Airframe Mechanic Certification Aircraft Assembly and Rigging 5 — Questions and Answers
Question 1: What is the purpose of the 'dead zone' (or neutral zone) in a flight control system?
- A small range of cockpit control movement near neutral that produces no control surface movement, used to reduce pilot fatigue (Correct answer)
- The range of movement where both ailerons deflect upward simultaneously
- The zone where trim tabs are fully effective and the primary surface is locked
- A structural zone in the fuselage where no control cables may be routed
Correct answer: A small range of cockpit control movement near neutral that produces no control surface movement, used to reduce pilot fatigue
A dead zone near neutral allows small inadvertent cockpit inputs without producing control surface movement, reducing pilot workload on long flights—it must remain within the manufacturer's published limits.
Question 2: During final rigging check of a manual flight control system, the mechanic applies force to deflect the aileron and then releases it. The aileron should:
- Return to the neutral position and remain there without binding or excessive friction (Correct answer)
- Stay in the deflected position due to control lock friction
- Return to neutral only when the opposite aileron is deflected
- Vibrate briefly and then center automatically via the trim tab
Correct answer: Return to the neutral position and remain there without binding or excessive friction
After deflection, flight controls must return to neutral under system forces (springs, weight, aerodynamic loads) and remain there without binding, sticking, or excessive breakout force.
Question 3: An aircraft's rudder control has more than the specified free play. After checking the rudder pedals and cables, the wear is found at the rudder horn attachment. What is the correct repair?
- Replace the worn bolt, bushing, or fitting to restore the specified clearance per the Maintenance Manual (Correct answer)
- Apply a corrosion-resistant grease to reduce movement
- Rerig the cables to take up the slack
- Install a larger diameter bolt to fill the worn hole
Correct answer: Replace the worn bolt, bushing, or fitting to restore the specified clearance per the Maintenance Manual
Worn attachment hardware (bolts, bushings, or fittings) must be replaced with serviceable parts of the correct specification—oversized fasteners without engineering approval are not permitted.
Question 4: What rigging check is performed to verify that a trim tab returns to the neutral position when the trim control is centered?
- Measure the tab deflection angle with a protractor at the rigged neutral and compare it to the manufacturer's datum (Correct answer)
- Pull the tab by hand and confirm it springs back
- Check that the trim indicator gauge reads zero when the tab appears level
- Verify that the aircraft flies straight and level at cruise with the control column released
Correct answer: Measure the tab deflection angle with a protractor at the rigged neutral and compare it to the manufacturer's datum
Trim tab neutral position is confirmed by measuring actual tab deflection angle with a rigging protractor and comparing it to the zero (datum) reference in the Maintenance Manual.
Question 5: Which condition would require replacement of a flight control cable rather than continued service?
- More than the allowable number of broken wires per lay length as specified in AC 43.13-1B or the AMM (Correct answer)
- Light surface oxidation that can be removed with a cloth
- Minor kink that fully straightens when the cable is laid flat
- Tension reading 5% below the specified value before temperature correction
Correct answer: More than the allowable number of broken wires per lay length as specified in AC 43.13-1B or the AMM
Broken wire limits per lay length are defined in AC 43.13-1B and the aircraft's Maintenance Manual; exceeding these limits requires immediate cable replacement.
Question 6: When assembling a quick-disconnect fitting on a flight control rod end, the technician must verify that the safety pin:
- Is fully seated, passes through both sides of the fitting, and is retained by its clip or locking feature (Correct answer)
- Is only partially inserted until the first ground run confirms proper operation
- Can be removed and reinserted with one hand in the installed position
- Is installed in the backup hole only if the primary hole is occupied
Correct answer: Is fully seated, passes through both sides of the fitting, and is retained by its clip or locking feature
Quick-disconnect safety pins must be fully inserted through both sides of the fitting and secured with their locking clip to prevent inadvertent disconnection.
Question 7: A mechanic is checking aileron differential rigging on a light aircraft. 'Differential' means:
- The upward-deflecting aileron travels farther than the downward-deflecting aileron to counteract adverse yaw (Correct answer)
- Both ailerons deflect the same number of degrees in opposite directions
- The ailerons deflect more at low speed and less at high speed automatically
- The left aileron travels farther than the right aileron regardless of input direction
Correct answer: The upward-deflecting aileron travels farther than the downward-deflecting aileron to counteract adverse yaw
Aileron differential means the up-going aileron deflects more than the down-going aileron, reducing the increased drag on the rising wing and minimizing adverse yaw.
Airframe Mechanic Certification Aircraft Assembly and Rigging 5
What is the purpose of the 'dead zone' (or neutral zone) in a flight control system?