492
14 CFR Ch. I (1–1–24 Edition)
§ 27.31
with respect to the weights of fuel, oil,
coolant, and installed equipment.
(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a),
1421, 1423, 1424, and 1425); and sec. 6(c) of the
Dept. of Transportation Act (49 U.S.C.
1655(c)))
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–14, 43 FR 2324, Jan. 16,
1978]
§ 27.31
Removable ballast.
Removable ballast may be used in
showing compliance with the flight re-
quirements of this subpart.
§ 27.33
Main rotor speed and pitch lim-
its.
(a)
Main rotor speed limits. A range of
main rotor speeds must be established
that—
(1) With power on, provides adequate
margin to accommodate the variations
in rotor speed occurring in any appro-
priate maneuver, and is consistent
with the kind of governor or synchro-
nizer used; and
(2) With power off, allows each appro-
priate autorotative maneuver to be
performed throughout the ranges of
airspeed and weight for which certifi-
cation is requested.
(b)
Normal main rotor high pitch limits
(power on). For rotocraft, except heli-
copters required to have a main rotor
low speed warning under paragraph (e)
of this section. It must be shown, with
power on and without exceeding ap-
proved engine maximum limitations,
that main rotor speeds substantially
less than the minimum approved main
rotor speed will not occur under any
sustained flight condition. This must
be met by—
(1) Appropriate setting of the main
rotor high pitch stop;
(2) Inherent rotorcraft characteris-
tics that make unsafe low main rotor
speeds unlikely; or
(3) Adequate means to warn the pilot
of unsafe main rotor speeds.
(c)
Normal main rotor low pitch limits
(power off). It must be shown, with
power off, that—
(1) The normal main rotor low pitch
limit provides sufficient rotor speed, in
any autorotative condition, under the
most critical combinations of weight
and airspeed; and
(2) It is possible to prevent over-
speeding of the rotor without excep-
tional piloting skill.
(d)
Emergency high pitch. If the main
rotor high pitch stop is set to meet
paragraph (b)(1) of this section, and if
that stop cannot be exceeded inadvert-
ently, additional pitch may be made
available for emergency use.
(e)
Main rotor low speed warning for
helicopters. For each single engine heli-
copter, and each multiengine heli-
copter that does not have an approved
device that automatically increases
power on the operating engines when
one engine fails, there must be a main
rotor low speed warning which meets
the following requirements:
(1) The warning must be furnished to
the pilot in all flight conditions, in-
cluding power-on and power-off flight,
when the speed of a main rotor ap-
proaches a value that can jeopardize
safe flight.
(2) The warning may be furnished ei-
ther through the inherent aerodynamic
qualities of the helicopter or by a de-
vice.
(3) The warning must be clear and
distinct under all conditions, and must
be clearly distinguishable from all
other warnings. A visual device that
requires the attention of the crew
within the cockpit is not acceptable by
itself.
(4) If a warning device is used, the de-
vice must automatically deactivate
and reset when the low-speed condition
is corrected. If the device has an audi-
ble warning, it must also be equipped
with a means for the pilot to manually
silence the audible warning before the
low-speed condition is corrected.
(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a),
1421, 1423, 1424, and 1425); and sec. 6(c) of the
Dept. of Transportation Act (49 U.S.C.
1655(c)))
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–2, 33 FR 962, Jan. 26,
1968; Amdt. 27–14, 43 FR 2324, Jan. 16, 1978]
P
ERFORMANCE
§ 27.45
General.
(a) Unless otherwise prescribed, the
performance requirements of this sub-
part must be met for still air and a
standard atmosphere.
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