TM 1-1510-224-10
Section VII. ENVIRONMENTAL RESTRICTIONS
5-30. ALTITUDE LIMITATIONS.
The maximum altitude that the aircraft may be
operated at is 35,000 feet. When operating with
inoperative yaw dam the altitude limit is 17,000 feet P
and 12,000 feet Q.
5-31. TEMPERATURE LIMITS.
a.
The aircraft shall not be operated when the
ambient temperatures are warmer than ISA +37C at
sea level to 25,000 feet, or ISA +31C above 25,000
feet.
b.
The ice vanes shall be extended for operations
in ambient temperatures of 5 C or below when flight
free of visible moisture cannot be assured.
c.
Minimum free air temperature for operation of
deicing boots shall be -40C .
d.
Many components of the RC-12P/Q Primary
Mission Equipment (PME) are classified as Commercial
Off The Shelf (COTS). The maximum storage limit of
COTS equipment is 65C (149F). If an aircraft is sitting
in the sun and the outside temperature reaches 55C
(131F), the cabin temperature could reach 82C
(180F). Under these conditions, measures must be
taken to lower the cabin temperature or damage could
result.
5-32. FLIGHT
UNDER
IMC
(INSTRUMENT
METEOROLOGICAL CONDITIONS).
This aircraft is qualified for operation in instrument
meteorological conditions.
5-33. TYPICAL ICING LIMITATIONS.
WARNING
While in icing conditions, if there is
an unexplained 30%
increase
of
torque needed to maintain airspeed
in level flight, a cumulative total of
two
or
more
inches
of
ice
accumulation
on
the
wing,
an
unexplained decrease of 15 knots
IAS, or an unexplained deviation
between pilot's and copilot's airspeed
indicators, the icing environment
should
be
exited
as
soon
as
practicable. Ice accumulation on the
pitot tube assemblies could cause a
complete loss of airspeed indication.
The
following
conditions
indicate
a
possible
accumulation of ice on the pitot tube assemblies and
unprotected aircraft surfaces. If any of these conditions
are observed, the icing environment should be exited as
soon as practicable.
a.
Total ice accumulation of two inches or more on
the wing surfaces. Determination of ice thickness can
be accomplished by summing the estimated ice
thickness on the wing prior to each pneumatic boot deice
cycle (e.g. four cycles of minimum recommended 1/2-
inch accumulation).
b.
A 30 percent increase in torque per engine
required to maintain a desired airspeed in level flight (not
to exceed 85 percent torque) when operating at
recommended holding speed.
c.
A decrease in indicated airspeed of 15 knots
after entering the icing condition (not slower than 1.4
power off stall speed) if maintaining original power
setting in level flight. This can be determined by
comparing preicing condition entry speed to the
indicated speed after a surface and antenna deice cycle
is completed.
d.
Any variations from normal indicated airspeed
between the pilot's and copilot's airspeed indicators.
5-34. SEVERE ICING LIMITATIONS.
WARNING
Severe
icing
may
result
from
environmental conditions outside of
those
for
which
the
aircraft
is
certificated. Flight in freezing rain,
freezing
drizzle,
or
mixed
icing
conditions (supercooled liquid water
and ice crystals) may result in a
buildup
on
protective
surfaces
exceeding the 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.
a.
During flight, severe icing conditions that exceed
those for which the aircraft is certificated 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
frame in areas not normally observed to collect ice.
(2)
Accumulation of ice on the upper (or
lower, as appropriate) surface of the wing aft of the
protected area.
5-12
