Helicopter Blade Mechanics Quiz

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Questions and Answers

What is the part of the blade that meets the air first?

Leading Edge (correct)

Tip

Trailing Edge

Span Line

Where are balance weights usually attached?

Trailing edge

Root

Blade tip cap (correct)

Span line

What is the location of the blade furthest from the center of rotation?

Trailing edge

Root

Span line

Tip (correct)

Where are damages often located and classified?

The span line (C) Signup and view all the answers

Which part of the airfoil is thicker?

Leading edge (B) Signup and view all the answers

What is the length of the rotor blade from root to tip?

Span (A) Signup and view all the answers

What is the thinnest section of the airfoil?

Trailing edge (C) Signup and view all the answers

Which part of the blade is strengthened to resist damage?

Trailing edge (A) Signup and view all the answers

What material is used to make the main load-carrying member of a fiberglass blade?

Fiberglass (D) Signup and view all the answers

What is the purpose of the root reinforcement plates in a composite blade?

To provide additional strength to the blade's root (B) Signup and view all the answers

What is the purpose of the steel socket threaded to the blade spar shank?

To provide an attaching point to the rotor head (C) Signup and view all the answers

What material is used to cover the fairing or pockets of a composite blade?

Fiberglass (B) Signup and view all the answers

What material is used to protect the leading edge of a composite blade?

Stainless steel (A) Signup and view all the answers

What are the two main categories of tail rotor blades?

Metal and Fiberglass (B) Signup and view all the answers

What material are fiberglass tail rotor blade spars made of?

Solid Titanium (A) Signup and view all the answers

What is the purpose of the internal grounding strips in a composite blade?

To transfer static electricity to the aircraft (C) Signup and view all the answers

What is the purpose of the trailing edge foam filler?

To improve the blade's aerodynamic shape (A) Signup and view all the answers

What is the primary purpose of the aluminum honeycomb and ribs in metal tail rotor blades?

To provide structural support for the blade skins (C) Signup and view all the answers

What material is used to fill the space around the spar in fiberglass tail rotor blades?

Foam plastic (D) Signup and view all the answers

What is the shape of the rotor blade when viewed from above?

Tapered or uniform (D) Signup and view all the answers

What is the purpose of spanwise blade balance?

To ensure the blades are balanced along their length (A) Signup and view all the answers

What is the purpose of trammeling tail rotor blades?

To ensure proper blade alignment (B) Signup and view all the answers

Which of these methods is NOT used to achieve spanwise balance?

Adding weights to the trailing edge of the blades near the cuff end (A) Signup and view all the answers

When removing weight from a blade, what happens to the center of gravity?

The center of gravity moves inward. (C) Signup and view all the answers

What is the primary purpose of tracking weights on helicopter blades?

To reduce vibrations caused by uneven blade rotation. (D) Signup and view all the answers

What is a potential consequence of blades failing to track correctly?

Damage to the helicopter's transmission system. (A) Signup and view all the answers

What are trim tabs used for in helicopter blade construction?

To align the rotor blades on the same plane of rotation. (B) Signup and view all the answers

Which of the following is NOT a potential benefit of using trim tabs instead of tracking weights?

Increased lifting capacity. (D) Signup and view all the answers

How are trim tabs adjusted to align rotor blades on the same plane?

By bending them up or down, affecting the leading edge of the blade. (A) Signup and view all the answers

Where are trim tabs typically located on a helicopter blade?

Near the tip of the blade. (A) Signup and view all the answers

What is the primary principle behind using trim tabs for rotor blade alignment?

The principle of aerodynamic lift. (A) Signup and view all the answers

What should be done with any rotor blade that has nonrepairable damage?

Condemn and dispose of it locally (D) Signup and view all the answers

What is the purpose of taping holes in the rotor blade?

To protect the interior from moisture and corrosion (C) Signup and view all the answers

Which surface of the rotor blade should be protected with a light coating of corrosion preventive?

The outboard eroded surfaces (B) Signup and view all the answers

What information should be placed in the waterproof bag inside the container?

Manufacturer’s blade records (C) Signup and view all the answers

What should be done with old markings on the rotor blade container?

Eliminate them before new shipment (B) Signup and view all the answers

What is the purpose of painting the bottom of the rotor blade a lusterless black?

To prevent glare into crew compartments (A) Signup and view all the answers

Which statement is true regarding the blade stations?

Station numbers increase as they move towards the blade tip. (B) Signup and view all the answers

Why is replacing the skin of a single pocket or fairing blade often not cost-effective?

Repairing the skin costs more than replacing the entire blade. (B) Signup and view all the answers

What is a significant advantage of multiple pocket or fairing blades?

Damaged pockets can be easily replaced without discarding the entire blade. (C) Signup and view all the answers

What materials are commonly used in the internal structure of rotor blades?

Ribs, I-beams, spanwise channels, and aluminum honeycomb foil (C) Signup and view all the answers

What bonding method is used to attach parts of rotor blades?

Adhesive bonding (D) Signup and view all the answers

How does using multiple-pocket rotor blades affect vibration?

It reduces vibrations due to increased flexibility. (C) Signup and view all the answers

What is a disadvantage of single-pocket rotor blades?

Minor damage can lead to the blade being discarded. (C) Signup and view all the answers

Study Notes

Rotor Wing Aerodynamics

Presented in a course AVIA-1035 at Fanshawe college.

Rotor Blades

Design and construction vary by manufacturer, but all aim for efficiency and cost-effectiveness.
Helicopter design specifics dictate blade requirements, influencing design and construction.
Most blades are symmetrical airfoils ensuring stable aerodynamic pitching.
Aerodynamic stability ensured when center of gravity, center of pressure, and blade-feathering axis align.
This consistent alignment maintains stability as the blade's pitch changes during flight.

