The P-3 empennage deicing system combines
both anti-icing and deicing for the vertical
and horizontal stabilizers. The system uses
electrical power to prevent or remove the
accumulation of ice. Electrical heating ele-
ments are in the leading edges and surfaces
of the empennage. The system has ac power
Figure 4-31.-Pitot tube anti-icing circuit.
and dc control. Parting strips in the leading
edge of each stabilizer accomplish anti-icing
requirements. The parting strips remain on
REVIEW SUBSET NUMBER 3
o n c e the system actuates. Twenty cyclic
heat areas accomplish deicing requirements.
Q1. The frictional temperature increase created
During normal operation, each of the cyclic
by ram compression on the skin surface of
areas heat for 8 seconds and are off for
the aircraft is known as
168 seconds. Overheat sensors and a thermal-
sensitive relay protect the system. Any time
the system detects an overheat, power is shut
Q2. What is the primary purpose of an air-
off automatically to prevent damage to the metal
Pitot Tube Anti-Icing
installed in electrically heated windshields?
To prevent the formation of ice over the
opening in the pitot tube, a built-in electric
Q4. What do aircraft equipped with wing deice
on the pilot's console controls power to the
systems use to prevent ice buildup on the
heaters. System power is from either the ac
or the dc bus. Exercise caution when ground
checking the pitot tube since the heater can not
operate for long periods unless the aircraft is in
flight. Also, the danger exists for ground
Q5. What does the P-3 empennage anti/deicing
personnel to be accidentally burned.
systems use to prevent ice buildup?