Airframe Mechanic Certification Assembly and Rigging 3 — Questions and Answers
Question 1: On a helicopter, tracking the main rotor blades is done to ensure:
- All blades rotate in the same plane of rotation (Correct answer)
- Blade chord angles are identical
- Blade weights are within limits
- Blade droop stops are properly adjusted
Correct answer: All blades rotate in the same plane of rotation
Rotor tracking verifies that all blades rotate in the same plane to minimize vibration caused by out-of-track blades.
Question 2: What is the function of a jury strut on a semi-cantilever wing?
- Carries the primary bending load from the wing to the fuselage
- Prevents the interplane strut from bowing under compression loads (Correct answer)
- Connects the wing leading edge to the forward fuselage
- Transfers fuel load to the center section
Correct answer: Prevents the interplane strut from bowing under compression loads
A jury strut braces the interplane or wing strut at its midpoint to prevent bowing or buckling under compressive loads.
Question 3: When checking flight control surface travel with a protractor, where is the protractor typically placed?
- On the spar of the control surface
- On the top surface of the control surface at the specified reference location (Correct answer)
- On the control column or stick
- On the adjacent fixed structure
Correct answer: On the top surface of the control surface at the specified reference location
The protractor (or inclinometer) is placed on the top surface of the control surface at the reference station specified in the maintenance manual.
Question 4: When rigging pushrods, what condition should be avoided to prevent binding or misalignment forces on the rod-end bearings?
- Installing the pushrod with offset rod-end threads
- Allowing the pushrod to carry side loads due to misalignment (Correct answer)
- Setting the pushrod length longer than specified
- Connecting the pushrod at the inboard end of a bellcrank
Correct answer: Allowing the pushrod to carry side loads due to misalignment
Rod-end (rod end) bearings are designed for axial loads; side loads from misalignment cause premature wear and possible failure.
Question 5: The rigging pin (alignment pin) used during assembly of a control surface to the airframe is intended to:
- Permanently lock the control surface in neutral position
- Hold components in precise alignment for installation of fasteners (Correct answer)
- Replace hinge bolts during ferry flights
- Balance the control surface during final rigging
Correct answer: Hold components in precise alignment for installation of fasteners
Rigging pins temporarily hold parts in the exact alignment position specified by the manufacturer so that fasteners can be installed correctly.
Question 6: An aircraft elevator is rigged with excessive up travel. The most likely result during flight is:
- Difficulty achieving climb attitude
- Risk of exceeding limit load factor in pitch-up maneuvers (Correct answer)
- Increased pitch stability
- Reduced elevator authority in turbulence
Correct answer: Risk of exceeding limit load factor in pitch-up maneuvers
Excessive up elevator travel allows the pilot to generate more than the design limit load factor in pitch, potentially causing structural damage.
Question 7: What is 'differential aileron travel' and why is it used?
- Ailerons deflect more up than down to compensate for adverse yaw (Correct answer)
- Ailerons on each wing deflect at different speeds
- The inboard and outboard aileron panels deflect different amounts
- Aileron deflection is reduced at high speed automatically
Correct answer: Ailerons deflect more up than down to compensate for adverse yaw
Differential aileron travel means the up-going aileron deflects more than the down-going aileron to reduce adverse yaw caused by increased drag on the down aileron.
Airframe Mechanic Certification Assembly and Rigging 3
On a helicopter, tracking the main rotor blades is done to ensure: