35056 Federal Register / Vol. 61, No. 129 / Wednesday, July 3, 1996 / Proposed Rules

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. 28617; Notice 96–6]

RIN 2120–AF79

Revision of Hydraulic Systems

Airworthiness Standards To

Harmonize With European

Airworthiness Standards for Transport

Category Airplanes

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking.

SUMMARY: This document proposes to

amend the airworthiness standards for

transport category airplanes to

harmonize hydraulic systems design

and test requirements with standards

proposed for the European Joint

Aviation Requirements (JAR). These

proposals were developed in

cooperation with the Joint Aviation

Authorities (JAA) of Europe and the

U.S. and European aviation industry

through the Aviation Rulemaking

Advisory Committee (ARAC). These

changes are intended to benefit the

public interest by standardizing certain

requirements, concepts, and procedures

contained in the airworthiness

standards without reducing, but

potentially enhancing, the current level

of safety.

DATES: Comments must be received on

or before October 1, 1996.

ADDRESSES: Comments on this notice

may be mailed in triplicate to: Federal

Aviation Administration, Office of the

Chief Counsel, Attention: Rules Docket

(AGC–200), Docket No. 28617, 800

Independence Avenue SW.,

Washington, DC 20591; or delivered in

triplicate to: Room 915G, 800

Independence Avenue SW.,

Washington, DC 20591.

Comments delivered must be marked

Docket No. 28617. Comments may also

be sent electronically to the following

internet address:

nrmpcmts@mail.hq.faa.gov. Comments

may be examined in Room 915G

weekdays, except Federal holidays,

between 8:30 a.m. and 5:00 p.m. In

addition, the FAA is in maintaining an

information docket of comments in the

Transport Airplane Directorate (ANM–

100), Federal Aviation Administration,

Northwest Mountain Region, 1601 Lind

Avenue SW., Renton, WA 98055–4056.

Comments in the information docket

may be examined weekdays, except

Federal holidays, between 7:30 a.m. and

4:00 p.m.

FOR FURTHER INFORMATION CONTACT:

Mahinder K. Wahi, Flight Test and

Systems Branch, ANM–111, Transport

Airplane Directorate, Aircraft

Certification Service, FAA, 1601 Lind

Avenue SW., Renton, WA 98055–4056;

telephone (206) 227–2142; facsimile

(206) 227–1320.

SUPPLEMENTARY INFORMATION:

Comment Invited

Interested persons are invited to

participate in this proposed rulemaking

by submitting such written data, views,

or arguments as they may desire.

Comments relating to any

environmental, energy, or economic

impact that might result from adopting

the proposals contained in this notice

are invited. Substantive comments

should be accompanied by cost

estimates. Commenters should identify

the regulatory docket or notice number

and submit comments in triplicate to

the Rules Docket address above. All

comments received on or before the

closing date for comments will be

considered by the Administrator before

taking action on this proposed

rulemaking. The proposals contained in

this notice may be changed in light of

comments received. All comments

received will be available in the Rules

Docket, both before and after the

comment period closing date, for

examination by interested persons. A

report summarizing each substantive

public contact with FAA personnel

concerning this rulemaking will be filed

in the docket. Persons wishing the FAA

to acknowledge receipt of their

comments must submit with those

comments a self-addressed, stamped

postcard on which is stated: ‘‘Comments

to Docket No. 28617.’’ The postcard will

be date stamped and returned to the

commenter.

Availability of the NPRM

An electronic copy of this document

may be downloaded using a modem and

suitable communications software from

the FAA regulations section of the

Fedworld electronic bulletin board

service (telephone: 703–321–3339), the

Federal Register’s electronic bulletin

board service (telephone 202–512–

1661), or the FAA’s Aviation

Rulemaking Advisory Committee

Bulletin Board service (telephone: 202–

267–5948).

Internet users may reach the FAA’s

web page at http://www.faa.gov or the

Federal Register’s web page at http://

www.access.gpo/su–docs for access to

recently published rulemaking

documents.

