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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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496 

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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