What is the status symbol for blade de-ice system fails self test, aircraft restricted from flight in known icing conditions?

• A. X
• B. (X)
• C. /
• D. -

Answer: (A)

When a blade de-ice system fails its self-test, the equipment cannot be trusted to operate properly, especially in known icing conditions. The symbol X is the code used to mark the item as unserviceable or inoperative, signaling that it must be repaired or replaced before flight. This status also places a flight restriction on the aircraft, meaning it is not cleared to fly in icing conditions until the system is fixed. The other symbols imply different statuses, but they do not convey the mandatory unserviceability and the associated icing flight restriction as clearly as X does.