Aircraft Rigid Fluid Lines: MS21900-4 Quiz and Flashcards

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Questions and Answers

What is the primary reason for replacing copper tubing with aluminium-alloy and corrosion-resistant steel lines in aircraft?

Copper tubing was prone to becoming hard and brittle from flight vibrations (correct)

Corrosion-resistant steel lines are more malleable than copper tubing

Copper tubing was too expensive to maintain

Aluminium tubing is lighter in weight than copper tubing

Which systems in aircraft typically utilize rigid tubing due to the requirement of long, relatively straight runs?

Air conditioning systems

Oxygen systems (correct)

Avionics systems

Hydraulic systems

In what pressure range are commercially pure aluminium tubing (1100-H14 or 3003-H14) commonly used in aircraft applications?

Above 3000 psi

Below 500 psi (correct)

Around 5000 psi

1000-2000 psi

How are aluminium-alloy tubes typically identified on larger tubes?

By stamping the alloy designation on the tube's surface Signup and view all the answers

Why did copper tubing prove troublesome in early aircraft applications?

It became hard and brittle from flight vibrations Signup and view all the answers

What is the typical width of the coloured bands used to identify aluminium-alloy tubes on small tubing in aircraft applications?

Less than 1 inch wide Signup and view all the answers

What is the external flare angle for AN fittings?

37° Signup and view all the answers

What color are AN steel fittings for identification purposes?

Black Signup and view all the answers

In what way are flareless fittings different from flared fittings?

Different external flare angles Signup and view all the answers

What material are AN flareless fittings made of?

Aluminium alloy Signup and view all the answers

What is the color of AN aluminium fittings for identification purposes?

Blue Signup and view all the answers

How many parts does an AN flareless fitting consist of?

Three parts Signup and view all the answers

How can aluminium alloy fittings be visually identified?

By their yellow color caused by anodising treatment Signup and view all the answers

What does the letter-number code in steel fittings such as MS21900-4 signify?

Fitting size Signup and view all the answers

Which material is used to make fittings indicated by MS21900-8-D?

Aluminium alloy Signup and view all the answers

What feature makes flareless fittings suitable for high-pressure systems with heavy wall tubing?

Leak-free attachments without flares Signup and view all the answers

What does the prefix 'MS' in fittings like MS21900-4 stand for?

Military Specification Signup and view all the answers

What is the significance of '4' in MS21900-4 fittings?

Fitting size Signup and view all the answers

What is the purpose of pre-setting when installing a new flareless tube assembly?

To apply pressure to the sleeve to cut into the outside of the tube Signup and view all the answers

What is the main function of universal bulkhead fittings?

To support a line passing through a bulkhead Signup and view all the answers

How do tapered pipe thread fittings create a seal?

By wedging the tapered external male thread and the tapered internal female threads Signup and view all the answers

What is NOT necessary when using bulkhead fittings for fluid lines?

Tapered pipe thread fittings Signup and view all the answers

Which type of fitting eliminates the need to flare the tube before installation?

Flareless fittings Signup and view all the answers

What happens during pre-setting in relation to the sleeve and the tube?

The sleeve cuts into the outside of the tube Signup and view all the answers

Why is the design of the reinforcement layers in a hose critical?

To prevent the hose from expanding and shrinking when pressure is applied Signup and view all the answers

What is the purpose of the outer cover on a hose?

To protect the hose from physical damage Signup and view all the answers

How is an outer cover in areas of high heat different from a standard outer cover?

It is designed as an integral fire-sleeve to provide extra protection Signup and view all the answers

What information can be found on the lay line of the outer cover of an aircraft flexible hose?

The date it was manufactured Signup and view all the answers

How does the lay line on the outer cover help identify if a hose is installed properly?

By running straight with no twists when installed correctly Signup and view all the answers

Why is it important that the lay line shows if a hose is twisted when installed?

To ensure proper installation and prevent issues Signup and view all the answers

Study Notes

Flareless Fittings

MS type fittings are commonly used in large transport category aircraft due to their ability to withstand high system working pressures (up to 8000 psi)
Flareless fittings are made of aluminum alloy or steel
Aluminum alloy fittings can be identified visually by their yellow color, which is caused by the anodizing treatment
Cadmium plating on steel fittings is identified by letter-number codes (e.g., MS21900-4)
MS number indicates the design part number, size of the fitting, and material (e.g., carbon steel, aluminum alloy, or corrosion-resistant steel)

Rigid Lines

Rigid lines are used in stationary applications and where long, relatively straight runs are possible
Systems that typically utilize rigid tubing include fuel, oil, oxygen, and instrument systems
Aluminum-alloy and corrosion-resistant steel lines have replaced copper in most applications
Aluminum tubing comes in various alloys (e.g., 1100-H14, 3003-H14) for low-pressure systems

Tube Identification

Aluminum-alloy tubes are identified by alloy designation stamped on the tube's surface or by colored bands on small tubing
Colored bands are no more than 4 in. wide and are painted on the tube's ends and mid-section

Flared-tube Fittings

Flared-tube fittings are made of aluminum alloy, steel, or copper base alloys
AN steel fittings are colored black, and AN aluminum fittings are colored blue
AN 819 aluminum bronze sleeves are cadmium plated and not colored
AN fittings come in various shapes and sizes, each with a specific use

Flareless Tube Fittings

Two types of tube fittings are used on modern aircraft: flared and flareless
AN fittings have a 37° external flare, while flareless fittings have an internal bevel of 24°
Flareless fittings eliminate the need to flare the tube, but pre-setting is necessary prior to installation
Pre-setting involves applying pressure to the sleeve to cause it to cut into the outside of the tube

Heavy Wall Flareless Fittings

Heavy wall flareless fittings are used in high-pressure systems

Universal Bulkhead Fittings

Universal bulkhead fittings are used to support lines that pass through a bulkhead
Bulkhead fittings have straight machine threads and require flared tube connections, crush washers, or synthetic seals to make connections fluid-tight

Tapered Pipe Thread Fittings

Tapered pipe thread fittings create a seal by wedging the tapered external male thread and the tapered internal female threads
These threads taper 1/16 in. to the inch

Hose Construction

Common reinforcement layers are made of cotton, rayon, polyester fabric, carbon-steel wire, or a stainless steel wire braid
The outer cover is usually made of rubber-impregnated fabric or stainless steel braid and protects the hose from physical damage
The outer cover is marked with a lay line, which consists of a yellow, red, or white stripe running the length of the hose

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Description

Explore the applications of rigid fluid lines in aircraft, including the types of lines used, specific applications, and materials commonly used. Learn about the systems that typically utilize rigid tubing and their importance in aviation.

Rigid Fluid lines in Aircraft: Applications

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