[Federal Register Volume 63, Number 175 (Thursday, September 10, 1998)]
[Rules and Regulations]
[Pages 48423-48425]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-24059]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-54-AD; Amendment 39-10747; AD 98-19-05]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757-200 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 757-200 series airplanes, that 
requires the application of a sealant, secondary fuel barrier, and 
corrosion-inhibiting compound to certain portions of the wing center 
section. This amendment is prompted by reports indicating that, during 
manufacture, the secondary fuel barrier was not applied to certain 
portions of the wing center section. The actions specified by this AD 
are intended to prevent leakage of fuel through the fasteners, sealant, 
or structural cracks in the center section structure, which could 
result in fuel or fuel vapors entering the cargo or passenger 
compartment of the airplane.

DATES: Effective October 15, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 15, 1998.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Registe, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Kathrine Rask, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-1547; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 757-200 
series airplanes was published in the Federal Register on September 25, 
1997 (62 FR 50263). That action proposed to require the application of 
a sealant, secondary fuel barrier, and corrosion-inhibiting compound to 
certain portions of the wing center section.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    One commenter supports the proposed rule.

Request for Extension of the Compliance Time

    Several commenters request that the compliance time for the actions 
required by this proposed AD be extended, and suggest that the 
compliance thresholds

[[Page 48424]]

be revised to coincide with the next scheduled heavy maintenance check. 
Compliance times of 36 months, 48 months, and 72 months are suggested 
as appropriate for the extension. The commenters state that the 
extensive access required to fully clean the corrosion inhibiting 
compound applied at the factory, the cure times for the sealants, and 
the application of the corrosion inhibiting compounds, are all factors 
making it prohibitive to incorporate the modification during ``C'' 
checks. One commenter estimates that it could save $36,000 by 
retrofitting its 17 airplanes during a heavy maintenance check instead 
of during a ``C'' check. Another operator states that to accomplish the 
modification on its affected fleet of airplanes within 18 months would 
require special scheduling and would create an economic burden. Another 
commenter states that it does not agree with the logic used to 
determine the urgency of this issue because there have not been any 
reports or evidence of fuel vapors reaching the pressurized area.
    The FAA concurs that the compliance times can be extended somewhat. 
The intent of the AD is that the inspections be conducted during a 
regularly scheduled maintenance visit for the majority of the affected 
fleet, when the airplanes would be located at a base where special 
equipment and trained personnel would be readily available, if 
necessary. Based on the information supplied by the commenters, the FAA 
now recognizes that a compliance time of 48 months corresponds more 
closely to the interval representative of most of the affected 
operators' normal maintenance schedules. Paragraph (a) of the final 
rule has been revised to require accomplishment of the required actions 
``at the next scheduled heavy maintenance check (i.e., a ``4C'' check) 
or within 48 months after the effective date of the AD, whichever 
occurs first.'' The FAA does not consider that this extension will 
adversely affect safety. The affected area is small, approximately 200 
square inches, and there have been no reported leaks in this area of 
the front spar of the wing center section. In addition, the barrier 
does not function as the primary barrier but is designed to provide a 
fume-proof and fuel-proof barrier in the event of a failure of the 
fastener sealant or structural cracks in the center section.

Request for Use of Equivalent Methods and Finishes

    One commenter requests that the proposed AD be revised to allow the 
use of an ``industry accepted standard or practice'' material, in lieu 
of ``original equipment manufacturer approved parts and procedures.'' 
The commenter states that Boeing Service Bulletin 757-57-0053, dated 
February 6, 1997, lists secondary fuel barrier BMS 5-81, Type II, which 
is not stocked by the airplane manufacturer or this operator.
    The FAA does not concur with the commenter's request. The material 
in question, secondary fuel barrier, is used on all current generation 
Boeing airplanes and, from time to time, may require replacement 
following structural work on the fuel tank walls. Although such 
material may not currently be stocked by this operator, it should be 
readily available. Further, BMS 5-81, Type II, has specific property 
requirements needed to ensure a fume-proof and fuel-proof barrier over 
the life of the airplane. Allowing use of other substances without a 
detailed review by the FAA could compromise the performance of the 
barrier. However, for any material or process an operator may wish to 
substitute, the operator may request approval of an alternative method 
of compliance in accordance with the provisions of paragraph (b) of 
this AD.