Any person may obtain a copy of this

notice of submitting a request to the

Federal Aviation Administration (FAA),

Office of Rulemaking, ARM–1, 800

Independence Avenue, S.W.,

Washington, D.C. 20591 or by calling

(202) 267–9680. Communications must

identify the notice number or docket

number of this notice.

Persons interested in being placed on

a mailing list for future rulemaking

documents should also request a copy of

Advisory Circular No. 11–2A, Notice of

Proposed Rulemaking Distribution

System, which describes the application

procedure.

Background

The airworthiness standards for

transport category airplanes are

contained in 14 CFR part 25.

Manufacturers of transport category

airplanes must show that each airplane

they produce of a different type design

complies with the relevant standards of

part 25. These standards apply to

airplanes manufactured within the U.S.

for use by U.S. registered operators and

to airplanes manufactured in other

countries and imported under a bilateral

airworthiness agreement.

In Europe, the Joint Aviation

Requirements (JAR) were developed by

the Joint Aviation Authorities (JAA) to

provide a common set of airworthiness

standards for use within the European

aviation community. The airworthiness

standards for European type

certification of transport category

airplanes, JAR–25, are based on part 25

of Title 14. Airplanes certificated to the

JAR–25 standards, including airplanes

manufactured in the U.S. for export to

Europe, receive type certificates that are

accepted by the aircraft certification

authorities of 23 European countries.

Although part 25 and JAR–25 are very

similar, they are not identical.

Differences between the FAR and the

JAR can result in substantial additional

costs when airplanes are type

certificated to both standards. These

additional costs, however, frequently do

not bring about an increase in safety.

For example, part 25 and JAR–25 may

use different means to accomplish the

same safety intent. In this case, the

manufacturer is usually burdened with

meeting both requirements, although the

level of safety is not increased

correspondingly. Recognizing that a

common set of standards would not

only economically benefit the aviation

industry, but would also maintain the

necessary high level of safety, the FAA

and JAA consider harmonization to be

a high priority.

In 1988, the FAA, in cooperation with

the JAA and other organizations

representing the American and

European aerospace industries, began a
Federal Register / Vol. 61, No. 129 / Wednesday, July 3, 1996 / Proposed Rules 35057

process to harmonize the airworthiness

requirements of the United States and

the airworthiness requirements of

Europe, especially in the areas of Flight

Test and Structures.

In 1992, the FAA harmonization effort

was undertaken by the ARAC. A

working group of industry and

government hydraulic systems

specialists of Europe and the United

States was chartered by notice in the

Federal Register (57 FR 58843,

December 12, 1992). The working group

was tasked to develop a draft notice of

proposed rulemaking (NPRM) and any

collateral documents, such as advisory

circulars, concerning new or revised

requirements for hydraulic systems, and

the associated test conditions for

hydraulic systems, installed in transport

category airplanes (§ 25.1435). The JAA

is to develop a similar proposal to

amend JAR–25, as necessary, to achieve

harmonization.

The rulemaking proposal contained in

this notice is based on a

recommendation developed by the

Hydraulic Systems Harmonization

Working Group, and was presented to

the FAA by the ARAC as a

recommendation.

The Aviation Rulemaking Advisory

Committee

The ARAC was formally established

by the FAA on January 22, 1991 (56 FR

2190) to provide advice and

recommendations concerning the full

range of the FAA’s safety-related

rulemaking activity. This advice was

sought to develop better rules in less

overall time using fewer FAA resources

than are currently needed. The

committee provides the opportunity for

the FAA to obtain firsthand information

and insight from interested parties

regarding proposed new rules or

revisions of existing rules.

There are 64 member organizations on

the committee, representing a wide

range of interests within the aviation

community. Meetings of the committee

are open to the public, except as

authorized by section 10(d) of the

Federal Advisory Committee Act.

The ARAC establishes working groups

to develop proposals to recommend to

the FAA for resolving specific issues.

Tasks assigned to working groups are

published in the Federal Register.

Although working group meetings are

not generally open to the public, all

interested parties are invited to

participate as working group members.

