586 

14 CFR Ch. I (1–1–24 Edition) 

§ 29.175 

forward movement of the control is 
necessary to obtain an airspeed more 
than the trim speed. 

(b) Throughout the full range of alti-

tude for which certification is re-
quested, with the throttle and collec-
tive pitch held constant during the ma-
neuvers specified in § 29.175(a) through 
(d), the slope of the control position 
versus airspeed curve must be positive. 
However, in limited flight conditions 
or modes of operation determined by 
the Administrator to be acceptable, the 
slope of the control position versus air-
speed curve may be neutral or negative 
if the rotorcraft possesses flight char-
acteristics that allow the pilot to 
maintain airspeed within 

±

5 knots of 

the desired trim airspeed without ex-
ceptional piloting skill or alertness. 

[Amdt. 29–24, 49 FR 44436, Nov. 6, 1984, as 
amended by Amdt. 29–51, 73 FR 11001, Feb. 29, 
2008] 

§ 29.175

Demonstration of static longi-

tudinal stability. 

(a) 

Climb.  Static longitudinal sta-

bility must be shown in the climb con-
dition at speeds from Vy 

¥ 

10 kt to Vy 

+ 10 kt with— 

(1) Critical weight; 
(2) Critical center of gravity; 
(3) Maximum continuous power; 
(4) The landing gear retracted; and 
(5) The rotorcraft trimmed at Vy. 
(b) 

Cruise.  Static longitudinal sta-

bility must be shown in the cruise con-
dition at speeds from 0.8 V

NE

¥

10 kt to 

0.8 V

NE

+ 10 kt or, if V

H

is less than 0.8 

V

NE

, from VH 

¥ 

10 kt to V

H

+ 10 kt, 

with— 

(1) Critical weight; 
(2) Critical center of gravity; 
(3) Power for level flight at 0.8 V

NE

or 

V

H

, whichever is less; 

(4) The landing gear retracted; and 
(5) The rotorcraft trimmed at 0.8 V

NE

 

or V

H

, whichever is less. 

(c) 

V

NE

. Static longitudinal stability 

must be shown at speeds from V

NE

¥ 

20 

kt to V

NE

with— 

(1) Critical weight; 
(2) Critical center of gravity; 
(3) Power required for level flight at 

V

NE

¥ 

10 kt or maximum continuous 

power, whichever is less; 

(4) The landing gear retracted; and 
(5) The rotorcraft trimmed at V

NE

¥ 

10 kt. 

(d) 

Autorotation.  Static longitudinal 

stability must be shown in autorota-
tion at— 

(1) Airspeeds from the minimum rate 

of descent airspeed 

¥ 

10 kt to the min-

imum rate of descent airspeed + 10 kt, 
with— 

(i) Critical weight; 
(ii) Critical center of gravity; 
(iii) The landing gear extended; and 
(iv) The rotorcraft trimmed at the 

minimum rate of descent airspeed. 

(2) Airspeeds from the best angle-of- 

glide airspeed 

¥ 

10kt to the best angle- 

of-glide airspeed + 10kt, with— 

(i) Critical weight; 
(ii) Critical center of gravity; 
(iii) The landing gear retracted; and 
(iv) The rotorcraft trimmed at the 

best angle-of-glide airspeed. 

[Amdt. 29–51, 73 FR 11001, Feb. 29, 2008] 

§ 29.177

Static directional stability. 

(a) The directional controls must op-

erate in such a manner that the sense 
and direction of motion of the rotor-
craft following control displacement 
are in the direction of the pedal motion 
with throttle and collective controls 
held constant at the trim conditions 
specified in § 29.175(a), (b), (c), and (d). 
Sideslip angles must increase with 
steadily increasing directional control 
deflection for sideslip angles up to the 
lesser of— 

(1) 

±

25 degrees from trim at a speed of 

15 knots less than the speed for min-
imum rate of descent varying linearly 
to 

±

10 degrees from trim at V

NE

; 

(2) The steady-state sideslip angles 

established by § 29.351; 

(3) A sideslip angle selected by the 

applicant, which corresponds to a 
sideforce of at least 0.1g; or 

(4) The sideslip angle attained by 

maximum directional control input. 

(b) Sufficient cues must accompany 

the sideslip to alert the pilot when ap-
proaching sideslip limits. 

(c) During the maneuver specified in 

paragraph (a) of this section, the side-
slip angle versus directional control 
position curve may have a negative 
slope within a small range of angles 
around trim, provided the desired head-
ing can be maintained without excep-
tional piloting skill or alertness. 

[Amdt. 29–51, 73 FR 11001, Feb. 29, 2008] 

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