37198 Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices

Expedited Composite Resolution 506

Special Surcharge Resolution from

Japan

(USA/US Territories)

Intended effective date: 1 July 2000

Dorothy Y. Beard,

Federal Register Liaison.

[FR Doc. 00–14880 Filed 6–12–00; 8:45 am]

BILLING CODE 4910–62–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

Notice of Intent To Rule on Application

00–06–C–00–CRW To Impose and Use

the Revenue From a Passenger Facility

Charge (PFC) at Yeager Airport,

Charleston, WV

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Notice of intent to rule on

application

SUMMARY: The FAA proposes to rule and

invites public comment on the

application to impose and use the

revenue from a PFC at Yeager Airport

under the provisions of the Aviation

Safety and Capacity Expansion Act of

1990 (Title IX of the Omnibus Budget

Reconciliation Act of 1990) (Pub. L.

101–508) and Part 158 of the Federal

Aviation Regulations (14 CFR part 158).

DATES: Comments must be received on

or before July 13, 2000.

ADDRESSES: Comments on this

application may be mailed or delivered

in triplicate to the FAA at the following

address: FAA Eastern Region, AEA–610,

1 Aviation Plaza, Jamaica, NY 11434–

4809.

In addition, one copy of any

comments submitted to the FAA must

be mailed or delivered to Mr. Tim

Murnahan, Assistant Director of The

Central West Virginia Regional Airport

Authority at the following address: 100

Airport Road, Suite 175, Charleston, WV

25311–1080.

Air carriers and foreign air carriers

may submit copies of written comments

previously provided to the Central West

Virginia Regional Airport Authority

under section 158.23 of Part 158.

FOR FURTHER INFORMATION CONTACT:

Kenneth Kroll, AIP/PFC Team Leader,

FAA Eastern Region, (AEA–610), 1

Aviation Plaza, Jamaica, NY 11434–

4809, (718) 553–3357. The application

may be reviewed in person at this same

location.

SUPPLEMENTARY INFORMATION: The FAA

proposes to rule and invites public

comment on the application to impose

and use the revenue from a PFC at

Yeager Airport under the provisions of

the Aviation Safety and Capacity

Expansion Act of 1990 (Title IX of the

Omnibus Budget Reconciliation Act of

1990) (Pub. L. 101–508) and Part 158 of

the Federal Aviation Regulations (14

CFR Part 158).

On June 2, 2000, the FAA determined

that the application to impose and use

the revenue from a PFC submitted by

Central West Virginia Regional Airport

Authority was substantially complete

within the requirements of section

158.25 of Part 158. The FAA will

approve or disapprove the application,

in whole or in part, no later than August

30, 2000.

The following is a brief overview of

the application.

PFC Application No.: 00–0C–CRW.

Level of the proposed PFC: $3.00.

Proposed charge effective date:

January 1, 2001.

Proposed charge expiration date:

August 1, 2002.

Total estimated PFC revenue:

$1,107,054.

Brief description of proposed

projects(s):

—Acquire two snow plows

—Benefit cost Analysis

—Main Terminal Apron Expansion

—Acquire Snow Broom

—Environmental Assessment—Runway

Safety Areas

—Emergency Generator connections

—Expand Main Terminal Building

—Two Loading bridges

—Passenger Access Tunnel

Class or classes of air carriers which

the public agency has requested not be

required to collect PFCs:

Under FAR Part 135—Charter Operators

for hire to the general public

Under FAR Part 121—Charter Operators

for hire to the general public

Any person may inspect the

application in person at the FAA office

listed above under FOR FURTHER

INFORMATION CONTACT and at the FAA

regional airports office located at:

Airports Division, AEA–610, 1 Aviation

Plaza, Jamaica, New York, 11434–04809.

In addition, any person may, upon

request, inspect the application, notice

and other documents germane to the

application in person at the Central

West Virginia Regional Airport

Authority.

Issued in New York City, NY on June 2,

2000.

Thomas Felix,

Manager, Planning and Programming, Eastern

Region.

[FR Doc. 00–14864 Filed 6–12–00; 8:45 am]

BILLING CODE 4910–13–M

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Policy Statement Number ACE–00–23.613–

01]

Proposed Issuance of Policy

Memorandum, Material Qualification

and Equivalency for Polymer Matrix

Composite Material Systems

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of policy statement;

request for comments.

SUMMARY: This document announces an

FAA proposed general statement of

policy applicable to the type

certification of normal, utility, acrobatic,

and commuter category airplanes. This

document advises the public, in

particular manufacturers of normal,

utility, acrobatic, and commuter

category airplanes, of additional

information related to material

qualification and equivalency for

polymer matrix composite material

systems. This notice is necessary to

advise the public of FAA policy and

give all interested persons an

opportunity to present their views on

the policy statement.

DATES: Comments submitted must be

received no later than July 13, 2000.

ADDRESSES: Send all comments on this

policy statement to the individual

identified under FOR FURTHER

INFORMATION CONTACT at Federal

Aviation Administration, Small

Airplane Directorate, ACE–111, Room

301, 901 Locust, Kansas City, Missouri

64106.

FOR FURTHER INFORMATION CONTACT:

Lester Cheng, Federal Aviation

Administration, Small Airplane

Directorate, ACE–111, Room 301, 901

Locust, Kansas City, Missouri 64106;

telephone (816) 329–4120; fax 816–329–

4090; e-mail: lester.cheng@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

comment on this proposed policy

statement, ACE–00–23.613–01, by

submitting such written data, views, or

arguments as they desire. Comment

should be marked, ‘‘Comments to policy

statement ACE–00–23.613–01,’’ and be

submitted in duplicate to the above

address. The Manager, Small Airplane

Directorate, will consider all

communications received on or before

the closing date for comments.

Background

This notice announces the availability

of the following proposed policy

Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices 37199

memorandum, ACE–00–23.613–01, for

review and comment. The purpose of

this memorandum is to address

certification projects initiated after the

final date of the memorandum.

