King Air C90GTi, Pilot Training Manual

Page: 233 / 557

PITOT MAST HEAT
Two pitot masts located on the nose of the
aircraft contain heating elements to protect
against ice accumulation (Figure 10-16).
The pitot masts are electrically heated to
ensure proper airspeed is indicated during
icing conditions. Pitot heat is controlled by
two circuit-breaker switches located on the
pilot’s right subpanel. The two switches plac-
arded “PITOT,” one for the left mast and one
for the right, are located next to the stall
war ning anti-ice switch. They are two-po-
sition switches, with down being OFF and
up being ON.
A failure is indicated by the illumination of
the L PITOT HEAT or R PITOT HEAT an-
nunciator in the war ning/caution/advisor y
annunciator panel. Illumination of these an-
nunciators indicates that pitot mast heat is
inoperative. The annunciators will also il-
luminate anytime the PITOT switches are in
the OFF position.
The pitot heat system should not be oper-
ated on the g round, except for testing or for
shor t inter vals to remove snow or ice from
the mast. Pitot heat should be tur ned on for
takeoff and can be left on in flight during
icing conditions, or whenever icing condi-
tions are expected. If during flight at alti-
tude there is a gradual reduction in airspeed
indication, there may be pitot icing. If tur n-
ing on the pitot heat restores airspeed, leave
the pitot heat on because icing conditions
exist. With many pilots, it is standard prac-
tice to keep the pitot heat on during all flights
at higher altitudes to prevent pitot icing.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
10-14
FOR TRAINING PURPOSES ONLY
10
ICE
AND
RAIN
PRO
TECTION
Figure 10-16. Pitot Mast and Heat Controls