange of the master rod.

Question 18Reciprocating Engines

Why is a reciprocating engine assembly dynamically balanced?

  1. Verify that the crankshaft is straight within runout limits
  2. Correct only the static weight distribution of the crankshaft and rods
  3. Balance the propeller separately from the engine
  4. Equalize rotation forces so vibration is reduced at operating speed Correct answer.

Explanation

Dynamic balancing corrects the distribution of mass so that centrifugal forces generated while the assembly rotates cancel each other. This reduces vibration that a static balance check cannot detect, because static balancing considers only weight, not the position of that weight about the axis.

Question 19Reciprocating Engines

Excessive clearance between a valve stem and its guide will most likely cause which condition?

  1. Loss of valve spring tension over time
  2. Increased valve lift and longer valve duration
  3. Oil to be drawn into the cylinder and burned Correct answer.
  4. The valve to stick in the guide when the engine is hot

Explanation

A worn guide allows oil from the rocker box to pass down the stem into the intake port or combustion chamber. The oil is burned, raising oil consumption and producing carbon deposits on the valve and piston.

Question 20Reciprocating Engines

A cylinder's exhaust valve clearance is found to be decreasing steadily between inspections. What is the most probable cause?

  1. Stretching of the pushrod under load
  2. The valve spring losing tension from heat
  3. The valve face wearing into the seat Correct answer.
  4. Wear in the rocker arm bushing

Explanation

As the valve face recedes into its seat, the valve stem moves farther toward the rocker arm and the clearance closes up. A rapidly decreasing clearance is a warning sign of seat recession or valve stretch and should be investigated before the valve is held off its seat.

Question 21Turbine Engines

Reciprocating engines operate on the Otto cycle. Which thermodynamic cycle describes the operation of a gas turbine engine?

  1. Brayton Correct answer.
  2. Rankine
  3. Carnot
  4. Diesel

Explanation

A gas turbine follows the Brayton cycle, in which air is compressed, heated at constant pressure during combustion, and expanded through a turbine. The Rankine cycle applies to steam plants, while the Otto and Diesel cycles describe reciprocating engines.

Question 22Turbine Engines

What is the primary function of the compressor section in a gas turbine engine?

  1. Increase the velocity of the air while lowering its pressure
  2. Raise the pressure of the air before combustion Correct answer.
  3. Extract energy from the exhaust gases to drive the turbine
  4. Mix fuel with air for combustion

Explanation

The compressor takes in air and raises its pressure so that a large amount of work can be extracted during combustion and expansion. Fuel mixing occurs in the combustion section, and energy extraction occurs in the turbine.

Question 23Turbine Engines

What does the exhaust gas temperature (EGT) indication primarily reflect?

  1. Indicate turbine section operating temperature Correct answer.
  2. Measure the fuel temperature at the nozzle
  3. Show the temperature of the air entering the compressor
  4. Indicate the speed of the high-pressure compressor

Explanation

EGT is measured downstream of the combustion and turbine sections and is used to monitor hot-section temperatures and to set power. Compressor speed is shown by tachometers such as N1 or N2, and inlet air temperature is measured separately.

Question 24Turbine Engines

Why do turbine engines use high-energy ignition units?

  1. Ignition must occur under low pressure at altitude Correct answer.
  2. The fuel is ignited only once during start
  3. The igniters must fire continuously during normal operation
  4. Spark plugs wear out quickly

Explanation

High-energy ignition provides a strong spark that can light the fuel-air mixture during starting and during altitude relight, when pressure and temperature are low. Continuous ignition is used only in specific conditions such as heavy precipitation or turbulence.

Question 25Turbine Engines

Compressor bleed air is commonly used for which purpose?

  1. Lubricating the main bearings
  2. Driving the fuel pump only
  3. Cooling the turbine and pressurizing the cabin Correct answer.
  4. Increasing the compressor pressure ratio during climb

Explanation

Bleed air is taken from the compressor and used for functions such as cabin pressurization, air-conditioning, anti-icing, and cooling hot engine components. It is not the lubricant and does not raise the compressor pressure ratio.

Question 26Turbine Engines

What is the purpose of a borescope inspection on a turbine engine?