Certification projects already in work do

not necessarily need to comply.

Effect of General Statement of Policy

The FAA is presenting this

information as a set of guidelines

appropriate for use. However, this

document is not intended to establish a

binding norm; it does not constitute a

new regulation and the FAA would not

apply or rely upon it as a regulation.

The FAA Aircraft Certification Offices

(ACO’s) that certify normal, utility,

acrobatic, and commuter category

airplanes should generally attempt to

follow this policy when appropriate.

Applicants should expect that the

certificating officials would consider

this information when making findings

of compliance relevant to new

certificate actions.

Also, as with all advisory material,

this statement of policy identifies one

means, but not the only means, of

compliance.

Because this proposed general

statement of policy only announces

what the FAA seeks to establish as

policy, the FAA considers it to be an

issue for which public comment is

appropriate. Therefore, the FAA

requests comment on the following

proposed general statement of policy

relevant to compliance with 14 CFR part

23, § 23.613, and other related

regulations.

General Statement of Policy

1.1 General

In the decades since the introduction

of advanced composite materials for use

in aircraft, the material qualification has

been a costly burden to the airframe

manufacturer. For each manufacturer,

extensive qualification testing has often

been performed to develop the base

material properties and allowables at

operating environmental conditions,

which are used as part of an aircraft’s

design data, regardless of whether this

material system had been previously

certificated by other manufacturers. In

addition to the use of such data in

design, qualification also provides a

population basis (e.g., in mean and

variability statistics) to continuously

ensure stable material production

practices by the material supplier. The

practice of qualification when

performed by each manufacturer for an

identical material system represents a

massive duplication of effort.

In recent years, NASA, Industry, and

the FAA have worked together to

develop a cost-effective method of

qualifying composite material systems

by the sharing of a central material

qualification database. This method is

built on the existing sections of MIL–

HDBK–17–1E, and allows credit for

FAA witnessed materials testing

performed by third parties such as

material vendors or industry consortia.

During the development process, the

Small Airplane Directorate worked

closely with members of the NASA

Advanced General Aviation Transport

Experiment (AGATE) research

consortium to ensure the acceptability

of this method of compliance to the

applicable airworthiness regulations.

Furthermore, the FAA and AGATE have

maintained a good communication with

the appropriate MIL–HBDK–17 Working

Groups by participating in their regular

meetings. Valuable thoughts have been

shared for the development of this

method.

This effort creates a new way of

conducting business with airframe

manufacturers and material suppliers. It

enables composite material suppliers to

work with the FAA to qualify their

composite material system and receive

approval (i.e., material qualification).

An airframe manufacturer can then

select this approved composite material

system to fabricate aircraft parts and

perform a smaller subset of testing to

substantiate their control of material

and fabrication processes tailored to a

specific application. The terms

‘‘material equivalency’’ will be used in

the current context to describe the

sampling process for a subset of testing

used to confirm equivalent mechanical,

physical and chemical properties for a

particular material or one undergoing

minor changes. For purposes of

example, a minor change would be a

new material production line, which

uses identical raw materials, processes

and equipment. Another example of a

minor change is the substitution of a

new supplier for the same chemical

constituent used to fabricate a given

fiber or matrix type. A major change

would involve more significant

differences in the fiber type, matrix

resin, and pre-impregnated fabrication

process. It is anticipated, significant cost

saving can be realized for both the

industry and the FAA by sharing the

approved central database and

standardizing engineering protocol to

demonstrate material equivalency.

As a precursor, efforts to establish

protocol for shared material databases

were documented in a letter, which was

disseminated by the Small Airplane

Directorate to both FAA certification

field offices and industry in 1998. In

that letter, the essential concepts of this

method have been outlined both in

terms of regulatory and technical

considerations. As a follow-up, the

current memorandum is intended to

serve as a policy and guidance for the

implementation of this newly developed

methodology of qualifying the material

systems. It is noted that currently this

method pertains only to part 23 aircraft.

1.2 Substantiation of Composite

Structures

It has been well recognized that

analysis and base material data alone is

generally not adequate for

substantiation of composite structural

designs. The ‘‘building-block approach’’

of testing, in concert with analysis, is

typically used to fulfill the certification

requirement. As outlined in Section 2.1

of MIL–HDBK–17–1E for Polymer

Matrix Composites, the building-block

approach consists of several levels of

activities from both the ‘‘structural

complexity’’ and ‘‘data application’’

considerations. The structural

complexity is geometry or form-based,

and may include levels of ‘‘constituent,’’

‘‘lamina,’’ ‘‘laminate,’’ ‘‘structural

element,’’ and ‘‘structural subcomponent.’’ On the other hand, the

data application is a specific activity

performed within the design

development and certification process.

The specific levels of structural

complexity required depend on the

distinct purpose of the data application.

For example, structural substantiation

may use tests and analysis at many

different levels of structural complexity,

whereas material acceptance may only

rely on the lowest levels (i.e., base

material properties).

The material qualification and

equivalency method discussed in this

memorandum is a data application

intended to be at the lower-levels of the

structural complexity consideration. It

includes testing to get mechanical and

physical properties at the lamina level.

Such tests are performed using

laminates with simple ply stacking

sequences to characterize the response

of the composite material. At this level,

the key properties represent un-notched

and un-damaged base material strength

allowables for loading in tension,

compression, and shear. Other

important results are the lamina moduli

for these load cases. This material

qualification testing provides

quantitative assessment of the

variability of key base material

properties, leading to various statistics

that are used to establish material

acceptance, equivalence, quality

control, and design basis.

37200 Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices

For clarification purposes, tests at

higher levels (i.e., structural laminate,

element and sub-component) are

typically needed to fulfill the remaining

parts of the structural substantiation

requirement. As the design moves closer

to application specific, the testing

program proceeds to a higher level.

