dal mio omb:
ENG ANTI ICE ............................................................ ........................ AS RQRD
If icing conditions last longer than 30 minutes, or if significant engine vibration
occurs, the engine should be accelerated to approximately 70 % N1 for 30
seconds before operating at higher thrust. (See also parking brake limitation
3.01.32). If airport surface conditions and congestion do not permit to accelerate
the engine to 70 % N1, then power setting and dwell time should be as high as
practical. This run up should also be performed just prior takeoff with particular
attention to engine parameters to ensure normal engine operation.
ATC should be informed of the intention to carry out this run up for traffic
sequencing considerations.
When operating in conditions of freezing rain, freezing drizzle, freezing fog or
heavy snow, ice shedding may be enhanced, by additional runups at intervals not
exceeding 10 minutes momentarily to 70% N1.
NOTE:
1 Icing conditions may be expected when the OAT (on the ground and for
takeoff), or when TAT (in flight) is 10°C or below with visible moisture in the
air or standing water, slush, ice or snow is present on the taxiways or runways.
Speevy