  1. Inspect internal components without disassembly Correct answer.
  2. Check the oil pressure
  3. Balance the compressor rotor
  4. Measure turbine blade tip clearance while running

Explanation

A borescope allows visual inspection of compressor and turbine internals through ports without removing the engine or splitting the case. Tip clearance, rotor balance, and oil pressure are checked by other means.

Question 27Turbine Engines

Compared with a centrifugal compressor of similar capacity, an axial-flow compressor:

  1. Is simpler and has fewer stages
  2. Is less susceptible to foreign object damage
  3. Has a smaller frontal area and higher mass flow Correct answer.
  4. Produces a higher pressure rise per stage

Explanation

Axial compressors pass a large mass flow through a small frontal area, which suits high-thrust engines. They typically have many stages, are more vulnerable to foreign object damage, and produce a smaller pressure rise per stage than a centrifugal compressor.

Question 28Turbine Engines

Which condition is most likely to cause a compressor stall?

  1. A gradual increase in compressor speed
  2. Excessive cooling of the compressor inlet
  3. A sudden fuel flow increase beyond available air Correct answer.
  4. A decrease in turbine inlet temperature

Explanation

A rapid fuel-flow increase raises combustor pressure and can back up airflow through the compressor, causing stall. Stall may produce a bang, EGT rise, and RPM fluctuation because the compressor cannot maintain smooth airflow.

Question 29Turbine Engines

What is the function of the nozzle guide vanes in a turbine section?

  1. Rotate the turbine rotor
  2. Cool the combustion chamber
  3. Seal the turbine bearing cavity
  4. Direct hot gases onto the turbine blades Correct answer.

Explanation

Nozzle guide vanes are stationary and turn and accelerate the hot combustion gases so they strike the turbine blades at the proper angle and velocity. They do not rotate the rotor or seal the bearing cavity.

Question 30Turbine Engines

Which description applies to a can-annular combustor?

  1. Individual cans linked by flame tubes Correct answer.
  2. A chamber located ahead of the compressor
  3. An annular chamber with no individual cans
  4. A single large chamber surrounding the turbine

Explanation

A can-annular combustor uses individual cans arranged around an annular casing and connected by flame tubes so combustion propagates from can to can. It differs from a pure annular combustor, which has no separate cans.

Question 31Turbine Engines

Why is a duplex fuel nozzle used in some turbine engines?

  1. To spray fuel only at high pressure
  2. To atomize fuel well over a wide flow range Correct answer.
  3. To mix fuel and air before the combustor
  4. To return excess fuel to the tank

Explanation

A duplex nozzle has primary and main fuel circuits so it can deliver a fine spray at low flow during start and idle as well as at high flow. This provides good atomization across the engine's operating range.

Question 32Turbine Engines

Why are starter duty cycle limits imposed on turbine engines?

  1. Prevent overheating of the starter Correct answer.
  2. Prevent the igniters from firing too long
  3. Limit fuel consumption during start
  4. Keep the compressor from surging

Explanation

Starters draw high current or high air flow and can overheat if cranked too long, so duty cycle limits specify maximum cranking time and required cooling intervals. Igniter firing and fuel consumption are controlled separately.

Question 33Turbine Engines

How does a target-type thrust reverser redirect the exhaust?

  1. Deflecting exhaust forward with buckets Correct answer.
  2. Rotating the fan blades to a negative pitch
  3. Closing the exhaust nozzle completely
  4. Reversing the rotation of the turbine

Explanation

Target-type reversers use bucket-shaped doors that close behind the exhaust and turn the gas stream forward to produce reverse thrust. They do not reverse turbine rotation or change fan pitch.

Question 34Turbine Engines

What does a full-authority digital engine control (FADEC) system do?

  1. Is used only on reciprocating engines
  2. Schedules fuel flow electronically Correct answer.
  3. Requires the pilot to manually set fuel flow at all times
  4. Controls only the ignition system

Explanation

A FADEC uses electronic sensors and computers to schedule fuel flow and other engine parameters for efficient and safe operation. It is used on turbine engines and can control functions beyond ignition.

Question 35Turbine Engines

What is the purpose of a fuel-oil heat exchanger on many turbine engines?

