149 

Federal Aviation Administration, DOT 

§ 21.93 

been designed and constructed in ac-
cordance with the airworthiness re-
quirements applicable to the issue of 
the type certificate for the aircraft; 

(2) The aircraft substantially com-

plies with the applicable flight char-
acteristic requirements for the type 
certificate; and 

(3) The aircraft can be operated safe-

ly under the appropriate operating lim-
itations in this subchapter. 

(f) The applicant must submit a re-

port showing that the aircraft incor-
porating the modifications involved 
has been flown in all maneuvers nec-
essary to show compliance with the 
flight requirements applicable to those 
modifications and to establish that the 
aircraft can be operated safely in ac-
cordance with the limitations specified 
in §§ 91.317 and 121.207 of this chapter. 

(g) The applicant must establish and 

publish, in a provisional aircraft flight 
manual or other document and on ap-
propriate placards, all limitations re-
quired for the issue of the type certifi-
cate applied for, including weight, 
speed, flight maneuvers, loading, and 
operation of controls and equipment, 
unless, for each limitation not so es-
tablished, appropriate operating re-
strictions are established for the air-
craft. 

(h) The applicant must establish an 

inspection and maintenance program 
for the continued airworthiness of the 
aircraft. 

(i) The applicant must operate a pro-

totype aircraft modified in accordance 
with the corresponding amendment to 
the type certificate for the number of 
hours found necessary by the FAA. 

[Amdt. 21–12, 31 FR 13388, Oct. 15, 1966, as 
amended by Amdt. 21–66, 54 FR 34329, Aug. 18, 
1989] 

Subpart D—Changes to Type 

Certificates 

S

OURCE

: Docket No. 5085, 29 FR 14567, Oct. 

24, 1964, unless otherwise noted. 

§ 21.91

Applicability. 

This subpart prescribes procedural 

requirements for the approval of 
changes to type certificates. 

§ 21.93

Classification of changes in 

type design. 

(a) In addition to changes in type de-

sign specified in paragraph (b) of this 
section, changes in type design are 
classified as minor and major. A 
‘‘minor change’’ is one that has no ap-
preciable effect on the weight, balance, 
structural strength, reliability, oper-
ational characteristics, or other char-
acteristics affecting the airworthiness 
of the product. All other changes are 
‘‘major changes’’ (except as provided in 
paragraph (b) of this section). 

(b) For the purpose of complying 

with Part 36 of this chapter, and except 
as provided in paragraphs (b)(2), (b)(3), 
and (b)(4) of this section, any voluntary 
change in the type design of an aircraft 
that may increase the noise levels of 
that aircraft is an ‘‘acoustical change’’ 
(in addition to being a minor or major 
change as classified in paragraph (a) of 
this section) for the following aircraft: 

(1) Transport category large air-

planes. 

(2) Jet (Turbojet powered) airplanes 

(regardless of category). For airplanes 
to which this paragraph applies, 
‘‘acoustical changes’’ do not include 
changes in type design that are limited 
to one of the following— 

(i) Gear down flight with one or more 

retractable landing gear down during 
the entire flight, or 

(ii) Spare engine and nacelle carriage 

external to the skin of the airplane 
(and return of the pylon or other exter-
nal mount), or 

(iii) Time-limited engine and/or na-

celle changes, where the change in type 
design specifies that the airplane may 
not be operated for a period of more 
than 90 days unless compliance with 
the applicable acoustical change provi-
sions of Part 36 of this chapter is shown 
for that change in type design. 

(3) Propeller driven commuter cat-

egory and small airplanes in the pri-
mary, normal, utility, acrobatic, trans-
port, and restricted categories, except 
for airplanes that are: 

(i) Designated for ‘‘agricultural air-

craft operations’’ (as defined in § 137.3 
of this chapter, effective January 1, 
1966) to which § 36.1583 of this chapter 
does not apply, or 

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14 CFR Ch. I (1–1–24 Edition) 

§ 21.95 

(ii) Designated for dispensing fire 

fighting materials to which § 36.1583 of 
this chapter does not apply, or 

(iii) U.S. registered, and that had 

flight time prior to January 1, 1955 or 

(iv) Land configured aircraft recon-

figured with floats or skis. This recon-
figuration does not permit further ex-
ception from the requirements of this 
section upon any acoustical change not 
enumerated in § 21.93(b). 

