Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 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, -800, and -900 series airplanes. This AD requires repetitive detailed, low frequency eddy current, and high frequency eddy current inspections of the webs of the aft pressure bulkhead at body station 1016 for cracks, and corrective action if necessary. This AD is prompted by a report of cracks found, during fatigue testing, at several of the fastener rows in the web lap splices at the dome apex of the aft pressure bulkhead. We are issuing this AD to detect and correct fatigue cracks in the webs of the aft pressure bulkhead, which could result in rapid decompression of the airplane.

DATES:

This AD becomes effective April 18, 2005.

The incorporation by reference of a certain publication listed in the AD is approved by the Director of the Federal Register as of April 18, 2005.

ADDRESSES:

For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Docket: The AD docket contains the proposed AD, comments, and any final disposition. You can 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 U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, Washington, DC. This docket number is FAA-2004-19022; the directorate identifier for this docket is 2004-NM-122-AD.

FOR FURTHER INFORMATION CONTACT:

Howard Hall, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6430; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

The FAA proposed to amend 14 CFR Part 39 with an AD for certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. That action, published in the Federal Register on September 7, 2004 (69 FR 54053), proposed to require repetitive detailed, low frequency eddy current, and high frequency eddy current inspections of the webs of the aft pressure bulkhead at body station 1016 for cracks, and corrective action if necessary.

Actions Since Notice of Proposed Rulemaking (NPRM) Was Issued

Since the NPRM was issued, Boeing has received a Delegation Option Authorization (DOA). We have revised this final rule to delegate the authority to approve an alternative method of compliance (AMOC) for any repair required by this AD to an Authorized Representative for the Boeing DOA Organization rather than a Designated Engineering Representative.

Comments

We provided the public the opportunity to participate in the development of this AD. We have considered the comment that has been submitted on the proposed AD.

Request for Repair or Preventative Modification

The commenter, an operator, requests that the manufacturer add either repair instructions or a preventative modification and task hour estimate for the respective action to Boeing Service Bulletin 737-53-1251, dated June 3, 2004. The commenter states that the service bulletin does not recommend any repair or terminating action if cracks are found during inspection of the aft pressure bulkhead, but instead specifies contacting the manufacturer if cracks are found.

Although we agree with the intent of the commenter's request, we also know that variations in the type and degree of damage at and around the web lap splices at the dome apex of the aft pressure bulkhead make it difficult to develop general repair instructions, or a preventative modification, that could be applicable to and effective for all conditions. Furthermore, the manufacturer has experience repairing damage in the area of the web lap splices of the aft pressure bulkhead and can assist in developing repairs appropriate for specific conditions. For these reasons, we are allowing the Manager, Seattle Aircraft Certification Office, FAA, or an Authorized Representative for the Boeing DOA Organization to approve repairs in accordance with paragraph (g) of this final rule. If general repair instructions or a preventative modification should be developed at a later time, and the service bulletin is revised to include either of these actions, we will consider approving the revised service bulletin as an AMOC to this final rule. Therefore, no change is necessary to this final rule in this regard.

Explanation of Editorial Change

For clarification, we have replaced the word “listed” with “identified” to specify the applicability in paragraph (c) of this AD.

Conclusion

We have carefully reviewed the available data, including the comment that has been submitted, 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 affects about 457 airplanes of U.S. registry and 1,166 airplanes worldwide. The actions will take about 8 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the AD for U.S. operators is $237,640, or $520 per airplane, per inspection cycle.

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. 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.

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

2005-05-18 Boeing: Amendment 39-14007. Docket No. FAA-2004-19022; Directorate Identifier 2004-NM-122-AD.

Effective Date

(a) This AD becomes effective April 18, 2005.

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 Service Bulletin 737-53-1251, dated June 3, 2004.

Unsafe Condition

(d) This AD was prompted by a report of cracks found, during fatigue testing, at several of the fastener rows in the web lap splices at the dome apex of the aft pressure bulkhead. We are issuing this AD to detect and correct fatigue cracks in the webs of the aft pressure bulkhead, which could result in rapid decompression of the airplane.

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.

Initial and Repetitive Inspections

(f) Prior to accumulating 26,000 total flight cycles or within 4,000 flight cycles after the effective date of this AD, whichever occurs later: Do a detailed inspection, low frequency eddy current inspection, and high frequency eddy current inspection of the webs of the aft pressure bulkhead at body station 1016 for cracks, in accordance with Boeing Service Bulletin 737-53-1251, dated June 3, 2004. Repeat the inspections thereafter at intervals not to exceed 4,000 flight cycles.

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.”

Corrective Action

(g) If any crack is found during any inspection required by paragraph (f) of this AD: Before further flight, repair according to a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or according to data meeting the certification basis of the airplane approved by an Authorized Representative for the Boeing Delegation Option Authorization (DOA) Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the approval must specifically reference this AD.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle 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) 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 DOA 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

(i) You must use Boeing Service Bulletin 737-53-1251, dated June 3, 2004, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approves the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. For copies of the service information, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. For information on the availability of this material at the National Archives and Records Administration (NARA), call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. You may view the AD docket at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, Nassif Building, Washington, DC.