TM 1-1520-240-10
Change 1 5-7-1
SECTION VII. ENVIRONMENTAL RESTRICTIONS
5-7-1. Engine Inlet Screen Limitation.
Refer to table 5-7-1 for information on engine bypass
panel removal.
5-7-2. Flight Under Instrument Meteorological Con-
ditions (IMC).
This helicopter is qualified for flight instrument metero-
logical conditions provided the following conditions exist:
NOTE
Should one AFCS fail during IMC flight, the
flight may be continued to destination.
Should both AFCS fail during IMC flight, a
landing should be made as soon as practical.
a.
Both AFCS are operational (ALT Hold and Hea-
ding not required for IMC Flight).
b.
Two vertical gyros and two vertical gyro indica-
tors (VGI) are installed and operative.
5-7-3. Flight in Ice.
NOTE
During flight in icing conditions with the EAPS
installed, the bypass doors must remain
closed.
Pitot tube and Advanced Flight Control Systems (AFCS)
yaw port heating, and windshield anti-icing systems en-
able safe flight in light-icing conditions. The EAPS is
designed to permit safe flight in light-icing conditions.
Continuous flight in light-icing conditions below 5_C is
not recommended since blade damage can occur from
asymmetric ice shedding. Intentional flight into known
icing conditions with rotor blade erosion protection mate-
rials installed is prohibited. Icing conditions include
“trace,” “light,” “moderate,” and “heavy.”
5-7-4. Thunderstorm Operation.
To ensure adequate lightning strike protection, the light-
ning protection cables and straps must be installed and
intact on all rotor blades. If any lightning cables or straps
are missing or broken, avoid flight in or near thunder-
storms, especially in areas of observed or anticipated
lightning discharges.
