[Federal Register Volume 60, Number 182 (Wednesday, September 20, 1995)]
[Proposed Rules]
[Pages 48790-48794]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-23208]




[[Page 48789]]

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Part IV





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 21



Type Certification Procedures for Changes in Helicopter Type Design; 
Proposed Rule

  Federal Register / Vol. 60, No. 182 / Wednesday, September 20, 1995 / 
Proposed Rules  

[[Page 48790]]


DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 21

[Docket No. 22334; Notice No. 95-15]
RIN 2120-AF10


Proposed Amendment of the Type Certification Procedures for 
Changes in Helicopter Type Design To Attach or Remove External 
Equipment

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes to amend the existing helicopter noise 
certification procedures with respect to certain changes in type 
designs. This proposal would amend the applicability of the noise 
certification procedures to exclude those changes in type design that 
involve the attachment or removal of external equipment, floats and 
skis, and certain airframe and operational changes made to accommodate 
such changes in type design (acoustical change requirements). This 
proposal would also exclude helicopter flight operations with doors 
and/or windows removed or in an open position from the applicability of 
the acoustical change requirements. This change would reconcile 14 CFR 
part 21 with the procedural treatment of external equipment in the 
original helicopter noise certification rulemaking effort and would 
make U.S. helicopter noise certification regulations more consistent 
with the International Civil Aviation Organization (ICAO) standards.

DATES: Comments must be submitted on or before November 20, 1995.

ADDRESSES: Send comments on this proposal to: Federal Aviation 
Administration, Office of the Chief Counsel, Attn.: Rules Docket (AGC-
10), Docket No. 28334, 800 Independence Avenue, S.W., Room 915G, 
Washington, DC 20591 or deliver comments in triplicate to: FAA Rules 
Docket, Room 915G, 800 Independence Avenue, S.W., Washington, DC 20591. 
Comments may also be submitted electronically to the following Internet 
address: [email protected]. Comments may be inspected in Room 
915G between 8:30 a.m. and 5 p.m., weekdays, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:
Mr. Kenneth E. Jones, Research and Engineering Branch (AEE-110), 
Technology Division, Office of Environment and Energy, FAA, 800 
Independence Avenue, SW., Washington, D.C. 20591; telephone (202) 267-
8933, facsimile (202) 267-5594.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in this rulemaking by 
submitting written data, views, or arguments and by commenting on the 
possible environmental, energy, or economic impacts of this proposal. 
Comments should identify the regulatory docket or notice number and be 
submitted in triplicate to the address above. All comments received, as 
well as a report summarizing any substantive public contact with 
Federal Aviation Administration (FAA) personnel on this rulemaking will 
be filed in the docket, and will be considered by the Administrator 
before taking action on this proposed rulemaking. The docket is 
available for public inspection both before and after the closing date 
for comments. The FAA will acknowledge the receipt of a comment if the 
commenter includes a self-addressed, stamped postcard on which the 
following statement is made: ``Comments to Docket No. 28334''. When the 
comment is received by the FAA, the postcard will be dated, time 
stamped, and returned to the commenter.

Availability of the NPRM

    Any person may obtain a copy of this notice of proposed rulemaking 
(NPRM) by submitting a request to the Federal Aviation Administration, 
Office of Public Affairs, Attention: Public Information Center, APA-
230, 800 Independence Avenue, SW, Washington, DC 20591, or by calling 
(202) 267-3474. Requests should be identified by the docket number of 
this proposed rule.
    Persons interested in being placed on a mailing list for future 
notices of proposed rulemaking should also request a copy of Advisory 
Circular No. 11-2A, Notice of Proposed Rulemaking Distribution System, 
which describes the application procedure.

