63624 Federal Register / Vol. 62, No. 230 / Monday, December 1, 1997 / Proposed Rules

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–NM–272–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 747–100, -200, and -300 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to all

Boeing Model 747–100, -200, and -300

series airplanes. This proposal would

require the installation of components

for the suppression of electrical

transients and/or the installation of

shielding and separation of the

electrical wiring of the fuel quantity

indication system (FQIS). This proposal

is prompted by testing results, which

revealed that excessive energy levels in

the electrical wiring and probes of the

fuel system could be induced by

electrical transients. The actions

specified by the proposed AD are

intended to prevent electrical transients

induced by electromagnetic interference

(EMI) or electrical short circuit

conditions from causing arcing of the

FQIS electrical wiring or probes in the

fuel tank, which could result in a source

of ignition in the fuel tank.

DATES: Comments must be received by

March 3, 1998.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 97–NM–

272–AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055–4056.

Comments may be inspected at this

location between 9:00 a.m. and 3:00

p.m., Monday through Friday, except

Federal holidays.

Information concerning this proposal

may be obtained from or examined at

the FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW.,

Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Chris Hartonas, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130S, FAA, Transport Airplane

Directorate, Seattle Aircraft Certification

Office, 1601 Lind Avenue, SW., Renton,

Washington 98055–4056; telephone

(425) 227–2864; fax (425) 227–1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

participate in the making of the

proposed rule by submitting such

written data, views, or arguments as

they may desire. Communications shall

identify the Rules Docket number and

be submitted in triplicate to the address

specified above. All communications

received on or before the closing date

for comments, specified above, will be

considered before taking action on the

proposed rule. The proposals contained

in this notice may be changed in light

of the comments received.

Comments are specifically invited on

the overall regulatory, economic,

environmental, and energy aspects of

the proposed rule. All comments

submitted will be available, both before

and after the closing date for comments,

in the Rules Docket for examination by

interested persons. A report

summarizing each FAA-public contact

concerned with the substance of this

proposal will be filed in the Rules

Docket.

Commenters wishing the FAA to

acknowledge receipt of their comments

submitted in response to this notice

must submit a self-addressed, stamped

postcard on which the following

statement is made: ‘‘Comments to

Docket Number 97-NM–272-AD.’’ The

postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this

NPRM by submitting a request to the

FAA, Transport Airplane Directorate,

ANM–103, Attention: Rules Docket No.

97–NM–272–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

On July 17, 1996, a Boeing Model 747

series airplane was involved in an

accident shortly after takeoff from John

F. Kennedy International Airport in

Jamaica, New York. In support of the

subsequent accident investigation, the

FAA participated in testing of the fuel

quantity indication system (FQIS).

Results of that testing revealed that

excessive energy could be induced by

high transient voltage levels in the

electrical wiring and probes of the fuel

system. These excessive levels occurred

when the wiring of the FQIS was

subjected to electrical transient testing.

These electrical transients may be

caused in the airplane when switching

electrical loads in the wiring adjacent to

the FQIS wiring.

The FQIS was tested to determine its

performance in accordance with

airplane electromagnetic interference

(EMI) requirements. In this test,

conductive debris, such as steel wool

and lockwire, was used to bridge the

FQIS probes to simulate debris that has

been found during inspections of

transport category airplanes. Results of

this test indicated that transient voltage

levels induced in the FQIS wiring and

probes could be in excess of 800 volts,

and the resulting energy levels in the

FQIS wiring and probes could be greater

than the energy required to ignite fuel

vapor inside a fuel tank.

In addition, recent inspections of the

fuel probe wiring in Model 747 fuel

tanks revealed damaged wiring

insulation, which exposed the

conductors inside the fuel tank. This

condition, together with the

introduction of induced transients or

short circuit conditions, increases the

likelihood for potential ignition sources

in the fuel tank.

The conditions described above, if not

corrected, could result in excessive

levels of energy in the FQIS wiring and

a consequent potential source of

ignition in the fuel tank.

FAA’s Conclusions

While none of the above conditions

have been identified at this time as the

cause of the accident discussed

previously, the FAA concludes that

results of the tests and inspections that

have been performed indicate that

modifications are required to limit the

energy level induced in the FQIS wiring

and probes. Further, the FAA has

determined that shielding and

separation of the FQIS electrical wiring

from adjacent wiring is necessary to

provide protection from wire-to-wire

electrical short circuit conditions,

which are a potential source of ignition

in the fuel tank.

