05-23056. Airworthiness Directives; Boeing Model 737-600, -700, -700C, and -800 Series Airplanes

AGENCY:

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

ACTION:

Final rule.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, and -800 series airplanes. This 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. This AD results 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 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.

DATES:

This AD becomes effective December 28, 2005.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of December 28, 2005.

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, PO Box 3707, Seattle, Washington 98124-2207, for service information identified in this 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:

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 [phone]) 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 737-600, -700, -700C, and -800 series airplanes. That NPRM was published in the Federal Register on November 24, 2004 (69 FR 68268). That NPRM proposed to require 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.

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

One commenter supports the actions described in the NPRM.

Notice of Service Bulletin Revision

One commenter, the manufacturer, notes that there is an error in the variable numbers listed in the effectivity of Boeing Service Bulletin 737-57-1275, dated September 4, 2003 (which was referenced as the appropriate source of service information for accomplishing the proposed actions). The commenter states that this error is corrected in the next revision of the service bulletin and that correcting this error in the service bulletin will not alter the NPRM's applicability.

We agree with the commenter that the applicability of this AD is not affected by the change in variable numbers. The applicability of this AD refers to the airplane line numbers and not to the variable numbers.

Since the issuance of the NPRM, Boeing has issued Service Bulletin 737-57-1275, Revision 1, dated August 18, 2005, which contains the same procedures as the original issue along with the corrected variable numbers. Revision 1 of the service bulletin also divides the effectivity into four groups in order to provide clarification on the different fastener installation configurations. We have revised this AD to reference Revision 1 as the appropriate source of service information for accomplishing the required actions. We have also added paragraph (h) to this AD to give credit for actions done before the effective date of this AD in accordance with the original issue of the service bulletin.

Clarification of Sealant Specification

One commenter notes that Figures 1 and 2 of Boeing Service Bulletin 737-57-1275, dated September 4, 2003, specify an obsolete sealant. The commenter states that the “Parts and Materials Supplied by the Operator” section of the service bulletin specifies to refer to the Qualified Parts List (QPL) at the end of the Boeing Material Specification (BMS) for supplier data; however, there is no QPL for BMS 5-26 because it is obsolete. The commenter points out that BMS 5-45 has superseded BMS 5-26.

We agree with the commenter that BMS 5-45 is the correct specification for the sealant. Boeing Service Bulletin 737-57-1275, Revision 1, dated August 18, 2005, does contain the correct references to BMS 5-45. As stated previously, we have revised this AD to reference Revision 1 as the appropriate source of service information for accomplishing the required actions. No further work is necessary for airplanes on which Boeing Service Bulletin 737-57-1275, dated September 4, 2003, was accomplished.

Request To Revise Compliance Time

One commenter requests that we revise the compliance time specified in paragraph (f)(2) of the NPRM from prior to the accumulation of “30,000 flight cycles or 30,000 flight hours, whichever is first” to prior to the accumulation of “30,000 flight cycles or 37,000 flight hours, whichever is first.” The commenter states that 15 of its airplanes are not scheduled for a heavy “C” check maintenance within the 30,000-flight-hour window and the proposed compliance time would result in unnecessary financial hardship. No technical justification was provided.

We do not agree with the commenter to revise the compliance time. In developing an appropriate compliance time, we considered the safety implications, the manufacturer's recommendation, and normal maintenance schedules for timely accomplishment of the inspection. 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 inspection is done. However, paragraph (i) of this AD provides affected operators the opportunity to apply for an adjustment of the compliance time if the operator also presents data that justify the adjustment. We have not revised this AD in this regard.

Explanation of Change Made to This AD

Boeing Commercial Airplanes has received a Delegation Option Authorization (DOA). We have revised this AD to delegate the authority to approve an alternative method of compliance for any repair required by this AD to an Authorized Representative for the Boeing Commercial Airplanes DOA rather than a Designated Engineering Representative (DER).

Clarification of Alternative Method of Compliance (AMOC) Paragraph

We have revised this AD 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

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 AD.

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 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

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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):

2005-24-03 Boeing: Amendment 39-14383. Docket No. FAA-2005-19682; Directorate Identifier 2004-NM-88-AD.

Effective Date

(a) This AD becomes effective December 28, 2005.

Affected ADs

(b) None.

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 was prompted by a report from the manufacturer that in production, during installation of certain attachment fasteners for the nacelle support fittings, only one washer was installed instead of two. 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.

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 airplanes modified by Supplemental Type Certificate (STC) ST00830SE as of the effective date of this AD: Prior to the accumulation of 25,000 total flight hours or 25,000 total flight cycles, whichever is first.

(2) For airplanes not modified by STC ST00830SE as of the effective date of this AD: Prior to the accumulation of 30,000 total flight hours or 30,000 total flight cycles, whichever is first.

(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 the effective date of this AD 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) 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.

(3) 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.

Material Incorporated by Reference

(j) You must use Boeing Service Bulletin 737-57-1275, Revision 1, dated August 18, 2005, 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 [phone], or go to http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

Issued in Renton, Washington, on November 10, 2005.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.