(4) Helicopters except: 
(i) Those helicopters that are des-

ignated exclusively: 

(A) For ‘‘agricultural aircraft oper-

ations’’, as defined in § 137.3 of this 
chapter, as effective on January 1, 1966; 

(B) For dispensing fire fighting mate-

rials; or 

(C) For carrying external loads, as 

defined in § 133.1(b) of this chapter, as 
effective on December 20, 1976. 

(ii) Those helicopters modified by in-

stallation or removal of external equip-
ment. For purposes of this paragraph, 
‘‘external equipment’’ means any in-
strument, mechanism, part, apparatus, 
appurtenance, or accessory that is at-
tached to, or extends from, the heli-
copter exterior but is not used nor is 
intended to be used in operating or 
controlling a helicopter in flight and is 
not part of an airframe or engine. An 
‘‘acoustical change’’ does not include: 

(A) Addition or removal of external 

equipment; 

(B) Changes in the airframe made to 

accommodate the addition or removal 
of external equipment, to provide for 
an external load attaching means, to 
facilitate the use of external equip-
ment or external loads, or to facilitate 
the safe operation of the helicopter 
with external equipment mounted to, 
or external loads carried by, the heli-
copter; 

(C) Reconfiguration of the helicopter 

by the addition or removal of floats 
and skis; 

(D) Flight with one or more doors 

and/or windows removed or in an open 
position; or 

(E) Any changes in the operational 

limitations placed on the helicopter as 
a consequence of the addition or re-
moval of external equipment, floats, 
and skis, or flight operations with 
doors and/or windows removed or in an 
open position. 

(5) Tiltrotors. 
(c) For purposes of complying with 

part 34 of this chapter, any voluntary 
change in the type design of the air-
plane or engine which may increase 
fuel venting or exhaust emissions is an 
‘‘emissions change.’’ 

[Amdt. 21–27, 34 FR 18363, Nov. 18, 1969] 

E

DITORIAL

N

OTE

: For F

EDERAL

R

EGISTER

ci-

tations affecting § 21.93, see the List of CFR 
Sections Affected, which appears in the 
Finding Aids section of the printed volume 
and at 

www.govinfo.gov. 

§ 21.95

Approval of minor changes in 

type design. 

Minor changes in a type design may 

be approved under a method acceptable 
to the FAA before submitting to the 
FAA any substantiating or descriptive 
data. 

§ 21.97

Approval of major changes in 

type design. 

(a) An applicant for approval of a 

major change in type design must— 

(1) Provide substantiating data and 

necessary descriptive data for inclu-
sion in the type design; 

(2) Show that the change and areas 

affected by the change comply with the 
applicable requirements of this sub-
chapter, and provide the FAA the 
means by which such compliance has 
been shown; and 

(3) Provide a statement certifying 

that the applicant has complied with 
the applicable requirements. 

(b) Approval of a major change in the 

type design of an aircraft engine is lim-
ited to the specific engine configura-
tion upon which the change is made 
unless the applicant identifies in the 
necessary descriptive data for inclu-
sion in the type design the other con-
figurations of the same engine type for 
which approval is requested and shows 
that the change is compatible with the 
other configurations. 

[Amdt. 21–40, 39 FR 35459, Oct. 1, 1974, as 
amended by Amdt. 21–92, 74 FR 53387, Oct. 16, 
2009; Amdt. 21–96, 77 FR 71695, Dec. 4, 2012] 

§ 21.99

Required design changes. 

(a) When an Airworthiness Directive 

is issued under Part 39 the holder of 
the type certificate for the product 
concerned must— 

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