Fluid lines and fittings Flashcards
What two general types of fluid lines are commonly used in aircraft plumbing?
Metal tubing and flexible hoses
How is metal tubing classified in size?
By the outside diameter in 1/16 inch increments and by wall thickness
How are flexible hose sizes designated?
By the internal diameter measured in 1/16 inch increments
What caution must be observed when deburring the end of tubing after cutting?
Wall thickness is not fractured or reduced in size
Name two kinds of flares commonly used in aircraft plumbing systems
The single flare and the double flare
Name the parts of the military standard flareless-tube fitting
Body, sleeve and nut
What type fittings material should be used with stainless steel tubing?
Stainless steel fittings
What is the purpose of a sleeve on a flared-tube connection?
The nut and sleeve together when tightened will draw the sleeve and tubing flare tightly against the male fitting to form the seal
What happens to a flareless tube fitting when it is overtightened?
The nut drives the cutting edge of the sleeve deeply into the tube, causing the tube to be weakened
What are the identification markings usually found on flexible rubber hose?
A lay line, hose size, date of manufacture, pressure and temperature limits
Name at least two synthetic materials commonly used in the manufacture of flexible hose
Nina-N, neoprene, butyl, ethylene propylene rubber and teflon
When selecting a flexible hose for use in a phosphate ester based hydraulic fluid system, the hose should be made of which synthetic rubber compound?
Butyl
What is the max interval for repeating the required markings on a flexible hose?
No more than 9” along the length of the hose
What percentage of flattening is allowed when bending metal tubing?
No more than 75% of original diameter
How can you determine if a fitting in an AN type rather than an AC type?
AN has a shoulder and AC does not
What is the most significant difference between AN and AC fittings?
Sleeve length, thread pitch and the shoulder between the threads and the flare cone on AN fittings
How do you a flareless fitting from a glare type fitting?
Flareless fitting don’t have a flare cone and there is no space between the threads and the end of the fitting
What is the effect of o er tightening a flare type fitting?
The sealing surface may be damaged or the flare cut off
In addition to being securely clamped, what is an additional requirement for installing metal fuel, oil and hydraulic lines?
The lines must be electrically grounded to the structure
What are some of the important advantages of Teflon tubing?
Compatible with most fluids, temperature range, low resistance to fluid flow and long shelf and service life
Describe the operation of quick disconnect couplings
Each half has a valve that is held open when coupled and spring loaded closed when disconnected
Why are quick disconnect fittings used?
Quick means to connect or disconnect a fluid line without loss of fluid or entrance of air into the system
When fabricating a flexible hose, what percent of the total length must be allowed for freedom of movement under pressure?
5-8% of its total length
How can you tell that a flexible hose has been installed in a twisted position?
A twisted lay line indicates an incorrect installation
