reciprocating engines Flashcards
what is the purpose of crankshaft dynamic dampers
they reduce engine vibration
what types of bearings are generally found in reciprocating engines
plain, ball, and roller
what type of connecting rods are commonly found in radial engines
master and articulating rod assemblies
are the connecting rods used in each cylinder of a radial engine the same
No, radial engines use master and articulating rod assemblies
name the different types of piston rings
oil control compression and oil scraper
where should piston ring gaps be installed relative to each other and why
compression ring gaps should be staggered so that they do not align, this prevents excessive blow-by
what could result from incorrectly installed piston rings
excessive oil consumption
what purpose do oil control rings serve
they regulate the thickness of the oil film on the cylinder walls
on engines equipped with hydraulic valve lifters, what should the running valve clearance be
zero
what is used to help prevent valve surge or floating in an aircraft engine?
two or more springs are used on each valve
what is the purpose of valve overlap
it allows better volumetric efficiency and lowers cylinder operating temps
what procedure should be followed when valve blow by is indicated by a hissing sound on a reciprocating engine when pulling through the propeller
perform a cylinder compression test to identify the faulty cylinder
when troubleshooting a running engine malfunction what does a cold cylinder indicate
lack of combustion in that cylinder
what factors about the condition of an engine can be learned by studying the results of a compression test
the results of a compression test determine if the valves, piston rings, and pistons are adequately sealing
what should be done to repair a loose stud in an engine crankcase
remove the loose stud, inspect the hold for size ad condition of the threads. it may be repaired using a helicoil insert
how is a cylinder barrel inspected for out of roundness
a dial indicator, telescopic gauge and micrometer, two readings should be taken 90 degrees to each other
where are cracks most likely to be found in a pistion
highly stressed areas; the base of the pin bosses inside at the junction of the head and walls and the ring lands
what is the purpose of valve overlap
it permits better volumetric efficiency and lowers the cylinder operating temperatures
what is meant when it is said that an engine part is within “serviceable limits”
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
what inspections should be preformed after a propeller strike without sudden stoppage
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
what is an indication that primer is leaking or open while the engine is running
the engine will not idle properly
when an engine is overhauled, how is its total time affected
the total time on the engine must be continued and the times since major overhaul is entered into the engine log
when an engine is rebuilt, how is it operating history affected
if the manufacturer rebuilds the engine, it is granted a zero-time status and is considered to have no previous operating history
name some of the precautions that should be performed prior to engine removal
disconnect the battery, turn off the fuel valves, chock the wheels, and if necessary install a tail stand
a weak cylinder is found during a compression check. what must be inspected
an internal inspection of the cylinder must be completed to determine the cause of failure
what could be the causes of low compression in a cylinder?
valves not seating properly, piston rings not seating correctly, piston or cylinder damage
what is an operational indication of an induction system leak
low power and uneven running
