640 

14 CFR Ch. I (1–1–14 Edition) 

§ 27.27 

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 
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. 

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