[Federal Register Volume 72, Number 61 (Friday, March 30, 2007)]
[Proposed Rules]
[Pages 15073-15075]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-5907]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27740; Directorate Identifier 2006-NM-290-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: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-600, -700, -700C, -800 and -900 series 
airplanes. This proposed AD would require an inspection of the fillet 
sealant at the inboard and outboard sides of the receptacles in the 
wheel wells of the main landing gear, and related investigative/
corrective actions if necessary. This proposed AD results from reports 
of in-production airplanes with missing or insufficient fillet sealant 
around the receptacles at the disconnect bracket. We are proposing this 
AD to prevent corrosion damage due to missing or insufficient fillet 
sealant. Such corrosion could result in insufficient electrical bonding 
between the connectors and the disconnect bracket, and consequent loss 
of the shielding that protects the wire bundles from lightning, 
electromagnetic interference (EMI), and high intensity radiated field 
(HIRF). Loss of lightning, EMI, and HIRF protection at those 
receptacles could cause failure of multiple electrical systems and 
subsequent loss of several critical control systems that are necessary 
for safe flight. In addition, a lightning strike could cause arcing in 
the fuel tank; this potential ignition source, 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 proposed AD by May 14, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Binh Tran, Aerospace Engineer, Systems 
and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6485; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
27740; Directorate Identifier 2006-NM-290-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may examine the 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 DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
receives them.

Discussion

    We have received a report indicating that 333 Boeing Model 737-600, 
-700, -700C, -800 and -900 series airplanes in the production factory 
had missing or insufficient fillet sealant around the receptacles in 
the wheel wells of the main landing gear (MLG). Missing or insufficient 
fillet sealant could result in corrosion damage, and consequent 
insufficient electrical bonding between the connectors and the 
disconnect bracket. The loss of electrical bonding could result in loss 
of the shielding that protects the wire bundles from lightning, 
electromagnetic interference (EMI), and high intensity radiated field 
(HIRF). The loss of lightning, EMI, and HIRF protection at those 
receptacles could cause multiple electrical systems failures. Those 
failures could result in the loss of several critical control systems 
that are necessary for safe flight.

[[Page 15074]]

In addition, a lightning strike could cause arcing in the fuel tank; 
this potential ignition source, in combination with flammable fuel 
vapors, could result in a fuel tank explosion and consequent loss of 
the airplane.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-24-
1169, dated December 15, 2006. The service bulletin describes 
procedures for a detailed inspection of the fillet sealant at the 
inboard and outboard sides of the receptacles in the MLG wheel wells. 
For airplanes on which the sealant is missing or otherwise 
insufficient, the service bulletin describes the following related 
investigative and corrective actions:
    <bullet> An additional detailed inspection to detect signs of 
corrosion damage of the connector and receptacle;
    <bullet> Cleaning of any corrosion-free connector;
    <bullet> Cleaning of any receptacle that has corrosion damage on 
less than 20 percent of the total surface area of the receptacle 
flange;
    <bullet> Replacement (with a new part having the same part number) 
of any receptacle that has corrosion on more than 20 percent of the 
total surface area of the receptacle flange;
    <bullet> Replacement of corroded connectors with connectors 
identified in the service bulletin; and
    <bullet> Application of fillet sealant around the receptacles.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 333 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                Number of U.S.-
                 Work hours                    Average labor       Cost per        registered       Fleet cost
                                               rate per hour       airplane        airplanes
----------------------------------------------------------------------------------------------------------------
1...........................................             $80              $80              118           $9,440
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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 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 proposed 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, 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-2007-27740; Directorate Identifier 2006-NM-
290-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 14, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, -800 
and -900 series airplanes; certificated in any category; as 
identified in Boeing Special Attention Service Bulletin 737-24-1169, 
dated December 15, 2006.

Unsafe Condition

    (d) This AD results from reports of in-production airplanes with 
missing or insufficient fillet sealant around the receptacles 
installed in the wheel wells of the main landing gear (MLG). We are 
issuing this AD to prevent corrosion damage due to missing or 
insufficient fillet sealant. Such corrosion could result in 
insufficient electrical bonding between the connectors and the 
disconnect bracket, and consequent loss of the shielding that 
protects the wire bundles from lightning, electromagnetic 
interference (EMI), and high intensity radiated field (HIRF). Loss 
of lightning, EMI, and HIRF protection at those receptacles could 
cause failure of multiple electrical systems and subsequent loss of 
several critical control systems that are necessary for safe flight. 
In addition, a lightning strike could cause arcing in the fuel tank; 
this potential ignition source, in combination with flammable fuel 
vapors, could result in a fuel tank explosion and consequent loss of 
the airplane.

[[Page 15075]]

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.

Inspection

    (f) Within 24 months after the effective date of this AD, 
perform a detailed inspection to determine if there is sufficient 
fillet sealant at the inboard and outboard sides of the receptacles 
in the MLG wheel wells, in accordance with the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-24-
1169, dated December 15, 2006. Do all applicable related 
investigative and corrective actions before further flight in 
accordance with the service bulletin.

Alternative Methods of Compliance (AMOCs)

    (g)(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) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

    Issued in Renton, Washington, on March 23, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-5907 Filed 3-29-07; 8:45 am]
BILLING CODE 4910-13-P