Document ID: FAA-2007-28348-0008
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800 and -900 Series Airplanes
Posted Date: 2008-01-02T05:00Z

[Federal Register: January 2, 2008 (Volume 73, Number 1)]
[Proposed Rules]               
[Page 73-75]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02ja08-16]                         

========================================================================
Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

========================================================================

[[Page 73]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28348; Directorate Identifier 2007-NM-060-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800 
and -900 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of 
comment period.

-----------------------------------------------------------------------

SUMMARY: The FAA is revising an earlier proposed airworthiness 
directive (AD) for certain Boeing Model 737-600, -700, -700C, -800 and 
-900 series airplanes. The original NPRM would have required sealing 
the fasteners on the front and rear spars inside the main fuel tank and 
on the lower panel of the center fuel tank, inspecting the wire bundle 
support installation in the equipment cooling system bays to identify 
the type of clamp installed and determine whether the Teflon sleeve is 
installed, and doing related corrective actions if necessary. The 
original NPRM resulted from a design review of the fuel tank systems. 
This action revises the compliance time for the corrective actions 
specified in the original NPRM. We are proposing this supplemental NPRM 
to prevent arcing at certain fuel tank fasteners in the event of a 
lightning strike or fault current event, which, in combination with 
flammable fuel vapors, could result in a fuel tank explosion and 
consequent loss of the airplane.

DATES: We must receive comments on this supplemental NPRM by January 
28, 2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov.
 Follow the instructions for submitting comments.

     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov
; or in person at the Docket Management Facility 

between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Kathrine Rask, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6505; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2007-
28348; Directorate Identifier 2007-NM-060-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov
, including any personal information you provide. We 

will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We proposed to amend 14 CFR part 39 with a notice of proposed 
rulemaking (NPRM) for an AD (the ``original NPRM'') for certain Boeing 
Model 737-600, -700, -700C, -800 and -900 series airplanes. The 
original NPRM was published in the Federal Registeron June 5, 2007 (72 
FR 30996). The original NPRM proposed to require sealing the fasteners 
on the front and rear spars inside the main fuel tank and on the lower 
panel of the center fuel tank, inspecting the wire bundle support 
installation in the equipment cooling system bays to identify the type 
of clamp installed and determine whether the Teflon sleeve is 
installed, and doing related corrective actions if necessary.

Actions Since Original NPRM Was Issued

    Since we issued the original NPRM, we have become aware that the 
compliance time for the corrective actions in the referenced service 
bulletin, Boeing Alert Service Bulletin 737-57A1279, dated January 24, 
2007, is specified incorrectly. Paragraph 1.E. of the service bulletin 
specifies replacing incorrect clamps within 5 years of the release date 
on the service bulletin. Paragraph (g) of this supplemental NPRM would 
require this action before further flight after discovery of the 
incorrect clamps.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Support for the NPRM

    Boeing concurs with the contents of the NPRM.

Request To Revise Compliance Time

    Air Transport Association (ATA), on behalf of its member American 
Airlines (AAL), requests that we revise the proposed compliance time 
for the sealant application and inspection from 60 months to 72 months. 
AAL states that its current maintenance schedule might not allow for 
accomplishment of the proposed actions on all of its

[[Page 74]]

affected airplanes within 60 months. AAL would therefore incur 
significant costs associated with special maintenance visits to meet 
the compliance time.
    We disagree with the request. In developing an appropriate 
compliance time for this action, we considered the safety implications, 
the manufacturer's recommendations, and normal maintenance schedules 
for most affected operators for the timely accomplishment of the 
required actions. We have determined that the compliance time, as 
proposed, represents the maximum interval of time allowable for the 
affected airplanes to continue to safely operate before the required 
actions are done. We have not changed the original NPRM regarding this 
issue. However, according to the provisions of paragraph (h) of this 
supplemental NPRM, we may approve requests to adjust the compliance 
time if the request includes data that prove that a different 
compliance time would provide an acceptable level of safety.