Working groups report directly to the

ARAC, and the ARAC must accept a

working group proposal before that

proposal can be presented to the FAA as

an advisory committee

recommendation.

The activities of the ARAC will not,

however, circumvent the public

rulemaking procedures. After an ARAC

recommendation is received and found

acceptable by the FAA, the agency

proceeds with the normal public

rulemaking procedures. Any ARAC

participation in a rulemaking package

will be fully disclosed in the public

docket.

Discussion of the Proposals

The FAA proposes to amend

§ 25.1435 to harmonize this section with

JAR–25. The JAA intend to publish a

Notice of Proposed Amendment (NPA),

also developed by the Hydraulic

Systems Harmonization Working Group,

to revise JAR–25 as necessary to ensure

harmonization in those areas for which

the proposed amendments differ from

the current JAR–25, Change 14. When it

is published, the NPA will be placed in

the docket for this rulemaking.

Generally, the FAA proposes to: (1)

Add appropriate existing-JAR

requirements to achieve harmonization;

(2) Move some of the existing regulatory

text to an advisory circular; (3)

Consolidate and/or separate

requirement subparagraphs for clarity;

and (4) Revise airplane static proof

pressure test requirements to require a

complete functional (dynamic) airplane

test at a lower pressure. A new proposed

Advisory Circular (AC) 25.1435–1 has

been developed by the ARAC to ensure

consistent application of these proposed

revised standards. Public comments

concerning the AC 25.1435–1 are

invited by separate notice published

elsewhere in this issue of the Federal

Register. The JAA intend to publish an

Advisory Material Joint (AMJ), also

developed by the Harmonization

Working Group, to accompany their

NPA. The proposed AC and the

proposed AMJ contain harmonized

advisory information. The following is a

discussion of the specific proposals

prescribed in this NPRM.

Proposal 1. The FAA proposes to

replace current § 25.1435(a)(1) to add

the existing requirements of JAR

25.1435(a)(10) and associated Appendix

K requirements regarding design load

factors for proof and ultimate pressure

conditions for elements of the hydraulic

system (see proposal 2 below regarding

current § 25.1435(a)(1)). The proof and

ultimate pressure conditions would be

defined as the design operating pressure

times the factors of safety. This would

be done to address unusually high

pressures which may be seen in service,

material defects and differences,

manufacturing/construction tolerances

and the consequences of failures (e.g.

pressure vessel failure). The proposed

load factors, ranging between 1.5 and

4.0, relate to the design operating

pressure (DOP) and would apply to

tubes, fittings, pressure vessels

containing gas at high pressure (e.g.,

accumulators) and at low pressure (e.g.

hydraulic reservoirs), hoses, and all

other elements.

By adopting these JAR minimum

factors of safety standards which

currently are not specifically stated in

the FAR, the FAA intends to maintain

an existing level of safety because

normal U.S. Industry practices meet or

exceed these standards.

DOP is the normal maximum steady

pressure. Excluded are reasonable

tolerances and transient pressure effects

such as may arise from acceptable pump

ripple or reaction to system functioning

or flow demands that may affect fatigue.

In localized areas of systems and system

elements the DOP may be different from

the DOP for the system as a whole due

to the range or normally anticipated

airplane operational, dynamic and

environmental conditions. Such

differences would be required to be

taken into account. The term ‘‘design

operating pressure’’ would be discussed

in AC 25.1435–1.

Proposal 2. The FAA proposes to

redesignate the current § 25.1435(a)(1)

as § 25.1435(a)(2), delete the word

‘‘loads’’ from ‘‘pressure loads’’ (‘‘loads’’

is redundant) and edit some text to

avoid repetition. The term ‘‘limit

structural load’’, and a recommended

minimum time to hold pressure would

be discussed in AC 25.1435–1.

Proposal 3. The FAA proposes to

redesignate the current § 25.1435(a)(2)

as a new § 25.1435(a)(3), delete the word

‘‘loads’’ from ‘‘pressure loads’’ (‘‘loads’’

is redundant) and edit some text to

avoid repetition. The term ‘‘ultimate

structural load’’ and a minimum time to

hold pressure would be discussed in AC

25.1435–1.

