GROUND SERVICING
AIRPLANE
OPERATIONS
MANUAL
1-12-20
Page
6
Code
01
REVISION 37
AOM-145/1114
GROUND DEICING STRATEGY
The flight crew must understand the overall deicing and anti-icing
strategies and insure that the procedures are performed properly to
assure themselves that they have a safe airplane for flight.
All soft snow can be mechanically removed by blowing cold air across
the airplane surface, using brooms, soft hand scrappers or rubber
scrappers. Do not use tools to scrape or scratch compacted snow from
the airframe surfaces or from the gaps between fixed or movable
surfaces.
Flaps should be up and ailerons in neutral position, parking brake and
gust lock should be applied. All doors should be closed.
For fluid applies, the following guidelines are recommended:
− Wings: Apply the fluid from the tip inboard to the root, sweeping
from the leading edge in the aft direction. No frozen contamination
is allowed on the wing upper surface. A 3 mm (1/8 in) frost layer is
permitted on the underwing surfaces.
− Horizontal Stabilizer: It is recommended to set Pitch Trim to any
position between 0° and full nose down to prevent APU soft
Foreign Object Damage (FOD) ingestion. The best spray is straight
in relation to the airplane centerline, in the aft direction (see figure).
This is applicable when spraying either over or under the stabilizer
surface. Straight spraying (cleaning from the stabilizer tip to the
root), will make the fluid flow aft, away from the leading edge area.
Spray angles up to 45° are acceptable (see figure), provided the
stabilizer is set to full nose down. Back spraying (from trailing edge
to leading edge - see figure) is not recommended as it will make
spray flow forward and drip from the leading edge into the APU.
Side spraying (90° in relation to airplane centerline) has also
proved to flow fluid into the APU, either when cleaning the upper or
the lower side of the stabilizer.
Cross spraying the upper side of the stabilizer (truck positioned on
the left side of the airplane, aiming the spray the right
elevator/stabilizer - see figure) has been proven also to be very
effective in removing contaminants and preventing fluids from
flowing down into the APU.
However, cross spray directs fluid to the stab/elevator gap. It may
result in fluid accumulation and subsequent dry out in the quiet
areas. Therefore, when cross spraying with fluids Type II, III or IV,
additional care is required to comply with the requirements of the
SNL 145-30-0006 that prescribes residues inspections on those
areas.
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