Code of Federal Regulations - Title 14

829

Federal Aviation Administration, DOT

Pt. 29, App. B

(1) The helicopter trimmed and power ad-

justed for level flight at 0.9 V

or 0.9 V

NEI

whichever is lower; and

(2) Landing gear retracted (if retractable).
(d)

Slow cruise. Stability must be shown

throughout the speed range from 0.9 V

MINI

1.3 V

MINI

or 20 knots above trim speed, which-

ever is greater, with—

(1) The helicopter trimmed and power ad-

justed for level flight at 1.1 V

MINI

; and

(2) Landing gear retracted (if retractable).
(e)

Descent. Stability must be shown

throughout the speed range 20 knots either
side of trim with—

(1) The helicopter trimmed at 0.8 V

or 0.8

NEI

(or 0.8 V

for the landing gear extended

case), whichever is lower;

(2) Power required for 1,000 fpm descent at

trim speed; and

(3) Landing gear extended and retracted, if

applicable.

(f)

Approach. Stability must be shown

throughout the speed range from 0.7 times
the minimum recommended approach speed
to 20 knots above the maximum rec-
ommended approach speed with—

(1) The helicopter trimmed at the rec-

ommended approach speed or speeds;

(2) Landing gear extended and retracted, if

applicable; and

(3) Power required to maintain a 3

glide

path and power required to maintain the
steepest approach gradient for which ap-
proval is requested.

Static Lateral Directional Stability

(a) Static directional stability must be

positive throughout the approved ranges of
airspeed, power, and vertical speed. In
straight and steady sideslips up to

from

trim, directional control position must in-
crease without discontinuity with the angle
of sideslip, except for a small range of side-
slip angles around trim. At greater angles up
to the maximum sideslip angle appropriate
to the type, increased directional control po-
sition must produce an increased angle of
sideslip. It must be possible to maintain bal-
anced flight without exceptional pilot skill
or alertness.

(b) During sideslips up to

from trim

throughout the approved ranges of airspeed,
power, and vertical speed there must be no
negative dihedral stability perceptible to the
pilot through lateral control motion or
force. Longitudinal cyclic movement with
sideslip must not be excessive.

VI.

Dynamic stability. (a) Any oscillation

having a period of less than 5 seconds must
damp to

⁄

amplitude in not more than one

cycle.

(b) Any oscillation having a period of 5 sec-

onds or more but less than 10 seconds must
damp to

⁄

amplitude in not more than two

cycles.

seconds or more but less than 20 seconds
must be damped.

(d) Any oscillation having a period of 20

seconds or more may not achieve double am-
plitude in less than 20 seconds.

(e) Any aperiodic response may not achieve

double amplitude in less than 9 seconds.

VII.

Stability Augmentation System (SAS)

(a) If a SAS is used, the reliability of the

SAS must be related to the effects of its fail-
ure. Any SAS failure condition that would
prevent continued safe flight and landing
must be extremely improbable. It must be
shown that, for any failure condition of the
SAS that is not shown to be extremely im-
probable—

(1) The helicopter is safely controllable

when the failure or malfunction occurs at
any speed or altitude within the approved
IFR operating limitations; and

(2) The overall flight characteristics of the

helicopter allow for prolonged instrument
flight without undue pilot effort. Additional
unrelated probable failures affecting the con-
trol system must be considered. In addi-
tion—

(i) The controllability and maneuver-

ability requirements in Subpart B must be
met throughout a practical flight envelope;

(ii) The flight control, trim, and dynamic

stability characteristics must not be im-
paired below a level needed to allow contin-
ued safe flight and landing;

(iii) For Category A helicopters, the dy-

namic stability requirements of Subpart B
must also be met throughout a practical
flight envelope; and

(iv) The static longitudinal and static di-

rectional stability requirements of Subpart
B must be met throughout a practical flight
envelope.

(b) The SAS must be designed so that it

cannot create a hazardous deviation in flight
path or produce hazardous loads on the heli-
copter during normal operation or in the
event of malfunction or failure, assuming
corrective action begins within an appro-
priate period of time. Where multiple sys-
tems are installed, subsequent malfunction
conditions must be considered in sequence
unless their occurrence is shown to be im-
probable.

VIII.

Equipment, systems, and installation.

The basic equipment and installation must
comply with Subpart F of Part 29 through
Amendment 29–14, with the following excep-
tions and additions:

(a)

Flight and navigation instruments. (1) A

magnetic gyro-stabilized direction indicator
instead of the gyroscopic direction indicator
required by § 29.1303(h); and

(2) A standby attitude indicator which

meets the requirements of §§ 29.1303(g)(1)
through (7), instead of a rate-of-turn indi-
cator required by § 29.1303(g). If standby bat-
teries are provided, they may be charged
from the aircraft electrical system if ade-
quate isolation is incorporated. The system

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