Additional structural laminate

specimen and element testing is

intended to evaluate the ability of the

material to tolerate common

discontinuities. Key properties include

open/filled hole tensile/compression

strengths, cutouts, joint bearing and

bearing/bypass strengths, bonded joint

element and attachments strengths, and

impact-damaged element strengths.

These strength tests are used to derive

the design values of the notched, bolted,

bonded, and damaged features. These

design values, in general, would be

lower than that of the base material

strength allowables established via the

material qualification testing program.

However, as the test element size and

complexity increases, it is more costly

to generate variability data. As a result,

conservative engineering practices are

typically applied to utilize statistics

collected at the lower (specimen) level

of tests.

Furthermore, the structural subcomponent (or full scale) testing is

typically required to confirm load paths

(i.e., validate analyses) and evaluate the

behavior and failure mode of

increasingly more complex structural

assemblies that are considered

application specific. At this scale, it is

unreasonable to think of shared

databases due to unique features in the

design of a given product.

2.0 Related Regulatory and Guidance

Materials

2.1 Federal Regulations

This new method for material

qualification and equivalency has been

developed as a means of showing

compliance with 14 CFR part 23

requirements for the field of application

defined. The regulations that are

directly related to this method include:

Section 23.601 General

Section 23.603 Materials and

workmanship

Section 23.605 Fabrication and

methods

Section 23.613 Material strength

properties and design values

Section 23.613 contains specific

requirements for material strength

properties and design values. Presented

below are the requirements that, in

particular, are tied to this method:

• ‘‘Material strength properties must

be based on enough tests of material

meeting specifications to establish

design values on a statistical basis.’’

[§ 23.613(a)]

• ‘‘Design values must be chosen to

minimize the probability of structural

failure due to material variability.’’

[§ 23.613(b)]. Section 23.613(b) requires

that the design values selected to ensure

structural integrity need to be

characterized by the probability

depending on the design configurations.

That is, A-Basis for single-load-path

design and B-Basis for multiple-loadpath.

• ‘‘The effect of temperature on

allowable stresses used for design in an

essential component or structure must

be considered where thermal effects are

significant under normal operating

conditions.’’ [§ 23.613(c)]. Similarly,

§ 23.603(a)(3) requires ‘‘Take into

account the effects of environmental

conditions such as temperature and

humidity, expected in service.’’

As discussed in Section 1.2, the

database from the qualification program

includes the base material strength

allowables, which represent the design

basis at the lamina level at appropriate

environmental conditions. Design

values utilized for any specific

application still need to be established

via some combination of additional

testing programs, rationale engineering

assumptions, and validated analyses.

Nevertheless, the qualification database

serves as a foundation upon which the

material can be controlled and design

values for higher-level application are

derived. For certification purposes, the

base material allowable is a subset of the

aircraft’s type design data.

2.2 Advisory Circulars

The following two FAA advisory

circulars (AC’s) present

recommendations for showing

compliance with FAA regulations

associated with composite materials:

AC 20–107A—Composite Aircraft

Structure

AC 21–26—Quality Control for the

Manufacture of Composite Structures

AC 20–107A sets forth an acceptable,

but not the only, means of showing

compliance with the provisions of 14

CFR parts 23, 25, 27, and 29 regarding

airworthiness type certification

requirements for composite aircraft

structures. Guidance information is also

presented on associated quality control

and repair aspects.

AC 21–26 provides information and

guidance pertaining to an acceptable,

but not the only, means of

demonstrating compliance with the

requirements of 14 CFR part 21

regarding quality control systems for the

manufacture of composite structures.

This AC also provides guidance

regarding the essential features of

quality control systems for composites

as mentioned in AC 20–107A.

2.3 MIL–HDBK–17

The MIL–HDBK–17 has been

developed and is maintained as a joint

effort of the Department of Defense

(DOD) and the Federal Aviation

Administration (FAA). This handbook

provides guidance in the development

of base material properties (allowables)

and design values acceptable to the

FAA. This new methodology is derived

based on the MIL–HDBK–17–1E

(Polymer Matrix Composites Volume 1:

Guidance). The sections that are closely

related to this method include:

Section 2.3.2 Material qualification

test matrices

Section 2.3.3 Material acceptance test

matrices

Section 2.3.4 Alternate material

equivalence test matrices

Section 8.4.3 Alternate material

statistical procedures

For the simplicity of this

memorandum, the MIL–HDBK–17–1E

can also serve as a reference for most of

the terminology used in this document.

For standardization purposes,

guidance for material database

presentation, both in terms of format

and content, has been well outlined in

MIL–HDBK–17–2E (Polymer Matrix

Composites Volume 2: Materials

Properties). Presentation of material

data per the guidance set forth in the

MIL–HDBK–17 is highly recommended.

2.4 AGATE Document (DOT/FAA

Technical Report)

The specific methodology outlined in

this memorandum has been developed

through the effort of Work Package 3

(Integrated Design and Manufacturing

Tasks) of the AGATE program.

Technical works have been conducted

mainly at the National Institute for

Aviation Research (NIAR) facility

affiliated with Wichita State University

at Wichita, Kansas. Throughout the

process, close coordination between the

FAA [the Small Airplane Directorate,

Technical Center and National Resource

Specialist (NRS)] and the NIAR has been

maintained to ensure this method is in

compliance with the applicable

airworthiness regulations.

Application of this method has been

demonstrated for the epoxy-based preimpregnated carbon or fiberglass

material systems cured at 250 °F with

low-pressure curing/processing cycles.

This effort has resulted in an AGATE

technical document entitled ‘‘Material

Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices 37201

Qualification and Equivalency for

Polymer Matrix Composite Material

Systems’’ where details of this

methodology are presented. To enhance

the accessibility of this document to the

industry in general, an effort is

underway by the FAA Technical Center

to edit and publish it as a DOT/FAA

Report.