  1. Increase fuel pressure for the nozzles
  2. Separate water from the fuel
  3. Cool the fuel with outside air
  4. Warm the fuel and cool the engine oil Correct answer.

Explanation

The fuel-oil heat exchanger transfers heat from the engine oil to the fuel, cooling the oil and warming the fuel. Warming the fuel helps prevent ice formation in the fuel system.

Question 36Turbine Engines

Why does a turboprop engine require a reduction gearbox?

  1. It increases the turbine's power output
  2. It reverses the direction of propeller rotation
  3. The turbine must turn faster than the propeller
  4. The propeller must turn slower than the turbine Correct answer.

Explanation

The turbine and compressor rotate at high speed, while an efficient propeller must turn much slower. The reduction gearbox matches the propeller speed to the engine's high output speed.

Question 37Turbine Engines

In an afterburner-equipped engine, how is additional thrust produced?

  1. Burning extra fuel downstream of the turbine Correct answer.
  2. Raising the turbine inlet temperature
  3. Increasing compressor mass flow
  4. Injecting water into the combustor

Explanation

An afterburner injects and burns fuel in the exhaust stream after the turbine, adding energy and velocity to the exhaust gases. It does not increase compressor mass flow or raise turbine inlet temperature.

Question 38Turbine Engines

How is turbine blade creep best described?

  1. A crack that propagates from the leading edge
  2. The erosion of the blade tip by foreign objects
  3. The thermal expansion of the blade during acceleration
  4. Permanent elongation from heat and centrifugal load Correct answer.

Explanation

Creep is a permanent deformation that occurs when blades are exposed to high temperature and sustained centrifugal stress. It is checked by measuring blade stretch or growth during hot-section inspections.

Question 39Turbine Engines

Why is engine trimming performed on a turbine engine?

  1. Set the fuel control to achieve specified power Correct answer.
  2. Set the ignition timing for altitude relight
  3. Balance the compressor rotor at cruise power
  4. Adjust turbine blade tip clearances for growth

Explanation

Trimming adjusts the fuel control so the engine meets specified performance parameters, such as EGT or RPM, at a given power setting. It compensates for manufacturing tolerances and wear.

Question 40Turbine Engines

What is the purpose of active clearance control in a turbine engine?

  1. Control casing cooling to hold tip clearance Correct answer.
  2. Balance the rotor at high speed
  3. Adjust the nozzle guide vane angle
  4. Control fuel flow during engine acceleration

Explanation

Active clearance control directs cooling air onto the turbine casing to control its expansion and maintain efficient blade tip clearance. It does not balance the rotor or schedule fuel flow.

Question 41Engine Inspection

During a differential compression test on a reciprocating engine cylinder, air is heard escaping from the exhaust stack. Which component is the source of the leak?

  1. Exhaust valve Correct answer.
  2. Piston rings
  3. Intake valve
  4. Cylinder-to-crankcase joint

Explanation

In a differential compression test, the path the escaping air takes identifies the leaking component. Air that exits through the exhaust stack has passed the exhaust valve seat, indicating a burned, warped, or carbon-fouled exhaust valve. Leakage past the intake valve would be heard at the intake or carburetor, and ring leakage would be heard at the crankcase breather or oil filler.

Question 42Engine Inspection

What is the primary purpose of inspecting the engine oil filter element at scheduled intervals?

  1. Measure the oil pump output volume
  2. Verify the oil pressure sending unit is accurate
  3. Confirm the oil is the correct viscosity grade
  4. Detect evidence of internal component wear Correct answer.

Explanation

The full-flow oil filter traps particles shed by wearing engine components, so the material captured on the element is a direct indicator of internal condition. Inspecting and opening the element allows the mechanic to identify the type and quantity of debris before a failure progresses. Oil grade, pressure indication, and pump output are checked by other means.

Question 43Engine Inspection

A borescope is used during an engine inspection primarily to

  1. Inspect internal areas without engine disassembly Correct answer.
  2. Check magneto internal timing
  3. Measure cylinder taper without removing the cylinder
  4. Measure crankshaft runout at the propeller flange

Explanation

A borescope carries light and optics into closed areas such as combustion chambers, compressor stages, and turbine sections so the mechanic can see internal condition without teardown. It provides a visual inspection only; it does not measure dimensions or timing. Dimensional checks still require micrometers, dial indicators, or other gauges.

