680 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 29, App. B 

a prominent location that reads: ‘‘The Air-
worthiness Limitations section is FAA ap-
proved and specifies maintenance required 
under §§ 43.16 and 91.403 of the Federal Avia-
tion Regulations unless an alternative pro-
gram has been FAA approved.’’ 

[Amdt. 29–20, 45 FR 60178, Sept. 11, 1980, as 
amended by Amdt. 29–27, 54 FR 34330, Aug. 18, 
1989; Amdt. 29–54, 76 FR 74664, Dec. 1, 2011] 

A

PPENDIX

B 

TO

P

ART

29—A

IRWORTHI

-

NESS

C

RITERIA FOR

H

ELICOPTER

I

N

-

STRUMENT

F

LIGHT

 

I. 

General. 

A transport category helicopter 

may not be type certificated for operation 
under the instrument flight rules (IFR) of 
this chapter unless it meets the design and 
installation requirements contained in this 
appendix. 

II. 

Definitions. 

(a) V

YI

means instrument 

climb speed, utilized instead of V

Y

for com-

pliance with the climb requirements for in-
strument flight. 

(b) V

NEI

means instrument flight never ex-

ceed speed, utilized instead of V

NE

for com-

pliance with maximum limit speed require-
ments for instrument flight. 

(c) V

MINI

means instrument flight min-

imum speed, utilized in complying with min-
imum limit speed requirements for instru-
ment flight. 

III. 

Trim. 

It must be possible to trim the 

cyclic, collective, and directional control 
forces to zero at all approved IFR airspeeds, 
power settings, and configurations appro-
priate to the type. 

IV. 

Static longitudinal stability. 

(a) 

General. 

The helicopter must possess positive static 
longitudinal control force stability at crit-
ical combinations of weight and center of 
gravity at the conditions specified in para-
graphs IV (b) through (f) of this appendix. 
The stick force must vary with speed so that 
any substantial speed change results in a 
stick force clearly perceptible to the pilot. 
The airspeed must return to within 10 per-
cent of the trim speed when the control force 
is slowly released for each trim condition 
specified in paragraphs IV (b) through (f) of 
this appendix. 

(b) 

Climb. 

Stability must be shown in climb 

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

(1) The helicopter trimmed at V

YI

; 

(2) Landing gear retracted (if retractable); 

and 

(3) Power required for limit climb rate (at 

least 1,000 fpm) at V

YI

or maximum contin-

uous power, whichever is less. 

(c) 

Cruise. 

Stability must be shown 

throughout the speed range from 0.7 to 1.1 V

H

 

or V

NEI

, whichever is lower, not to exceed 

±

20 

knots from trim with— 

(1) The helicopter trimmed and power ad-

justed for level flight at 0.9 V

H

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

to 

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

H

or 0.8 

V

NEI

(or 0.8 V

LE

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. 

V. 

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 

±

10

° 

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 

±

10

° 

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 

1

⁄

2

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 

1

⁄

2

amplitude in not more than two 

cycles. 

(c) Any oscillation having a period of 10 

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

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