3.0 Material Qualification

3.1 Field of Application

The developed material qualification

methodology is intended, in general, for

polymer matrix material systems. The

purposes of this method include:

• To solidify and finalize material

and process (M&P) specifications,

including specific acceptance criteria

for sampling relative to the qualification

database

• To quantify base material variability

• To provide a central database with

stabilized material processes

Application of this method has been

conducted/demonstrated via the effort

of the AGATE program. The AGATE

program has applied this method to

material systems that are characterized

by the following specifics:

• Epoxy-based pre-impregnated

carbon or fiberglass

• Unidirectional tape or woven fabric

• Cure temperature at 240 °F or

higher

• Low-pressure curing/processing

cycles (i.e., autoclave and vacuum

bagging)

Testing requirements and data

reduction procedures needed to certify

the composite material system for

complying with airworthiness

regulations are presented in the AGATE

document. The testing defined in the

AGATE document represents the

minimum requirement. In some cases,

unique characteristics of a material

system or its application may require

testing beyond that defined by this

method (i.e., more rigorous procedures

and larger qualification databases). In

these situations, Aircraft Certification

Offices (ACO’s) may require additional

testing to demonstrate compliance with

the applicable airworthiness

regulations.

3.2 Qualification Approval Procedures

Material qualification bears the

objective of establishing the FAA

approved base material properties of an

‘‘original’’ material system. Test

materials are fabricated using ‘‘original’’

process specifications. This effort may

be part of ongoing certification programs

and can be managed by the appropriate

project ACO. In some cases, such as a

consortium crossing geographic

boundaries, the Small Airplane

Directorate may manage this effort.

All specimen shall be fabricated

according to the appropriate process

specification to the geometry described

in the AGATE document. Prior to

testing, conformity of the test specimen

must be performed by Manufacturing

District Inspection Office (MIDO)

inspectors at the request of ACO

engineers. The MIDO inspector may

elect to delegate this responsibility to a

Designated Manufacturing Inspection

Representative (DMIR) or Designated

Airworthiness Representative (DAR).

Testing must be witnessed by the

FAA. Witnessing can be performed by

ACO engineers, or they may delegate

this responsibility to a Designated

Engineering Representative (DER) or

MIDO inspector.

3.3 Environmental Conditions

In order to substantiate the

environmental effects with respect to

the material properties, several

environmental conditions are defined to

represent extreme cases of exposure.

The selection of these conditions shall

be based on the nature of the material

system and its intended application as

well.

To illustrate, the conditions defined

as extreme cases for the AGATE

program are as follows:

• Cold Temperature Dry (CTD) .............................................................. ¥65° F (±5 °F) with an ‘‘as fabricated’’ moisture content.

• Room Temperature Dry (RTD) ............................................................ ambient laboratory conditions with an ‘‘as fabricated’’ moisture content.

• Elevated Temperature Dry (ETD) ........................................................ 180° F (±5°F) with an ‘‘as fabricated’’ moisture content.

• Elevated Temperature Wet (ETW) ...................................................... 180° F (±5° F) with an equilibrium moisture weight gain in a 85%

relative humidity (±5% R.H.) environment.

Properties for less extreme

temperature conditions are determined

through documented interpolation

procedures.

3.4 Material Quality Control

As part of material qualification,

physical and chemical property tests are

recommended for each batch of material

received from the material vendor.

These tests should be traceable to each

referenced test. Prior to a significant

investment in material qualification

testing, the quality control procedures of

the material vendor should be reviewed

to ensure that quality control programs

are in place for the fiber and neat resin,

as well as pre-impregnation of the

material form (e.g., tape or fabric). The

recommended testing items (e.g., resin

content, fiber areal weight, and gel

time), along with the test methods, are

presented in the AGATE document.

In order to support the maximum

operational temperature (MOT) limit of

the material system and the specific

data to be used in the statistical design

allowable generation, cured lamina

physical property tests (e.g., glass

transition temperature, fiber/resin

volume, and void content) are also

required. These tests, along with the test

methods, are defined in the AGATE

document.

3.5 Batch-to-Batch Variability

For a composite material system base

properties (allowables), several batches

of material must be characterized to

establish the statistically-based material

property for each of the material

systems. For this qualification method,

a minimum of three (3) batches of

material are required to establish a Bbasis design allowable. For an A-basis

design allowable, three (3) batches may

also be used, but five (5) batches of

material are highly recommended to

establish more statistically stable

properties. It is noted that the minimum

number of batches used in AGATE

methodology is less than that

recommended in MIL–HDBK–17–1E.

In order to account for processing and

panel-to-panel variability, the material

system being qualified must also be

representative of multiple processing

cycles. For this qualification method,

each batch of material must be

represented by a minimum of two

independent processing/curing cycles

(e.g., low-pressure autoclave and

vacuum bagging). One engineering

observation, which led to this AGATE

methodology, was that the variation

from composite panel processing can be

as important as batch-to-batch material

variability.

3.6 Property Testing Requirement

The required material property tests

are specified in the AGATE document,

along with the recommended test

method and the required number of

batches/replicates per environmental

condition (i.e., CTD, RTD, ETW and

ETD). In the AGATE document, a format

37202 Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices

has been defined to represent the

required number of batches and

replicates per batch. The format reads:

#×#, where the first # represents the

required number of batches and the

second # represents the required

number of replicates per batch. For

example, ‘‘3×6’’ refers to three batches

of material and six specimen per batch

for a total requirement of 18 specimen.

To illustrate, the tests required by the

AGATE document for qualification at

the environmental condition of ‘‘Room

Temperature Dry (RTD)’’ are listed as

follows:

No. Test

Specimen

(RTD)

1. 0° (warp) Tensile Strength ..... 3×4

2. 0° (warp) Tensile Modulus,

Strength and Poisson’s

Ratio.

3×2

3. 90° (fill) Tensile Strength ........ 3×4

4. 90° (fill) Tensile Modulus and

Strength.

3×2

5. 0° (warp) Compressive

Strength.

3×6

6. 0° (warp) Compressive Modulus.3×2

7. 90° (fill) Compressive

Strength.

