Fluid Lines and Fitttings Flashcards

1
Q

What are two types of fluid lines commonly found in aircraft?

A

Rigid metal lines and flexible hoses.

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2
Q

Describe the method of classifying metal tube according to size.

A

Metal tubing is sized according to wall thickness and outside diameter. Outside diameter is measured in 1/16th inch increments.

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3
Q

When installing stainless steel tubing, what type of fittings should be used?

A

Stainless steel fittings.

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4
Q

What is the function of the sleeve on a flared-tube fitting?

A

The nut fits over the sleeve and draws the sleeve and the tubing flare tightly against the male fitting to form the seal.

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5
Q

Describe the two types of flares commonly used on aircraft tubing.

A

The single flare and the double flare.

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6
Q

How can you determine if a fitting is an AN type rather than an AC type?

A

AN fittings have a shoulder between the flare cone and the end of the threads, AC fittings do not.

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7
Q

What are the significant differences between AN and AC fittings?

A

Sleeve length, thread pitch, and the shoulder between the threads and the flare cone on AN fittings.

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8
Q

What are the names of the parts of a flareless tube fitting?

A

The nut and sleeve.

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9
Q

How do you tell a flareless fitting from a flare-type fitting?

A

Flareless fittings don’t have a flare cone and there is no space between the threads and the end of the fitting.

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10
Q

What is the effect of over-tightening a flare type fitting?

A

The sealing surface may be damaged or the flare cut off.

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11
Q

In addition to being securely clamped, what is an additional requirement for installing metal fuel, oil, and hydraulic lines.

A

The lines must be electrically bonded to the structure.

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12
Q

What are some of the important advantages of Teflon tubing?

A

It is compatible with nearly every liquid, has a broad operating temperature range, low resistance to fluid flow and has a very long shelf and service life.

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13
Q

Describe the identification markings commonly found on flexible hoses.

A

A lay line, identification such as a Mil Spec number, the manufacturer’s name or symbol, the hose size and a date code.

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14
Q

How can you determine if a flexible hose has been correctly or incorrectly installed?

A

The lay line will be straight if the hose if properly installed. A twisted lay line indicates an incorrect installation.

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15
Q

How are flexible hose sizes designated?

A

By the inside diameter, measured in 1/16th inch increments.

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16
Q

What precautions must be observed when deburring the end of a tube after it is cut?

A

The wall thickness must not be reduced in size or fractured.

17
Q

Describe the operation of quick disconnect couplings.

A

Each half has a valve that is held open when coupled and is spring-loaded closed when disconnected.

18
Q

If you fabricate a replacement for a flexible hose, what percentage of the total length must be added to allow for movement under pressure?

A

5 to 8 percent.

19
Q

What happens to the tube when a flareless fitting is overtightened?

A

The tube is weakened when the nut drives the cutting edge of the sleeve too deeply into the tube.

20
Q

Why are quick disconnect fittings used?

A

To provide a quick means to connect or disconnect a fluid line without loss of fluid or entrance of air into the system.

21
Q

Name the parts of a Military Standard flareless-tube fitting?

A

A body, sleeve, and nut.

22
Q

What are the identification markings that are usually found on flexible rubber hose?

A

Hose size, manufacturer, date of manufacture, pressure, and temperature limits.

23
Q

Name at least two synthetic materials commonly used in the manufacture of flexible hose.

A

Buna-N, Neoprene, Butyl, Ethylene, Propylene-Diene rubber, Teflon.

24
Q

When selecting a flexible hose for use in a phosphate-ester based hydraulic fluid (Skydrol) system, the hose should be made of which synthetic rubber compound?

A

Butyl.

25
Q

What is the maximum interval for repeating the required markings on a flexible hose?

A

Not more than nine inches along the length of the hose.

26
Q

What percentage of flattening is allowed when bending metal tubing?

A

Do not exceed 75% of original diameter.

27
Q

How can you tell that flexible hose has been installed in a twisted position?

A

By the identification stripe running along the hose length.

28
Q

Name at least two considerations when installing flexible hose assemblies.

A

Slack, flexing, twisting, bending, clearance, and clamps.

29
Q

Flexible hose should be clamped at least every how many inches?

A

24 inches.

30
Q

Scratches and nicks may be repaired if they are less than what percentage of the wall thickness?

A

10%.

31
Q

What is the difference between flare angles for aviation and automotive flares?

A

Aviation is 37 degrees, automotive is 45 degrees.