FAA Aviation Mechanic General (AMG)Materials, Hardware and ProcessesEasy
A mechanic is selecting replacement flight control cable that must route around several pulleys and remain flexible without kinking. Which cable construction should be selected?
- A3x7 (minimal flex construction)
- B1x19 (solid, non-flexible)
- C7x7 (moderately flexible construction)
- D7x19 (extra-flexible construction)
Show answer & explanationAnswer & explanation
Correct answer: D. 7x19 (extra-flexible construction)
7x19 cable (7 strands of 19 wires each = 133 wires) is the most flexible aircraft cable construction and is used for primary control cables that bend around pulleys. 1x19 is a rigid, solid construction used for standing rigging, and 7x7 is used where less flexibility is needed, such as trim tab cables.
Why the other options are wrong
- A. 3x7 has minimal flexibility and is rarely used for control runs.
- B. 1x19 is a solid, rigid cable used for standing rigging, not flexing around pulleys.
- C. 7x7 is flexible but less so than 7x19, typically used for trim tab or push-pull cables.
Aircraft Cable Construction
Aircraft control cables are classified by strand and wire count, which determines flexibility; more wires per strand means greater flexibility.
- 7x19 (133 wires) = most flexible, used for control cables
- 7x7 (49 wires) = moderate flexibility, used for trim/tab cables
- 1x19 (19 wires) = solid/rigid, used for standing rigging
Memory trick: 'Nineteen times seven wires makes it flex like heaven' - more strands, more bends