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Questions and Answers
What is the life expectancy of a fiberglass blade?
What is the life expectancy of a fiberglass blade?
Which type of blade is more susceptible to notch damage?
Which type of blade is more susceptible to notch damage?
What is a key material feature of metal blades?
What is a key material feature of metal blades?
What component is used to attach blades to the yoke in metal blade construction?
What component is used to attach blades to the yoke in metal blade construction?
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What material is primarily used in the main rigid section of composite rotor blades?
What material is primarily used in the main rigid section of composite rotor blades?
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What is the primary purpose of the rotor blades in a helicopter?
What is the primary purpose of the rotor blades in a helicopter?
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Which type of rotor blade construction is the most recent development?
Which type of rotor blade construction is the most recent development?
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What was a significant characteristic of the first manned helicopter built by Paul Cornu?
What was a significant characteristic of the first manned helicopter built by Paul Cornu?
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What materials were commonly used for the first production rotor blades?
What materials were commonly used for the first production rotor blades?
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Which feature of the rotor blade helps balance its mass?
Which feature of the rotor blade helps balance its mass?
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What purpose do the cheek plates serve on the rotor blades?
What purpose do the cheek plates serve on the rotor blades?
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What loads must rotor blades withstand that are uncommon for fixed-wing aircraft?
What loads must rotor blades withstand that are uncommon for fixed-wing aircraft?
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What feature is included on the upper surface of the rotor blade for maintenance purposes?
What feature is included on the upper surface of the rotor blade for maintenance purposes?
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What is the purpose of the trim tab located on the outboard trailing edge of a rotor blade?
What is the purpose of the trim tab located on the outboard trailing edge of a rotor blade?
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Which construction aspect is common to both wooden and metal rotor blades?
Which construction aspect is common to both wooden and metal rotor blades?
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What is a significant disadvantage of metal rotor blades compared to wooden blades?
What is a significant disadvantage of metal rotor blades compared to wooden blades?
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What purpose do weights serve at the tip pocket of a rotor blade?
What purpose do weights serve at the tip pocket of a rotor blade?
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What is the main structural component of a typical metal rotor blade?
What is the main structural component of a typical metal rotor blade?
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What differentiates the blade inspection systems BIM and BIS?
What differentiates the blade inspection systems BIM and BIS?
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What component is added to the root of a metal blade to manage attachment stresses?
What component is added to the root of a metal blade to manage attachment stresses?
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How does the use of a stainless-steel strip benefit rotor blades?
How does the use of a stainless-steel strip benefit rotor blades?
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What is a unique feature of the semi-composite rotor blade construction?
What is a unique feature of the semi-composite rotor blade construction?
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What effect does moisture have on wooden rotor blades, and how can it be corrected?
What effect does moisture have on wooden rotor blades, and how can it be corrected?
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Which of the following statements is true regarding the lifespan of wooden blades compared to metal blades?
Which of the following statements is true regarding the lifespan of wooden blades compared to metal blades?
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What type of indicator is used in the Blade Inspection Method to detect cracks?
What type of indicator is used in the Blade Inspection Method to detect cracks?
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What is a disadvantage of bonded type construction in rotor blades?
What is a disadvantage of bonded type construction in rotor blades?
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What is the primary role of weights placed inboard on a rotor blade?
What is the primary role of weights placed inboard on a rotor blade?
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What major advantage does fiberglass construction have over metal blades?
What major advantage does fiberglass construction have over metal blades?
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Which component is primarily responsible for the majority of load-carrying ability in the Sikorsky S-76 main rotor blade?
Which component is primarily responsible for the majority of load-carrying ability in the Sikorsky S-76 main rotor blade?
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Which type of construction does NOT belong to fiberglass blades?
Which type of construction does NOT belong to fiberglass blades?
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What is the main structural component of a fiberglass spar blade?
What is the main structural component of a fiberglass spar blade?
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What is NOT a common material used in metal spar blades?
What is NOT a common material used in metal spar blades?
