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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493 

Federal Aviation Administration, DOT 

§ 27.65 

(b) The performance must correspond 

to the engine power available under the 
particular ambient atmospheric condi-
tions, the particular flight condition, 
and the relative humidity specified in 
paragraphs (d) or (e) of this section, as 
appropriate. 

(c) The available power must cor-

respond to engine power, not exceeding 
the approved power, less— 

(1) Installation losses; and 
(2) The power absorbed by the acces-

sories and services appropriate to the 
particular ambient atmopheric condi-
tions and the particular flight condi-
tion. 

(d) For reciprocating engine-powered 

rotorcraft, the performance, as affected 
by engine power, must be based on a 
relative humidity of 80 percent in a 
standard atmosphere. 

(e) For turbine engine-powered rotor-

craft, the performance, as affected by 
engine power, must be based on a rel-
ative humidity of— 

(1) 80 percent, at and below standard 

temperature; and 

(2) 34 percent, at and above standard 

temperature plus 50 degrees F. Between 
these two temperatures, the relative 
humidity must vary linearly. 

(f) For turbine-engine-powered rotor-

craft, a means must be provided to per-
mit the pilot to determine prior to 
takeoff that each engine is capable of 
developing the power necessary to 
achieve the applicable rotorcraft per-
formance prescribed in this subpart. 

(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))) 

[Amdt. 27–14, 43 FR 2324, Jan. 16, 1978, as 
amended by Amdt. 27–21, 49 FR 44432, Nov. 6, 
1984] 

§ 27.49

Performance at minimum oper-

ating speed. 

(a) For helicopters— 
(1) The hovering ceiling must be de-

termined over the ranges of weight, al-
titude, and temperature for which cer-
tification is requested, with— 

(i) Takeoff power; 
(ii) The landing gear extended; and 
(iii) The helicopter in-ground effect 

at a height consistent with normal 
takeoff procedures; and 

(2) The hovering ceiling determined 

under paragraph (a)(1) of this section 
must be at least— 

(i) For reciprocating engine powered 

helicopters, 4,000 feet at maximum 
weight with a standard atmosphere; 

(ii) For turbine engine powered heli-

copters, 2,500 feet pressure altitude at 
maximum weight at a temperature of 
standard plus 22 

°

C (standard plus 40 

°

F). 

(3) The out-of-ground effect hovering 

performance must be determined over 
the ranges of weight, altitude, and 
temperature for which certification is 
requested, using takeoff power. 

(b) For rotorcraft other than heli-

copters, the steady rate of climb at the 
minimum operating speed must be de-
termined over the ranges of weight, al-
titude, and temperature for which cer-
tification is requested, with— 

(1) Takeoff power; and 
(2) The landing gear extended. 

[Amdt. 27–44, 73 FR 10998, Feb. 29, 2008] 

§ 27.51

Takeoff. 

The takeoff, with takeoff power and 

r.p.m. at the most critical center of 
gravity, and with weight from the max-
imum weight at sea level to the weight 
for which takeoff certification is re-
quested for each altitude covered by 
this section— 

(a) May not require exceptional pilot-

ing skill or exceptionally favorable 
conditions throughout the ranges of al-
titude from standard sea level condi-
tions to the maximum altitude for 
which takeoff and landing certification 
is requested, and 

(b) Must be made in such a manner 

that a landing can be made safely at 
any point along the flight path if an 
engine fails. This must be dem-
onstrated up to the maximum altitude 
for which takeoff and landing certifi-
cation is requested or 7,000 feet density 
altitude, whichever is less. 

[Amdt. 27–44, 73 FR 10999, Feb. 29, 2008] 

§ 27.65

Climb: all engines operating. 

(a) For rotorcraft other than heli-

copters— 

(1) The steady rate of climb, at 

V

Y,

 

must be determined— 

(i) With maximum continuous power 

on each engine; 

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