3×6

8. 90° (fill) Compressive Modulus.3×2

9. In-Plane Shear Strength ......... 3×4

10. In-Plane Shear Modulus and

Strength.

3×2

11. Short Beam Shear .................. 3×6

3.7 Base Material Allowable

Generation

Upon completion of the property

testing, the statistical base material

allowable can be generated for each

mechanical strength property per the

data reduction procedure described in

the AGATE document. Software for the

data reduction procedure has been made

available in the form of a disk-file as an

attachment to the AGATE document.

Raw test values are normalized to a

specified fiber volume as the fibers are

the primary load-carrying component of

the composite material. This provides a

consistent basis for property

comparisons and generally reduces

variability in fiber-dominated

properties. The procedure used for this

is consistent with that recommended by

MIL–HDBK–17–1E.

Proper consideration of the inherent

material property variability in

composite materials needs to be

addressed in assigning design basis

value to each mechanical property.

Although the statistical procedures

presented in the AGATE document may

account for most common types of

variability, these procedures may not

account for all sources of variability.

B-basis and A-basis material

allowables are determined for each

strength property using the statistical

procedures outlined in the AGATE

document. The specific procedures used

assume a normal distribution for the

population and take advantage of

pooling of data between environments

in calculating statistical variations. The

latter is dependent on the assumptions

that the failure mode for a given type of

test does not vary significantly between

environments and that the material

variability across environments is

comparable. The AGATE document

describes the additional statistical tests

and engineering data analysis needed to

ensure all assumptions are not violated

for a given material system. If evidence

of deviations from the assumptions

exists, more general procedures in MIL–

HDBK–17–1E should be followed. For

the moduli and Poisson’s ratio, the

average value of all corresponding tests

for each environmental condition is

used.

If maximum strain material

allowables are required, simple onedimensional linear stress-strain

relationships may be employed. The

linear assumption works well for tensile

and compressive strain behavior but

may produce rather conservative strain

values in shear due to nonlinear

behavior. More realistic engineering

guidelines to derive shear strain

allowables are given in MIL–HDBK–17–

1E (Section 5.7.6).

3.8 Material Performance Envelope

Referring back to the discussions in

Sections 1.2, 2.1, and 3.1, base material

strength allowables and elastic moduli

generated by the procedures given in the

AGATE document serve a purpose in

stable composite material control within

the industry and certification of specific

aircraft products. Standard test methods

and accepted statistical data treatment

facilitate their use for the former, where

a wide segment of the material supplier

and aircraft manufacturing industry can

share in the cost of generating the

database. When it comes to the use of

this data for the development and

certification of structure for a specific

aircraft, complementary test data and

analysis is needed to account for the

effects of design detail, structural scale,

and damage.

Using the statistical allowables, a base

material performance envelope can be

generated for a material system by

plotting these values as a function of

temperature. Each specific aircraft

application of the qualified material

may have a different maximum

operational temperature (MOT) limit

than those tested for the material

qualification. Some applications may

require a reduced MOT. For these cases,

interpolation may be used to obtain the

corresponding basis values at the new

application MOT.

Interpolation schemes and examples

are presented in the AGATE document.

The schemes provided in the document

are practical for materials obeying

typical mechanical behavior. In most

cases, some minimal amount of testing

may also be required to verify the

interpolated values.

Since unforeseen material property

drop-offs with respect to temperature

and environment can occur,

extrapolation to a higher MOT should

not be attempted without additional

testing and verification.

4.0 Material Equivalency

For clarification purposes, the terms

‘‘material equivalency’’ used in the

current memorandum refer to the

process of substantiating material

properties for purposes of sharing a

composite material qualification

database and/or demonstrating that

minor changes in material production

processes have a negligible effect. This

is achieved by test sampling and passing

the acceptance criteria, which were

derived from a larger population of

material data.

4.1 Field of Application

Composite material equivalence

testing, which constitutes reduced data

sampling (e.g., a single batch), may be

performed by a manufacturer to

establish a link with the original

qualification database and associated

specifications. Depending on the

manufacturer’s use of the qualification

database, specifications for processing a

particular product and the associated

design data may even change

significantly after establishing the link.

For example, if the only intent of a link

with the qualification database is to

establish a population from which

acceptance criteria are derived for

standard tests performed in base

material control, then significant

changes in processing for a particular

product may be allowed. On the other

hand, if the base material qualification

database has greater use in design (e.g.,

applied in deriving design values), then

additional testing may be needed to

show equivalency with the process

variations. In short, the role of material

equivalency testing in certification will

depend on details of the particular

project.

For example, consider the use of a

given material in sandwich

construction, which may have process

variations (e.g., lower autoclave

Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices 37203

pressures) and changes in laminate

characteristics resulting from the

sandwich panel design configuration

(e.g., dimpling of the face-sheets on

honeycomb cells). In such a case,

standard tests for base material

properties in the AGATE approach use

flat laminates, which may yield

different properties than occur in

sandwich panels. If the manufacturer’s

intended use of the qualification

database is limited to control of the base

material as purchased, the manufacturer

may elect to demonstrate equivalency

using original specifications. On the

other hand, if the qualification database

will have greater use in design, then

equivalency testing should expand to

consider the effects of product process

and design variations on the base

material properties. Alternatively,

subsequent tests within the building

block approach used for certification

may also be defined to account for such

differences. Again, the role of material

equivalency testing in certification will

depend on details of the particular

project.

The material equivalence testing may

also be used to assess the effects of

minor changes in constituent(s), the

constituent manufacturing process, and/

or the resin pre-impregnation process,

for the purpose of utilizing the existing

material qualification database. This

testing evaluates the key properties for

test populations large enough to provide

a definitive conclusion but small

enough to provide significant cost

savings as compared to establishing a

new database.

