(M) One may be inoperative provided:
a) Engine Anti-Ice Valve remains OPEN, and
b) Takeoff and landing field temperatures are not in excess of 10 degrees C.
(M) May be inoperative provided:
a) Engine Anti-Ice Valve is failed closed,
b) The flight is conducted in day VMC, and
c) Aircraft is not operated in known or forecast icing conditions.
NOTE: See AFM Performance Data.
MAINTENANCE PROCEDURES
CAUTION: ENGINE ANTI-ICE SWITCHES OPERATE BOTH THE WING LEADING EDGE AND ENGINE INLET SYSTEMS. DO NOT OPERATE THE SYSTEM LONGER THAN FIVE (5) MINUTES. FOLLOW TEST WITH A THIRTY (30) MINUTE COOLING PERIOD.
1. With engines shut down, make note of the temperature of the Engine Inlets (use of hand touch is sufficient).
2. Position the aircraft in a suitable run-up area.
3 Verify LH and RH ENG ANTI-ICE circuit breakers are engaged.
4. To verify whether the affected valve has failed open or closed:
a) Verify the AIR SOURCE SELECT switch, and WINDSHIELD BLEED (Anti-Ice) switch, are OFF.
b) Verify WING/ENGINE ANTI-ICE switches are OFF.
c) Set the parking brake and start both engines. Refer to AFM Normal Checklist for engine start.
NOTE: LH and RH ENG ANTI-ICE, LH and RH WING ANTI-ICE, and both MASTER CAUTION lights will illuminate at low engine power settings as a normal condition.
d) Gradually increase both throttles to achieve 70% N2.
e) After approximately 15 seconds, select Engine Anti-Ice ON for both engines. Verify both ENG ANTI-ICE annunciators illuminate.
f) As soon as each ENG ANTI-ICE annunciator extinguishes, immediately select Engine Anti-Ice OFF on that engine and gently retard the associated throttle to idle.
g) If the annunciator on the affected side extinguishes immediately, or substantially sooner than the unaffected side, the valve has failed open.
h) If the annunciator for the affected side does not extinguish within 20 seconds of the unaffected
side, retard the affected throttle to idle. The associated valve is failed closed.
i) Select both WING/ENGINE ANTI-ICE switches to OFF.
j) Shut down engines.
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