05-23515. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 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 all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The original NPRM would have required an inspection for chafing of certain wire bundles located above the center fuel tank, corrective actions if necessary, and replacement of wire bundle clamps with new clamps. The original NPRM resulted from fuel system reviews conducted by the manufacturer. This action revises the original NPRM by adding an inspection for damage to the fuel vapor barrier area located below the wire bundles and corrective action, if necessary. We are proposing this supplemental NPRM to prevent chafed wire bundles near the center fuel tank, which could cause electrical arcing through the tank wall and ignition of fuel vapor in the fuel tank, and result in a fuel tank explosion.

DATES:

We must receive comments on this supplemental NPRM by December 27, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this supplemental NPRM.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, Room PL-401, Washington, DC 20590.
• Fax: [phone].
• 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 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 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this supplemental NPRM. Send your comments to an address listed in the ADDRESSES section. Include the docket number “Docket No. FAA-2005-20354; Directorate Identifier 2004-NM-166-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this supplemental NPRM. We will consider all comments received by the closing date and may amend this supplemental NPRM in light of those comments.

We will post all comments submitted, 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 supplemental NPRM. 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 the 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 [phone]) is located on the plaza level in the Nassif Building at the DOT street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

We proposed to amend 14 CFR part 39 with a notice of proposed rulemaking (NPRM) for an AD (the “original NPRM”) for all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The original NPRM was published in the Federal Register on February 15, 2005 (70 FR 7697). The original NPRM proposed to require an inspection for chafing of certain wire bundles located above the center fuel tank, corrective actions if necessary, and replacement of wire bundle clamps with new clamps.

Actions Since Original NPRM Was Issued

Since we issued the original NPRM, the airplane manufacturer has published Boeing Service Bulletin 737-28-1208, Revision 1, dated August 25, 2005. (The original issue, dated July 8, 2004, was referenced in the original NPRM as the appropriate source of service information for addressing the unsafe condition.) Revision 1 includes the following revisions to the accomplishment instructions of the service bulletin:

• Adds an inspection for damage to the fuel vapor barrier area located below the wire bundles and corrective action, if the fuel vapor barrier is present. The corrective action is to repair any damage in accordance with paragraph 8 of chapter 28-11-0 or paragraph 11 of chapter 28-11-00, as applicable, Integral Fuel Tanks—Approved Repairs, Secondary Fuel Barrier Sealant Approved Repairs, of the Boeing 737 Airplane Maintenance Manual.
• Removes reference to repairing wire damage in accordance with “an approved equivalent procedure.”
• Adds instructions for installing a protective sleeve on the upper bundle of the bundle run at station 616, right buttock line (RBL) and left buttock line (LBL) 24.50.

Based on the changes made in Revision 1, we have made the following changes to this supplemental NPRM:

• Added the inspection of the fuel vapor barrier area to paragraph (f).
• Removed the difference statement, not allowing repair of wire damage in accordance with an approved equivalent procedure, from paragraph (f).
• Added the installation of the protective sleeve to paragraph (g).
• Referenced Revision 1 of Boeing Service Bulletin 737-28-1208 as the appropriate source of service information for accomplishing the proposed actions in paragraphs (f) and (g).

Accomplishing the actions specified in Revision 1 of the service bulletin is intended to adequately address the unsafe condition.

Comments

We have considered the following comments on the original NPRM.

Support for Original NPRM

One commenter, the manufacturer, supports the original NPRM.

Request To Revise Service Information

One commenter requests that Boeing Service Bulletin 737-28-1208, dated July 8, 2004, be revised to incorporate several proposed changes to the accomplishment instructions. The commenter states that it has coordinated these changes on-site with the airplane manufacturer. The commenter also states that if the original NPRM is mandated as proposed, the commenter would have to request approval for an alternative method of compliance (AMOC) for each airplane that incorporated the revised work instructions.

We agree, since the airplane manufacturer has published Revision 1 of Boeing Service Bulletin 737-28-1208, which incorporates the commenter's proposed changes. As discussed previously, we have revised this supplemental NPRM to reference Revision 1 as the appropriate source of service information for accomplishing the actions specified in paragraphs (f) and (g) of this supplemental NPRM.

Request To Revise “Costs of Compliance”

The same commenter states that it completed the accomplishment instructions of Boeing Service Bulletin 737-28-1208, dated July 8, 2004, in 10 man-hours. The commenter also states that this figure excluded time for opening and closing access. We infer the commenter would like us to revise the “Costs of Compliance” section.

We disagree with the commenter's estimate. The “Cost of Compliance” section in this supplemental NPRM describes only the direct costs of the proposed actions. Based on the best data available, Revision 1 of Boeing Service Bulletin 737-28-1208 estimates 2 hours to inspect the wire bundles, 2 hours to replace the clamps, and 3 hours (rounded up from 2.25 hours) to install the protective sleeve. We recognize that, in doing these proposed actions, 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 and close access, time necessary for planning, or time necessitated by other administrative actions. Those incidental costs, which may vary significantly among operators, are almost impossible to calculate. In this case, we agree with the manufacturer's estimate and accordingly have revised the “Cost of Compliance” section of this supplemental NPRM.

Clarification of Inspection Terminology

Boeing Service Bulletin 737-28-1208, Revision 1, specifies to “inspect” the fuel vapor barrier area located below the wire bundles. This supplemental NPRM, however, would require doing a detailed inspection. We have included the definition for a detailed inspection in a note in this supplemental NPRM.

Clarification of AMOC Paragraph

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

FAA's Determination and Proposed Requirements of the Supplemental NPRM

The changes discussed above expand 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.

Costs of Compliance

There are about 2,871 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this supplemental NPRM.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number U.S.- registered airplanes	Fleet cost
Inspection	2	$65	None	$130	1,042	$135,460.
Replacement of wire bundle clamps and installation of protective sleeve	5	65	$688 or $1,245, depending on applicable kit	$1,013 or $1,570	1,042	Between $1,055,546 and $1,635,940.

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 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.

§ 39.13

[Amended]

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

Boeing: Docket No. FAA-2005-20354; Directorate Identifier 2004-NM-166-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by December 27, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent chafed wire bundles near the center fuel tank, which could cause electrical arcing through the tank wall and ignition of fuel vapor in the fuel tank, and result in a fuel tank 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.

Inspection of Wire Bundles and Fuel Vapor Barrier and Corrective Actions

(f) Within 60 months after the effective date of this AD: Do a detailed inspection for chafing of the wire bundles located below the passenger compartment, above the center fuel tank, aft of station 540 to approximately station 663.75, right buttock line (RBL) and left buttock line (LBL) 24.50; do a detailed inspection for damage to the fuel vapor barrier area located below the wire bundles, as applicable; and do any applicable corrective actions; by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Boeing Service Bulletin 737-28-1208, Revision 1, dated August 25, 2005. Any corrective actions must be done before further flight.

Note 1:

For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”

Adjustment/Replacement of Wire Bundle Clamps and Installation of Protective Sleeve

(g) After performing the actions required by paragraph (f) of this AD: Before further flight, adjust and replace, as applicable, the wire bundle clamps located aft of station 540; and install a protective sleeve on the upper bundle of the bundle run at station 616, RBL and LBL 24.50; by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Boeing Service Bulletin 737-28-1208, Revision 1, dated August 25, 2005.

Alternative Methods of Compliance (AMOCs)

(h)(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 § 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 November 18, 2005.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.