§25.1326 Flight instrument external probes heating systems

alert (See AMC 25.1326) If a flight instrument external probe heating system is installed, an alert must be provided to the flight crew when the flight instrument external probe heating system is not operating or not functioning normally. The alert must comply with the following requirements: (a) The alert provided must conform to the Caution alert indications. (b) The alert provided must be triggered if either of the following conditions exists: (1) The flight instrument external probe heating system is switched ‘off’. (2) The flight instrument external probe heating system is switched ‘on’ and is not functioning normally.