Question 44Engine Inspection

Cracks in a welded tubular engine mount are most likely to be found

  1. On the flat surface of the firewall plate
  2. Under the mounting bolt heads
  3. In the middle of the longest unsupported tube
  4. At the welded cluster joints Correct answer.

Explanation

Welded tube clusters concentrate vibration and thermal stress, so cracks typically start at the edge of the weld bead or in the heat-affected zone next to it. Inspections therefore focus on the weld clusters, tube ends, and attachment fittings. Clean the area and use a magnifier or dye penetrant when a crack is suspected.

Question 45Engine Inspection

A cracked exhaust muffler is a serious airworthiness item because the escaping gas of greatest concern is

  1. Carbon dioxide
  2. Nitrogen
  3. Water vapor
  4. Carbon monoxide Correct answer.

Explanation

Exhaust gas contains carbon monoxide, an odorless gas that can enter the cabin through a cracked muffler or a leak at a heat-exchanger joint and incapacitate the crew. Carbon monoxide is also the gas detected by the common cockpit warning indicators. Mufflers and heat exchangers are therefore inspected for cracks, thin spots, and soot trails.

Question 46Engine Inspection

Excessive cylinder head temperature on an air-cooled engine is often traced to

  1. Low oil pressure
  2. Damaged cooling baffles Correct answer.
  3. A very rich fuel mixture
  4. Incorrect valve clearance

Explanation

Baffles and seals force cooling air to flow through the cylinder fins instead of around them; cracks, missing sections, or bad seals let the air bypass the fins and head temperatures climb. Inspecting baffles for cracks, gaps, and deteriorated seals is a standard part of engine inspection. Valve clearance, oil pressure, and a rich mixture do not produce this signature.

Question 47Engine Inspection

Spectrometric oil analysis (SOAP) is used to

  1. Establish the oil's viscosity index
  2. Confirm the oil pressure relief valve setting
  3. Verify the oil cooler is not plugged
  4. Measure wear metal concentrations in the oil Correct answer.

Explanation

SOAP burns or excites an oil sample and measures the concentration, in parts per million, of elements such as iron, aluminum, copper, and chromium. Rising trends in a particular element point to wear of the component made from that alloy. The method detects chemical makeup, not pressure, flow, or viscosity behavior.

Question 48Engine Inspection

A magnetic chip detector installed in a turbine engine oil system is designed to collect

  1. Carbon and sludge
  2. Ferrous metal particles Correct answer.
  3. Nonferrous particles such as aluminum
  4. Sand and foreign debris

Explanation

The chip detector uses a permanent magnet to attract ferrous particles from the oil, so it is most effective for monitoring steel gears and bearings. Nonferrous debris, sand, and sludge do not respond to the magnet and are captured by filters instead. Chips found are evaluated against the manufacturer's limits before further flight.

Question 49Engine Inspection

During trend monitoring, a turbine engine shows a gradual exhaust gas temperature increase at the same power setting over many flight cycles. This most likely indicates

  1. Compressor or turbine deterioration Correct answer.
  2. A decrease in outside air temperature
  3. An EGT probe reading lower than actual
  4. A fuel schedule that is too rich

Explanation

A used engine with eroded compressor efficiency or increased turbine clearances needs a higher temperature to produce the same power, so EGT at a fixed power setting trends upward over time. The trend is meaningful because the comparison is made against the same baseline power setting. A single out-of-trend reading should be confirmed against ambient conditions and instrument accuracy before action is taken.

Question 50Engine Inspection

When checking a reciprocating engine cylinder barrel for wear, measurements are normally taken

  1. At the midpoint in one direction
  2. At top, middle, and bottom in two directions Correct answer.
  3. Only at the bottom of the barrel
  4. Only at the top of the barrel

Explanation

Cylinder wear is not uniform; the bore wears most near the top and on the thrust faces. Taking readings at several heights and at right angles to each other reveals taper and out-of-roundness, which are compared with the manufacturer's service limits. A single reading cannot establish either condition.