Engine Anti-Ice Annunciations
When the NAC switches are selected ON,
“NAC” is annunciated next to each engine
ITT display on the EICAS (Figure 10-4). The
“NAC” annunciators are displayed in green
when nacelle heat is on and the bleed air pres-
sure to each nacelle lip is adequate (6.5 psi or
greater). The pressure is sensed on the outlet
side of each nacelle anti-ice shutoff valve, lo-
cated in the engine pylons. A “NAC” annun-
ciator turns amber when the nacelle heat is ON
and bleed-air pressure to that engine nacelle
lip is less than 6.5 psi or when electrical cur-
rent to the corresponding engine inlet pres-
sure/temperature probe (Pt
2
Tt
2
) is not detected.
Whenever a “NAC” annunciator is displayed
in amber for the above reasons, there is a cor-
responding amber “L or R NAC HT” message
displayed on the CAS.
A “NAC” annunciator will also be amber if the
NAC heat switch is off and the pressure switch
senses 6.5 psi or more bleed-air pressure to that
engine nacelle. In this case there will be a
corresponding amber “L or R NAC HT FAIL”
ON message displayed on the CAS.
Table 10-1 lists the anti-ice system warning,
caution and advisory CAS messages and the
associated logic for each message.
10-5
FOR TRAINING PURPOSES ONLY
LEARJET 45 PILOT TRAINING MANUAL
FlightSafety
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