title-14-part-29-sec29-173

585

Federal Aviation Administration, DOT

§ 29.173

(2) Critical center of gravity;
(3) Critical rotor r.p.m.; and
(4) Power off (except for helicopters

demonstrating compliance with para-
graph (f) of this section) and power on.

least 17 knots, from all azimuths, must
be established in which the rotorcraft
can be operated without loss of control
on or near the ground in any maneuver
appropriate to the type (such as cross-
wind takeoffs, sideward flight, and
rearward flight), with—

(1) Critical weight;
(2) Critical center of gravity;
(3) Critical rotor r.p.m.; and
(4) Altitude, from standard sea level

conditions to the maximum takeoff
and landing altitude capability of the
rotorcraft.

(d) Wind velocities from zero to at

least 17 knots, from all azimuths, must
be established in which the rotorcraft
can be operated without loss of control
out-of-ground effect, with—

(1) Weight selected by the applicant;
(2) Critical center of gravity;
(3) Rotor r.p.m. selected by the appli-

cant; and

(4) Altitude, from standard sea level

conditions to the maximum takeoff
and landing altitude capability of the
rotorcraft.

(e) The rotorcraft, after (1) failure of

one engine, in the case of multiengine
rotorcraft that meet Transport Cat-
egory A engine isolation requirements,
or (2) complete power failure in the
case of other rotorcraft, must be con-
trollable over the range of speeds and
altitudes for which certification is re-
quested when such power failure occurs
with maximum continuous power and
critical weight. No corrective action
time delay for any condition following
power failure may be less than—

(i) For the cruise condition, one sec-

ond, or normal pilot reaction time
(whichever is greater); and

(ii) For any other condition, normal

pilot reaction time.

(f) For helicopters for which a V

(power-off) is established under
§ 29.1505(c), compliance must be dem-
onstrated with the following require-
ments with critical weight, critical
center of gravity, and critical rotor
r.p.m.:

(1) The helicopter must be safely

slowed to V

(power-off), without ex-

ceptional pilot skill after the last oper-
ating engine is made inoperative at
power-on V

(2) At a speed of 1.1 V

(power-off),

the margin of cyclic control must
allow satisfactory roll and pitch con-
trol with power off.

(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. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–3, 33 FR 965, Jan. 26,
1968; Amdt. 29–15, 43 FR 2326, Jan. 16, 1978;
Amdt. 29–24, 49 FR 44436, Nov. 6, 1984; Amdt.
29–51, 73 FR 11001, Feb. 29, 2008]

§ 29.151

Flight controls.

(a) Longitudinal, lateral, directional,

and collective controls may not exhibit
excessive breakout force, friction, or
preload.

(b) Control system forces and free

play may not inhibit a smooth, direct
rotorcraft response to control system
input.

[Amdt. 29–24, 49 FR 44436, Nov. 6, 1984]

§ 29.161

Trim control.

The trim control—
(a) Must trim any steady longitu-

dinal, lateral, and collective control
forces to zero in level flight at any ap-
propriate speed; and

(b) May not introduce any undesir-

able discontinuities in control force
gradients.

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–24, 49 FR 44436, Nov. 6,
1984]

§ 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.

§ 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

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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

10 kt to

0.8 V

+ 10 kt or, if V

is less than 0.8

, from VH

10 kt to V

+ 10 kt,

with—

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

, whichever is less;

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

or V

, whichever is less.

(c)

. Static longitudinal stability

must be shown at speeds from V

kt to V

with—

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

10 kt or maximum continuous

power, whichever is less;

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

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

;

(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.

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.