Background

Statement of the Problem

    The certification procedures for aeronautical products and parts 
are contained in 14 CFR part 21. Under part 21, an applicant for 
approval of a change to a helicopter type certificate must show 
compliance with the noise regulations in 14 CFR part 36 (part 36) if 
the change in type design may increase the noise level of the 
helicopter (an acoustical change). Section 21.93 defines an 
``acoustical change'' and classifies the aircraft which must 
demonstrate compliance with part 36 following an acoustical change. 
Section 21.93(b)(4) described helicopters required to demonstrate 
compliance with part 36 for an acoustical change, and specifically 
excludes helicopters designated exclusively for ``agricultural aircraft 
operations,'' ``dispensing firefighting materials,'' or ``carrying 
external loads.'' The intent of the existing Sec. 21.93(b)(4) is to 
exclude helicopters designated exclusively to carry external loads from 
the requirement to demonstrate compliance with part 36.
    This proposal addresses type certification (including noise 
requirements) procedures for changes to helicopter type designs to 
configure helicopters for carriage of external equipment. External 
equipment is defined herein as any instrument, mechanism, part, 
apparatus, 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. Examples of external equipment are spotlights, 
cameras, airborne signs, and cargo tanks and baskets.
    External equipment may be attached to a helicopter as a Class A 
Rotorcraft External Load Combination under 14 CFR part 133 (part 133) 
``Rotorcraft External Load Operations'', or alternatively, the external 
equipment may be attached to the helicopter as a change in type design 
under Subpart D of part 21. The noise certification requirements do not 
apply to any helicopter, regardless of airworthiness certification 
category, that is designated exclusively for carrying external loads 
pursuant to part 133. Section 133.51 states that ``[a] Rotorcraft 
External-Load Operator Certificate is a current and valid airworthiness 
certificate for each rotorcraft . . . listed by registration number on 
a list attached to the certificate, when the rotorcraft is being used 
in operations conducted under [part 133].'' However, when the original 
helicopter noise certification rules were adopted in part 21, external 
equipment was not excluded from the acoustical change provisions of 
Sec. 21.93. Thus, except for helicopters operated under part 133, the 
addition of external equipment is currently subject to the acoustical 
change provisions of Sec. 21.93. This proposed change to Sec. 21.93 
would reconcile the procedural treatment of external equipment added to 
helicopters with the intent of Sec. 21.93(b)(4) by expanding the 
acoustical change 

[[Page 48791]]
exception to include carriage of external equipment.
    While many helicopter operators would like to use their aircraft to 
perform specialized operations that require the use of external 
equipment, many of these operations do not take place because the cost 
of complying with the noise regulations is financially impractical; 
i.e., the cost of demonstrating compliance with the noise regulations 
would substantially deplete any profit the operation might generate. 
Some helicopter operators suggest that the current acoustical change 
type certification procedures are hampering the growth of their 
industry because compliance costs deter them from performing certain 
operations that require the addition of external equipment.

History of Aircraft Noise Certification Regulations Relevant to This 
Proposed Amendment

    On November 3, 1969, the Administrator of the FAA adopted part 36 
entitled ``Noise Standards: Aircraft Type Certification.'' That action 
implemented the FAA's regulatory noise abatement program by prescribing 
type certification noise standards for subsonic turbojet powered 
airplanes. Procedural changes were concurrently made to part 21, 
``Certification Procedures for Products and Parts,'' to provide 
criteria and requirements for demonstrating compliance with the 
specifications in part 36 (34 FR 13855, November 18, 1969). The noise 
certification requirements of parts 21 and 36 are designed to promote 
the incorporation of noise abatement technology into aircraft design. 
Parts 21 and 36 have been amended as appropriate to add new aircraft 
types to the certification requirements or change the technical 
specifications as necessary. Subsequently, helicopter noise 
certification requirements were adopted with amendment 36-14 to part 36 
and amendment 21-61 to part 21 (53 FR 3534, February 5, 1988).
    The first amendment to part 21 relevant to the original aircraft 
noise certification regulation was amendment 21-27 (34 FR 18355, 
November 10, 1969). That amendment established the general requirement 
that an applicant must demonstrate compliance with the applicable 
provisions of the part 36 procedures prior to issuance of an original, 
amended, or supplemental type certificate. The same amendment to part 
21 included the addition under Sec. 21.93(b) that specified an 
``acoustical change'' as any voluntary change in type design of a 
transport category or turbojet-powered airplane that may increase the 
noise levels of that airplane. Section 21.93 was subsequently amended 
in response to the promulgation of part 36 noise standards for 
propeller-driven small airplanes (Amdt. 21-42; 40 FR 1029, January 6, 
1975), supersonic airplanes (Amdt. 21-47; 43 FR 28406, June 29, 1978), 
commuter category airplanes (Amdt. 21-59; 52 FR 1806, January 15, 
1987), and helicopters (Amdt. 21-61; 53 FR 3534, February 5, 1988).
    Section 21.93 has also been amended to exclude certain changes in 
aircraft type design from the acoustical change requirements. The 
necessity for exempting these changes in type design became apparent 
only after experience was gained from implementation of the original 
noise certification regulations for the aircraft type in question. For 
turbojet-powered airplanes, amendment 21-56 (47 FR 756, January 7, 
1982) excludes 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, and amendment 21-62 (53 FR 16360, 
May 6, 1988) excludes both gear down flight with one or more 
retractable landing gear down during the entire flight and spare engine 
and nacelle carriage external to the skin of the aircraft. For 
propeller-driven commuter category and propeller-driven small 
airplanes, amendment 21-63 (53 FR 47394, November 22, 1988) excludes 
``antique'' airplanes (i.e., those airplanes that have flight time 
before January 1, 1955) and land configured aircraft reconfigured with 
floats and skis.

