Electrical Systems & Avionics Flashcards
7 cards from real ACS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Systems & Avionics flashcards as text
What is the purpose of a diode installed in parallel with a relay coil in an aircraft electrical circuit?
Answer: To suppress the voltage spike (back-EMF) generated when the relay de-energizes
A flyback (snubber) diode connected across a relay coil absorbs the inductive voltage spike that occurs when coil current is interrupted, protecting other circuit components.
When troubleshooting an avionics system, a technician finds that the navigation display loses memory every time power is removed. What is the most likely cause?
Answer: Loss of keep-alive (standby) power to the unit's memory circuit
Memory retention in avionics units depends on a continuous low-current standby voltage; loss of this keep-alive power causes memory to clear on shutdown.
What is the correct wire termination technique when installing a ring terminal on stranded copper wire?
Answer: Crimp first, then optionally apply solder for vibration resistance per applicable data
The preferred aircraft practice is to use an appropriately sized crimping tool per manufacturer specs; soldering alone can cause stress cracking under vibration.
An aircraft's pitot-static system is equipped with a pitot heat circuit. When pitot heat is ON, the ammeter shows zero current draw. What should the technician check first?
Answer: The pitot heat element for an open circuit
Zero current draw with the heater switch ON indicates an open circuit, most likely in the heating element itself which has burned out.
What is the function of a sense antenna in an ADF system?
Answer: To remove ambiguity (180° error) from the loop antenna signal
The non-directional sense antenna works with the loop antenna to resolve the 180-degree directional ambiguity inherent in a loop antenna alone.
Which regulation requires that aircraft ELTs be inspected and the battery replaced or recharged at specific intervals?
Answer: 14 CFR Part 91.207
14 CFR Part 91.207 specifies ELT inspection, battery replacement, and operational requirements including the 50% cumulative use or expiration date rule.
A technician measures 13.8 volts at the battery terminals with the engine running and all avionics on. What does this indicate?
Answer: The battery is fully charged and the alternator is maintaining system voltage correctly
13.8V is a normal regulated charging voltage for a 12V aircraft system, indicating the alternator is properly maintaining the bus voltage.