Proposal 4. The FAA proposes to add

a new § 25.1435(a)(4) that would

contain the current requirements of

§ 25.1435(b)(2)(i) and (b)(2)(ii) regarding

induced loads, pressure transients, and

fatigue as well as the current JAR

25.1435(a)(11) requirements regarding

fatigue design considerations

accounting for fluctuating or repeated

external or internal loads and pressure

transients. These loads could be

structurally or environmentally

induced. By delineating these

requirements, the FAA intends to

ensure that each element is designed to

provide fatigue resistance capability

consistent with anticipated element

usage, thus maintaining the current
35058 Federal Register / Vol. 61, No. 129 / Wednesday, July 3, 1996 / Proposed Rules

level of safety. The terms ‘‘fatigue’’, and

‘‘externally induced loads’’ would be

discussed in AC 25.1435–1.

Proposal 5. The FAA proposes to add

a new § 25.1435(a)(5) that would

contain the current requirements of

§ 25.1435(b)(2)(i) through (b)(2)(v),

except those addressed under proposal

4 above, as well as parts of the current

JAR 25.1435 (a)(5) and (a)(6)

requirements addressing excessive

vibration, abrasion, corrosion,

mechanical damage, and the ability to

withstand inertia loads. These

requirements would be consolidated

and simplified by stating that each

element must be designed to perform as

intended under all environmental

conditions for which the airplane is

certificated. An acceptable means of

compliance would be included in AC

25.1435–1.

Proposal 6. The FAA proposes to add

a modified version of the existing JAR

25.1435(a)(2) as § 25.1435(a)(1),

requiring means to indicate appropriate

system parameters at a flight

crewmember station if (1) the system

performs a function necessary for

continued safe flight and landing, or (2)

in the event of hydraulic system

malfunction, corrective action by the

crew is required to ensure continued

safe flight and landing. The existing JAR

25.1435(a)(2) requires fluid quantity and

pressure indication under specified

circumstances; prior to Amendment 25–

72, § 25.2435 contained an identical

requirement. It was considered at the

time that this requirement is covered by

§ 25.1309(c), which requires that

warning information must be provided

to alert the crew to unsafe system

operating conditions, and to enable

them to take appropriate corrective

action, and the § 25.1435 requirement

was therefore deleted. It is, however,

now recognized that there is value in

defining indication requirements for

hydraulic systems and implications of

their loss. The existing level of safety

would not be impacted since the FAA

is proposing the adopt an existing

industry practice. The term

‘‘appropriate system parameters’’ would

be discussed in AC 25.1435–1. (Note:

see proposal 12 below with respect to

status of current § 25.1435(b)(1)

requirements).

Proposal 7. The FAA proposes to

replace the current § 25.1435(b)(2) by

adding a modified version of the current

JAR 25.1435 (a)(4) and (a)(7) to require

that each system have means to ensure

that system pressures remain within the

design capabilities of each element.

Prior to Amendment 25–72, § 25.1435

contained a requirement that was

identical to the current JAR

requirement, but it was characterized as

both containing arbitrary pressure

transient limits and unnecessary

because the intent is covered under

§ 25.1309. The requirement was

therefore deleted from § 25.1435. The

proposed version deletes the arbitrary

limits but would require that the intent

be specifically addressed by

§ 25.1435(b)(2) to ensure consideration

of the pressure and volume related

transients that are unique to the

hydraulic systems. There would be no

impact on level of safety since an

existing industry practice is being

adopted. An acceptable means of

compliance with § 25.1435(b)(2) would

be included in AC 25.1435–1.

Proposal 8. The FAA proposes to add

a new § 25.1435(b)(3) which would

contain a modified version of the

existing JAR 25.1435(a)(5) requirements

regarding the means to minimize

harmful or hazardous concentrations of

the hydraulic fluid or vapors, if

liberated in any form, into the crew and

passenger compartments during flight.

