Unless icing conditions are indicated by the ICING annunciator or airframe ice accumulation, at ram air temperatures above what value should anti/deice systems not be operated?

Unless icing conditions are indicated by the ICING annunciator or airframe ice accumulation, at ram air temperatures above what value should anti/deice systems not be operated?

• A. 8 degrees C
• B. 10 degrees C
• C. 12 degrees C
• D. 15 degrees C

Answer: (B)

The key idea is that anti-ice and deice systems are used only when icing is present or likely. If ram air temperature is above a certain level, the chance of ice forming is negligible, so these systems should not be run unless icing is indicated or ice accumulation is observed. For the Beechjet 400A, that threshold is 10°C. So, unless the ICING annunciator shows icing or you can see airframe ice, do not operate the anti/deice systems when ram air temperatures exceed 10°C. Using them above this temperature wastes bleed-air energy and can cause unnecessary wear or adverse effects without any icing risk.

The key idea is that anti-ice and deice systems are used only when icing is present or likely. If ram air temperature is above a certain level, the chance of ice forming is negligible, so these systems should not be run unless icing is indicated or ice accumulation is observed.

For the Beechjet 400A, that threshold is 10°C. So, unless the ICING annunciator shows icing or you can see airframe ice, do not operate the anti/deice systems when ram air temperatures exceed 10°C. Using them above this temperature wastes bleed-air energy and can cause unnecessary wear or adverse effects without any icing risk.