[Federal Register Volume 71, Number 139 (Thursday, July 20, 2006)]
[Rules and Regulations]
[Pages 41113-41116]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-11418]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20731; Directorate Identifier 2004-NM-260-AD; 
Amendment 39-14685; AD 2006-15-05]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-200, -300, and -400 
Series Airplanes

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

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 737-200, -300, and -400 series airplanes. This AD 
requires replacing the existing fueling float switch in the auxiliary 
fuel tank with a new, improved fueling float switch, installing a new 
liner system inside the float switch conduit, and performing related 
investigative and other specified actions. This AD results from reports 
of chafing of the direct-current-powered float switch wiring insulation 
in the center fuel tank. We are issuing this AD to prevent 
contamination of the fueling float switch of the auxiliary fuel tank by 
moisture or fuel, and chafing of the float switch wiring against the 
float switch conduit in the fuel tank, which could present an ignition 
source inside the fuel tank that could cause a fire or explosion.

DATES: This AD becomes effective August 24, 2006.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of August 24, 
2006.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Sherry Vevea, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6514; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at http://dms.dot.gov or in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that would apply to certain Boeing Model 
737-200, -300, and -400 series airplanes. That NPRM was published in 
the Federal Register on March 31, 2005 (70 FR 16445). That NPRM 
proposed to require replacing the existing fueling float switch in the 
auxiliary fuel tank with a new, improved fueling float switch, 
installing a new liner system inside the float switch conduit, and 
performing related investigative and other specified actions.

New Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-28A1192, Revision 2, 
dated April 27, 2006. (The NPRM refers to Boeing Service Bulletin 737-
28A1192, Revision 1, dated August 21, 2003, as the appropriate source 
of service information for the proposed actions.) Revision 2 adds a new 
Part B, which describes procedures for adding environmental protection 
to the splice and conduit. We have revised paragraph (f) of this AD to 
refer to Revision 2 as the appropriate source of service information 
for the actions required by that paragraph. Also, we have revised 
paragraph (h) of this AD to give credit for actions previously 
accomplished in

[[Page 41114]]

accordance with Revision 1 of the service bulletin.

Comments

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

Support for the Proposed AD

    Two commenters, Boeing and the National Transportation Safety Board 
(NTSB), support the proposed AD.

Request to Correct Subject Part Number (P/N)

    Continental Airlines (Continental) notes that the P/N specified in 
paragraph (g) of the proposed AD is different than the P/N specified in 
paragraph (j) of AD 2004-15-04, amendment 39-13738 (69 FR 44580, July 
27, 2004). (The NPRM explains that AD 2004-15-04 requires actions on 
the fueling float switches in the center and wing fuel tanks which are 
similar to the actions proposed for the auxiliary fuel tanks.) 
Similarly, BMI submits a single page from Boeing Service Bulletin 737-
28A1192, Revision 1, marked to indicate that the float switch P/N is 
F8300-146.
    We infer that Continental and BMI are asking us to revise paragraph 
(g) of the proposed AD to correct the float switch P/N. We agree. We 
made a typographical error in the P/N in paragraph (g) of the NPRM. 
There is no float switch that has P/N 8300-146. We have revised 
paragraph (g) of this AD to correct the P/N to F8300-146.

