Flight Controls (S1) Flashcards
What are the requirements of the rotor head
Provide attachment point for rotor blades
Transmit drive from engine to the rotor blades
Allow blade freedom of movement
Allow a control interface to change the pitch
Support the blades
What are the main types of rotor head
Fully articulated
Semi rigid
Rigid
What additions can be present on a rotor head
Lifting eye
Flapping restrainer
Droop restrainer
What is a drag damper used for
To reduce the rate of dragging and absorb shock loads
What type of drag dampers are there
Elastomeric
Hydraulic
What is the purpose of the tie bar
To absorb centrifugal loads generated by rotating blades
What 3 attachments does the MRBS have
Pitch bearings
Tie bar
Damper support
What does the tie bar do and how does it work
Connects the sleeve to the rotor head, is made using miles of wound wire around 2 bushes, wound at an angle to offset the aerodynamic affects on pitch
What is the purpose of the rotor blades
Produce a force greater than the weight of the aircraft to provide thrust
How can blade lift be evenly distributed
Wash-out
Tapered blades
What can be used to balance blades
Weights
What is used to aid the instalment of blade pins
Bullet adaptors that help get past any misalignments without damaging the pin
What is a bonding lead and its purpose
A cable completing the electrical path from the rotor head to the blade to reduce damage to aircraft during lightning strikes, to prevent static buildup and reduce electric shock hazard
What are trim tabs
Small device fitted to the trailing edge to balance the blade aerodynamically. Done by manufacturers
What does a static wick do
Discharges static electricity
What is the lift load path
MRB
Rotor head
Rotor mast
Gearbox casting
Gearbox supports
Airframe mountings
What methods ore there of negating vibration
Mass/spring main rotor head vibration absorber (MRHVA)
Bifilar vibration absorber
Active vibration cancellation
What are the 3 types of tail rotor
Free (Lynx, Apache)
Shrouded (Gazelle)
NOTAR
What are the disadvantages of shrouded tail rotors
Increase in weight
Increase in power requirement
Increase in drag
Higher costs
What are the 5 main parts of a tail rotor blade
Spar
Root end
Skin
Erosion shield
Blade tip
What should be checked for during rotor blade maintenance
Dents, cracks, distortions
Attachments
Bearing wear
Damage to tips and tabs
Balancing
What 2 systems are used to alter MRB pitch
Swash plate system
Spider system
What is geometric lock
Where cables and rods aren’t correctly adjusted and can cause controls to become locked after they get caught on each other
What 2 measures are there to make sure control rods are correctly tightened
Witness hole
Witness line
What is used to change rod inputs to cables or vice versa
Quadrant
What are control stops
Adjustable or fixed stops that restrict the movement of the control inputs, to prevent geometric locking and prevent dangerous inputs
What type of cable is used on cable control systems
Preformed cable
Kink resistant and will not unravel
What are turnbuckles
Used to join and adjust the length of wire control systems.
How are turnbuckles secured
Wire locking
Provided locking clips
What types or turnbuckles are there
Tension
Barrel
What is a swaged end
Clamping and forming the end of a cable to secure it
What are fairleads
Restrainers along a cable system to limit the amount of movement of the cable during vibrations
How can left hand threads be identified
Notches in the nut
Grooves
What is an interlink assembly
Linked controls to deal with collective, cyclic or yaw inputs that keep the aircraft level
How can constant rotor speed be maintained
Automatic fuel supply changes to the engine made by a computer to change the output from the engine
What is rigging
The truing and checking the system to ensure the flying controls operate correctly
What are rigging pins
Pins used to hold control systems into a predefined position for tests to be carried out (neutral position)
What are the 2 parts of an independent inspection
Correct assembly check
Functional systems check
When is rigging carried out
At specific intervals laid down by AMM
After disturbing any part of the control system
What are the design requirements of rotor blades
Have good lift:drag ratio
Maximum lift required
Minimise pitching moments
What are the 3 areas of a blade
Root
Centre
Tip
What are doubler plates
Plates at the blade root, increase the strength of the blade in critical area
How can rotor blades be identified
Colour coding
