Fluid lines & Fittings

Question 1

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

Answer 1

37 degrees

Question 2

Scratches or nicks on the straight portion of aluminum alloy tubing may be repaired if they are no deeper than

Answer 2

10 percent of the wall thickness

Question 3

If a flared tube coupling but is overtightened, where is the tube most likely to be weakened/damaged?

Answer 3

At sleeve and flare junction.

Question 4

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

Answer 4

Corrosion-resistant steel annealed or 1/4H

Question 5

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 he aircraft?

Answer 5

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

Question 6

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

Answer 6

0.606 inch

Question 7

Metal tubing fluid lines are sized by wall thickness and

Answer 7

Outside diameter in 1.16 inch increments.

Question 8

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

Answer 8

Appear in the heel of a bend.

Question 9

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

Answer 9

Contracts in length and expands in diameter.

Question 10

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.
2) AC and AN fittings are considered identical except for material composition and identifying colors.
3) AN fittings are generally interchangeable with ac fittings of compatible material composition.

Answer 10

1

Question 11

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 connecter eliminates

Answer 11

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

Question 12

Flexible hose used in aircraft systems is classified in size according to the

Answer 12

Inside diameter

Question 13

Which statement(S) about military standard (MS) flare-less fittings is/are correct?

1) During installation, MS flare-less fittings are normally tightened by turning the nut a specified amount, rather than being torqued.
2) New MS flare-less tubing/fittings should be assembled clean and dry without lubrication.
3) During installation, MS flare-less fittings are normally tightened by applying a specified torque to the nut

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

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

Answer 15

Black

Question 16

The term ‘cold flow’ is generally associated with

Answer 16

Impressions left in natural or synthetic rubber nose material.

Question 17

A gas or fluid line marked with the letters PHDAN is

Answer 17

Used to carry a hazardous substance

Question 18

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

Answer 18

Prevent excessive stress on the tubing

Question 19

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

Answer 19

more resistant to damage when the joint is tightened.

Question 20

Excessive stress on fluid or pneumatic metal tubing caused by expansion and contraction due to temperature changes can best be avoided by

Answer 20

Providing bends in the tubing

Question 21

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

Answer 21

Have equivalent flow characteristics

Question 22

The maximum distance between end fittings to which a straight hose assembly is to be connected is 50 inches. The minimum hose length to make such a connection should be

Answer 22

52- 1/2 inches

Question 23

Which statement is true regarding flattening of tubing in bends?

Answer 23

Flattening by not more than 35 percent of the original diameter is permissible

Question 24

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

Answer 24

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

Question 25

When installing bonded clamps to support metal tubing,

Answer 25

Remove paint or anodizing from tube at clamp location.

Question 26

Which statement concerning Bernoulli’s principle is true?

Answer 26

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

Question 27

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

Answer 27

Change the nut or washer and try again.

Question 28

Rolling-type flaring tools are used to flare X,X, and X tubing

Answer 28

Soft copper, aluminum, brass

Question 29

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

1) Butyl
2) Teflon
3) Buna-N
4) Neoprene

Answer 29

1 and 2

Question 30

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

Answer 30

An 818-8

Question 31

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

Answer 31

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

Question 32

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

Answer 32

Hand operated wheel-type tubing center.

Question 33

2 Unbonded clamps are used for support when installing wiring.
Regarding the above and below statements
1-Bonded clamps are used for support when installing metal tubing

Answer 33

Both no.1 and no.2 are true

Question 34

in a metal tubing installation

Answer 34

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

Question 35

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

Answer 35

The minimum radius for steel is greater than for alumminum

Question 36

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 of a mallet and turn the plunger one-half turn after each blow.
5) Tighten the clamp bar securely to prevent slippage.
6) Center the plunger of flaring pin over the tube.

Answer 36

3,1,6,2,5,4