Synopsis of the Proposal

    The FAA has determined that this proposed rulemaking would provide 
benefits in the form of regulatory relief to the helicopter industry 
and to individual helicopter operators. From a number of noise 
certification studies, the FAA has concluded that this rulemaking will 
result in little or no increase of public exposure to helicopter noise 
emissions. The portion of the existing helicopter regulations relevant 
to this rulemaking imposes an undue financial burden on the helicopter 
industry and operators without providing any measurable benefit to the 
public.
    This proposal would amend the acoustical change provisions of 
Sec. 21.93 to exclude helicopters that have been modified by the 
addition or removal of external equipment mounted on the helicopter 
airframe or floats (rigid or bag) and skis. The proposal would also 
exclude certain changes in helicopter type design from the acoustical 
change requirements to certain airframe changes made to accommodate the 
external equipment, and to helicopter flight operations with doors and/
or windows removed or in an open position. The proposal also applies to 
any operating limitations placed on, or removed from, the helicopter as 
a consequence of the addition or removal of external equipment, floats, 
and skis.
    The FAA recognizes the utility aspect of the helicopter as an 
aerial platform for external equipment. It is a common practice in the 
helicopter industry to add or remove external equipment as mission 
requirements vary. Although external equipment may be offered by the 
original manufacturer of the helicopter, it is usually added as an 
after-market addition by individual operators to meet specific mission 
needs. Given the potential variety of external equipment, the nature of 
the external equipment is not considered part of the basic design of a 
given helicopter and does not influence the basic aerodynamic design or 
the incorporation of noise abatement technology into the helicopter 
design. As stated in the preamble of the final rule (cited previously) 
for the original helicopter noise certification rulemaking, ``* * * the 
[helicopter] noise standards apply [only] to internal load 
configurations.''
    This proposed rule is consistent with a similar provision in the 
applicability section of the helicopter noise certification standard 
approved by the ICAO under its International Standards and Recommended 
Practices: Environmental Protection; Annex 16, Volume 1, Chapters 8 and 
11 (Third Edition-July 1993). The proposed rule change would bring the 
acoustical change provision in the U.S. noise certification regulations 
into closer harmony with that used by foreign noise certification 
authorities.
    Details of the proposed amendment and limitations of the amendment 
are provided in the following analysis.

