Aircraft Maintenance Technology

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Questions and Answers

What type of cutting tool for Sheet Metal Construction and Repair have straight blades with cutting edges sharpened to an 85° angle?

Straight snips, or sheet metal shears

Aviation Snips (correct)

Files

None of the above

What size of the rivet do we need to join these 2 pieces of metal?

RD = 5/32, RL = 5/16

What is measured from the rivet center to the rivet center?

Rivet

Transverse pitch (correct)

Edge Distance

None of the above

A well designed rivet joint will subject the rivets to compressive loads.

False Signup and view all the answers

Match the following rivet head types with their descriptions:

Flat Head Rivet (AN442) = Flush type rivet used for specific applications Brazier Head Rivet (AN455) = Used throughout the interior aircraft structure Round Head Rivet (AN430) = About twice the diameter of the shank and slightly flattened on top Signup and view all the answers

What is the primary purpose of refrigerating 2017 and 2024 aluminum alloy rivets after heat treatment?

To relieve internal stresses Signup and view all the answers

What is one purpose of a fuel tank vent?

To decrease tank internal air pressure Signup and view all the answers

Which gas is used for purging an aircraft fuel tank?

Helium or argon Signup and view all the answers

A capacitance type fuel quantity indicating system measures fuel in

Gallons Signup and view all the answers

To prevent vapor lock in fuel lines at high altitude, some aircraft are equipped with

Booster pumps Signup and view all the answers

The pole pieces or shoes used in a DC generator are a part of the:

Field assembly Signup and view all the answers

Aircraft fuse capacity is rated in

Amperes Signup and view all the answers

What are antiskid generators used for?

Measure wheel rotational speed and any speed change Signup and view all the answers

What are composite materials with high temperature applications made of?

Aramid Fiber Signup and view all the answers

Kevlar composite has __ times better tensile strength than aluminum.

8 Signup and view all the answers

Match the following fiber orientations with their descriptions:

Unidirectional = Major fibers run in one direction for strength Bi-directional = Fibers run in two directions for strength Mat = Randomly oriented fibers for balance Satin fiber = Woven fibers for aesthetics Signup and view all the answers

What is the method used for detecting cracks in metallic surfaces?

Magnetic particle inspection Signup and view all the answers

What is the composite component repair method that uses heat gradients to detect flaws?

Thermography Signup and view all the answers

What is the method that features the use of a laser light source for inspection?

Laser shearography Signup and view all the answers

Study Notes

Metallic Structures (Sheet Metal):
- Uses stressed skin to support almost all loads
- Consists of determining the number of rivets required, style of rivet to be used, material temper condition and strength, distance of rivet holes, and spacing of rivets throughout the repair
- Filler patch is flush to the skin when applied, supported by and riveted to a reinforcement plate, which is riveted to the inside of the skin
Cutting Tools for Sheet Metal Construction and Repair:
- Straight snips or sheet metal shears with straight blades and cutting edges sharpened to an 85° angle
- Available in sizes ranging from 6 to 14 inches, can cut aluminum up to 1/16 of an inch
- Can be used for straight cutting and large curves
Rivet Joint:
- A well-designed rivet joint will subject the rivets to shear loads
- Rivet gauge or transverse pitch is the distance between the center of adjacent rivets in the same row
Aluminum Alloys:
- 2024-T36 alloy has copper as its primary alloying agent
- Annealing of aluminum removes stresses caused by forming
Rivet Types:
- Flat Head Rivet (AN442): used throughout the interior aircraft structure where special rivets are not required
- Round Head Rivet (AN430): used for applications where countersinking is not required
- Brazier Head Rivet (AN455): used where high shear strength and resistance to vibration are required
Layout Tools for Sheet Metal Construction and Repair:
- Consists of a steel scale with three heads that can be moved to any position on the scale and locked in place
- Heads include a stock head that measures 90° and 45° angles, a protractor head that can measure any angle, and a center head that uses one side of the blade as the bisector of a 90° angle
Marking Tools for Sheet Metal Construction and Repair:
- Graphite pencils should not be used on aluminum as they can cause corrosion
- Preferred method of marking lines and hole locations directly on aluminum is with a scribe or marker

Aircraft Structures

Semi-Monocoque Fuselage:
- Longitudinal structural members are called longerons and stringers
- Relies largely on the strength of skin or covering
Monocoque Fuselage:
- Relies largely on the strength of skin or covering
Helicopter Controls:
- Movement about the longitudinal axis (roll) is effected by cyclic pitch control
- Movement about the lateral axis (pitch) is effected by collective pitch control
- Movement about the vertical axis (yaw) is effected by tail rotor pitch control

Landing Gear

Shock Strut:
- Should be checked for proper extension and compression
- Should be checked for signs of damage or wear
Torque Links:
- Limit compression stroke and maintain correct wheel alignment

Hydraulic Systems

Pressure Regulator:
- Maintains system operating pressure within a predetermined range
- Unloads the pump
Fluid:
- MIL-H-8446 (Skydrol 500 A & B) is a phosphate ester base, fire-resistant fluid
- Compatible with natural rubber seals and packings
Instruments:
- Pitot static system connects to airspeed indicator, altimeter, and vertical speed indicator

Avionics and Electrical Systems

Autopilot:
- Fully integrated autopilot controls the aircraft around three axes
Antenna Installation:
- Must be grounded to the airframe
Radio Signals:
- VHF signals are commonly used in ATC communications
Dutch Roll:
- Counteracted with a yaw damper system

Fuel Systems

Fuel Tank System:
- Allows all tanks to be serviced through a single connection
- Any engine can be fed from any tank
- All engines can be fed from all tanks simultaneously
- A damaged tank can be isolated from the rest of the fuel system
Fuel Tank Vent:
- Prevents bubble formation in the fuel after it leaves the tank when atmospheric pressure is lower than fuel vapor pressure
Fuel Quantity Indicating System:
- Measures fuel in pounds
Fuel Purging:
- Helium or argon gas is used to purge an aircraft fuel tank

Non-Metallic Structures (Composite)

Reinforcing Materials:
- Carbon/Graphite Fiber: used when high temperature application is needed
- Ceramic Fiber: used when high temperature application is needed
Composite Properties:
- Fatigue resistance: Fiberglass Fiber has high fatigue resistance
- Tensile strength: Kevlar composite has higher tensile strength than aluminum
Fiber Orientation:
- Unidirectional: all major fibers run in one direction, giving strength in that direction
- Bi-directional: fibers run in two directions, giving strength in both directions
Resin Types:
- Thermoplastic: can be reheated and reformed
- Thermoset: cannot be reheated and reformed
Surface Attachments:
- Adhesives: used to bond composite parts together
- Additives: used to improve the properties of the resin
Manufacturing Methods:
- Hand or Wet Layup: most widely accepted form of applying composite materials
- Fitament Winding: used for parts with a circular cross-section
- Fiber Placement or Tape Laying: used for complex shapes
Curing Methods:
- Heat Curing: uses heat to cure the resin
- Room Temperature Curing: uses a catalyst to cure the resin at room temperature
- Ramp and Soak Curing: uses a controlled temperature and pressure to cure the resin

Composite Repair

Damage Detection:
- Visual inspection: detects cracks, delamination, and cosmetic damage
- Infrared inspection: detects temperature variations at the surface of a damaged part
- Laser inspection: uses a laser light source and an infrared camera to detect cracks and delamination