For ambient temperatures between 0 C and -16 C, what is the heating sequence for the Propeller De-Ice system?

• A. All zones heat for 60 seconds, then off for 60 seconds
• B. Inner zones heat for 45 seconds, then outer zones, then off for 90 seconds
• C. Outer zones heat for 45 seconds, then inner zones
• D. All zones heat continuously

Answer: (B)

For ambient temps from 0 C down to -16 C, the Propeller De-Ice system uses a staged heating cycle to manage heat delivery and protect the blade structure. Start by energizing the inner zones for 45 seconds to rapidly raise the temperature where ice tends to stick most, then switch to heating the outer zones to spread the heat along the blade. After that, the system turns off for 90 seconds to cool and prevent excessive thermal buildup. This sequence provides effective ice protection with efficient power use and reduces thermal stress from abrupt, blanket heating. Heating all zones continuously or in a different order would waste energy or risk overheating, and skipping the staged approach could compromise de-icing effectiveness.