491 

Federal Aviation Administration, DOT 

§ 27.29 

(ii) The weight of usable fuel appro-

priate to the intended operation with 
full payload; 

(iii) The weight of full oil capacity; 

and 

(iv) For each seat, an occupant 

weight of 170 pounds or any lower 
weight for which certification is re-
quested. 

(b) 

Minimum weight. The minimum 

weight (the lowest weight at which 
compliance with each applicable re-
quirement of this part is shown) must 
be established so that it is— 

(1) Not more than the sum of— 
(i) The empty weight determined 

under § 27.29; and 

(ii) The weight of the minimum crew 

necessary to operate the rotorcraft, as-
suming for each crewmember a weight 
no more than 170 pounds, or any lower 
weight selected by the applicant or in-
cluded in the loading instructions; and 

(2) Not less than— 
(i) The lowest weight selected by the 

applicant; 

(ii) The design minimum weight (the 

lowest weight at which compliance 
with each applicable structural loading 
condition of this part is shown); or 

(iii) The lowest weight at which com-

pliance with each applicable flight re-
quirement of this part is shown. 

(c) 

Total weight with jettisonable exter-

nal load. A total weight for the rotor-
craft with a jettisonable external load 
attached that is greater than the max-
imum weight established under para-
graph (a) of this section may be estab-
lished for any rotorcraft-load combina-
tion if— 

(1) The rotorcraft-load combination 

does not include human external cargo, 

(2) Structural component approval 

for external load operations under ei-
ther § 27.865 or under equivalent oper-
ational standards is obtained, 

(3) The portion of the total weight 

that is greater than the maximum 
weight established under paragraph (a) 
of this section is made up only of the 
weight of all or part of the jettisonable 
external load, 

(4) Structural components of the 

rotorcraft are shown to comply with 
the applicable structural requirements 
of this part under the increased loads 
and stresses caused by the weight in-

crease over that established under 
paragraph (a) of this section, and 

(5) Operation of the rotorcraft at a 

total weight greater than the max-
imum certificated weight established 
under paragraph (a) of this section is 
limited by appropriate operating limi-
tations under § 27.865(a) and (d) of this 
part. 

(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. 29, 1964, as 
amended by Amdt. 27–11, 41 FR 55468, Dec. 20, 
1976; Amdt. 25–42, 43 FR 2324, Jan. 16, 1978; 
Amdt. 27–36, 64 FR 43019, Aug. 6, 1999; Amdt. 
27–44, 73 FR 10998, Feb. 29, 2008; 73 FR 33876, 
June 16, 2008] 

§ 27.27

Center of gravity limits. 

The extreme forward and aft centers 

of gravity and, where critical, the ex-
treme lateral centers of gravity must 
be established for each weight estab-
lished under § 27.25. Such an extreme 
may not lie beyond— 

(a) The extremes selected by the ap-

plicant; 

(b) The extremes within which the 

structure is proven; or 

(c) The extremes within which com-

pliance with the applicable flight re-
quirements is shown. 

[Amdt. 27–2, 33 FR 962, Jan. 26, 1968] 

§ 27.29

Empty weight and cor-

responding center of gravity. 

(a) The empty weight and cor-

responding center of gravity must be 
determined by weighing the rotorcraft 
without the crew and payload, but 
with— 

(1) Fixed ballast; 
(2) Unusable fuel; and 
(3) Full operating fluids, including— 
(i) Oil; 
(ii) Hydraulic fluid; and 
(iii) Other fluids required for normal 

operation of roto-craft systems, except 
water intended for injection in the en-
gines. 

(b) The condition of the rotorcraft at 

the time of determining empty weight 
must be one that is well defined and 
can be easily repeated, particularly 

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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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