Prior to Amendment 25–72, § 25.1435

contained an identical requirement. It

was considered at the time that

§ 25.831(b) covers this requirement

under a general statement that the

ventilation air must be free of hazardous

or harmful gases or vapors. However,

§ 25.831(b) specifies allowable limits for

carbon monoxide and carbon dioxide,

but no other products. It could be

construed that those two gases are the

only hazardous products. Section

25.1435 would therefore be revised to

state the specific requirement with

respect to the hydraulic fluid or vapors.

The JAR requirement currently states,

in relevant part, that ‘‘there must be a

means to prevent harmful or hazardous

concentration of fluid. * * *’’ In

recognition of the fact that absolute

prevention of such concentrations is not

an achievable objective, the FAA

proposes that the hydraulic system must

have ‘‘means to minimize the release of

harmful or hazardous concentrations

* * *’’ To show compliance with this

requirement, an applicant would have

to show, both that the likelihood of

releases has been minimized, and that,

if there is such a release, the

concentrations from the release would

also be minimized. The level of safety

would remain unaffected because it’s an

existing industry practice to address this

issue. An acceptable means of

compliance with § 25.1435(b)(3) and a

discussion of the terms ‘‘harmful’’ and

‘‘hazardous’’ would be included in AC

25.1435–1.

Proposal 9. The FAA proposes to

redesignate the existing § 25.1435(c) as

§ 25.1435(b)(4); this is identical to the

existing JAR 25.1435(c) requirements

regarding use of flammable hydraulic

fluid and fire protection. A discussion

of the term ‘‘flammable hydraulic fluid’’

would be included in AC 25.1435–1.

Proposal 10. The FAA proposes to

add a new § 25.1435(b)(5), containing

the current JAR 25.1435(d) requirements

that the airplane manufacturer must

specify the approved hydraulic fluid(s)

suitable to be used in the system(s) and

ensure that the system(s) meet the

applicable placarding requirements of

the current § 25.1541. Although it is a

standard U.S. industry practice to

identify the compatible hydraulic fluid

on each component’s name plate, the

practice may not be universal. In order

to minimize the potential use of

incompatible fluids, seals, etc. in any

system, it is necessary to include this

requirement. A discussion of mixability

of hydraulic fluids would be included

in AC 25.1435–1.

Proposal 11. Current § 25.1435(b)(2)

requirements for hydraulic system

compliance by test and analysis would

be separated into §§ 25.1435 (c), (c)(1)

and (c)(2); the list of environmental

factors [current § 25.1435 (b)(2)(ii)

through (b)(2)(v)] would be moved to

AC 25.1435–1; and, text in the

aforementioned sections would be

clarified. In addition, analysis would be

permitted in place of or to supplement

testing, where shown to be reliable and

appropriate. A discussion on endurance

and fatigue testing, and simulated

failures would be included in AC

25.1435–1.

Proposal 12. Current § 25.1435(b)(1)

requirements for static testing of a

complete hydraulic system to 1.5 times

the design operating pressure (without

deformation of any part of the system

that would prevent performance of

intended function) would be replaced

with a new § 25.1435(c)(3) requirement

that ‘‘the complete hydraulic system

must be functionally tested on the

airplane over the range of motion of all

associated user systems.’’ Also, the

section would require that ‘‘the test

must be conducted at the system relief

pressure or 1.25 times the DOP if a

system pressure relief device is not part

of the system design.’’ This proposal

reflected the recently granted petition

for exemption to the Boeing Company,

Regulatory Docket No. 27384. The

petition, any comments received, and a

copy of the final disposition are filed in

the assigned regulatory docket and are

available for examination in the Rules

Docket (AGC 200), room 915G, FAA

Headquarters Building (FOB 10A), 800

Independence Avenue SW.,

Washington, DC 20591; telephone (202)

267–3132. A discussion on relief
Federal Register / Vol. 61, No. 129 / Wednesday, July 3, 1996 / Proposed Rules 35059

pressure settings and an acceptable

means of compliance with

§ 25.1435(c)(3) would be included in AC

25.1435–1.

The FAA considers that the proposed

functional (i.e., dynamic) test more

closely approximates actual operating

conditions than the existing static test.

