title-14-part-27-sec27-143

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]

LIGHT

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

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

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.

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

(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

(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

(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]