Fluid lines and fittings Flashcards
What are the two categories of fluid lines commonly used in aircraft?
Rigid, metal lines, and flexible hoses
Describe the method of classifying metal tube according to size
Metal tubing a size accordingly to wall thickness and outside diameter outside diameter is measured and 1/16 inch increments
Describe the method of classifying, flexible hose according to size 
Flexible hose sized according to inside diameter in 1/16 inch increments
When installing stainless steel tubing, what type of fittings should be used
Stainless steel fittings
What is the function of the sleeve on a flared tube feeding
The nut fits over the sleeve and draws the sleeve, and the tubing flared tightly against the male fitting to form the seal
Describe the two types of flares, commonly used on aircraft tubing
The single flare, and the double flare
What is the flare angle of aviation flares?
37°
What is the difference between flare angles for aviation in automotive flares?
Aviation is 37° automotive is 45°
How can you determine if a fitting is an AN type rather than an AC type
AN fittings have a shoulder between the flare cone, and the end of the threads AC fittings do not
What are the most significant differences between AN and AC fittings
Sleeve length, thread pitch, in the shoulder between the threads, and the flare cone on AN fittings
How do you tell a flare-less fitting from a flare type fitting?
Flare-less fittings 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 overtightening a flare type fitting?
The sealing surfaces 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 bonded to the structure
What are some of the important advantages of Teflon tubing?
It is compatible with nearly every liquid, has a broad operating temperature range low resistance to fluid flow and has a very long shelf life
When selecting, flexible hose for use in a phosphate Ester based hydraulic fluid (skydrol) system the hose should be made of which synthetic rubber compound
Butyl
Describe the identification markings, commonly found on flexible hoses
A Layline identification, such as a mil spec number, the manufactures name, or symbol the whole size, and a date code
What is the maximum interval for repeating the required markings on a flexible hose?
Not more than 9 inches along the length of the hose
How can you determine if a flexible hose has been correctly or incorrectly installed?
The lay line will be straight. If the hose is properly installed a twisted le line indicates an incorrect installation.
When installing a flexible hose or rigid lines, next to electrical conduit or water bundles, what precautions should be
Route the hose or rigid line below the electrical conduit or wire bundles, and make certain that they are clamped and properly bonded
When installing flexible hoses, what considerations should be made?
Slack, flexing, twisting, bending, clearance, and clamps
How can a flexible hose be designated?
By the inside diameter measured and 1/16 inch increments
What percentage of flattening is allowed when bending metal tubing?
Do not exceed 75% of original diameter
Scratches and nicks may be repaired if they are less than what percent of the wall thickness
10%
What precautions must be observed when deburring the end of a tube after it is cut
The wall thickness must not be reduced in size or fractured
Describe the operation of quick disconnect couplings
Each half has a valve that is held open when coupled and is spring loaded closed when disconnected
Why are quick disconnect fittings used?
To provide a quick means to connect or disconnect, a fluid line, without loss of fluid or entrance of air into the system
If you fabricate a replacement for a flexible hose, what percentage of total length must be allowed for movement under pressure
5 to 8%
What happens to the tube when a flare-less fitting is overtightened
The tube is weakened when the nut drives the cutting edge of the sleeve too deeply into the tube
