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184 

14 CFR Ch. I (1–1–18 Edition) 

§ 23.2240 

(a) Limit loads without— 
(1) Interference with the safe oper-

ation of the airplane; and 

(2) Detrimental permanent deforma-

tion. 

(b) Ultimate loads. 

§ 23.2240

Structural durability. 

(a) The applicant must develop and 

implement inspections or other proce-
dures to prevent structural failures due 
to foreseeable causes of strength deg-
radation, which could result in serious 
or fatal injuries, or extended periods of 
operation with reduced safety margins. 
Each of the inspections or other proce-
dures developed under this section 
must be included in the Airworthiness 
Limitations Section of the Instructions 
for Continued Airworthiness required 
by § 23.1529. 

(b) For Level 4 airplanes, the proce-

dures developed for compliance with 
paragraph (a) of this section must be 
capable of detecting structural damage 
before the damage could result in 
structural failure. 

(c) For pressurized airplanes: 
(1) The airplane must be capable of 

continued safe flight and landing fol-
lowing a sudden release of cabin pres-
sure, including sudden releases caused 
by door and window failures. 

(2) For airplanes with maximum op-

erating altitude greater than 41,000 
feet, the procedures developed for com-
pliance with paragraph (a) of this sec-
tion must be capable of detecting dam-
age to the pressurized cabin structure 
before the damage could result in rapid 
decompression that would result in se-
rious or fatal injuries. 

(d) The airplane must be designed to 

minimize hazards to the airplane due 
to structural damage caused by high- 
energy fragments from an uncontained 
engine or rotating machinery failure. 

§ 23.2245

Aeroelasticity. 

(a) The airplane must be free from 

flutter, control reversal, and diver-
gence— 

(1) At all speeds within and suffi-

ciently beyond the structural design 
envelope; 

(2) For any configuration and condi-

tion of operation; 

(3) Accounting for critical degrees of 

freedom; and 

(4) Accounting for any critical fail-

ures or malfunctions. 

(b) The applicant must establish tol-

erances for all quantities that affect 
flutter. 

D

ESIGN

 

§ 23.2250

Design and construction 

principles. 

(a) The applicant must design each 

part, article, and assembly for the ex-
pected operating conditions of the air-
plane. 

(b) Design data must adequately de-

fine the part, article, or assembly con-
figuration, its design features, and any 
materials and processes used. 

(c) The applicant must determine the 

suitability of each design detail and 
part having an important bearing on 
safety in operations. 

(d) The control system must be free 

from jamming, excessive friction, and 
excessive deflection when the airplane 
is subjected to expected limit airloads. 

(e) Doors, canopies, and exits must be 

protected against inadvertent opening 
in flight, unless shown to create no 
hazard when opened in flight. 

§ 23.2255

Protection of structure. 

(a) The applicant must protect each 

part of the airplane, including small 
parts such as fasteners, against dete-
rioration or loss of strength due to any 
cause likely to occur in the expected 
operational environment. 

(b) Each part of the airplane must 

have adequate provisions for ventila-
tion and drainage. 

(c) For each part that requires main-

tenance, preventive maintenance, or 
servicing, the applicant must incor-
porate a means into the aircraft design 
to allow such actions to be accom-
plished. 

§ 23.2260

Materials and processes. 

(a) The applicant must determine the 

suitability and durability of materials 
used for parts, articles, and assemblies, 
accounting for the effects of likely en-
vironmental conditions expected in 
service, the failure of which could pre-
vent continued safe flight and landing. 

(b) The methods and processes of fab-

rication and assembly used must 
produce consistently sound structures. 

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