Section 21.93  Classification of Changes in Type Design

    Part 21 prescribes that certain types of aircraft, including 
helicopters, must demonstrate compliance with the applicable 
requirements of part 36 if a change in type design results in an 
acoustical change. Section 21.93 specified an ``acoustical change'' as 
any voluntary change in type design (including operational limitations) 
that may increase the noise levels of an aircraft. The proposed rule, 
applicable only to helicopters, would exclude the installation or 
removal of external equipment from being considered an acoustical 
change. The proposed rule 

[[Page 48792]]
would specifically exclude from the acoustical change provision the 
addition or removal of all external equipment where ``external 
equipment'' means any instrument, mechanism, part, apparatus, 
appurtenance, or accessory (e.g., spotlights, cameras and other optical 
devices, public address systems, hoists, airborne signs, tow banners, 
cargo tanks and baskets, emergency flotation gear, personnel platforms, 
wire strike kits, crop spraying equipment, scientific apparatus and 
their accessories) that is not used or intended to be used in operating 
or controlling an aircraft in flight, that is attached to the 
helicopter, and is not part of an airframe or engine. The proposed rule 
would apply to changes in the airframe made to:
    (1) Accommodate the addition or removal of external equipment;
    (2) facilitate the use of external equipment; or
    (3) facilitate the safe operation of the helicopter with external 
equipment mounted on the helicopter.
    Examples of airframe changes that would be excepted include 
fairings, attachment hardware, cavities constructed in the airframe to 
accommodate conformally attached equipment, and bubble windows. The 
proposed rule would also exclude from the acoustical change provision 
external load attaching means, the airworthiness certification of which 
is specified in Secs. 27.865 and 29.865.
    The proposed rule change would also exclude the addition or removal 
of floats and skis on helicopters from the acoustical change provision. 
The proposal would also make it clear that any changes in the operating 
limitations placed on the helicopter as a consequence of the addition 
or removal of external equipment, floats, and skis is not an acoustical 
change. Similarly, it would also exclude flight operations conducted 
with one or more doors and/or windows removed or in an open position.
    The FAA has included addition or removal of floats and skis on 
helicopters under this proposed rule change in order to provide the 
same provision for helicopters as is currently provided small propeller 
driven airplanes and propeller driven commuter category airplanes under 
Sec. 21.93(b)(3). The acoustical change requirements of Sec. 21.93 do 
not require a noise certification compliance demonstration for such 
airplanes, and would not for helicopters under this proposal, because 
the FAA did not have a rational basis to consider such design 
configurations in the original rulemaking that established noise 
certification requirements for these aircraft. While the additions of 
floats and skis adversely affects the aerodynamic performance, and 
consequently the noise levels, of both small airplanes and helicopters, 
the FAA lacks the acoustical and performance data necessary to develop 
noise certification regulations relevant to small airplanes and 
helicopters that are reconfigured by the addition of floats or skis.
    If a noise compliance demonstration is otherwise required for 
compliance with part 36, the noise flight test must be conducted 
without any external equipment, floats, or skis mounted to the 
helicopter and with doors and windows mounted and closed (i.e., 
aerodynamically clean configuration) unless otherwise approved or 
required by the FAA. In granting exemptions and establishing conditions 
of exemptions, the rationale for the FAA's decision will be based on 
whether or not the measured helicopter noise levels from a proposed 
noise compliance demonstration would be representative of a ``clean 
configured'' helicopter. For example, assume a cavity was created in 
the fuselage (as a related airframe change) to accommodate a 
conformally (flush) fitted camera. Under the proposed rule change, both 
the camera and the cavity would be exempt from the acoustical change 
requirements of part 21. However, in the event of any future noise 
testing of that helicopter for a change in type design unrelated to the 
camera and cavity, such a noise test without the camera mounted and the 
cavity exposed would likely lead to unrepresentative noise levels due 
to alteration of the aerodynamic performance of the helicopter. In this 
example, during the actual noise test for the unrelated change in type 
design, the FAA would probably require that the flush-mounted camera be 
inserted in its associated fuselage cavity or that the fuselage cavity 
be covered in a manner that would return the fuselage to its original 
aerodynamic shape. Similarly, any analysis for the purpose of 
demonstrating a ``nonacoustical change'' under Sec. 21.93 must assume 
performance levels consistent with an aerodynamically clean helicopter 
(relative to the changes in type design excepted under this proposed 
rulemaking). That is, a decrease in a noise certification level 
effected by the addition of equipment exempted under this proposed 
rulemaking may not be used to ``mathematically' offset an increase in 
noise from a change in type design not affected by this proposed 
rulemaking. For example, assuming the certification basis for a given 
helicopter is part 36 Appendix J, an increase in flyover noise 
certification level caused by the upgrade of a transmission may not be 
offset by the decrease in noise from the assumed addition of external 
equipment, floats or skis as part of the change in type design for the 
transmission.
    The FAA also proposed to delete the current text in 
Sec. 21.93(b)(4) (i) and (ii). These paragraphs indicate examples of 
design changes which would be considered acoustical changes. Since 
Sec. 21.93(b) already makes it clear that ``any voluntary change in the 
type design of an aircraft that may increase the noise levels of the 
aircraft is an `acoustical change' * * *'' existing paragraphs 
Sec. 21.93(b)(4) (i) and (ii) may be erroneously interpreted to 
indicate that (any) change to a muffler (including a change to a 
quieter muffler) is by regulation an acoustical change. The existing 
paragraphs (i) and (ii) do not represent a regulatory requirement and 
add nothing toward the interpretation of the acoustical change 
requirements for helicopters. The proposed new text addresses the 
definition of external equipment and the exclusions discussed earlier 
in this synopsis.
    During development of this proposed rule change, the FAA has 
examined such factors as the utility aspect of the helicopter mission, 
the necessity for the addition or removal of external equipment to meet 
mission needs, the relevance of such equipment with regard to the 
incorporation of noise abatement technology in the design of the 
helicopter, and the desire for commonality of U.S. noise certification 
regulations with relevant international standards and foreign national 
regulations. After consideration of these factors, the Administrator 
has determined that the proposed rule change is consistent with the 
criteria set forth for proposing and amending aircraft noise abatement 
regulations under the authority of Sec. 611(d) of the Federal Aviation 
Act of 1958.

