[Federal Register Volume 64, Number 136 (Friday, July 16, 1999)]
[Proposed Rules]
[Pages 38382-38383]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18201]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-374-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777-200 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 777-200 
series airplanes. This proposal would require the application of 
sealant to the front spar and upper surface of the wing center section 
to ensure the integrity of the secondary fuel barrier. This proposal is 
prompted by reports from the airplane manufacturer that the sealant was 
inadvertently not applied to portions of the wing center section on 
certain Boeing Model 777-200 series airplanes. The actions specified by 
the proposed AD are intended to prevent fuel or fuel vapors from 
entering the cargo and passenger compartments in the event of a failure 
of the primary seal or development of a crack in the wing center 
section structure. Leakage of fuel or fuel vapors into the cargo and 
passenger compartments could be hazardous to personnel, and could cause 
a fire in those compartments.

DATES: Comments must be received by August 30, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-374-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.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle 
Washington, 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Larry Reising, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2683; 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 98-NM-374-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-114, Attention: Rules 
Docket No. 98-NM-374-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report that, due to an error during airplane 
manufacture, the sealant that serves as a secondary fuel barrier may 
not have been applied to the front spar and upper surface of the wing 
center section on certain Boeing Model 777-200 series airplanes. This 
condition, if not corrected, could permit fuel or fuel vapors to enter 
the passenger and cargo compartments of the airplane if there is a 
failure of the primary seal or a crack develops in the center section 
structure. Leakage of fuel or fuel vapors into the cargo and passenger 
compartments could be hazardous to personnel, and could cause a fire in 
those compartments.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 777-57-
0033, dated March 26, 1998, which describes procedures for accessing 
the overwing stub beams on the left and right sides of the airplane, 
and for application of a sealant to the front spar and upper surface of 
the wing center section to ensure the integrity of the secondary fuel 
barrier. Accomplishment of the actions specified in the service 
bulletin is intended to adequately address the identified unsafe 
condition.

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 application of sealant to the front spar and 
upper surface of the wing center section to ensure the integrity of the 
secondary fuel barrier. These actions

[[Page 38383]]

would be required to be accomplished in accordance with the service 
bulletin described previously, except as discussed below.

Differences Between the Proposed Rule and the Service Bulletin

    Operators should note that, although the service bulletin 
recommends accomplishment of the application of sealant prior to the 
accumulation of 4,000 total flight cycles or within 750 days (after 
receipt of the service bulletin), whichever occurs earlier, this 
proposed AD would require the application of sealant within 24 months 
after the effective date of this AD. In developing an appropriate 
compliance time for this proposed AD, the FAA considered not only the 
manufacturer's recommendation, but the degree of urgency associated 
with addressing the subject unsafe condition, the average utilization 
of the affected fleet, and the time necessary to perform the actions 
(two hours). In light of all of these factors, the FAA finds a 
compliance time of 24 months after the effective date of this AD for 
accomplishing the proposed actions to be warranted, in that it 
represents an appropriate interval of time allowable for affected 
airplanes to continue to operate without compromising safety. The FAA 
also finds that such a compliance time will provide operators with 
approximately the same amount of time to accomplish the proposed 
actions as what was specified in the service bulletin.

Cost Impact

    There are approximately 37 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 8 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
2 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Required parts would cost 
approximately $100 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be $1,760, 
or $220 per airplane.
    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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 98-NM-374-AD.

    Applicability: All Model 777-200 series airplanes, line numbers 
41 through 91 inclusive, 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 fuel or fuel vapors from entering the passenger and 
cargo compartments of the airplane in the event of a failure of the 
primary seal or development of a crack in the wing center section 
structure, accomplish the following:

Corrective Actions

    (a) Within 24 months after the effective date of this AD, apply 
sealant to the front spar and upper surface of the wing center 
section under the overwing stub beams on the left and right sides of 
the airplane, in accordance with Boeing Service Bulletin 777-57-
0033, dated March 26, 1998.

Alternative Methods of Compliance

    (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 Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. 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.

Special Flight Permits

    (c) Special flight permits may be issued in accordance with 
Sec. 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 July 12, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-18201 Filed 7-15-99; 8:45 am]
BILLING CODE 4910-13-P