When the aircraft is parked, it is recommended to install protective covers
on the air data probes (static ports, pitot probes, AOA probes, TAT
probes). The protective covers help protect the
probes from contamination.
The covers should be marked with REMOVE BEFORE FLIGHT. Ground
personnel must insure that the covers are removed before flight or before
power is applied to the probes (engine start or ground test).
The probe heat system operates automatically to power the air data probe
heaters when at least one engine is running. It is also designed to operate
automatically when the aircraft is in flight. During the troubleshooting
and the on ground operations, observe the following precautions:
– if the Probe Heat Computer (PHC) power supply C/B is pulled, the
PHC internal relay will relax and the related probes will be heated. Make
sure to pull ALL of the associated probe heat C/B’s (Static supply
(28VDC), AOA supply, Pitot supply & TAT supply (all 115 VAC)).
– if the Engine Interface Unit (EIU) power supply C/B is pulled, the PHC
will sense an “engine running” condition and the probes will be heated.
Make sure to pull ALL of the probe heat C/B’s (Static supply (28VDC),
AOA supply, Pitot supply & TAT supply (all 115 VAC)).
– if the C/B of the LGCIU is pulled, it simulates FLIGHT situation. So
the probe heating is also switched ON.
on the air data probes (static ports, pitot probes, AOA probes, TAT
probes). The protective covers help protect the
probes from contamination.
The covers should be marked with REMOVE BEFORE FLIGHT. Ground
personnel must insure that the covers are removed before flight or before
power is applied to the probes (engine start or ground test).
The probe heat system operates automatically to power the air data probe
heaters when at least one engine is running. It is also designed to operate
automatically when the aircraft is in flight. During the troubleshooting
and the on ground operations, observe the following precautions:
– if the Probe Heat Computer (PHC) power supply C/B is pulled, the
PHC internal relay will relax and the related probes will be heated. Make
sure to pull ALL of the associated probe heat C/B’s (Static supply
(28VDC), AOA supply, Pitot supply & TAT supply (all 115 VAC)).
– if the Engine Interface Unit (EIU) power supply C/B is pulled, the PHC
will sense an “engine running” condition and the probes will be heated.
Make sure to pull ALL of the probe heat C/B’s (Static supply (28VDC),
AOA supply, Pitot supply & TAT supply (all 115 VAC)).
– if the C/B of the LGCIU is pulled, it simulates FLIGHT situation. So
the probe heating is also switched ON.
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