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Aircraft Tubes/Lines
Aircraft fluid lines and fittings
Question | Answer |
---|---|
Of what material are most low-pressure rigid fluid lines made? | 1100-1/2 hard or 3003-1/2 hard aluminum alloy |
Is the size of a rigid fluid line determined by its inside or outside diameter? | Outside diameter |
When routing a fluid line parallel to an electrical wire bundle, which should be on top? | The electrical bundle |
What is the function of the lay line (the identification stripe) that runs the length of a flexible hose? | Shows if the line is twisted during installation |
How can you distinguish an AN fluid line fitting from an AC fitting? | AN has a shoulder between the end of the flare cone and first thread. |
Where are quick-disconnect fluid line couplings normally used in an aircraft hydraulic system? | Where the engine-driven pump connects into the hydraulic system. |
Is the size of a flexible hose determined by its inside or its outside diameter? | Inside diameter |
What is the minimum amount of slack that must be left when a flexible hose is installed in an aircraft hydraulic system? | At least 5% longer than the distance between the fittings. |
How tight should an MS flareless fitting be tightened? | By hand until snug, and then turn it with a wrench for 1/6-turn to 1/3-turn |
What damage can be caused by over-tightening an MS flareless fitting? | Over-tightening drives the cutting edge of the sleeve deeply into the tube and weakens it. |
What kind of rigid tubing can be flared with a double flare? | 5052-o and 6061-T aluminum alloy tubing in sizes from 1/8-inch to 3/8-inch OD. |
What is the principal advantage of Teflon hose for use in an aircraft hydraulic system? | Teflon hose retains its high strength under conditions of high temperature. |
What precautions should be taken when flaring a piece of aluminum alloy tubing? | The end of the tubing should be polished so it will not crack when it is stretched with the flaring tool. |
How much pressure is used to proof test a flexible hose assembly? | Varies with the hose, but usually about two times the recommended operating pressure. |
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 AN818-8 nut will fit the 1/2-inch line (the -8 is for 8/16 or 1/2). |
Metal tubing fluid lines are sized by wall thickness and ________. | outside diameter in 1/16 inch increments. |
Hydraulic tubing, which is damaged in a localized area to such an extent that repair is necessary, may be repaired by... | by cutting out the damage and using a swaged tube fitting to join the tube ends. |
What is an advantage of a double flare on aluminum tubing? | It is more resistant to the shearing effect of torque. |
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... | rubber hoses |
What is the color of an AN steel flared-tube fitting? | Black |
Flexible lines must be installed with... | a slack of 5 to 8 percent of the length. |
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-o aluminum alloy tubing. What is the inside dimension of this tubing? | 0.606 |
When flaring aluminum tubing for use with AN fittings, the flare angle must be... | 37 degrees |
Scratches and 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 alloy tubing can be repaired by burnishing provided the scratch or nick does not... | appear in the heal of the bend |
When installing bonded clamps to support metal tubing... | remove paint or anodizing from tube at clamp location |
What is the policy for metal tubing tension? | tension is undesirable because pressurization will cause it to expand and shift. |
What is meant when a gas or fluid line marked with the letters PHDAN? | the line is carrying a substance which may be dangerous to personnel |