Note that MIL–HDBK–17–1E goes

beyond the discussions in this

memorandum to describe methods for

demonstrating alternate material

acceptance. The discussion can be

found in Section 2.3.4. Although the

term equivalence is used in this section

of MIL–HDBK–17–1E, the test matrices

presented are much more extensive,

highlighting additional issues for the

problems being addressed (i.e., changes

in fiber type, fiber tow size, resin, and

pre-impregnated manufacturer). Table

2.3.4.1.3 of this volume covers a wide

variety of changes to a material system

and highlights the fact that the

performance of a material system is

determined by both the materials and

processes used in its manufacture.

The AGATE methodology of

demonstrating material equivalency is

derived from MIL–HDBK–17–1E. This

methodology only applies to situations

with minor changes to the ‘‘original’’

material system in terms of material

constituents and/or manufacturing

processes. These situations may

include:

• Identical materials, processed by

same manufacturer using identical

fabrication process at different

locations;

• Identical materials, processed by

different manufacturer using a ‘‘followon’’ process that is equivalent to the

‘‘original’’ fabrication process;

• Identical materials, processed by

different manufacturer using a ‘‘followon’’ process that is slightly different to

the ‘‘original’’ fabrication process;

• Minor changes in constituent(s)

and/or constituent manufacturing

process, processed by same/different

manufacturer using a ‘‘follow-on’’

process that is slightly different to the

‘‘original’’ fabrication process;

• Combinations of the above.

In summary, the purposes of this

equivalency method include:

• To share and make use of the

central database by a new user (i.e.,

original material qualification);

• To continue surveillance of material

and process (e.g., Section 5.0 as applied

in material quality control);

• To show that minor changes to

material and processes do not affect

base material properties;

• To make final adjustment on

material and process specifications for

specific application and demonstrate

that it has little affect on base material

properties.

4.2 Equivalency Approval Procedures

For the ‘‘follow-on’’ applicants to use

the database, they need to develop their

own material and process specifications

based on the ‘‘original’’ material and

process specifications. The applicants

submit these specifications along with

the necessary test plans to their

geographically responsible ACO for

review. In all cases of material

equivalency, an ‘‘original’’ should exist

that contains base material mechanical

properties and strength allowables, as

well as the chemical and physical

properties, for the initially qualified

material system.

As is the procedure on any

certification program, the ACO reviews

the test plans and the updated material/

process specifications prior to the

initiation of testing. The review of the

applicants’ specifications should

determine if they meet the application

limitations outlined in Section 4.1, and

are, therefore, candidates for material

equivalency testing. Since the basis

properties of a composite material

system are sensitive to both its material

constituents and manufacturing process,

vigilant engineering judgement must be

exercised during the evaluation process.

The fabrication methods of the

applicants’ structure must meet the

applicable airworthiness regulations

including, but not limited to, §§ 23.603

and 23.605.

Testing is required to qualify the

‘‘follow-on’’ material system by

demonstrating material equivalency to

the ‘‘original’’ material system. Testing

must be witnessed by the FAA. Testing

requirements, data reduction

procedures, and material equivalency

criteria/guidance are presented in the

AGATE document.

In addition to the base material level

coupon testing, certification programs

may require some element or subcomponent testing in demonstrating

equivalency for minor changes in the

material production processes over

time, which are suspected to have some

effect on part manufacturing processes.

These requirements will depend on the

degree of change as well as on the

application (e.g., complexity of the

components or parts to be

manufactured).

4.3 Equivalency Testing Requirement

As described in Section 4.1, the

AGATE material equivalency

methodology is derived based on the

most compatible situations existing, as

discussed in MIL–HDBK–17–1E (i.e., an

identical material is used or changes in

the material are minor). Based upon the

batch-to-batch variability established in

the original qualification database,

material equivalency testing should be

conducted to investigate the processing

or panel-to-panel variability inherent in

the follow-on manufacturer or location.

As a minimum requirement to initiate

such an exercise, the material and

process controls used to generate the

initial database must be known (i.e., the

‘‘original’’ material and process

specifications or ‘‘pedigree’’ must be

known). This issue has come up relative

to some of the data that has been

published in MIL–HDBK–17–2E, and a

plan has been initiated to ensure such

information is available for data

utilization.

The equivalency tests required are

presented in the AGATE document

along with the recommended test

methods and the required number of

batches/replicates per environmental

condition (i.e., RTD and ETW). One (1)

batch of material is the minimum

required for this testing program. As

with material qualification, two

separately processed panels are used in

obtaining specimen for strength tests.

To illustrate, the tests required by the

AGATE document to demonstrate

equivalency under the environmental

condition of ‘‘Room Temperature Dry

(RTD)’’ are listed as follows:

37204 Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices

No. Test

Specimen

(RTD)

1. 0° (warp) Tensile Strength .... 8

2. 0° (warp) Tensile Modulus

and Poisson’s Ratio.

4

3. 90° (fill) Tensile Strength ...... 8

4. 90° (fill) Tensile Modulus ...... 4

5. 0° (warp) Compressive

Strength.

8

6. 0° (warp) Compressive Modulus.4

7. 90° (fill) Compressive

Strength.

8

8. 90° (fill) Compressive Modulus.4

9. In-Plane Shear Strength ....... 8

10. In-Plane Shear Modulus ....... 4

11. Short Beam Shear ................ 8

4.4 Success Criteria for Equivalency

Results derived from the equivalency

testing are compared with the original

qualification database. The statistical

procedures and the success criteria for

equivalency are presented in the

AGATE document. As with

qualification, the acceptance criteria

adopted by AGATE to demonstrate

equivalency assumes a normal

distribution. If a normal distribution

was not confirmed by checks performed

as part of the ‘‘original’’ material

qualification, the acceptance criteria

will need to change to reflect the

statistical distribution that was adopted

for the population. In such a case, the

more general procedures in MIL–

HDBK–17–1E should be followed.

First, the qualification database shall

present the property of interest in terms

of ‘‘mean’’ and ‘‘standard deviation.’’

