Fluid Lines and Fittings Flashcards
Of what material are most low-pressure rigid fluid lines made?
1100-1/2 hard or 3003-1/2 hard aluminum alloy tubing.
Is the size of a rigid fluid line determined by its inside or its outside diameter?
By its outside diameter.
When routing a fluid line parallel to an electrical wire bundle, which should be on top?
The electrical wire bundle should be on top.
How can you distinguish an AN fluid line fitting from an AC fitting?
The AN fitting has a shoulder between the end of the flare cone and the first thread. The threads of an AC fitting extend all the way to the flare cone.
How tight should an MS flareless fitting be tightened?
Tighten the fitting by hand until it is snug, and then turn it with a wrench for 1/6-turn to 1/3-turn. Never turn it more than 1/3-turn with a wrench.
What damage can be caused by overtightening an MS flareless fitting?
Overtightening drives the cutting edge of the sleeve deep 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.
Of what material should rigid fluid lines be made that carry high-pressure (3,000 psi or greater) hydraulic fluid?
Annealed or 1/4-hard corrosion-resistant steel.
What is the difference between the flare angle for aircraft and automotive fittings?
Aircraft fittings have a 37° flare angle and automotive fittings use 45°.
What should be done to the end of a tube that is to be flared?
The cut end should be polished to remove any sharp edges that could cause the tubing to crack.
What is the function of the lay line (the identification stripe) that runs the length of a flexible hose?
To show the mechanic whether or not the line was twisted when it was installed. The line should be straight, not spiraled.
Where are quick-disconnect fluid line couplings normally used in an aircraft hydraulic system?
In the lines that connect the engine-driven pump into the hydraulic system.
Is the size of a flexible hose determined by its inside or its outside diameter?
By its inside diameter.
What is the minimum amount of slack that must be left when a flexible hose is installed in an aircraft hydraulic system?
The hose should be at least 5% longer than the distance between the fittings. This extra length provides the needed slack.
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.