International Compatibility

    The FAA has reviewed corresponding ICAO standards and JAA 
regulations, where they exist. These proposed amendments would make 
U.S. helicopter noise certification regulations more consistent with 
the ICAO standards.

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1980 (Pub. L. 96-
511), there are no requirements for information collection associated 
with this proposed rule.

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Regulatory Evaluation Summary

    Three principal requirements pertain to the economic impacts of 
changes to the Federal Regulations. First, Executive Order 12866 
directs Federal agencies to promulgate new regulations or modify 
existing regulations only if the expected benefits to society outweigh 
the expected costs. Second, the regulatory Flexibility Act of 1980 
requires agencies to analyze the economic impact of regulatory changes 
on small entities. Finally, the Office of Management and Budget directs 
agencies to assess the effect of regulatory changes on international 
trade. In conducting these analyses, the FAA has determined that this 
rule: (1) will generate benefits exceeding costs; (2) is not 
``significant'' as defined in the Executive Order and DOT's policies 
and procedures; (3) will not have a significant impact on a substantial 
number of small entities; and (4) will lessen restraints on 
international trade. These analyses, available in the docket, are 
summarized below.

Benefits

    The proposed rule would provide regulatory relief and a cost 
savings of $31,690,468 (non-discounted) or $23,409,159 discounted, over 
a ten year period, to helicopter manufacturers, modifiers, and 
operators. Of this amount, the projected cost savings for part 36 noise 
certification testing under Appendix H for major helicopter 
manufacturers is $4,800,000 (non-discounted) or $4,264,244 discounted; 
Appendix J Testing for light helicopter manufacturers, $3,000,000 (non-
discounted) or $2,330,305 discounted; and Appendix J Testing for 
modifiers, $22,500,000 (non-discounted) or $15,803,025 discounted. The 
FAA would also realize a cost savings under these appendices: Appendix 
H, $222,460 (non-discounted) or $178,312 discounted; Appendix J, 
$231,740 (non-discounted) or $173,525 discounted; and Appendix J (for 
modifiers), $936,268 (non-discounted) or $659,748 discounted.