Request To Address Defective Parts Manufacturing Authority (PMA) Parts

    The Modification and Replacement Parts Association (MARPA) requests 
that we revise the proposed AD to cover possible defective PMA 
alternative parts, rather than just a single P/N, so that those 
defective PMA parts also are subject to the proposed AD. The MARPA also 
asks that we determine whether one known PMA part contains the same 
defect as the original equipment manufacturer's (OEM) part.
    The MARPA notes that the proposed AD does not address the 
possibility that PMA parts may be installed in lieu of the part 
referenced in Boeing Service Bulletin 737-28A1192. The commenter 
indicates that Ametek Aerospace has received a PMA for a float switch 
having P/N F8300-146 which may be installed in lieu of the OEM part. 
The MARPA states that, by referring solely to the Boeing service 
bulletin, the proposed AD would not apply to this or any other PMA 
alternative, though the commenter assumes a PMA part would contain the 
same defect as the OEM part. The commenter states that this loophole 
could create a safety issue by allowing defective parts to remain in 
service.
    We concur with the MARPA's general comment that, if we know that an 
unsafe condition also exists in PMA parts, the AD should address those 
parts, as well as the OEM parts.
    However, we find that we may have caused confusion for the 
commenter with the typographical error addressed previously under 
``Request to Correct Subject Part Number (P/N).'' The typographical 
error appears to have caused the commenter to think that there are two 
float switches of similar design--one produced by the OEM having P/N 
8300-146, and the one produced by Ametek Aerospace having P/N F8300-
146. This is not the case. We are aware of only one float switch of 
this design, and this is the float switch having P/N F8300-146 produced 
by Ametek Aerospace. Thus, the part to which the commenter refers is 
already subject to the requirements of this AD.
    However, the commenter's remarks are timely in that the Transport 
Airplane Directorate currently is in the process of reviewing this 
issue as it applies to transport category airplanes. We acknowledge 
that there may be other ways of addressing this issue to ensure that 
unsafe PMA parts are identified and addressed. Once we have thoroughly 
examined all aspects of this issue, including input from industry, and 
have made a final determination, we will consider whether our policy 
regarding addressing PMA parts in ADs needs to be revised. We consider 
that to delay this AD action would be inappropriate, since we have 
determined that an unsafe condition exists and that replacement of 
certain parts must be accomplished to ensure continued safety.
    We have not changed the final rule in this regard.

Request To Provide Information for Maintaining Configuration

    Continental recommends installing identification sleeves on the 
wiring near the float switch connector at the auxiliary fuel tank. 
Continental states that such identification sleeves would assist 
operators in maintaining the configuration after the proposed actions 
have been done. The commenter notes that, while the proposed AD changes 
float switch wiring routing and conduit P/Ns, a maintenance person 
could unintentionally change this configuration at some point in the 
future. The commenter suggests that the sleeves be marked with a 
cautionary message that refers to the service bulletin number or other 
identifying number. The commenter states that similar identification 
sleeves are used for the wiring installation for the isolated fuel 
quantity transmitter on Model 737 airplanes.
    We agree with the commenter's intent. But we do not agree that any 
change is necessary. The design of the float switch, conduit, liner, 
and wiring system will be listed as a critical design configuration 
control limitation (CDCCL) for the fuel system on Model 737 series 
airplanes. This will ensure that operators do not modify the fuel 
system without appropriate design review. Boeing states that it will 
also ensure that maintenance instructions will require that the conduit 
liner be replaced with a new liner whenever the wiring is removed from 
the float switch conduit for any reason.

Request To Revise Statement Regarding Parts

    Continental requests that note (a) be removed from Section 2.C., 
``Parts Necessary for Each Airplane,'' of the service bulletin. The 
commenter specifically objects to the instruction in note (a), ``Keep 
the existing part if there are other uses for it.''
    We infer that the commenter is concerned that an existing float 
switch removed from the auxiliary fuel tank could be used again. We do 
not agree that any change is necessary. Note (b) of the same section 
states, ``You cannot use the existing part to replace the new or 
changed part.'' This addresses the concern that the part could be 
reinstalled in the affected area of an airplane subject to this AD. We 
have not changed the AD in this regard.

Request To Provide for Removed Fuel Tanks

    The Air Transport Association (ATA), on behalf of its member Delta 
Airlines, states no objections to the proposed AD, but suggests adding 
a statement that no action is required for airplanes that are included 
in the applicability statement but that have had the auxiliary fuel 
tank removed.
    We acknowledge the commenter's suggestion, but do not agree that 
any change is necessary. The applicability statement in paragraph (c) 
of this AD already states that this AD applies to ``Boeing Model 737-
200, -300, and -400 series airplanes * * * equipped with auxiliary fuel 
tanks.''

