the necessary suction at the suction port and in
the main suction line to the distributor valves for
deflating the deice boots.
SUCTION RELIEF VALVE. The suction
relief valve installed in the suction manifold lines
leading from the ejector to the tail section
distributor valve regulates deice system suction.
When suction in the manifold lines becomes
excessive, the spring tension that seats the relief
valve is overcome, and the valve opens to permit
compartment air into the suction manifold
lines until the suction pressure is reduced to
approximately 6 in. Hg.
An adjusting nut on the relief valve is used
to adjust the tension on the spring that seats the
relief valve. On aircraft adjustment is generally
DEICE BOOTS. The rubber deice boots
(fig. 1-7) are attached to the leading edge surfaces
with cement or fairing strips and screws, or a
combination of both. On the E-2A, they are
bonded to the leading edges with cement and
tapered slightly to provide a smooth airflow over
the boot and wing, when the boots are deflated.
PRESSURE GAGE. The deice system
cockpit-mounted pressure gage indicates the
pressure available for inflating the deice boots
when the system is operating. The gage is
calibrated from 0 to 20 psi in 1 psi increments.
Normal system operation is indicated by a slight
pressure fluctuation of the pointer. This fluctua-
tion is caused by a momentary drop in pressure
at the beginning of each inflation period for each
deice boot group. A steady reading of 18 psi on
the gage indicates a nonoperating condition.
SUCTION GAGE. The deice system cock-
pit-mounted suction gage indicates the suction
available for deflating the deice boots. The 0 to
10 in. Hg gage is calibrated in major increments
of 1 in. Hg and minor increments of 0.2 in. Hg.
Slight pointer fluctuation indicates proper system
operation, as was the case with the pressure gage.
A steady reading of 6 in. Hg on the gage indicates
a nonoperating condition.
Deice Boot System Maintenance
Maintenance of deice boot systems is normally
performed by personnel of the AE, AME,
and AMS ratings. Personnel of the AMS
rating are primarily concerned with the removal,
installation, and miscellaneous repairs of the deice
boots. AE personnel are concerned with removal,
replacement, and repair of deice system electrical
components. The AME is generally responsible
for all other components of the deice system.
AME personnel assigned to the organizational
level of maintenance are responsible for removal
and replacement of malfunctioning components,
maintenance of associated plumbing, and render-
ing of assistance to senior personnel in the
performance of operational checkouts and
Some steps of the operational check, as out-
lined in the applicable MIM, are performed
using external electrical power and an external air
supply. The air supply is connected to the bleed-
air line test connection and must be capable of
supplying a pressure of 50 to 90 psi. Remaining
steps of the operational checkout require that one
of the aircrafts engines be started.
NOTE: Personnel turning up naval aircraft
must be fully qualified, designated in writing, and
carry a current turnup card in accordance with
All steps of the operational checkout must be
performed in the sequence outlined in the MIM.
When a malfunction occurs during a step, it must
be corrected before proceeding to the next step.
Troubleshooting, removal and replacement of
components, and the operational checkout should
always be accomplished in accordance with the
specific instructions provided in the applicable
MIM with appropriate emphasis on quality
workmanship and inspection.
DEICE AND ANTI-ICING SYSTEMS
FOR THE S-3 AIRCRAFT
The S-3 aircraft ice protection system
provides deicing of wing leading edge flaps and
horizontal stabilizer leading edges and anti-icing
of the air-conditioning ram air inlet, engine
nacelle, and parts of the engine. The bleed air
temperature control anticipator and thermostat,
the deice temperature control regulator valve, and
the engine anti-icing valve interface with the ice
The deice function of the ice protection system
removes ice that forms on the leading edges of
the wing and horizontal stabilizer. The vertical
stabilizer leading edge is not deiced. Bleed air from
the engine compressors 10th stage is the basic
source of heat. One requirement of the bleed-air