Saab 340B, Operation Manual, Page: 560 / 670

ICE AND RAIN PROTECTION
Operation
Aircraft Operations Manual
11.2
PAGE 2
CONDITIONS NORMAL PROCEDURES
2.2 DEFINITIONS
AND FOD
PREVENTION DEFINITIONS
Definition of icing conditions for engine anti
− icing operation
For engine anti − ice system operation, icing conditions exist whenever the out-
side air temperature (OAT) or static air temperature (SAT) is + 5 degrees C
(Plus 5
° C) (+10 according to FAA AD 96 − 01 − 04 R1 and 2008 − 06 − 11) or colder
and:
− There is any type of visible moisture present (such as clouds, fog with visibil-
ity of one mile or less, rain, snow, sleet, ice crystals); or
− When on the ground, there is standing water, slush, or snow (hard packed
snow excluded) on the ramps, taxiways or runways.
When anticipating engine anti − ice operation turn on engine anti − ice early. Turn-
ing engine anti − ice on well in advance will preheat the surface and thereby pre-
vent ice formation. Turn engine anti − ice on if there is any possibility that icing
conditions exist.
Definition of icing conditions for propeller de − icing system operation
For propeller de − ice system operation, icing conditions exist when the OAT or
SAT is − 5 degrees C (Minus 5
°
C) or colder and any ice accretion is observed on
any part of the aircraft.
Definition of icing conditions for operation of wing and stabilizer de − ic-
ing boots and for adherence to minimum airspeed and autopilot/flight di-
rector limitations for icing conditions
For operation of wing and stabilizer de − icing boots and for adherence to mini-
mum airspeed and autopilot/flight director limitations for icing conditions, icing
conditions exist when:
− The OAT or SAT is +5 degrees C (Plus 5 ° C) or colder and there is any type
of visible moisture present (such as clouds, fog with visibility of one mile or
less, rain, snow, sleet, ice crystals); or
− Any amount of ice is observed on any part of the aircraft; or
− If it is not certain that there is no ice accumulation on the aircraft.
FOD PREVENTION
Ice must never be allowed to build up on the engine air intake lips or intake. Once
ice formation occurs, turning on anti
− ice may free the ice build − up in chunks that
could be sucked through the engine compressor, possibly causing Foreign Object
Damage (FOD) and a power interruption.
CAUTION
DO NOT RELY ON AIRFRAME VISUAL ICING CUES TO TURN ENGINE
ANTI
− ICE ON. USE THE TEMPERATURE AND VISUAL MOISTURE CRI-
TERIA SPECIFIED FOR ICING CONDITIONS.
(Cont’d)
Dec 01/20