Pipes EASA

Questions and Answers

Where can the correct replacement part for a hydraulic pipe be found?

Maintenance manual

Repair history log

Maintenance schedule

Parts catalogue (correct)

What categorization is used for flexible hoses?

By elasticity grade

By maximum pressure (correct)

By diameter

By length

What material are rigid pipes on gas turbine engines typically made from?

Aluminium alloy

Titanium

Stainless steel (correct)

Copper

What is the appropriate method to test a hydraulic hose?

Pressure test 1.5 * working pressure Signup and view all the answers

What should be used to prevent damage to seals on fitment?

Use a cardboard protector over threaded portions Signup and view all the answers

Flexible pipes are primarily identified by which characteristic?

Material Signup and view all the answers

What color identifies a pipe carrying lubricant?

Yellow Signup and view all the answers

What is the purpose of using a cardboard protector on threaded portions?

To prevent seal damage Signup and view all the answers

What material is primarily used to make a hydraulic fluid hose?

Teflon Signup and view all the answers

What material are hydraulic pipes typically made from?

Annealed Steel Signup and view all the answers

What does the continuous colored line on a hose assembly indicate?

Detection of twist Signup and view all the answers

What is the maximum storage life of a flexible hose?

5 years Signup and view all the answers

What essential marking must a flexible hose include?

Date of manufacture Signup and view all the answers

When replacing a flexible hose, what must be ensured?

Sufficient clearance from aircraft structure Signup and view all the answers

How are MIL-H-5606 hydraulic fluid O-rings identified?

Blue dot Signup and view all the answers

What material specification is required for hydraulic pipes on an undercarriage?

Stainless steel, annealed, 14H Signup and view all the answers

What are the limits for a small indentation on a metal pipe?

No dent on a bend Signup and view all the answers

What does a stamped number on an aircraft pipe signify?

Serial number Signup and view all the answers

How is the length of a straight hose assembly measured?

Between extremities of the nipples Signup and view all the answers

Metal tubing fluid lines are sized by what parameters?

Outside diameter and 1/16 inch increments Signup and view all the answers

What happens to a flexible hose under pressure in terms of its dimensions?

Contracts in length, expands in diameter Signup and view all the answers

The term 'cold flow' is primarily associated with which material?

Rubber hose Signup and view all the answers

Flexible lines must have what percentage of slack during installation?

At least 5 - 8 % of length Signup and view all the answers

For a 3/4 inch, 0.072 5052-0 aluminium alloy tubing, what is the inside dimension?

0.606 inch Signup and view all the answers

What method can minimize stress on fluid or pneumatic metal tubing due to temperature changes?

Using short, straight sections between fixed parts. Signup and view all the answers

How are flexible hoses in aircraft systems classified in size?

By inside diameter. Signup and view all the answers

Which type of tubing is suitable for high pressure hydraulic systems in aircraft?

Corrosion resistant steel annealed 1/4H. Signup and view all the answers

What does the marking PHDAN indicate about a fluid line?

It carries a dangerous substance. Signup and view all the answers

When comparing a 3/8 inch high pressure flexible hose to a metal tubing of the same size, what is true?

They have equivalent flow characteristics. Signup and view all the answers

To properly assemble a banjo hose, where should washers be placed?

Either side of the banjo. Signup and view all the answers

For a 0.5 inch diameter pipe joined with standard nuts and fittings, which coupling is appropriate?

AN8-8852-8. Signup and view all the answers

What is the installation requirement for a flareless coupling?

Turn until torque is felt plus 2 flats. Signup and view all the answers

What material is ideal for a Skydrol hydraulic seal?

Butyl rubber or Teflon. Signup and view all the answers

In which context are adapter nipples not required?

Pipe to externally coned adapter. Signup and view all the answers

What material is a butyl rubber seal made from?

Synthetic rubber. Signup and view all the answers

What color denotes an AN steel flared-tube fitting?

Black. Signup and view all the answers

Which statement about Military Standard (MS) flareless fittings is accurate?

Tightened to a specific torque. Signup and view all the answers

What is a flexible sealing element primarily used under motion?

Packing. Signup and view all the answers

Study Notes

Hydraulic Systems and Components

Replacement Parts: Obtain hydraulic pipe replacement parts from a parts catalogue.
Flexible Hose Classification: Categorized by maximum pressure.

Materials

Rigid Pipes in Gas Turbine Engines: Constructed from stainless steel due to high heat resistance.
Hydraulic Fluid Hose: Typically made from Teflon.
Hydraulic Pipes: Commonly manufactured using annealed steel or stainless steel, particularly in undercarriage legs.

Testing and Installation Practices

Testing Hydraulic Hoses: Pressure tested at 1.5 times the working pressure for safety.
Seals Damage Prevention: Use a cardboard protector over threaded portions during fitment.
Fitting Flexible Hoses: Ensure adequate clearance between the hose and aircraft structure.

Hose Specifications

Flexible Hose Identification: Based on material used.
Inside Dimension Calculation: For a 3/4 inch, 0.072 wall thickness 5052-0 aluminium alloy tube, the inside dimension is 0.606 inches.
Brake/Cooling Fluid System Hoses: Recognized by specific color coding, such as yellow for lubricant lines.

Assembly Guidelines

Banjo Hose Assembly: Requires washers on either side of the banjo fitting for proper sealing.
Fitting Tightening: Flareless couplings are installed until torque is felt, plus two flats.

Guidelines for Flexible Hoses

Storage Life: Flexible hoses can be stored for up to 5 years.
Slack in Flexible Hoses: Maintain a slack of 5-8% of the hose's length during installation to accommodate flexing.
Cold Flow Phenomenon: Refers to a permanent impression caused by excessive pressure from clamps on rubber hoses.

Safety and Color Codes

Identification Markings on Hoses: Must include the date of manufacture.
Dangerous Materials Marking: PHDAN designation indicates a line carrying potentially dangerous substances.

Fittings and Couplings Specifics

AN Steel Flared-Tube Fittings: Are identified by their black color while aluminum fittings are blue.
MS Flareless Fittings: Generally tightened to a specific torque; they necessitate a different installation technique compared to standard fittings.

Summary of Key Points

Pressure Testing: Critical for hose reliability; adhere strictly to guidelines for pressure tests.
Material Characteristics: Knowledge of materials is essential for safety and efficiency in aerospace applications.
Attentive Installation: Proper installation techniques are vital to prevent leaks and ensure functionality in hydraulic systems.

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Description

Test your knowledge on hydraulic systems with this quiz focused on maintenance and replacement parts. You'll answer questions about finding the correct parts and the classification of hoses. Perfect for students and professionals in engineering and mechanics.