For base material strength properties,

the qualification database also provides

B-basis and/or A-basis values, which

can be used for purposes of comparison

in establishing specific acceptance

criteria. In addition, two statistical

parameters for sampling need to be

defined, and they are: ‘‘α’’ (probability

of rejecting a good material) and ‘‘n’’

(number of specimen to be tested for the

property of interest).

A selection of α = 0.01, for example,

represents 1% of the chance of wrongly

rejecting a good material. A higher ‘‘α’’

value represents a more conservative

criteria, yet at the expense of a higher

chance of rejecting a good material.

Also, as the number of specimen

increases, the chance for the mean of the

specimen (tests sample) to appear

different from the original qualification

data decreases. Statistically, the two

parameters reflect the Type I errors in

test on either means or minimum

individual values. The Type I error

refers to the situation of rejecting the

null hypothesis when it is true. The Bbasis and A-basis values, which were

derived in population testing, have

limited statistical meaning when

assessing the equivalency from a small

sample size. However, they may have

some engineering value in setting the α

for a particular application.

For strength properties, material

equivalency is established by using both

the means and the minimum individual

values as the acceptance criteria. The

material equivalence is not acceptable

when either one of the two comparisons

fails. The ‘‘α’’ represents the probability

of failing either one of the two, or both,

comparisons.

Based on a limited ‘‘round robin’’

testing program, the AGATE method

currently recommends an ‘‘n’’ value of

‘‘8’’, and an ‘‘α’’ value of ‘‘0.05’’ for

material equivalency tests to link with

the complete material qualification

database. As the exposure and

experience increase through time, the

values for these two parameters may be

revised from lessons learned. Also,

considering the intrinsic difference both

in terms of the nature of material system

and the specific of application, the

certification offices (ACO’s) may adjust

this set of values reflecting their unique

circumstances.

Although specific criteria are not

given, strength properties from

equivalency testing should also not be

excessively higher than those obtained

for the original qualification database.

Engineering judgement should be used

to detect such increases in base strength,

which may affect structural failure

modes or reductions in untested

strength properties. For example, unnotched (or small notch) tensile strength

properties have been found to be

inversely related to the tensile residual

strength of composite structure with

larger flaws.

For modulus, a simple comparison of

means is used. The criterion is not

satisfied when either the test sample

mean is too high or too low in reference

to the original maximum/minimum

mean of the qualification database.

There are also statistical tests that

interrogate the new samples as to their

equivalency to the baseline sample

qualification database. These can be

used as an alternative to the test on

means and minimum individual values

described above. MIL–HDBK–17–1E

recommends the k-sample AndersonDarling (A–D) statistical test (Section

8.3.2.2) or the ANOVA (analysis of

variance) method described in Section

8.4.3.1. The k-sample A–D test can be

used for unequal sample sizes that will

be encountered when comparing the

baseline data to the new data.

Discussion on the use of a significance

level of (α = 0.05 is given in MIL–

HDBK–17. The value chosen should be

agreed upon by the particular

application and should be the same if

the ANOVA method is used.

Other alternate tests (if normal

distribution is assumed) are to use the

F-test to show equivalency of the means

(Section 8.3.5.2.2) and Levene’s test to

show equivalency of the variances

(Section 8.3.5.2.1). An ‘‘α’’ value for

these tests must also be selected.

Successful completion of the

equivalency testing allows the applicant

to use the properties contained in the

original qualification database. In the

case when the testing of the first batch

fails, a second opportunity using a

different batch of material can be

allowed for this equivalency testing. In

order to limit the undesirable,

statistically termed as the Type II error,

only permission of retest to the 2nd

batch is recommended. The Type II

error refers to the situation of accepting

the null hypothesis when it is false.

Should the applicant fail criteria for

equivalency testing of the second batch,

the original base material allowable

database can no longer be used, and a

new base material allowable database

needs to be established per material

qualification procedures. Such a

scenario requires engineering to identify

material and/or processing differences,

which led to changes in the base

material properties, and the associated

update to specifications (i.e., a new

material qualification). In addition,

careful planning of material

procurement, panel fabrication and

testing may be considered at the start of

a material equivalency exercise to

ensure that equivalency testing of a first

and second batch can be expanded to be

part of a new qualification if required.

For example, the material order and

panel sizes fabricated for a particular

batch of material may be sufficiently

large enough to yield additional

specimens, as needed for the larger test

matrix in a qualification effort.

5.0 Continuous Quality Control

Material supplier and purchaser tests

performed as part of a continuous

quality control process may be

considered a special case of material

equivalency testing. In this case, the

sample size is typically smaller than

recommended for the material

equivalence exercise described in

Section 4.0. Nevertheless, the tests are

typically performed on a per batch basis

and a link with the qualification

database can be developed using the

same statistical methods (Section 4.4).

For purposes of continuous quality

control, a recommended ‘‘α’’ value of

Federal Register / Vol. 65, No. 114 / Tuesday, June 13, 2000 / Notices 37205

0.01 (i.e., 1% probability of rejecting

‘‘good’’ material) and an ‘‘n’’ value of 3

to 5 are appropriate. Note the less

stringent requirement here than for

obtaining access to the ‘‘original’’

qualification database discussed in

Section 4.4. In the latter case, all future

batches of material are being admitted

while in the former case only one batch

is under scrutiny. As the exposure and

experience along this line increase

through time, a new set of values for

these two parameters may be provided.

Also, considering the intrinsic

difference both in terms of the nature of

the material system and the specifics of

application, the certification offices

(ACO’s) may adjust this set of values

reflecting their unique circumstances.

If quality control testing fails,

engineering evaluation can be

performed to justify a retest of the same

batch of material. As part of this effort,

engineers should search for other

reasons to believe the material is ‘‘bad’’

or identify a problem in specimen

fabrication and/or testing. The number

of ‘‘retests’’ should be limited to one

which, from a purely statistical

perspective, yields a probability of

rejecting good material in two sets of

receiving inspection tests for the same

batch is only 0.01% for the

recommended ‘‘α’’.

