Fluids Line and Fittings Flashcards
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 nuts, sleeves, and fittings?
AN-818-8
Metal tubing fluid lines are sized by wall thickness and
Outside diameter in 1/16 inch incriments
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. Center the plunger or flaring pin over the tube.
3,1,6,2,5,4
Hydraulic tubing, which is damaged in a localized area to such an extent that repair is necessary, may be
repaired
By cutting out the damaged area and utilizing a swaged tube fitting to join the tube ends
What is an advantage of a double flare on aluminum tubing?
More resistant to damage when the joint is tightened
A certain amount of slack must be left in a flexible hose during installation because, when under
pressure, it
Contracts in length and expands in diameter
The term ‘cold flow’ is generally associated with
Impression left in natural or synthetic rubber hose material
What is the color of an AN steel flared-tube fitting?
Black
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.
1
Flexible lines must be installed with
A slack of 5 to 8 percent of the length
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
52 1⁄2 inches
Excessive stress on fluid or pneumatic metal tubing caused by expansion and contraction due to
temperature changes can best be avoided by
Providing bends in the tubing
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?
0.606 inch
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
The possibility of reducing the flare thickness by wiping or ironing during the tightening process
Which statement(s) about Military Standard (MS) flareless fittings is/are correct?
1. During installation, MS flareless fittings are normally tightened by turning the nut a specified amount,
rather than being torqued.
2. New MS flareless tubing/fittings should be assembled clean and dry without lubrication.
3. During installation, MS flareless fittings are normally tightened by applying a specified torque to the
nut
1
When flaring aluminum tubing for use with AN fittings, the flare angle must be
37 degrees
Scratches or nicks on the straight portion of aluminum alloy tubing may be repaired if they are no
deeper than
10 percent of the wall thickness
Flexible hose used in aircraft systems is classified in size according to the
Inside diameter
A scratch or nick in aluminum tubing can be repaired provided it does not
Appear in the heal of the bend
Which of the following hose materials are compatible with phosphate-ester base hydraulic fluids?
1. Butyl.
2. Teflon.
3. Buna-N.
4. Neoprene.
1 and 2
Which tubings have the characteristics (high strength, abrasion resistance) necessary for use in a high-
Corrosion resistant steel annealed or 1/4H
When installing bonded clamps to support metal tubing,
Remove paint or anodizing from tube clamp location.
In a metal tubing installation,
Tension is undesirable because pressurization will cause it to expand and shift
The best tool to use when cutting aluminum tubing, or any tubing of moderately soft metal is a
Hand operated wheel type tubing cutter
The primary purpose of providing suitable bends in fluid and pneumatic metal tubing runs is to
Prevent excessive stress on the tubing
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?
The minimum radius for steel is greater than for aluminum
A gas or fluid line marked with the letters PHDAN is
Used to carry a hazardous substance
Which statement is true regarding the variety of symbols utilized on the identifying color-code bands
that are currently used on aircraft plumbing lines?
Symbols are always black against white background regardless of the line content
If a flared tube coupling nut is overtightened, where is the tube most likely to be weakened/damaged?
At the sleeve and flare junction
Which statement concerning Bernoulli’s principle is true?
The pressure of the fluid decreases at point where the velocity of the fluid increases
(1) Bonded clamps are used for support when installing metal tubing.
(2) Unbonded clamps are used for support when installing wiring.
Regarding the above statements,
Both 1 and 2 are true
Which statement is true regarding flattening of tubing in bends?
Flattening may not be more than 25 percent of the original diameter is permissible
A 3/8 inch aircraft high pressure flexible hose as compared to 3/8 inch metal tubing used in the same
system will
Have equivalent flow characteristics
