FAA Aviation Mechanic Airframe (AMA)Airframe Electrical and InstrumentsMedium
A technician performs a preflight operational check of the pitot heat system on a cold ramp. Which indication confirms the pitot heat is functioning properly?
- AThe ammeter or annunciator shows increased current draw, and the pitot tube becomes noticeably warm to the touch
- BThe static port becomes warm along with the pitot tube
- CThe airspeed indicator immediately reads zero when the heat is activated
- DThe pitot heat switch draws no measurable current when turned on
Show answer & explanationAnswer & explanation
Correct answer: A. The ammeter or annunciator shows increased current draw, and the pitot tube becomes noticeably warm to the touch
A properly functioning pitot heat element draws additional current when energized, which can be verified on an ammeter or annunciator, and the tube itself becomes warm. No current draw or no temperature rise indicates a failed heating element or open circuit.
Why the other options are wrong
- B. The static port is a separate opening and is not heated by the pitot heater in most systems.
- C. Airspeed reading zero is unrelated to pitot heat function during a ground check.
- D. No current draw indicates a failed or inoperative pitot heat circuit.
Pitot Heat System Check
An operational test verifying the pitot tube's electric heating element is functioning, confirmed by increased current draw and a warm tube when activated.
- Prevents pitot tube icing in flight
- Verified by ammeter/annunciator current increase
- Failure results in blocked pitot tube and unreliable airspeed indications
Memory trick: Warm tube + rising ammeter needle = heat is working