Issued in Kansas City, Missouri, on May

30, 2000.

Marvin Nuss,

Acting Manager, Small Airplane Directorate,

Aircraft Certification Service.

[FR Doc. 00–14482 Filed 6–12–00; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Surface Transportation Board

[STB Ex Parte No. 558 (Sub-No. 3)]

Railroad Cost of Capital—1999

AGENCY: Surface Transportation Board.

ACTION: Notice of decision.

SUMMARY: On June 12, 2000 the Board

served a decision to update its

computation of the railroad industry’s

cost of capital for 1999. The composite

after-tax cost of capital rate for 1999 is

found to be 10.8%, based on a current

cost of debt of 7.2%; a cost of common

equity capital of 12.9%; a cost of

preferred equity capital of 6.3%; and a

capital structure mix comprised of

35.5% debt, 62.7% common equity, and

1.8% preferred equity. The cost of

capital finding made in this proceeding

will be used in a variety of Board

proceedings.

EFFECTIVE DATE: This action is effective

June 12, 2000.

FOR FURTHER INFORMATION CONTACT:

Leonard J. Blistein, (202) 565–1529.

[TDD for the hearing impaired: (202)

565–1695.]

SUPPLEMENTARY INFORMATION: The cost

of capital finding in this decision shall

be used for a variety of regulatory

purposes. To obtain a copy of the full

decision, write to, call, or pick up in

person from: Da-To-Da Office

Solutions., Room 405, 1925 K Street,

NW., Washington, DC 20423.

Telephone: (202) 466–5530. [Assistance

for the hearing impaired is available

through TDD services (202) 565–1695.]

The decision is also available on the

Board’s internet site at www.stb.dot.gov.

Environmental and Energy

Considerations

This action will not significantly

affect either the quality of the human

environment or the conservation of

energy resources.

Regulatory Flexibility Analysis

Pursuant to 5 U.S.C. 605(b), we

conclude that our action in this

proceeding will not have a significant

economic impact on a substantial

number of small entities. The purpose

and effect of this action are to update

the annual railroad industry cost of

capital finding by the Board. No new

reporting or other regulatory

requirements are imposed, directly or

indirectly, on small entities.

Authority: 49 U.S.C. 10704(a).

Decided: June 6, 2000.

By the Board, Chairman Morgan, Vice

Chairman Burkes, and Commissioner

Clyburn.

Vernon A. Williams,

Secretary.

[FR Doc. 00–14879 Filed 6–12–00; 8:45 am]

BILLING CODE 4915–00–P

DEPARTMENT OF TRANSPORTATION

Surface Transportation Board

[STB Docket No. 42052]

Union Pacific Railroad Company—

Petition for Declaratory Order—

Imposed Interchange Charges

AGENCY: Surface Transportation Board.

ACTION: Institution of declaratory order

proceeding; request for comments.

SUMMARY: The Board is instituting a

proceeding under 5 U.S.C. 554(e) to

resolve questions concerning the right of

a rail carrier to impose charges

unilaterally against other carriers for

events that may occur when cars are

interchanged.

DATES: Comments by or on behalf of all

interested parties are due July 12, 2000.

Replies are due August 1, 2000.

ADDRESSES: The original and 10 copies

of comments referring to STB Docket

No. 42052 must be sent to: Surface

Transportation Board, Office of the

Secretary, Case Control Unit, 1925 K

Street, NW, Washington, DC 20423–

0001, ATTN: STB Docket No. 42052.

In addition, send one copy of

comments to: (1) Union Pacific Railroad

Company, Robert T. Opal, General

Commerce Counsel, 1416 Dodge Street,

Room 830, Omaha, Nebraska 68179; (2)

Iowa Interstate Railroad, Ltd., Edward J.

Krug, Krug & Beckelman, P.L.C., 401

First Street S.E., Suite 330, P.O. Box

186, Cedar Rapids, IA 52406–0186; (3)

City of Tacoma Public Utilities, d/b/a

Tacoma Rail, Mark Bubenik, Chief

Assistant City Attorney, P.O. Box 11007,

Tacoma, WA 98411–0007; (4) Roger A.

Serpe, General Counsel, Indiana Harbor

Belt Railroad Company, 111 West

Jackson Boulevard, Suite 1128, Chicago,

Illinois 60604–3502; and (5) William C.

Sippel, Thomas J. Litwiler, Fletcher &

Sippel LLC, Two Prudential Plaza, Suite

3125, 180 North Stetson Avenue,

Chicago, Illinois 60601–6710.

FOR FURTHER INFORMATION CONTACT:

Beryl Gordon, (202) 565–1600. [TDD for

the hearing impaired: 1–800–877–8339.]

SUPPLEMENTARY INFORMATION: On

February 14, 2000, Union Pacific

Railroad Company (UP or petitioner)

filed a petition seeking a declaratory

order to resolve a dispute over the right

of a rail carrier to impose charges

unilaterally against other carriers for

events that may occur when cars are

interchanged. Replies to the petition

have been filed by respondents Indiana

Harbor Belt Railroad Company (Indiana

Harbor Belt), Iowa Interstate Railroad,

Ltd. (Iowa Interstate), and City of

Tacoma, Tacoma Public Utilities, d/b/a

Tacoma Rail and Tacoma Beltline

Railroad (Tacoma Beltline) (collectively,

respondents).

Specifically, UP seeks a declaration

that, under 49 U.S.C. 11121, a rail

carrier may not unilaterally impose

charges on another carrier for

interchange of cars, either by ‘‘tariff’’ or

otherwise, and that interchange-related

charges imposed by one carrier on

another must be either permitted by

agreement of the carriers involved or

specifically authorized by the Board.

The controversy arises as a consequence

of ‘‘tariff’’ provisions issued by

respondents, pursuant to which charges

may be imposed when cars are not

pulled from interchange within