spaschal on DSK3GDR082PROD with CFR

Federal Aviation Administration, DOT

Section 21.99

(ii) Designated for dispensing fire
fighting materials to which Section 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 reconfigured with floats or skis. This reconfiguration does not permit further exception from the requirements of this
section upon any acoustical change not
enumerated in Section 21.93(b).
(4) Helicopters except:
(i) Those helicopters that are designated exclusively:
(A) For  - agricultural aircraft operations - , as defined in Section 137.3 of this
chapter, as effective on January 1, 1966;
(B) For dispensing fire fighting materials; or
(C) For carrying external loads, as
defined in Section 133.1(b) of this chapter, as
effective on December 20, 1976.
(ii) Those helicopters modified by installation or removal of external equipment. For purposes of this paragraph,
 - external equipment -  means any instrument, mechanism, part, apparatus,
appurtenance, or accessory that is attached to, or extends from, the helicopter 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 equipment or external loads, or to facilitate
the safe operation of the helicopter
with external equipment mounted to,
or external loads carried by, the helicopter;
(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 removal 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 airplane or engine which may increase
fuel venting or exhaust emissions is an
 - emissions change. - 
[Amdt. 21-27, 34 FR 18363, Nov. 18, 1969]
EDITORIAL NOTE: For FEDERAL REGISTER citations affecting Section 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.

Section 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.
Section 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 inclusion in the type design;
(2) Show that the change and areas
affected by the change comply with the
applicable requirements of this subchapter, 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 limited to the specific engine configuration upon which the change is made
unless the applicant identifies in the
necessary descriptive data for inclusion in the type design the other configurations 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]

Section 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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