Request To Revise Costs of Compliance

    Continental states that doing the actions in the Accomplishment 
Instructions of the service bulletin took approximately 40 work hours 
(20 elapsed hours) per airplane, excluding

[[Page 41115]]

the time needed to gain access and close up.
    We infer that Continental is asking that we revise the Costs of 
Compliance to reflect the work hours that it found were necessary. We 
do not agree. We recognize that the time necessary to do the actions 
required by an AD may vary somewhat from operator to operator. It is 
not possible for us to account for all of the potential variances. The 
estimate of 38 work hours specified in this AD is consistent with the 
estimate specified in the service bulletin. We find no change is needed 
in this regard.

Clarification of AD Requirements

    As we noted previously, Revision 2 of the service bulletin adds a 
new Part B, which describes procedures for adding environmental 
protection to the splice and conduit. Revision 2 of the service 
bulletin recommends that the actions in Part B be accomplished but does 
not provide a compliance time for those actions. We find that the 
actions specified in Part B are not necessary to address the unsafe 
condition addressed by this AD. Thus, this AD requires accomplishing 
only Part A of the service bulletin. We have revised paragraph (f) of 
this AD accordingly. We also added Note 1 to this AD to clarify that 
this AD does not require the actions in Part B.

Clarification of AMOC Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    This AD will affect about 103 airplanes worldwide and 44 airplanes 
of U.S. registry. The required actions will take about 38 work hours 
per airplane, at an average labor rate of $65 per work hour. Required 
parts will cost about $1,634 per airplane. Based on these figures, the 
estimated cost of this AD for U.S. operators is $180,576, or $4,104 per 
airplane.

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 AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect 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.
    For the reasons discussed above, I certify that this AD:
    (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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

2006-15-05 Boeing: Amendment 39-14685. Docket No. FAA-2005-20731; 
Directorate Identifier 2004-NM-260-AD.

Effective Date

    (a) This AD becomes effective August 24, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-200, -300, and -400 
series airplanes, certificated in any category, equipped with 
auxiliary fuel tanks.

Unsafe Condition

    (d) This AD was prompted by reports of chafing of the direct-
current-powered float switch wiring insulation in the center fuel 
tank. We are issuing this AD to prevent contamination of the fueling 
float switch of the auxiliary fuel tank by moisture or fuel, and 
chafing of the float switch wiring against the float switch conduit 
in the fuel tank, which could present an ignition source inside the 
fuel tank that could cause a fire or explosion.

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.

Replacement

    (f) Within 24 months after the effective date of this AD: 
Replace the existing fueling float switch in the auxiliary fuel tank 
with a new, improved fueling float switch, install a new liner 
system inside the float switch conduit, and perform related 
investigative and other specified actions, by doing all of the 
actions in accordance with Part A of the Accomplishment Instructions 
of Boeing Service Bulletin 737-28A1192, Revision 2, dated April 27, 
2006.

    Note 1: This AD does not require doing the actions in Part B of 
the Accomplishment Instructions of Boeing Service Bulletin 737-
28A1192, Revision 2, dated April 27, 2006.

Parts Installation

    (g) As of the effective date of this AD, no person may install a 
fueling float switch having P/N F8300-146 on the auxiliary fuel tank 
of any airplane.

Actions Accomplished Previously

    (h) Replacements and conduit liner system installations 
accomplished before the effective date of this AD in accordance with 
Boeing Alert Service Bulletin 737-28A1192, dated March 27, 2003; or 
Boeing Service Bulletin 737-28A1192, Revision 1, dated August 21, 
2003; are acceptable for compliance with the requirements of this 
AD.

[[Page 41116]]

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with 14 CFR 
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Material Incorporated by Reference

    (j) You must use Boeing Service Bulletin 737-28A1192, Revision 
2, dated April 27, 2006, to perform the actions that are required by 
this AD, unless the AD specifies otherwise. The Director of the 
Federal Register approved the incorporation by reference of this 
document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for a copy of this service information. You 
may review copies at the Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street, SW., room PL-401, Nassif 
Building, Washington, DC; on the Internet at http://dms.dot.gov; or 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at the NARA, call 
(202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on July 7, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-11418 Filed 7-19-06; 8:45 am]
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