Request for Revision of Cost Impact Information

    Two commenters state that the proposed AD underestimates the cost 
of the modification, in that the economic analysis did not include the 
18 to 36 work hours required to gain access to the front spar of the 
wing center section and to return the airplane to a serviceable 
condition. Another commenter states that the airplane downtime required 
to accomplish the modification during a ``C'' check was not included in 
the cost impact information.
    The FAA acknowledges that the cost impact information, below, 
describes only the ``direct'' costs of the specific actions required by 
this AD. The estimate of 2 work hours necessary to accomplish the 
required actions was provided to the FAA by the manufacturer, and 
represents the time necessary to perform only the actions actually 
required by this AD. The FAA recognizes that, in accomplishing the 
requirements of any AD, operators may incur ``incidental'' costs in 
addition to the ``direct'' costs. The cost analysis in AD rulemaking 
actions, however, typically does not include incidental costs, such as 
the time required to gain access and close up; planning time; or time 
necessitated by other administrative actions. Because incidental costs 
may vary significantly from operator to operator, they are almost 
impossible to calculate.
    Furthermore, because the FAA generally attempts to impose 
compliance times that coincide with operators' scheduled maintenance, 
the FAA considers it inappropriate to attribute the costs associated 
with aircraft ``downtime'' to the cost of the AD because, normally, 
compliance with the AD will not necessitate any additional downtime 
beyond that of a regularly scheduled maintenance hold. Even if, in some 
cases, additional downtime is necessary for some airplanes, the FAA 
does not possess sufficient information to evaluate the number of 
airplanes that may be so affected or the amount of additional downtime 
that may be required. Therefore, attempting to estimate such costs 
would be futile. No change to the final rule is necessary.

Explanation of Changes Made to Proposal

    Since the issuance of the proposed AD, the manufacturer has issued 
Boeing Service Bulletin 757-57-0053, Revision 1, dated January 15, 
1998. This revision is essentially the same as Boeing Service Bulletin 
757-57-0053, dated February 6, 1997 (which is cited in the proposal as 
the appropriate source of service information for accomplishment of the 
requirements of the AD), with minor editorial changes incorporated. The 
FAA has reviewed and approved this revision as an additional source of 
service information for accomplishment of the actions required by this 
AD, and has revised the final rule accordingly.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 724 Boeing Model 757-200 series airplanes 
of the affected design in the worldwide fleet. The FAA estimates that 
463 airplanes of U.S. registry will be affected by this AD, that it 
will take approximately 2 work hours per airplane to accomplish the 
required actions, and that the average labor rate is $60 per work hour. 
Required parts will cost approximately $100 per airplane. Based on 
these figures, the cost impact of the AD on U.S. operators is estimated 
to be $101,860, or $220 per airplane.

[[Page 48425]]

    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the 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 adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

98-19-05  Boeing: Amendment 39-10747. Docket 97-NM-54-AD.

    Applicability: Model 757-200 series airplanes, line numbers 1 
through 724 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 
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 leakage of fuel through the fasteners, sealant, or 
structural cracks in the center section structure, which could 
result in fuel or fuel vapors entering into the cargo or passenger 
compartment of the airplane, accomplish the following:
    (a) At the next scheduled heavy maintenance check (i.e., ``4C'' 
check) or within 48 months after the effective date of this AD, 
whichever occurs first, apply sealant, secondary fuel barrier, and 
corrosion-inhibiting compound to areas on the front spar of the wing 
center section, in accordance with Figure 3 of Boeing Service 
Bulletin 757-57-0053, dated February 6, 1997, or Boeing Service 
Bulletin 757-57-0053, Revision 1, dated January 15, 1998.
    (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.

    (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.
    (d) The actions shall be done in accordance with Boeing Service 
Bulletin 757-57-0053, dated February 6, 1997, or Boeing Service 
Bulletin 757-57-0053, Revision 1, dated January 15, 1998. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Boeing Commercial Airplane Group, 
P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (e) This amendment becomes effective on October 15, 1998.

    Issued in Renton, Washington on September 1, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-24059 Filed 9-9-98; 8:45 am]
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