Request To Approve Alternative Part Numbers and Other Specifications

    ATA and AAL request that we revise the original NPRM to allow 
alternatives to parts and other specifications identified in Alert 
Service Bulletin 737-57A1279. AAL states that including an option to 
choose among multiple vendors or specifications should reduce any part 
availability issues for the operator.
    We disagree with the request. We understand that, when developing 
service information, Boeing tries to identify alternative parts and 
other specifications to give operators as many options as possible. We 
review those options when we approve the service information. AAL did 
not make any specific proposals for alternative specifications. We need 
to approve the use of all such substitutions to ensure that the unsafe 
condition is adequately addressed. We have not changed this 
supplemental NPRM regarding this issue. However, paragraph (h) of this 
supplemental NPRM provides operators the opportunity to request 
alternative methods of compliance if data are presented that prove that 
the proposed options will provide an acceptable level of safety.

Request To Revise Cost Estimate

    ATA and AAL request that we revise the proposed cost estimate to 
reflect additional work that might be necessary to comply with the 
proposed AD. First, AAL states that the original NPRM provides no costs 
for open/close actions, although the proposed actions might not always 
be accomplished at the same time as other maintenance work that 
involves similar open/close actions (removing A/C packs, opening wing 
fuel tanks, and deploying Krueger Flaps). To ensure timely compliance, 
AAL suggests that an additional 42.5 hours per airplane might be 
necessary for open/close actions. Second, AAL states that the NPRM 
provides no costs for clamp/sleeve replacement, although an additional 
58 hours per airplane might be necessary for this action (depending on 
the inspection results).
    We disagree with the request to revise the cost estimate. The cost 
impact figures discussed in AD rulemaking actions represent only the 
time necessary to perform the specific actions actually required by the 
AD. These figures typically do not include incidental costs, such as 
the time required to gain access and close up, or the costs of ``on-
condition'' actions such as repairs (that is, actions needed to correct 
an unsafe condition). We have not changed the supplemental NPRM 
regarding this issue.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

    The compliance time for one of the corrective actions discussed 
above expands the scope of the original NPRM; therefore, we have 
determined that it is necessary to reopen the comment period to provide 
additional opportunity for public comment on this supplemental NPRM.

Differences Between the Supplemental NPRM and the Service Bulletin

    As stated previously, where the service bulletin specifies a 
compliance time for replacing incorrect clamps within 5 years after the 
date on the service bulletin, this supplemental NPRM would require this 
action before further flight after discovery of the incorrect clamps.

Costs of Compliance

    There are about 1,754 airplanes of the affected design in the 
worldwide fleet; of these, 645 airplanes are U.S. registered. The 
following table provides the estimated costs for U.S. operators to 
comply with this supplemental NPRM, at an average hourly labor rate of 
$80.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                              Average                     Number of U.S.-
                         Action                                Group        Work hours     hourly labor      Cost per       registered      Fleet cost
                                                                                               rate          airplane        airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sealant application.....................................               1              62             $80          $4,960             586      $2,906,560
                                                                       2              28              80           2,240              44          98,560
                                                                       3              28              80           2,240              15          33,600
Inspection..............................................               1               3              80             240             586         140,640
                                                                       2               3              80             240              44          10,560
                                                                       3               2              80             160              15           2,400
--------------------------------------------------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or

[[Page 75]]

on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this supplemental NPRM and placed it in the AD docket. See 
the ADDRESSES section for a location to examine the regulatory 
evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-28348; Directorate Identifier 2007-NM-
060-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
28, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model 737-600, -700, -700C, -800 and -900 
series airplanes, certificated in any category; as identified in 
Boeing Alert Service Bulletin 737-57A1279, dated January 24, 2007.

Unsafe Condition

    (d) This AD results from a design review of the fuel tank 
systems. We are issuing this AD to prevent arcing at certain fuel 
tank fasteners in the event of a lightning strike or fault current 
event, which, in combination with flammable fuel vapors, could 
result in a fuel tank explosion and consequent loss of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Fastener Sealant

    (f) Within 60 months after the effective date of this AD: Seal 
the fasteners on the front and rear spars inside the main fuel tank 
and on the lower panel of the center fuel tank, as applicable, in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-57A1279, dated January 24, 2007.

Inspection

    (g) Within 60 months after the effective date of this AD: 
Perform a general visual inspection of the wire bundle support 
installation in the equipment cooling system bays to identify the 
type of clamp installed, and determine whether the Teflon sleeve is 
installed. Do these actions in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-57A1279, dated 
January 24, 2007. Do all applicable corrective actions before 
further flight in accordance with the service bulletin.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on December 20, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-25477 Filed 12-31-07; 8:45 am]

BILLING CODE 4910-13-P