Fits And Clearances

Question 1

What is a Fit?

Answer 1

How tight or loose two joined parts fit together

Question 2

What is a shaft?

Answer 2

A rounded part that fits into a bore including pegs, axles, bolts, pins, etc

Question 3

What is Nominal Size?

Answer 3

Measurement calculated in the draft also a dimension

Idea, dimension

Question 4

What is a tolerance?

Answer 4

A deviation from the Nominal size

Question 5

What is a Clearance fit?

Answer 5

There will always be some play between the two assembled items when joined

Question 6

What is a Transition fit?

Answer 6

There can be some play between two assembled items or interference depending on their Nominal sizes

Question 7

What is an Interference fit?

Answer 7

The hole is always smaller than the shaft and will require force to fit together

Question 8

What is the difference between a Hole Based system and a Shaft Based system?

Answer 8

Capital letters indicate Hole deviations
Lowercase letters indicate Shaft deviations

Hole Based - the minimum hole size is the basic size
Shaft Based - the maximum shaft size is the basic size

Question 9

What is a Dial Tester?

Answer 9

Precision instrument for measuring movement between parts

Question 10

What process is used to harden solid rivets soon after solution heat treatment?

Answer 10

Age hardening

Question 11

What angle countersinks are available and which is most common?

Answer 11

82 degrees
100 degrees
120 degrees

Most common is 100 degrees

Question 12

Which rivets require heat treatment?

How many times can they be treated?

Answer 12

D
DD
E

Once

Question 13

What does AN470DD-5-6 indicate?

Answer 13

Universal head
2024 alloy
5/32 diameter
6/16 length

Question 14

What is the centre to centre distance of two fasteners in a single row called?

Answer 14

Pitch

Question 15

What is Sphere of Influence?

Answer 15

The area of sheet metal over which a rivet will achieve a water-tight joint

Question 16

How is inter-buckling prevented?

Answer 16

The maximum permissible rivet spacing of a pressurised fuselage should be 6D or 18t (whichever is smaller)

Question 17

Why would you need to dimple material?

Answer 17

Skin is too thin to cut - countersink is shaped (dented) to accept the head of a countersunk fastener by dimpling

Question 18

Which dimpling process is best used for limited access?

Answer 18

Radius dimpling greater than 100 degrees so cannot nest, dies smaller than radius for getting into hard to reach areas

Question 19

What refinement to the dimpling process prevents cracking of hard material?

Answer 19

Hot dimpling for 7075

Same as coin

Question 20

Which dimpling process provides sharply defined edges?

Answer 20

Coin dimpling

Question 21

What tool is required for reaction riveting?

Answer 21

Rivet gun

Question 22

What is the meaning of the term percussion riveting?

Answer 22

Hand riveting

Question 23

What method is preferred for installation of solid fasteners?

Answer 23

Squeeze followed by pneumatic

Question 24

What tool is required for squeeze riveting?

Answer 24

Squeeze tool

Question 25

What tool is required for percussion riveting?

Answer 25

Hammer | Dolly

Question 26

What must be taken into account before countersinking material?

Answer 26

Added thickness due to tape or protective coating

Question 27

How is depth adjusted on a microstop countersinker?

Answer 27

Pulling sleeve back and turning the stop to increase or decrease the cut. Sleeve is then dropped back into its original position

Question 28

Where can general requirements of riveting a particular aircraft be found?

Answer 28

SRM

Question 29

How is a solid rivet removed without damaging the structure?

Answer 29

``` Centre punch head for drill Drill into head Position punch Snap off head Push out ```

Question 30

What system is used to protect hose assemblies from chafing and temperature extremes?

Answer 30

Sleeve: Heat shrink Nylon spiral wrap Teflon

Question 31

What is the usual corrective/repair action for springs found to be unserviceable?

Answer 31

Replaced

Question 32

What law of physics pertains to the behaviour of springs and what does it state?

Answer 32

Hooke’s Law Within its elastic limit it is said to obey Hooke’s Law