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How are trim tabs designed for easy replacement in fiberglass blades?
How are trim tabs designed for easy replacement in fiberglass blades?
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One of the reasons fiberglass blades are preferred is their resistance to what?
One of the reasons fiberglass blades are preferred is their resistance to what?
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What happens to the nickel cap on fiberglass blades?
What happens to the nickel cap on fiberglass blades?
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Which feature enhances the aerodynamics of a blade?
Which feature enhances the aerodynamics of a blade?
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Why are epoxy resin injections beneficial for fiberglass blade maintenance?
Why are epoxy resin injections beneficial for fiberglass blade maintenance?
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What material is commonly used for the leading-edge abrasion strip in fiberglass spar blades?
What material is commonly used for the leading-edge abrasion strip in fiberglass spar blades?
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What construction feature does NOT help in reducing corrosion?
What construction feature does NOT help in reducing corrosion?
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What problem is fiberglass less susceptible to compared to metal blades?
What problem is fiberglass less susceptible to compared to metal blades?
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Which of the following is true about replacement parts for helicopter blades?
Which of the following is true about replacement parts for helicopter blades?
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Study Notes
Rotor Blades
- The rotor blade is the wing of a helicopter, responsible for generating lift
- The blade design has evolved from wood to metal to composite materials
- Wood blades (originally with steel core) were used in early helicopters and some are still in use
- Metal blades, often bonded, have been in production since the 1960s
- Composite blades, which utilize materials like fiberglass, are the newest type
- The blade experiences forces like centrifugal force, twisting, and rapid span movements
Wood Blades
- Made of laminated wood, like birch, spruce, pine, and balsa
- Steel core acts as a mass balance
- Covered with resin-impregnated fiberglass cloth
- Leading edge is protected with a stainless-steel cap
- Cheek plates at the butt are used for grip attachment and drag brace assembly
- Tow pins on the upper surface indicate center of gravity and center of pressure
- Trim tab on the trailing edge allows track adjustment
- Tip pocket used for spanwise balance by adding weights
Metal Blades
- Construction varies among manufacturers but typically uses aluminum alloy
- Spar is the main structural component, running along the blade's span
- Skin is bonded to the spar and trailing edge strip
- Stainless-steel leading edge strip protects from abrasion
- Trim tab facilitates track adjustment
- Weights are added for balance purposes in the tip pocket and inboard
- Bonded construction ensures even stress distribution, continuous surface contact, and smoother contours
Metal Blade Inspection
- Integral Inspection System (BIS) utilizes a detector unit with a memory and crack detection circuit
- Blade Inspection Method (BIM) uses pressure to check for cracks in the spar
- A flashing red light on BIS indicates a satisfactory condition; a steady red light suggests a possible blade crack
Fiberglass (Composite) Blades
- These blades are made with various materials, often including metal spars
- Two main types: fiberglass spar and metal spar
- Fiberglass spar blades (like the Bell 412) have a fiberglass spar assembly, Nomex honeycomb core, and stainless-steel tip cap
- Metal spar composite blades (like the Sikorsky S-76) utilize a welded titanium spar for structural support, with composite coverings and Nomex honeycomb core
- Composite blades often incorporate materials like carbon fiber, Kevlar, and titanium
Fiberglass Blade vs. Metal Blade
- Advantages of fiberglass blades:
- Infinite life
- Less susceptible to notch damage
- No corrosion
- Easier to repair
- Disadvantages of metal blades:
- Finite life
- More susceptible to notch damage
- Prone to corrosion
Tail Rotor Blades
- Constructed from various materials, including metal and composites
- Metal blades feature an aluminum sheet aerofoil with bonded trailing edge and honeycomb core
- Composite blades often utilize fiberglass spars and skins
- Tail rotor blades may be two or multi-bladed
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Description
Explore the evolution and construction of helicopter rotor blades, including wood, metal, and composite materials. Understand the design features that contribute to their functionality, such as balance and aerodynamics. This quiz provides insights into the forces experienced by rotor blades during flight.