Costs

    From the number of noise certification studies, the FAA has learned 
that allowing applicants to attach external equipment to their 
helicopters will result in no net increase in helicopter noise or, at 
worst, insignificant increases in noise levels.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) was enacted by 
Congress to ensure that small entities are not unnecessarily and 
disproportionately burdened by government regulations. The RFA requires 
a Regulatory Flexibility Analysis if a rule would have a significant 
economic impact, either detrimental or beneficial, on a substantial 
number of small entities. FAA Order 2100.14A, Regulatory Flexibility 
Criteria and Guidance prescribes standards for complying with RFA 
review requirements in FAA rulemaking actions. The order defines 
``small entities'' in terms of size thresholds, ``significant economic 
impact'' in terms of annualized cost threshold, and ``substantial 
number'' as a number that is not less than eleven and that is more than 
one-third of the small entities subject to the proposed rule.
    The FAA has determined that, in accordance to the above order, the 
proposed rule to part 21 would not have a significant economic impact 
on a substantial number of small entities. The proposed rule would 
directly affect two types of entities: (1) Light helicopter 
manufacturers, and (2) small helicopter modifiers.
    For small aircraft and aircraft parts manufacturers, Order 2100.14A 
specifies a size threshold for classification as a small entity as 75 
or fewer employees. Based upon this size threshold, all of the affected 
U.S. manufacturers are large. For the purpose of the regulatory 
flexibility determination, an aircraft modifier is considered a small 
entity if it has 200 or fewer employees.
    The FAA concludes that a substantial number of small entities (less 
than one third) would not be significantly affected by the proposed 
rule. Therefore, the proposed rule would not impose a significant 
economic impact on a substantial number of small entities, and a 
regulatory flexibility analysis is not required.

Trade Impact Assessment

    The FAA has determined that the proposed rule would neither affect 
the sale of foreign aviation products and services in the United States 
nor the sale of U.S. products and services in foreign countries. This 
determination is based on the FAA's contention that the proposed rule 
would parallel more closely the U.S. standards with foreign standards 
for noise certification of external equipment.

Federalism Implications

    The regulations herein will not have substantial direct effects on 
the states, on the relationship between the national government and the 
states, or on the distribution of power and responsibilities among the 
various levels of government. Therefore, in accordance with Executive 
Order 12612, it is determined that this proposed rule would not have 
sufficient federalism implications to warrant the preparation of a 
Federalism Assessment.

Environmental Analysis

    Pursuant to the Department of Transportation ``Policies and 
Procedures for Considering Environmental Impacts'' (FAA Order 1050.1D), 
a draft environmental analysis will be prepared and placed in the 
docket.

Conclusion

    The FAA has determined that this proposed rule: (1) is not a 
significant regulatory action under Executive Order 12866; (2) is not a 
significant regulatory action under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. In addition, this proposed rule would have little or 
no effect on trade opportunities for U.S. firms doing business 
overseas, or on foreign firms doing business in the United States.

List of Subjects in 14 CFR Part 21

    Aircraft, Helicopters, Noise control.

The Proposed Amendment

    Accordingly, the Federal Aviation Administration proposes to amend 
14 CFR part 21 as follows:

PART 21--CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS

    1. The authority citation for part 21 continues to read as follows:

    Authority: 49 U.S.C. App. 1344, 1348(c), 1352, 1354(a), 1355, 
1421 through 1431, 1502, 1651(b)(2); 42 U.S.C. 7572; E.O. 11514; 49 
U.S.C. 106(g).

    2. Section 21.93 is amended by revising paragraph (b)(4) to read as 
follows:


Sec. 21.93   Classification of changes in type design.

* * * * *
    (b) * * *
    (4) Helicopters except:
    (i) Those helicopters that are designated exclusively:
    (A) For ``agricultural aircraft operations'', as defined in 
Sec. 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 Sec. 133.1(b) of 
this chapter, as effective on December 20, 1976.

[[Page 48794]]

    (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.
* * * * *
    Issued in Washington, DC, on September 11, 1995.
James D. Erickson,
Director, Office of Environment and Energy.
[FR Doc. 95-23208 Filed 9-19-95; 8:45 am]
BILLING CODE 4910-13-M