FAA Aviation Mechanic Airframe (AMA)Airframe StructuresMedium
A wing spar experiences a twisting load along its longitudinal axis during flight maneuvers. What type of stress is primarily being applied to the spar?
- ACompression
- BBearing
- CTorsion
- DTension
Show answer & explanationAnswer & explanation
Correct answer: C. Torsion
Torsion is the stress produced when a structure is twisted about its longitudinal axis, which is exactly the loading described. Tension and compression are pulling and pushing loads along an axis, while bearing stress occurs at a fastener hole where a bolt or rivet presses against the material.
Why the other options are wrong
- A. Compression is a squeezing (pushing together) stress, not twisting.
- B. Bearing stress relates to a fastener bearing against the wall of its hole, not a twisting spar.
- D. Tension is a stretching (pulling apart) stress, not twisting.
Torsion Stress
A stress that results when a structural member is twisted about its longitudinal axis, common in wing spars and shafts.
- Five basic stresses: tension, compression, shear, bending, torsion
- Torsion twists a member about its long axis
- Wing spars and drive shafts commonly experience torsion
Memory trick: 'Torsion Twists, like Twisting a wet towel.'