This is because for the static test, several

parts of the system and associated relief

valves (including return lines) may need

to be disabled to allow system

pressurization at 1.5 times the design

operating pressure because the relief

valves are designed to open at a

pressure lower than 1.5 times the design

operating pressure. Although the

proposed test pressure would be lower

than 1.5 times the design operating

pressure, all elements would still be

required to be able to withstand at least

1.5 times the design operating pressure

per current § 25.1435(a)(2) (proposed

§ 25.1435(a)(3)), at least retaining and

potentially enhancing the current level

of safety by identification of additional

dynamic interference problems.

Regulatory Evaluation Summary

Regulatory Evaluation, Regulatory

Flexibility Determination, and Trade

Impact Assessment

Changes to federal regulations must

undergo several economic analyses.

First, Executive Order 12866 directs

Federal agencies to promulgate new

regulations or modify existing

regulations only if the potential benefits

to society outweigh the potential 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 assessments,

the FAA has determined that this

proposed rule: (1) Would generate

benefits exceeding its costs and is not

‘‘significant’’ as defined in Executive

Order 12866; (2) Is not ‘‘significant’’ as

defined in DOT’s Policies and

Procedures; (3) would not have a

significant impact on a substantial

number of small entities; and (4) would

lessen restraints on international trade.

These analyses, available in the docket,

are summarized below.

Although several revisions would be

made to § 25.1435, only three of them

would impose additional costs (see

below—proposals 1, 4, and 12, with the

latter having potential cost savings for

some manufacturers). Most of the

changes codify current industry practice

or conform § 25.1435 to corresponding

sections of the JAR. Adoption of the

proposed changes would increase

harmonization and commonality

between American and European

airworthiness standards. Harmonization

would eliminate unnecessary

duplication of airworthiness

requirements, thus reducing

manufacturers’ certification costs. One

manufacturer of part 25 large airplanes

estimated such cost-savings could range

between $60,000 and 600,000 per type

certification (pertaining to hydraulic

systems only); a manufacturer of part 25

small airplanes estimated such savings

at $30,000 to $90,000 per type

certification; Potential safety benefits

resulting from specification of minimum

accepted standards would supplement

these cost-savings.

Proposal 1. These changes codify

existing industry standards. As such,

they would not result in additional costs

for most manufacturers, However, one

manufacturer of small transport category

airplanes estimated increased testing

costs of approximately $25,000 per type

certification Codification of the

proposed standards would ensure that

current safety levels are retained.

Proposals 2, 3, and 9. There would be

no additional costs associated with

these minor changes.

Proposal 4. Although some of the

changes described are new requirements

in the FAR, most American

manufacturers of large transport

category airplanes are already in

compliance with the similar current

European standards, which had to be

met in order to market airplanes in JAA

member countries. The modified testing

and analysis regime is already in place.

Initial first-time costs have already been

incurred; such costs have diminished in

recent certifications. Consequently,

actual incremental costs would be

negligible. One manufacturer, however,

indicated that additional testing and

analysis costs, ranging between

$100,000 and $200,000 per type

certification, would be incurred for the

first one or two type certifications.

Learning curve efficiencies would likely

reduce these costs thereafter.

Manufacturers of small transport

category airplanes, on the other hand,

expect no or negligible additional costs

attributable to the new fatigue-related

proposals. Codification of the proposed

standards would ensure that minimum

acceptable fatigue requirements are

specified with potential for safety

enhancement.

Proposals 5, 6, 7, 8, and 10. These

changes codify existing industry

standards and would not result in

additional certification/production

costs. Codification of the proposed

standards would ensure that current

safety levels are retained.

Proposal 11. There would be no

additional costs associated with these

revisions. The use of analysis in lieu of

or supplemental to testing may reduce

certification costs in some cases.

Proposal 12. Most manufacturers of

part 25 airplanes would not experience

additional costs associated with

dynamic testing of hydraulic systems. In

fact, testing time and associated costs

could be reduced to some small extent

since, unlike static testing, the proposed

dynamic testing would not entail

disabling any system(s) or otherwise

reconfiguring the airplane. One

manufacturer of part 25 large airplanes

estimated potential savings between

$100,000 and $200,000 per type

certification in this regard (another

estimated such savings at only $25,000).

