E6-9174. Airworthiness Directives; Boeing Model 737-600, -700, -700C, and -800 Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to revise an existing airworthiness directive (AD) that applies to certain Boeing Model 737-600, -700, -700C, and -800 series airplanes. The existing AD currently requires inspecting/measuring the length of the attachment fasteners between the nacelle support fittings and the lower wing skin panels, and related investigative/corrective actions if necessary. This proposed AD would correct errors found in the existing AD. This proposed AD results from detection of those inadvertent errors. We are proposing this AD to prevent inadequate fastener clamp-up, which could result in cracking of the fastener holes, cracking along the lower wing skin panels, fuel leaking from the wing fuel tanks onto the engines, and possible fire.

DATES:

We must receive comments on this proposed AD by July 28, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• 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:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, 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 proposed AD. Send your comments to an address listed in the ADDRESSES section. Include docket number “Docket No. FAA-2006-25000; Directorate Identifier 2006-NM-096-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 a docket, 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 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

On November 10, 2005, we issued AD 2005-24-03, amendment 39-14383 (70 FR 70713, November 23, 2005), for certain Boeing Model 737-600, -700, -700C, and -800 series airplanes. That AD requires inspecting/measuring the length of the attachment fasteners between the nacelle support fittings and the lower wing skin panels, and related investigative/corrective actions if necessary. That AD resulted from a report from the manufacturer that in production, during the installation of certain attachment fasteners for the nacelle support fittings, only one washer was installed instead of two. We issued that AD to prevent inadequate fastener clamp-up, which could result in cracking of the fastener holes, cracking along the lower wing skin panels, fuel leaking from the wing fuel tanks onto the engines, and possible fire.

Actions Since Existing AD Was Issued

Since we issued AD 2005-24-03, inadvertent errors were found in the existing AD. Those errors include no grace period provided in paragraphs (f)(1) and (f)(2) of the existing AD; and incorrect airplanes referred to for accomplishing the requirements specified in paragraphs (f)(1) and (f)(2).

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 revise AD 2005-24-03 and would retain the requirements of the existing AD. In addition, we have included a grace period of 12 months in paragraphs (f)(1) and (f)(2) of this proposed AD. We also have limited the airplanes referred to in paragraph (f)(1) to Model 737-700 series airplanes only (no other airplanes modified by the supplemental type certificate (STC) are affected by those requirements). We have changed the airplanes referred to in paragraph (f)(2) of the existing AD to “all other airplanes,” and removed the STC reference in that paragraph.

Costs of Compliance

There are about 751 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. The requirements that were previously required by AD 2005-24-03 are retained in this proposed AD and add no additional economic burden. The current costs are repeated for the convenience of affected operators, as follows:

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.- registered airplanes	Fleet cost
Inspection/Measurement	12	$65	Nominal	$780	302	$235,560

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 place 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 removing amendment 39-14383 (70 FR 70713, November 23, 2005), and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-25000; Directorate Identifier 2006-NM-096-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by July 28, 2006.

Affected ADs

(b) This AD revises AD 2005-24-03.

Applicability

(c) This AD applies to Boeing Model 737-600, -700, -700C, and -800 series airplanes; line numbers 1 through 761 inclusive, except for line numbers 596, 683, 742, 749, 750, 751, 754, 755, 759, and 760; certificated in any category.

Unsafe Condition

(d) This AD results from a determination that errors were inadvertently included in the existing AD. We are issuing this AD to prevent inadequate fastener clamp-up, which could result in cracking of the fastener holes, cracking along the lower wing skin panels, fuel leaking from the wing fuel tanks onto the engines, and possible fire.

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.

Restatement of Requirements In AD 2005-24-03

Inspection/Measurement and Related Investigative and Corrective Actions

(f) At the applicable time specified in paragraph (f)(1) or (f)(2) of this AD: Inspect/measure the length of certain attachment fasteners between the lower wing skin panels and the nacelle support fittings. Do the inspection/measurement, and all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57-1275, Revision 1, dated August 18, 2005, except as provided by paragraph (g) of this AD.

(1) For Model 737-700 series airplanes modified by Supplemental Type Certificate (STC) ST00830SE as of December 28, 2005 (the effective date of AD 2005-24-03): Accomplish the actions at the later of the times specified in paragraphs (f)(1)(i) and (f)(1)(ii) of this AD.

(i) Prior to the accumulation of 25,000 total flight hours or 25,000 total flight cycles, whichever is first.

(ii) Within 12 months after December 28, 2005.

(2) For all other airplanes: Accomplish the actions at the later of the times specified in paragraphs (f)(2)(i) and (f)(2)(ii) of this AD.

(i) Prior to the accumulation of 30,000 total flight hours or 30,000 total flight cycles, whichever is first.

(ii) Within 12 months after December 28, 2005.

(g) If accomplishing a corrective action as required by paragraph (f) of this AD, and the service bulletin specifies to contact Boeing for repair information: Before further flight, do the repair using a method approved in accordance with paragraph (i) of this AD.

Actions Accomplished According to Previous Issue of Service Bulletin

(h) Actions accomplished before December 28, 2005, in accordance with Boeing Service Bulletin 737-57-1275, dated September 4, 2003, are considered acceptable for compliance with the corresponding action specified in this AD.

Alternative Methods of Compliance (AMOCs)

(i)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

(2) AMOCs approved previously in accordance with AD 2005-24-03, amendment 39-14383, are approved as AMOCs for the corresponding provisions of this AD.

(3) 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.

(4) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on June 5, 2006.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.