Section 21.91

14 CFR Ch. I (1-1-19 Edition)

been designed and constructed in accordance with the airworthiness requirements applicable to the issue of
the type certificate for the aircraft;
(2) The aircraft substantially complies with the applicable flight characteristic requirements for the type
certificate; and
(3) The aircraft can be operated safely under the appropriate operating limitations in this subchapter.
(f) The applicant must submit a report showing that the aircraft incorporating the modifications involved
has been flown in all maneuvers necessary to show compliance with the
flight requirements applicable to those
modifications and to establish that the
aircraft can be operated safely in accordance with the limitations specified
in SectionSection 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 appropriate placards, all limitations required for the issue of the type certificate applied for, including weight,
speed, flight maneuvers, loading, and
operation of controls and equipment,
unless, for each limitation not so established, appropriate operating restrictions are established for the aircraft.
(h) The applicant must establish an
inspection and maintenance program
for the continued airworthiness of the
aircraft.
(i) The applicant must operate a prototype 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
SOURCE: Docket No. 5085, 29 FR 14567, Oct.
24, 1964, unless otherwise noted.

spaschal on DSK3GDR082PROD with CFR

Section 21.91

Applicability.

This subpart prescribes procedural
requirements for the approval of
changes to type certificates.

Section 21.93 Classification
type design.

of

changes

(a) In addition to changes in type design 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 appreciable effect on the weight, balance,
structural strength, reliability, operational characteristics, or other characteristics 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 airplanes.
(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 external mount), or
(iii) Time-limited engine and/or nacelle 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 provisions of Part 36 of this chapter is shown
for that change in type design.
(3) Propeller driven commuter category and small airplanes in the primary, normal, utility, acrobatic, transport, and restricted categories, except
for airplanes that are:
(i) Designated for  - agricultural aircraft operations -  (as defined in Section 137.3
of this chapter, effective January 1,
1966) to which Section 36.1583 of this chapter
does not apply, or

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