However, a manufacturer of part 25

small transport category airplanes

estimates $25,000 in additional testing,

analysis, and report preparation costs

per type certification attributable to this

proposal. The proposed requirements

would at least retain, and potentially

enhance, the current level of safety by

identification of additional dynamic

interference problems.

Summary of Costs and Benefits

Manufacturers of part 25 small

airplanes could experience additional

costs totalling approximately $50,000

per type certification resulting from

proposals 1 (design load factors) and 12

(dynamic testing). The estimated

$30,000–$90,000 harmonization cost

savings, coupled with potential safety

benefits from proposals 4 and 12, would

exceed these costs.

For manufacturers of part 25 large

airplanes, the cost differential could

range from a $25,000–$200,000

reduction (resulting from proposal 12)

to a $100,000–$200,000 increase

(resulting from proposal 4). The

proposal 12 cost savings coupled with

the estimated $60,000–$600,000

harmonization cost savings would

exceed the additional costs of proposal

4; potential safety benefits from

proposals 4 and 12 would supplement

the cost-savings.

The FAA finds the proposed rule,

therefore, to be cost-beneficial for both

part 25 small and large transport

manufacturers.

Regulatory Flexibility Determination

The Regulatory Flexibility Act of 1980

(RFA) was enacted by Congress to

ensure that small entities are not

unnecessarily or disproportionately

burdened by government regulations.

The RFA requires a Regulatory
35060 Federal Register / Vol. 61, No. 129 / Wednesday, July 3, 1996 / Proposed Rules

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 which is not less than eleven

and which is more than one-third of the

small entities subject to the proposed or

final rule.

The proposed rule would affect

manufacturers of transport category

airplanes produced under future new

airplane type certifications. For

manufacturers, Order 2100.14A

specifies a size threshold for

classification as a small entity as 75 or

fewer employees. Since no transport

category airplane manufacturer has 75

or fewer employees, the proposed rule

would not have a significant economic

impact on a substantial number of small

manufacturers.

International Trade Impact Assessment

The proposed rule would not

constitute a barrier to international

trade, including the export of American

airplanes to foreign countries, and the

import of foreign airplanes into the

United States. Instead, the proposed

changes to the FAR would harmonize

with corresponding existing or proposed

standards in the JAR, thereby lessening

restraints on trade.

Federalism Implications

The amended regulations proposed in

this rulemaking would 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 proposal

would not have sufficient federalism

implications to warrant preparing a

Federalism Assessment.

International Compatibility

In keeping with U.S. obligations

under the Convention on International

Civil Aviation, it is FAA policy to

comply with International Civil

Aviation Organization (ICAO) standards

and recommended practices to the

maximum extent practicable. The FAA

has determined that this rule does not

conflict with any international

agreement of the United States.

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.

Conclusion

Because the proposed changes to

standardize specific hydraulic systems

test requirements of part 25 are not

expected to result in substantial

economic cost, the FAA has determined

that this proposed regulation would not

be significant under Executive Order

12866. Because this is an issue which

has not prompted a great deal of public

concern, the FAA has determined that

this action is not significant under DOT

Regulatory Policies and Procedures (44

FR 11034, February 25, 1979). In

addition since there are no small

entities affected by this proposed

rulemaking, the FAA certifies, under the

criteria of the Regulatory Flexibility Act,

that this rule, if adopted, will not have

a significant economic impact, positive

or negative, on a substantial number of

small entities. An initial regulatory

evaluation of the proposal, including a

Regulatory Flexibility Determination

and Trade Impact Analysis, has been

placed in the docket. A copy may be

obtained by contacting the person

identified under FOR FURTHER

INFORMATION CONTACT.

List of Subjects in 14 CFR Part 25

Aircraft, Aviation safety, Reporting

and recordkeeping requirements.

