Code of Federal Regulations - Title 14

216

14 CFR Ch. I (1–1–14 Edition)

§ 23.369

resulting from the failure of the crit-
ical engine including the following con-
ditions in combination with a single
malfunction of the propeller drag lim-
iting system, considering the probable
pilot corrective action on the flight
controls:

(1) At speeds between

and

the

loads resulting from power failure be-
cause of fuel flow interruption are con-
sidered to be limit loads.

(2) At speeds between

and

the

loads resulting from the disconnection
of the engine compressor from the tur-
bine or from loss of the turbine blades
are considered to be ultimate loads.

(3) The time history of the thrust

decay and drag buildup occurring as a
result of the prescribed engine failures
must be substantiated by test or other
data applicable to the particular en-
gine-propeller combination.

(4) The timing and magnitude of the

probable pilot corrective action must
be conservatively estimated, consid-
ering the characteristics of the par-
ticular engine-propeller-airplane com-
bination.

(b) Pilot corrective action may be as-

sumed to be initiated at the time max-
imum yawing velocity is reached, but
not earlier than 2 seconds after the en-
gine failure. The magnitude of the cor-
rective action may be based on the
limit pilot forces specified in § 23.397
except that lower forces may be as-
sumed where it is shown by analysis or
test that these forces can control the
yaw and roll resulting from the pre-
scribed engine failure conditions.

[Amdt. 23–7, 34 FR 13089, Aug. 13, 1969]

§ 23.369

Rear lift truss.

(a) If a rear lift truss is used, it must

be designed to withstand conditions of
reversed airflow at a design speed of—

V=8.7

√

(W/S) + 8.7 (knots), where W/

S=wing loading at design maximum
takeoff weight.

(b) Either aerodynamic data for the

particular wing section used, or a value
of

equalling ¥0.8 with a chordwise

distribution that is triangular between

a peak at the trailing edge and zero at
the leading edge, must be used.

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–7, 34 FR 13089, Aug. 13,
1969; 34 FR 17509, Oct. 30, 1969; Amdt. 23–45, 58
FR 42160, Aug. 6, 1993; Amdt. 23–48, 61 FR
5145, Feb. 9, 1996]

§ 23.371

Gyroscopic and aerodynamic

loads.

(a) Each engine mount and its sup-

porting structure must be designed for
the gyroscopic, inertial, and aero-
dynamic loads that result, with the en-
gine(s) and propeller(s), if applicable,
at maximum continuous r.p.m., under
either:

(1) The conditions prescribed in

§ 23.351 and § 23.423; or

(2) All possible combinations of the

following—

(i) A yaw velocity of 2.5 radians per

second;

(ii) A pitch velocity of 1.0 radian per

second;

(iii) A normal load factor of 2.5; and
(iv) Maximum continuous thrust.
(b) For airplanes approved for aero-

batic maneuvers, each engine mount
and its supporting structure must meet
the requirements of paragraph (a) of
this section and be designed to with-
stand the load factors expected during
combined maximum yaw and pitch ve-
locities.

commuter category, each engine
mount and its supporting structure
must meet the requirements of para-
graph (a) of this section and the gust
conditions specified in § 23.341 of this
part.

[Doc. No. 27805, 61 FR 5145, Feb. 9, 1996]

§ 23.373

Speed control devices.

If speed control devices (such as

spoilers and drag flaps) are incor-
porated for use in enroute conditions—

(a) The airplane must be designed for

the symmetrical maneuvers and gusts
prescribed in §§ 23.333, 23.337, and 23.341,
and the yawing maneuvers and lateral
gusts in §§ 23.441 and 23.443, with the de-
vice extended at speeds up to the
placard device extended speed; and

(b) If the device has automatic oper-

ating or load limiting features, the air-
plane must be designed for the maneu-
ver and gust conditions prescribed in

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