reciprocating engines

Question 1

what is the purpose of crankshaft dynamic dampers

Answer 1

they reduce engine vibration

Question 2

what types of bearings are generally found in reciprocating engines

Answer 2

plain, ball, and roller

Question 3

what type of connecting rods are commonly found in radial engines

Answer 3

master and articulating rod assemblies

Question 4

are the connecting rods used in each cylinder of a radial engine the same

Answer 4

No, radial engines use master and articulating rod assemblies

Question 5

name the different types of piston rings

Answer 5

oil control compression and oil scraper

Question 6

where should piston ring gaps be installed relative to each other and why

Answer 6

compression ring gaps should be staggered so that they do not align, this prevents excessive blow-by

Question 7

what could result from incorrectly installed piston rings

Answer 7

excessive oil consumption

Question 8

what purpose do oil control rings serve

Answer 8

they regulate the thickness of the oil film on the cylinder walls

Question 9

on engines equipped with hydraulic valve lifters, what should the running valve clearance be

Answer 9

zero

Question 10

what is used to help prevent valve surge or floating in an aircraft engine?

Answer 10

two or more springs are used on each valve

Question 11

what is the purpose of valve overlap

Answer 11

it allows better volumetric efficiency and lowers cylinder operating temps

Question 12

what procedure should be followed when valve blow by is indicated by a hissing sound on a reciprocating engine when pulling through the propeller

Answer 12

perform a cylinder compression test to identify the faulty cylinder

Question 13

when troubleshooting a running engine malfunction what does a cold cylinder indicate

Answer 13

lack of combustion in that cylinder

Question 14

what factors about the condition of an engine can be learned by studying the results of a compression test

Answer 14

the results of a compression test determine if the valves, piston rings, and pistons are adequately sealing

Question 15

what should be done to repair a loose stud in an engine crankcase

Answer 15

remove the loose stud, inspect the hold for size ad condition of the threads. it may be repaired using a helicoil insert

Question 16

how is a cylinder barrel inspected for out of roundness

Answer 16

a dial indicator, telescopic gauge and micrometer, two readings should be taken 90 degrees to each other

Question 17

where are cracks most likely to be found in a pistion

Answer 17

highly stressed areas; the base of the pin bosses inside at the junction of the head and walls and the ring lands

Question 18

what is the purpose of valve overlap

Answer 18

it permits better volumetric efficiency and lowers the cylinder operating temperatures

Question 19

what is meant when it is said that an engine part is within “serviceable limits”

Answer 19

a part that is within “serviceable limits” will not likely wear to the point of causing engine failure within the next time between overhaul (TBO) interval

Question 20

what inspections should be preformed after a propeller strike without sudden stoppage

Answer 20

inspect engine mounts, the crankcase, nose section for damage

inspect the oil and oil filters/screens for metal particles

inspect the crankshaft or drive shaft for cracks or misalignments

Question 21

what is an indication that primer is leaking or open while the engine is running

Answer 21

the engine will not idle properly

Question 22

when an engine is overhauled, how is its total time affected

Answer 22

the total time on the engine must be continued and the times since major overhaul is entered into the engine log

Question 23

when an engine is rebuilt, how is it operating history affected

Answer 23

if the manufacturer rebuilds the engine, it is granted a zero-time status and is considered to have no previous operating history

Question 24

name some of the precautions that should be performed prior to engine removal

Answer 24

disconnect the battery, turn off the fuel valves, chock the wheels, and if necessary install a tail stand

Question 25

a weak cylinder is found during a compression check. what must be inspected

Answer 25

an internal inspection of the cylinder must be completed to determine the cause of failure

Question 26

what could be the causes of low compression in a cylinder?

Answer 26

valves not seating properly, piston rings not seating correctly, piston or cylinder damage

Question 27

what is an operational indication of an induction system leak

Answer 27

low power and uneven running