The Proposed Amendments

Accordingly, the Federal Aviation

Administration proposes to amend 14

CFR part 25 as follows:

PART 25—AIRWORTHINESS

STANDARDS—TRANSPORT

CATEGORY AIRPLANES

1. The authority citation for part 25

continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701,

44702, 44704.

2. Section 25.1435 is revised to read

as follows:

§ 25.1435 Hydraulic systems.

(a) Element design. Each element of

the hydraulic system must be designed

to:

(1) Withstand the proof pressure

without leakage or permanent

deformation that prevents it from

performing its intended function, and

the ultimate pressure without rupture.

The proof and ultimate pressures are

defined in terms of the design operating

pressure (DOP) as follows:

Element Proof

(xDOP)

Ultimate

(xDOP)

1. Tubes & fittings ......... 1.5 3.0

2. Pressure vessels

containing gas:

High pressure (e.g.,

accumulators) ........ 3.0 4.0

Low pressure (e.g.,

reservoirs) .............. 1.5 3.0

3. Hoses ........................ 2.0 4.0

4. All other elements ..... 1.5 2.0

(2) Withstand, without deformation

that would prevent it from performing

its intended function, the design

operating pressure in combination with

limit structural loads that may be

imposed;

(3) Withstand, without rupture, the

design operating pressure multiplied by

a factor of 1.5 in combination with

ultimate structural load that can

reasonably occur simultaneously;

(4) Withstand the fatigue effects of all

cyclic pressures, including transients,

and associated externally induced loads,

taking into account the consequences of

element failure; and

(5) Perform as intended under all

environmental conditions for which the

airplane is certificated.

(b) System design. Each hydraulic

system must:

(1) Have means located at a flightcrew

station to indicate appropriate system

parameters.

(i) It performs a function necessary for

continued safe flight and landing; or

(ii) In the event of hydraulic system

malfunction, corrective action by the

crew to ensure continued safe flight and

landing is necessary;

(2) Have means to ensure that system

pressures, including transient pressures

and pressures from fluid volumetric

changes in elements that are likely to

remain closed long enough for such

changes to occur, are within the design

capabilities of each element, such that

they meet the requirements defined in

§ 25.1435(a)(1) through (a)(5);

(3) Have means to minimize the

release of harmful of hazardous

concentrations of hydraulic fluid or

vapors into the crew and passenger

compartments during flight;

(4) Meet the applicable requirements

of §§ 25.863, 25.1183, 25.1185, and

25.1189 if a flammable hydraulic fluid

is used; and

(5) Be designed to use any suitable

hydraulic fluid specified by the airplane

manufacturer, which must be identified

by appropriate markings as required by

§ 25.1541.

(c) Tests. To demonstrate compliance

with § 25.1435 and support compliance

with § 25.1309, tests must be conducted

on the hydraulic system(s), and/or
Federal Register / Vol. 61, No. 129 / Wednesday, July 3, 1996 / Proposed Rules 35061

subsystem(s) and elements, except that

analysis may be used in place of or to

supplement testing, where the analysis

is shown to be reliable and appropriate.

All internal and external influences

must be taken into account to an extent

necessary to evaluate their effects, and

to assure reliable system and element

functioning and integration. Failure or

unacceptable deficiency of an element

or system must be corrected and be

sufficiently retested, where necessary.

(1) The system(s), subsystem(s), or

element(s) must be subjected to

performance, fatigue, and endurance

tests representative of airplane ground

flight operations.

(2) The complete system must be

tested to determine proper functional

performance and relation to the other

systems, including simulation of

relevant failure conditions, and to

support or validate element design.

(3) The complete hydraulic system(s)

must be functionally tested on the

airplane in normal operation over the

range of motion of all associated user

systems. The test must be conducted at

the system relief pressure 1.25 times the

DOP if a system pressure relief device

is not part of the system design.

Clearances between hydraulic system

elements and other systems or structural

elements must remain adequate and

there must be no detrimental effects.

Issued in Washington, DC, on June 26,

1996.

Ava L. Robinson,

Acting Director, Aircraft Certification Service.

[FR Doc. 96–17034 Filed 7–2–96; 8:45 am]

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