Federal Aviation Administration, DOT

Section 29.177

Section 29.171 Stability: general.
The rotorcraft must be able to be
flown, without undue pilot fatigue or
strain, in any normal maneuver for a
period of time as long as that expected
in normal operation. At least three
landings and takeoffs must be made
during this demonstration.

spaschal on DSK3GDR082PROD with CFR

Section 29.173 Static longitudinal stability.
(a) The longitudinal control must be
designed so that a rearward movement
of the control is necessary to obtain an
airspeed less than the trim speed, and a
forward movement of the control is
necessary to obtain an airspeed more
than the trim speed.
(b) Throughout the full range of altitude for which certification is requested, with the throttle and collective pitch held constant during the maneuvers specified in Section 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 airspeed curve may be neutral or negative
if the rotorcraft possesses flight characteristics that allow the pilot to
maintain airspeed within Section5 knots of
the desired trim airspeed without exceptional piloting skill or alertness.

(4) The landing gear retracted; and
(5) The rotorcraft trimmed at 0.8 VNE
or VH, whichever is less.
(c) VNE. Static longitudinal stability
must be shown at speeds from VNE Section 20
kt to VNE with - 
(1) Critical weight;
(2) Critical center of gravity;
(3) Power required for level flight at
VNE Section 10 kt or maximum continuous
power, whichever is less;
(4) The landing gear retracted; and
(5) The rotorcraft trimmed at VNE Section
10 kt.
(d) Autorotation. Static longitudinal
stability must be shown in autorotation at - 
(1) Airspeeds from the minimum rate
of descent airspeed Section 10 kt to the minimum 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-ofglide airspeed Section 10kt to the best angleof-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. 29-24, 49 FR 44436, Nov. 6, 1984, as
amended by Amdt. 29-51, 73 FR 11001, Feb. 29,
2008]

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

Section 29.175 Demonstration of static longitudinal stability.
(a) Climb. Static longitudinal stability must be shown in the climb condition at speeds from Vy Section 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 stability must be shown in the cruise condition at speeds from 0.8 VNESection10 kt to
0.8 VNE + 10 kt or, if VH is less than 0.8
VNE, from VH Section 10 kt to VH + 10 kt,
with - 
(1) Critical weight;
(2) Critical center of gravity;
(3) Power for level flight at 0.8 VNE or
VH, whichever is less;

(a) The directional controls must operate in such a manner that the sense
and direction of motion of the rotorcraft following control displacement
are in the direction of the pedal motion
with throttle and collective controls
held constant at the trim conditions
specified in Section 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) Section25 degrees from trim at a speed of
15 knots less than the speed for minimum rate of descent varying linearly
to Section10 degrees from trim at VNE;
(2) The steady-state sideslip angles
established by Section 29.351;
(3) A sideslip angle selected by the
applicant, which corresponds to a
sideforce of at least 0.1g; or

Section 29.177

Static directional stability.

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