Module 7.12

Question 1

when does overloading wear occur?

Answer 1

when metal has been removed due to a sliding action

Question 2

what does heavy contact cause

Answer 2

squeezes out lubricant and causes microwelds to form

Question 3

what does overload wear look like?

Answer 3

burrs on edges, ripples and ridges.

Question 4

what is pitting and spalling caused by?

Answer 4

thin oil films or high temps

Question 5

what can spalling cracks usually lead to?

Answer 5

chunks of metal flaking away, which can damage other teeth

Question 6

what is cracking usually caused by?

Answer 6

failure in heat treatment process or improper machining

Question 7

what is interference wear caused by?

Answer 7

misalignment of gears or incorrect mating of the teeth

Question 8

where is heavy contact caused because of interference wear?

Answer 8

at teeth tips and roots

Question 9

abrasion of the gear teeth is caused by what?

Answer 9

scratching or scoring

Question 10

what affects the size of the abrasion marks?

Answer 10

size of particles in the lubricant

Question 11

what is wear pattern

Answer 11

the print that one set of gear teeth leaves on another

Question 12

how can the tooth contact pattern be established?

Answer 12

by using prussian blue a blue dyed paste

Question 13

what is the purpose of backlash ?

Answer 13

prevents jamming and contact on both sides

Question 14

what is backlash?

Answer 14

play between the teeth on the gears

Question 15

what is the backlash variation?

Answer 15

difference between max and min backlash in a whole revolution of the larger of a mating pair of gears

Question 16

how can backlash in a gear train be measured?

Answer 16

lock one end and measure limits of movements at the other with a DTI

Question 17

what can affect the amount of backlash?

Answer 17

change change in centre distance
variance in tooth thickness
temperature ranges

Question 18

what are the primary and secondary inspections of a chain?

Answer 18

primary: chain runs smoothly over sprocket
secondary: checks that require an applied load

Question 19

in a secondary inspection, what should the elongation be?

Answer 19

1.5% to 3%

Question 20

when should a chain be replaced from a worn contact?

Answer 20

when 5% worn

Question 21

what causes pin galling and how can it be corrected?

Answer 21

inadequate lube -> reduce load or speed, proper chain lube

Question 22

what are tight joints caused by?

Answer 22

dust and foreign objects caught in the joints

Question 23

what must be done to a sprocket with hooked teeth

Answer 23

replace chain and the sprocket

Question 24

what causes abnormal protrusions or turned pins

Answer 24

high loading and inadequate lubricant

Question 25

what is the cause of cracked plates?

Answer 25

loading beyond the chains dynamic capacity

Question 26

fractured plates are caused by what?

Answer 26

high overload of the chain

Question 27

what are cracked plates caused by?

Answer 27

static pressure at press fit plus severe corrosion or acid exposure

Question 28

what are enlarged holes caused by ?

Answer 28

high overload

Question 29

what is a rusted chain caused by?

Answer 29

moisture exposure or poor lube

Question 30

in the case of an emergency, what can be used to extend the landing gear?

Answer 30

sprocket and chain system

Question 31

what is the main role of a sprocket ?

Answer 31

rotory to linear or vice versa

Question 32

what does the sprocket act as in long chain runs?

Answer 32

acts as support

Question 33

what is the load capacity of a belt compared to a chai drive?

Answer 33

much smaller

Question 34

what are the benefits to a belt drive system?

Answer 34

-shock resistant
- quieter
-smoother
-do not need to lube

Question 35

are belts life’s limited?

Answer 35

yes they are

Question 36

what must a belt be inspected for?

Answer 36

-wear and degradation
-cracking or splitting
-chipping or fraying

Question 37

what defects require the replacement of the belt?

Answer 37

-cracking and splitting
-shipping and fraying

Question 38

how can the tension be tested on a belt?

Answer 38

by pushing on an unsupported section

Question 39

why is the work and peg mechanism not used in aircraft?

Answer 39

excessive backlash

Question 40

the worm and nut mechanism is used in aircraft, how is actuation of the mechanism generated?

Answer 40

turn shaft to drive nut or nut to drive shaft

Question 41

what is the recirculating ball mechanism referred to as ?

Answer 41

ball screw actuator

Question 42

how does the nut move on a recirculating ball mechanism’s shaft ?

Answer 42

shaft turns making the balls circulate. nut moves as long as it’s fixed so it doesn’t rotate.

Question 43

screw jacks are primarily used where?

Answer 43

flap drive systems

Question 44

what are the primary concerns when inspecting a screw jack?

Answer 44

lubrication and backlash

Question 45

what should be checked for in a push pull rod?

Answer 45

straightness, wear in the ends, security of check nuts and end fittings

Question 45

where are push pull rods used?

Answer 45

aircraft aileron and trim tab

Question 46

what are bell cranks used for ?

Answer 46

transmit a force or motion or permit a change in direction