Explanation of Requirements of

Proposed Rule

Since an unsafe condition has been

identified that is likely to exist or

develop on other products of this same

type design, the proposed AD would

require the installation of components

for the suppression of electrical

transients and/or the installation of

shielding and separation of the

electrical wiring of the FQIS. The

actions would be required to be

accomplished in accordance with a

method approved by the FAA.

Cost Impact

There are approximately 650 Model

747–100, -200, and -300 series airplanes

of the affected design in the worldwide

fleet. The FAA estimates that 167
Federal Register / Vol. 62, No. 230 / Monday, December 1, 1997 / Proposed Rules 63625

airplanes of U.S. registry would be

affected by this proposed AD.

Since the manufacturer has not yet

developed a modification

commensurate with the requirements of

this proposal, the FAA is unable at this

time to provide specific information as

to the number of work hours or the cost

of parts that would be required to

accomplish the proposed modification.

A further problem in developing a

specific cost estimate is the fact that

modification costs are expected to vary

from operator to operator and from

airplane to airplane depending upon

airplane configuration. The proposed

compliance time of 12 months should

provide ample time for the

development, approval, and installation

of an appropriate modification.

However, based on similar

modifications accomplished previously

on other airplane models, the FAA can

reasonably estimate that the proposed

modification would require 40 work

hours to accomplish, at an average labor

rate of $60 per work hour. The cost of

required parts is estimated to be $10,000

per airplane. Based on these figures, the

cost impact of the proposed AD on U.S.

operators is estimated to be $2,070,800,

or $12,400 per airplane.

As indicated earlier in this preamble,

the FAA specifically invites the

submission of comments and other data

regarding this economic aspect of

proposal.

The cost impact figure discussed

above is based on assumptions that no

operator has yet accomplished any of

the proposed requirements of this AD

action, and that no operator would

accomplish those actions in the future if

this AD were not adopted.

Regulatory Impact

The regulations proposed herein

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 the

preparation of a Federalism Assessment.

For the reasons discussed above, I

certify that this proposed regulation (1)

is not a ‘‘significant regulatory action’’

under Executive Order 12866; (2) is not

a ‘‘significant rule’’ under the DOT

Regulatory Policies and Procedures (44

FR 11034, February 26, 1979); and (3) if

promulgated, will not have a significant

economic impact, positive or negative,

on a substantial number of small entities

under the criteria of the Regulatory

Flexibility Act. A copy of the draft

regulatory evaluation prepared for this

action is contained in the Rules Docket.

A copy of it may be obtained by

contacting the Rules Docket at the

location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation

safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the Federal Aviation

Administration proposes to amend part

39 of the Federal Aviation Regulations

(14 CFR part 39) as follows:

PART 39—AIRWORTHINESS

DIRECTIVES

1. The authority citation for part 39

continues to read as follows:

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

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

Boeing: Docket 97-NM–272-AD.

Applicability: All Model 747–100, -200,

and -300 series airplanes, certificated in any

category.

Note 1: This AD applies to each airplane

identified in the preceding applicability

provision, regardless of whether it has been

otherwise modified, altered, or repaired in

the area subject to the requirements of this

AD. For airplanes that have been modified,

altered, or repaired so that the performance

of the requirements of this AD is affected, the

owner/operator must request approval for an

alternative method of compliance in

accordance with paragraph (b) of this AD.

The request should include an assessment of

the effect of the modification, alteration, or

repair on the unsafe condition addressed by

this AD; and, if the unsafe condition has not

been eliminated, the request should include

specific proposed actions to address it.

Compliance: Required as indicated, unless

accomplished previously. To prevent

electrical transients induced by

electromagnetic interference (EMI) or

electrical short circuit conditions from

causing arcing of the fuel quantity indication

system (FQIS) electrical wiring or probes in

the fuel tank, which could result in a source

of ignition in the fuel tank, accomplish the

following:

(a) Within 12 months after the effective

date of this AD, install components for the

suppression of electrical transients and/or

install shielding and separation of the wiring

of the FQIS, in accordance with a method

approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport

Airplane Directorate.

(b) An alternative method of compliance or

adjustment of the compliance time that

provides an acceptable level of safety may be

used if approved by the Manager, Seattle

ACO, FAA. Operators shall submit their

requests through an appropriate FAA

Principal Maintenance Inspector, who may

add comments and then send it to the

Manager, Seattle ACO.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Seattle ACO.

(c) Special flight permits may be issued in

accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to

a location where the requirements of this AD

can be accomplished.

Issued in Renton, Washington, on

November 26, 1997.

Stewart R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–31668 Filed 11-28-97; 10:56 am]

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