5-35. ICING LIMITATIONS (S EVERE).
Severe icing may result from environ-
mental conditions outside of those for
which the aircraft is certified. Flight in
freezing rain, freezing drizzle, or mixed
icing conditions (supercooled liquid water
and ice crystals) may result in a buildup on
capability of the ice protection system, or
may result in ice forming aft of these
protected surfaces. This ice may not shed
using ice protection systems, and may
seriously degrade the performance and
controllability of the aircraft.
All icing detection lights must be operative
prior to flight into icing conditions at night.
This supersedes any relief provided by the
a. During flight, severe icing conditions that
exceed those for which the aircraft is certified shall be
determined by the following visual cues. If one or
more of these visual cues exist, immediately request
priority handling from air traffic control to facilitate a
route or an altitude change to exit the icing conditions.
1. Unusually extensive ice accreted on the
airframe in areas not normally observed to
2. Accumulation of ice on the upper (or
lower, as appropriate) surface of the wing
aft of the protected area; or
3. Accumulation of ice on the propeller
spinner farther aft than normally observed.
b. Since the autopilot may mask tactile cues that
indicate adverse changes in handling characteristics,
use of the autopilot is prohibited when any of the visual
cues specified above exist, or when unusual lateral
trim requirements or autopilot trim warnings are
encountered while the aircraft is in icing conditions.
5-36. CROSSWIND LIMITATIONS.
Landing with wind conditions in excess of
the demonstrated crosswind component
may result in damage to the aircraft. This
component is 25 knots at 90.
5-37. OXYGEN REQUIREMENTS.
a. Oxygen requirements will be in accordance
with AR 95-1.
b. Oxygen system data/duration tables are
found in Chapter 2.
5-38. CABIN PRESSURE LIMITS.
Maximum cabin differential pressure is 6.6 psi.
5-39. CRACKED WINDSHIELD.
Heating elements may be inoperative in
area of crack.
a. External Crack In-flight. If an external
windshield crack is noted, no action is required in
b. Internal Crack In-flight. If it is determined
that an internal crack has occurred in flight, perform
the Internal Crack In-flight procedure in Chapter 9.
c. External Crack on Ground. If the cracking
of only the windshield's outer ply is observed on the
ground, unpressurized flight may be conducted
provided the following procedures are observed:
1. Cracking must not significantly impair
2. Cracking must not interfere with use of
3. Heating elements must be operative for
flight into icing.
4. A temporary placard must be fabricated
and placed in clear view of the pilot until
the windshield is replaced. The placard
should read as follows: