Fluid lines and Fittings Flashcards
Last dash number for tubes is…
the tube diameter in 1/16-inch increments.
How is metal tubing used in aircraft fluid power installations sized?
By wall thickness and outside diameter measured in sixteenths of an inch.
Double flares are…
smoother than single flares and are more concentric + more resistant to shearing effect when the fittings are torqued.
Steel AN/Aluminum AN fittings colors are…
Steel is Black/Aluminum is Blue.
Extra slack in flexible lines provides…
allowance for expansion in the system due to heat.
Bends are necessary to….
permit the tubing to expand/contract and to absorb vibration.
What are the two types of flare fittings used in hydraulic systems?
A single-piece AN817 nut
A two piece MS20819 sleeve and an AN818 nut.
The sleeve and the nut are preferred because it eliminates the possibility of reducing the thickness of the flare by wiping or ironing action when the nut is tightened.
With the two-piece fitting, there is no relative motion between the fitting and the flare when the nut is being tightened.
How is presetting MS flareless fittings accomplished when attached to the end of a metal tube?
Presetting consists of putting enough pressure on the fitting to deform the ferrule and cause it to cut into the outside of the tube. Presetting is done by lubricating the threads of the presetting tool and the nut with hydraulic fluid, assembling the nut and ferrule on the tube, putting it in the presetting tool, and tightening the nut by hand until resistance is felt, then turning it with a wrench from 1 to 1-1/4 turns.
When installing the fitting in an aircraft hydraulic system, tighten the nut by hand until resistance is felt and then turn it 1/6 to 1/3 of a turn (one hex to two hexes) with a wrench.
Butyl is not suitable for use with…
petroleum products
When installing bonded clamps paint/oxide film should be removed because…
they are electrical insulators.
