FAA Aviation Mechanic Airframe (AMA)Airframe Electrical and InstrumentsMedium
A technician notices thin conductive wire braids attached to the trailing edges of the ailerons and rudder. What is the primary purpose of these devices?
- ATo reduce radio interference from the engine ignition system
- BTo dissipate precipitation static charge safely into the air
- CTo provide a bonding path for the primary flight control cables
- DTo improve aerodynamic efficiency at the control surface trailing edge
Show answer & explanationAnswer & explanation
Correct answer: B. To dissipate precipitation static charge safely into the air
Static discharge wicks (static dischargers) are mounted on trailing edges of flight control surfaces to provide a low-resistance path for static electricity buildup from precipitation and airflow friction to discharge into the atmosphere, preventing radio and navigation interference. They are not for structural bonding of control cables, engine ignition noise, or aerodynamic shaping.
Why the other options are wrong
- A. Ignition system interference is addressed by shielded ignition harnesses, not static wicks.
- C. Bonding of control cables uses separate bonding jumpers/straps, not trailing-edge wicks.
- D. They serve an electrical function, not an aerodynamic one, though they are shaped to minimize drag.
Static Discharge Wicks
Small conductive devices mounted on trailing edges of control surfaces that provide a path for static electricity to discharge from the airframe into the atmosphere.
- Prevent P-static interference with radios and navigation
- Mounted at trailing edges where airflow separates
- Must maintain proper resistance value per maintenance manual specs
Memory trick: Wicks 'wick away' static like a candle wick draws wax