495
Federal Aviation Administration, DOT
§ 27.143
§ 27.87
Height-velocity envelope.
(a) If there is any combination of
height and forward velocity (including
hover) under which a safe landing can-
not be made under the applicable power
failure condition in paragraph (b) of
this section, a limiting height-velocity
envelope must be established (includ-
ing all pertinent information) for that
condition, throughout the ranges of—
(1) Altitude, from standard sea level
conditions to the maximum altitude
capability of the rotorcraft, or 7000 feet
density altitude, whichever is less; and
(2) Weight, from the maximum
weight at sea level to the weight se-
lected by the applicant for each alti-
tude covered by paragraph (a)(1) of this
section. For helicopters, the weight at
altitudes above sea level may not be
less than the maximum weight or the
highest weight allowing hovering out-
of-ground effect, whichever is lower.
(b) The applicable power failure con-
ditions are—
(1) For single-engine helicopters, full
autorotation;
(2) For multiengine helicopters, OEI
(where engine isolation features ensure
continued operation of the remaining
engines), and the remaining engine(s)
within approved limits and at the min-
imum installed specification power
available for the most critical com-
bination of approved ambient tempera-
ture and pressure altitude resulting in
7000 feet density altitude or the max-
imum altitude capability of the heli-
copter, whichever is less, and
(3) For other rotorcraft, conditions
appropriate to the type.
(Secs. 313(a), 601, 603, 604, Federal Aviation
Act of 1958 (49 U.S.C. 1354(a), 1421, 1423, 1424),
sec. 6(c), 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; Amdt. 27–21, 49 FR 44433, Nov. 6, 1984;
Amdt. 27–44, 73 FR 10999, Feb. 29, 2008; Amdt.
27–51, 88 FR 8737, Feb. 10, 2023]
F
LIGHT
C
HARACTERISTICS
§ 27.141
General.
The rotorcraft must—
(a) Except as specifically required in
the applicable section, meet the flight
characteristics requirements of this
subpart—
(1) At the altitudes and temperatures
expected in operation;
(2) Under any critical loading condi-
tion within the range of weights and
centers of gravity for which certifi-
cation is requested;
(3) For power-on operations, under
any condition of speed, power, and
rotor r.p.m. for which certification is
requested; and
(4) For power-off operations, under
any condition of speed and rotor r.p.m.
for which certification is requested
that is attainable with the controls
rigged in accordance with the approved
rigging instructions and tolerances;
(b) Be able to maintain any required
flight condition and make a smooth
transition from any flight condition to
any other flight condition without ex-
ceptional piloting skill, alertness, or
strength, and without danger of ex-
ceeding the limit load factor under any
operating condition probable for the
type, including—
(1) Sudden failure of one engine, for
multiengine rotorcraft meeting Trans-
port Category A engine isolation re-
quirements of Part 29 of this chapter;
(2) Sudden, complete power failure
for other rotorcraft; and
(3) Sudden, complete control system
failures specified in § 27.695 of this part;
and
(c) Have any additional char-
acteristic required for night or instru-
ment operation, if certification for
those kinds of operation is requested.
Requirements for helicopter instru-
ment flight are contained in appendix
B of this part.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–2, 33 FR 962, Jan. 26,
1968; Amdt. 27–11, 41 FR 55468, Dec. 20, 1976;
Amdt. 27–19, 48 FR 4389, Jan. 31, 1983; Amdt.
27–21, 49 FR 44433, Nov. 6, 1984]
§ 27.143
Controllability and maneuver-
ability.
(a) The rotorcraft must be safely con-
trollable and maneuverable—
(1) During steady flight; and
(2) During any maneuver appropriate
to the type, including—
(i) Takeoff;
(ii) Climb;
(iii) Level flight;
(iv) Turning flight;
(v) Autorotation;
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14 CFR Ch. I (1–1–24 Edition)
§ 27.151
(vi) Landing (power on and power
off); and
(vii) Recovery to power-on flight
from a balked autorotative approach.
(b) The margin of cyclic control must
allow satisfactory roll and pitch con-
trol at V
NE
with—
(1) Critical weight;
(2) Critical center of gravity;
(3) Critical rotor r.p.m.; and
(4) Power off (except for helicopters
demonstrating compliance with para-
graph (f) of this section) and power on.
(c) Wind velocities from zero to at
least 17 knots, from all azimuths, must
be established in which the rotorcraft
can be operated without loss of control
on or near the ground in any maneuver
appropriate to the type (such as cross-
wind takeoffs, sideward flight, and
rearward flight)—
(1) With altitude, from standard sea
level conditions to the maximum take-
off and landing altitude capability of
the rotorcraft or 7000 feet density alti-
tude, whichever is less; with—
(i) Critical Weight;
(ii) Critical center of gravity;
(iii) Critical rotor r.p.m.;
(2) For takeoff and landing altitudes
above 7000 feet density altitude with—
(i) Weight selected by the applicant;
(ii) Critical center of gravity; and
(iii) Critical rotor r.p.m.
(d) Wind velocities from zero to at
least 17 knots, from all azimuths, must
be established in which the rotorcraft
can be operated without loss of control
out-of-ground-effect, with—
(1) Weight selected by the applicant;
(2) Critical center of gravity;
(3) Rotor r.p.m. selected by the appli-
cant; and
(4) Altitude, from standard sea level
conditions to the maximum takeoff
and landing altitude capability of the
rotorcraft.
(e) The rotorcraft, after (1) failure of
one engine in the case of multiengine
rotorcraft that meet Transport Cat-
egory A engine isolation requirements,
or (2) complete engine failure in the
case of other rotorcraft, must be con-
trollable over the range of speeds and
altitudes for which certification is re-
quested when such power failure occurs
with maximum continuous power and
critical weight. No corrective action
time delay for any condition following
power failure may be less than—
(i) For the cruise condition, one sec-
ond, or normal pilot reaction time
(whichever is greater); and
(ii) For any other condition, normal
pilot reaction time.
(f) For helicopters for which a V
NE
(power-off) is established under
§ 27.1505(c), compliance must be dem-
onstrated with the following require-
ments with critical weight, critical
center of gravity, and critical rotor
r.p.m.:
(1) The helicopter must be safely
slowed to V
NE
(power-off), without ex-
ceptional pilot skill, after the last op-
erating engine is made inoperative at
power-on V
NE.
(2) At a speed of 1.1 V
NE
(power-off),
the margin of cyclic control must
allow satisfactory roll and pitch con-
trol with power off.
(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 963, Jan. 26,
1968; Amdt. 27–14, 43 FR 2325, Jan. 16, 1978;
Amdt. 27–21, 49 FR 44433, Nov. 6, 1984; Amdt.
27–44, 73 FR 10999, Feb. 29, 2008]
§ 27.151
Flight controls.
(a) Longitudinal, lateral, directional,
and collective controls may not exhibit
excessive breakout force, friction, or
preload.
(b) Control system forces and free
play may not inhibit a smooth, direct
rotorcraft response to control system
input.
[Amdt. 27–21, 49 FR 44433, Nov. 6, 1984]
§ 27.161
Trim control.
The trim control—
(a) Must trim any steady longitu-
dinal, lateral, and collective control
forces to zero in level flight at any ap-
propriate speed; and
(b) May not introduce any undesir-
able discontinuities in control force
gradients.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–21, 49 FR 44433, Nov. 6,
1984]
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