7.9: Pipes and Hoses

Question 1

What are pipe forming processes?

Answer 1

Cutting
Bending
Belling
Flaring

Question 2

What are metal piping sized by?

Answer 2

Diameter which is measured in 16ths of an inch

Question 3

What pipe measurement can be bent by hand?

Answer 3

Below 1/4 inch

Question 4

What TPI should a pipe be cut by if a hacksaw is needed?

Answer 4

32 TPI

Question 5

How much longer should pipes be than required to allow for bending?

Answer 5

10% longer

Question 6

What can too much pressure on the cutting wheel cause?

Answer 6

Can deform the piping or cause excessive burring

Question 7

What should be done to steel pipes in terms of marking bends and why?

Answer 7

Should arc the bend a little further than the marking on a scale as the pipe springs back a little after bending

Question 8

Should there be any tension when bending a pipe?

Answer 8

No

Question 9

How widely are pipes bent for small offset angles

Answer 9

As wide as possible

Question 10

How much should the outside flattened portion of a bent pipe be?

Answer 10

Not less than 75%

Question 11

What does the sleeve of flared pipes do?

Answer 11

Add strength and support during vibrations

Question 12

What are the flared angle fittings?

Answer 12

37 degrees

Question 13

What are types of flares?

Answer 13

Single
Double

Question 14

How are single flares formed?

Answer 14

Impact type
Flaring cone with a rolling action

Question 15

What is impact type for flares?

Answer 15

Uses a plunger that is driven into the end of the pipe using light hammer blow while rotating the plunger

Question 16

What is roll type for flares?

Answer 16

The preferred method, involving an entirely self contained unit producing a good flare

Question 17

What type of piping can be double flared?

Answer 17

Soft aluminium piping, with an outside diameter of 3/8 inch or smaller

Question 18

How is a double flare compared to a single flare?

Answer 18

It is smoother and more concentric, providing a better seal that is more vibration resistant

Question 19

What is swage fitting/harrison-type?

Answer 19

Good for thin wall pipes and is almost totally vibration resistant

Question 20

What are permaswage fittings good and bad for?

Answer 20

They are good because they can be made quickly and is light and gives a good seal. The disadvantage is it cannot be separated

Question 21

What is belling?

Answer 21

Used for rigid piping lines carrying low pressure fluids or air connecting to rubber hoses by belling the end of the pipe

Question 22

What piping can be belled with a hand belling tool?

Answer 22

Outside diameter of 1/4 - 1 inch

Question 23

What do modern aircraft use as materials for extruded pipe material?

Answer 23

Various non-corrosive steels, aluminium and titanium alloys

Question 24

How does high quality materials result in less weight?

Answer 24

It allows for thinner walls, with a larger inner diameter

Question 25

What are pressure line classifications?

Answer 25

High pressure lines: over 1500 psi Medium pressure lines: below 1500 psi Low pressure lines: suction and return lines

Question 26

What materials do medium and low pressure lines use in comparison to high pressure lines?

Answer 26

Aluminium to save weight while steel ones are for high pressure

Question 27

What are lay lines?

Answer 27

Tabs or bands fitted to hoses which show information about the hoses properties

Question 28

What materials can be used with what other materials if a pipe of the same material is not available for repair?

Answer 28

Aluminium alloy with CRES or titanium CRES with titanium (except the pylon) Titanium with CRES

Question 29

What are the 3 hose pressure classifications ?

Answer 29

High pressure - over 3000psi Medium pressure - up to 3000psi Low pressure - up to 600psi

Question 30

What percentage of scratches or nicks in aluminium pipes can be repaired?

Answer 30

Not deeper than 10% of wall thickness and not in the heel of a bend

Question 31

What are damage limits for hard thin walled CRES and titanium pipes compared to aluminium?

Answer 31

CRES and titanium are less than aluminium

Question 32

What is the acceptability for crack or deformity in a flare

Answer 32

Any crack or deformity is unacceptable

Question 33

What is the percentage that a dent of the pipe diameter can be accepted?

Answer 33

Less than 20% and not in the heel of a bend

Question 34

How are dents repaired in pipes?

Answer 34

A bullet of the right diameter is drawn through the pipe to flatten it

Question 35

How much of sharp bottomed surface defects are permitted?

Answer 35

A maximum of 5% of the pipes wall thickness and traces of impact

Question 36

How much of round bottomed surface defects are permitted?

Answer 36

A maximum of 10% of the wall thickness and traces of impact a maximum of 2%

Question 37

What colours could be on lay lines be and what does it indicate?

Answer 37

They could be yellow, red or white stripes and indicates both the hose specification and if the assembly is twisted

Question 38

How are hose assemblies proof tested and with what pressure?

Answer 38

By capping one end and using generally 1.5 times the working pressure

Question 39

Before installing a hose, what should be checked?

Answer 39

Applicability Length Cleanliness Damage

Question 40

What should the identification tag of a hose be checked for?

Answer 40

Part number Cure date Assembly date

Question 41

How much support should there consistently be for hoses?

Answer 41

Every 60cm (24 in)

Question 42

What is the minimum bend radius determined by?

Answer 42

Operating pressure Hose type Nominal size

Question 43

What should be used on hoses that become twisted in operation?

Answer 43

Clamps

Question 44

What are the materials of sleeving for hoses including?

Answer 44

Heat shrink Nylon spiral wrap Teflon

Question 45

What compartment should fluid lines never be routed through?

Answer 45

Passenger compartments

Question 46

What type of clamps are used to support fluid lines?

Answer 46

Rubber cushioned clamps and plain clamps

Question 47

What type of clamps should be used in areas subject to vibration and contamination by fuel or hydraulic fluid

Answer 47

Rubber cushioned clamps using teflon, which are highly resistant to deterioration

Question 48

Where are bonded clamps used?

Answer 48

Used to secure fuel, oil or hydraulic lines made of metal, with an electrical lead attached to connect the aircraft structure to the ground line

Question 49

Where should pipes be lubricated?

Answer 49

The thread on the male fitting The shoulder of the sleeve

Question 50

Where should lubrication never be applied to on pipes?

Answer 50

One female threads or on the contact surface between the sleeve and sealing surface, as it can cause rotation

Question 51

Where should a witness mark be applied once a hydraulic fitting is torqued?

Answer 51

A witness mark of red paint 2-4mm wide