FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsMedium
A technician performing a preflight functional check of the pitot heat system on a turbine aircraft notes that ammeter current draw increases significantly when the pitot heat switch is turned on. What does this indicate?
- AThe pitot heat element has failed open (no continuity)
- BThe static port heater is short-circuited
- CThe pitot tube heating element is functioning normally
- DThe airspeed indicator has a blocked drain hole
Show answer & explanationAnswer & explanation
Correct answer: C. The pitot tube heating element is functioning normally
A properly functioning heating element draws current when energized; a noticeable increase in ammeter reading confirms the element is heating normally. A failed-open element would draw no current at all.
Why the other options are wrong
- A. An open element would show no current draw, not an increase.
- B. A short circuit typically causes excessive current draw well beyond normal or trips a breaker, not simply 'increased' draw as expected.
- D. A blocked drain hole affects airspeed accuracy, not electrical current draw.
Pitot Heat System Check
A functional test verifying the pitot tube's electric heating element operates properly by observing expected current draw when energized.
- Prevents ice blockage of the pitot tube
- Checked via ammeter current draw during preflight
- No current draw indicates an open heating element
Memory trick: Current flows = heat glows; no current = frozen pitot woes.