Asymmetrical Airfoils

Less common, gaining popularity; producing greater lift over a comparable symmetric airfoil.
Increased lift achieved through a 3° upward angle on the trailing edge section.
Prevents excessive center-of-pressure shift during changes in the rotor blade's angle of attack.

Rotor Blade Materials

Common materials used include aluminum, steel, brass, and fiberglass.
Early rotor blades were made of wood, a common material still used in some contemporary models.
Following wood, metal and composite blades became prevalent. Metal blades have a longer history, and composite blades are contemporary.

Wooden Rotor Blades

First production used laminated wood (birch, spruce, pine, balsa).
A steel core was integrated near the blade's leading edge.
Exterior surfaces were coated with resin-impregnated fiberglass cloth for protection.
Typically used in matched pairs, due to wood variations.
Can be vulnerable to moisture damage and thus some short run-ups may be needed.

Metal (Aluminum) Rotor Blades

Been in use for over 40 years.
Construction varies greatly due to manufacturing expenses and the variety of manufacturers.
Usually a hollow extrusion of aluminum serves as the spar in the blade forming the leading edge.
Quality control during construction is a major advantage.
Blades can be changed independently of other blades in a set.

Metal Rotor Blades (Continued)

Aluminum pockets bonded to the trailing edge enhance streamlining.
Aluminum tip cap secures the blade tip.
Similar to other metal components, blade life is determined by stresses and wear during flight.

Composite Rotor Blades

The load-carrying component is made of either fiberglass or metal.
A typical fiberglass spar relies on procured roving spar (glass strands).
Roving is imbued with epoxy resin and wound around a foam core.
Outer layers are fiberglass cloth.
Root reinforcement plates are added for structural integrity.

Composite Rotor Blades (continued)

Trailing edge frequently utilizes further roving strips
The blade's skin might be covered with a fiberglass fairing/pocket (single or multiple), or aluminum honeycomb material for insulation and structural support.

Rotor Blade - Additional Components

Leading edge is often reinforced by a stainless steel abrasion strip.
Steel cuff attaches rotor blade to the head.
Internal grounding strips conduct static electricity away to prevent damage to the helicopter's electronics.

Rotor Blade Nomenclature: Planform

The planform of a rotor blade is its shape as seen from above.
Uniform or tapered planforms are common shapes, the latter being more challenging to manufacture.
Uniform shapes are often favored due to the relatively simple manufacturing process.

Rotor Blade - Figure 3-8 (Uniform/Tapered Planform)

Diagrammatic representations show uniform and tapered planforms.

Rotor Blade - Figure 3-10

Represents blade tip with balance weights and blade tracking mechanisms

Rotor Blade Leading Edge

The blade portion encountering air first, also commonly referred to as the front edge.
Must be shaped thicker than the trailing edge for proper aerodynamic function.
Often reinforced with hard abrasion-resistant material.

Rotor Blade Trailing Edge

Part of the blade following the leading edge.
Usually thinner than the leading edge.

Rotor Blade Span and Span Line

A span of a rotor blade is measured from root to tip.
A span line is an imaginary line running parallel to the leading edge, from root to tip.
Crucial for damage location and classification during repair.

Rotor Blade Chord and Chord Line

A chord of a rotor blade is its width at its widest point.
The chord line is an imaginary line running between leading and trailing edges, and perpendicular to the span line.
Often used as a reference line for angular measurement.

Rotor Blade Spar

The primary support component of a rotor blade.
Typically made of aluminum, steel, or fiberglass, extending along the span line.
Often D-shaped to form the leading edge of the airfoil.

Rotor Blade Doublers

Typically flat plates bonded on the root end of certain rotor blades to provide added strength, particularly against centrifugal forces.

Rotor Blade - Top

The underside of the blade facing away from the ground when situated on the rotor.

Rotor Blade - Bottom

The counterpart of the top, seen from below during ground viewing.
Often painted a dull black to reduce glare inside the crew compartment.

Blade Stations

The rotor blade sections are numbered, starting from the mast (station 0) and progressing towards the tip, increasing in number.

Single Pocket or Fairing Blade Construction

The skin is a cohesive single piece from the top to bottom, covering the entire span and chord, which is also located behind the spar.
Requires fewer parts than multiple-pocket constructions.

Multiple Pockets or Fairings Blade Construction

Large rotor blades often characterized by multiple pockets or fairings behind the spar.
This structure allows only the pocket/fairing to be replaced in the event of damage, making it potentially cost-effective.

Blade Balance

Three main types of balancing weights (chordwise, spanwise, and tracking) are used to balance blades, generally fixed into position on the leading edge during manufacturing process.

Blade Trammeling

Necessary for fully articulated tail rotor systems before balancing.
Involves aligning blades to an equal distance, with a 2° lead angle, before balancing.

Rotor Blade Preservation and Storage

Maintaining rotor blades involves several steps:
- Condemning and discarding damaged, non-repairable blades.
- Repairing/patching/covering holes with protective tape
- Removal/cleaning of debris from the surface.

Rotor Blade Outboard Preservation and Storage

Protecting blade outer surfaces from erosion and corrosion through surface coating
Protecting exposed metal components with a corrosion coating
Securing blades in shock-mounted supports/containers before storage.

Additional Rotor Blade Information

Maintaining records to identify the rotor blade.
Identifying and noting blade damage with respect to the span line.

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Description

Test your knowledge on helicopter blade mechanics and components. This quiz covers various aspects such as the structure, materials, and design of helicopter blades, focusing on airfoils and rotor blades. Perfect for aviation enthusiasts and students studying rotorcraft design.