Fluid Lines and Fittings

Question 1

Which coupling nut should be selected for used with 1/2 inch aluminum oil lines which are to be assembled using flared tube ends and standard AN nuts, sleeves and fittings?

Answer 1

AN-818-8

Question 2

Metal tubing fluid lines are sized by wall thickness and

Answer 2

outside diameter in 1/16 inch increments

Question 3

Rolling type flaring tools are used to flare ____, ____, and _____ tubing?

Answer 3

Soft copper, aluminium, brass

Question 4

Which coupling nut should be selected for used with 3/8 inch aluminum oil lines which are to be assembled using flared tube ends and standard AN nuts, sleeves and fittings?

Answer 4

AN-818-6

Question 5

From the following sequences of steps, indicate the proper order you would use to make a single flare on a piece of tubing:
1. Place the tube in the proper size hole in the flaring block
2. Project the end of the tube slightly from the top of the flaring tool, about the thickness of a dime
3. Slip the fitting nut and sleeve on the tube
4. Strike the plunger several light blows with a lightweight hammer or mallet and turn the plunger one half turn after each blow
5. Tighten the clamp bar securely to prevent slippage
6. Centre ther plunger or flaring pin over the tube

Answer 5

3, 1, 6, 2, 5, 4

Question 6

Hydraulic tubing, which is damaged in a localized area to such an extent that repair is necessary, may be repaired

Answer 6

by cutting out the damaged area and utilizing a swaged tube fitting to join the tube ends

Question 7

What is an advantage of a double flare on aluminum tubing?

Answer 7

More resistant to damage when the joint is tightened

Question 8

A certain amount of slack must be left in a flexible hose during installation beacusrm when under pressure, it

Answer 8

contracts in length and expands in diameter

Question 9

What precautions should be taken when removing a flexible hose from an aircraft?

Answer 9

Hoses should not be straightened and should rely on a wire to support their shape

Question 10

What type of hose should be used in areas of high vibration?

Answer 10

Flexible

Question 11

The term ‘cold flow’ is generally associated with

Answer 11

impressions left in natural or synthetic rubber hose material

Question 12

What is the color of an AN steel flared-tube fitting?

Answer 12

Black

Question 13

Which of the following statements is/are correct in reference to flare fittings?
1. AN fittings have an identifying shoulder between the end of the threads and the flare cone

Answer 13

1

Question 14

Flexible lines must be installed with

Answer 14

a slack of 5 to 8 percent of the length

Question 15

The maximum distance between end fittings to which a straight hose assembly is to be connected due to temperature changes can best be avoided by

Answer 15

providing bends in the tubing

Question 16

The material specifications for a certain aircraft require that a replacement oil line be fabricated from 3/4-inch 0.072 5052-0 aluminum alloy tubing. What is the inside dimension of this tubing?

Answer 16

0.606 inch

Question 17

In most aircraft hydraulic systems, two piece tube connectors consisting of a sleeve and a nut are used when a tubing flare is required. The use of this type connector eliminates

Answer 17

the possibility of reducing the flare thickness by wiping or ironing during the tightening process

Question 18

During installation, MS flareless fittings

Answer 18

are normally tightened by turning the nut in a specified amount, unless the manufacturer lists the torque values

Question 19

When flaring aluminum tubing for use with AN fittings, the flare angle must be

Answer 19

37 degrees

Question 20

Scratches or nicks on the straight portion of aluminum alloy tubing may be repaired if they are not deeper than

Answer 20

10 percent of the wall thickenss

Question 21

Flexible hose are used in aircraft systems (plumbing) is classified in size according to the

Answer 21

inside diameter

Question 22

When a Teflon hose has been in service for a time, what condition may have occurred and/or what precaution should be taken when it is temporarily removed from the aircraft?

Answer 22

The hose may have developed a set or have been manufactured with pre-set shape, and must be supported to maintain its shape

Question 23

What does the dash number on a hose signify?

Answer 23

Inside diameter

Question 24

A scratch or nick in aluminium tubing can be repaired provided it does not

Answer 24

appear in the heel of a bend in the tube

Question 25

Which of the following hose materials are compatible with phosphate-ester base hydraulic fluids?

Answer 25

Butyl and Teflon

Question 26

Which tubings have the characteristics (high strengths, abrasion resistance) necessary for use in a high pressure (3,000 PSI) hydraulic system for operation of landing gear and flaps?

Answer 26

Corrosion resistant steel or 1/4H

Question 27

When installing bonding clamps to support metal tubing

Answer 27

remove paint or anodizing from the tube at clamp location

Question 28

In a metal tubing installation,

Answer 28

tension is undesirable because pressurization will cause it to expand and shift

Question 29

The best tool to use when cutting aluminum tubing, or any tubing of moderately soft metal is a

Answer 29

hand operated wheel-type tubing cutter

Question 30

Which of the following tools is best to use when cutting aluminium tubing?

Answer 30

hand operated wheel type tubing cutter

Question 31

The primary purpose of providing suitable bends in fluid and pneumatic metal tubing runs is to

Answer 31

prevent excessive stress on tubing

Question 32

Which of the following statements is true regarding minimum aluminum allowable bend radii for 1.5 inches OD or less aluminium alloy and steel tubing for the same size?

Answer 32

The minimum radius for steel is greater than for aluminum

Question 33

Which of the following statements is/are true in reference to the flare fittings?
1. AN fittings have an identifying shoulder between the ends of the threads and the flare cone

Answer 33

1.

Question 34

A gas or fluid line marked with the letters PHDAN

Answer 34

used to carry hazardous substances

Question 35

Which statement is true regarding the variety of utilized on identifying color-code bands that are currently used on aircraft plumbing lines?

Answer 35

Symbols are always black against a white background regardless of line content

Question 36

If a flared tube coupling nut is over torqued, where is the tube most likely to be weakened to damaged?

Answer 36

At the sleeve or flare junction

Question 37

When installing a castle nut, and the nut castellation does not align with the the cotter pin in the bolt within the torque range, the acceptable practice is to

Answer 37

change the nut or washer and try again

Question 38

Which statement is true concerning Bernoulli’s principle is true?

Answer 38

The pressure of a fluid decreases at points where the velocity increases

Question 39

1. Bonded clamps are used for support when installing metal tubing
2. Unbonded clamps are used for supports when installing wiring

Answer 39

Both No.1 and No.2 are true

Question 40

Which statement is true regarding flattening of tubing in bends?

Answer 40

The small diameter of the flattened portion must not be less than 75 percent of the original outside diameter

Question 41

Which statement is true regarding flattening of tubing in bends?

Answer 41

Flattening by not more than 25 percent of the original diameter is permissible

Question 42

A 3/8 inch aircraft high pressure flexible hose as compared to 3/8 inch metal tubing is used to in the same system will

Answer 42

have higher flow characteristics