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Srinivasan Helicopter Maintenance Question Paper

Unit-I

1. Mention the color coding systems in the helicopters :
** Red & white- semi rigid rotors
** Blue & yellow- multi bladed systems

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2. What are the safeties precautions must be followed while ground handling techniques?
** A bar must be used both for raising and lowering the wheels
** Bar must be secured firmly
** Avoid the slippages of the bar
** Hands or feet never be place under the skid gear

3. What are the safeties precautions must be followed while moving the fixed wing aircraft? :
** No movement should be made without sufficient help
** Tow must be moved slowly and evenly
** All the rotating components must be secured
** Tow bar turning radius must be observed

4. Mention the types of bearings :
** Ball bearings
** Roller bearings
** Spherical bearings

5. Mention the common defects of bearings :
** Broken or cracked rings
** Dented seals and shields
** Cracked and broken seperators
** Broken or cracked balls or rollers
** Flaked areas on balla
** Discoloration due to heat
** Brinelled bearings

6. What are the general procedures should be followed in the installations :
** Clean shafts and bearing housing
** Clean splines, grooves and keyways
** Press bearing on straight and square
** A hand operated arbor press should be used whenever possible
** Press bearings until they are seated against the shaft or housing shoulder

7. Define Elastomeric bearing :
The elastomeric bearings are sandwich type bearings, which is used for oscillating the loads where complete rotation is necessary

8. Mention the types of Elastomeric bearings :
** Cylindrical bearings
** Spherical bearings
** Conical bearings

9. Write the advantages of the elastomeric bearings :
** No lubrication is necessary
** No dis assembly
** No seizure is possible because of design
** Controlled stiffness may be obtained by the elastomers

10. Write the disadvantages of the elastomeric bearings :
** High cost
** Size is depends upon the loads and motions required
** No longer life

Unit-II

1. Mention the types of rotor blades :
** Wooden rotor blades
** Metal rotor blades
** Fibre glass or composite blades

2. Write the advantages of metal rotor blades :
** Even distribution of stresses
** Continuous contact between mating surfaces
** Smoother contours
** Flexible joints
** Reduced weight

3. Classify the vibrations which takes place in the helicopter :
** Low frequency vibrations
** High frequency vibrations
** Medium frequency vibrations

4. Define tracking :
Tracking is the procedure used to check that all the blades are travelling with in the same tip path plane

5. When we need to track the helicopters :
The helicopter requires tracking when the blades, heads or pitch change components of the head are replaced

6. What are methods used to determine the track on helicopters? :
** Stick method
** Flag method
** Light reflector method
** Pre-track method
** Electronic or strobe method

7. Define trim tabs :
Trim tabs that may be used in ground tracking, these tabs are fixed to the blade and are simply bent to change the angle of attack of the blade.

8. What is blade sweeping? :
It is a procedure used after installation of new blades, head or major components of the head to obtain chordwise dynamic balance

9. What are procedures to be carried out for adjusting the chordwise balance? :
** Mark the drag brace with a soft lead pencil or crayon
** Shorten the drag brace by loosening the jam nuts
** Retighten the jam nuts and operate the helicopters

10. What do you mean by dampener? :
Dampener which affects the position of advancing and retreating the blade