E8-31395. 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 a one-time general visual inspection of frames between body station (BS) 360 and BS 907 to determine if certain support brackets of the air conditioning (A/C) outlet extrusions are installed; medium- and high-frequency eddy current inspections for cracking of the frames around the attachment holes of the subject brackets; and repair if necessary. This AD also requires installing new, improved fittings for all support brackets of the A/C outlet extrusions between BS 360 and BS 907. This AD results from numerous reports of multiple cracks in the frames around the attachment holes of certain support brackets of the A/C outlet extrusions. We are issuing this AD to prevent frame cracking, which, if not corrected, could lead to a severed frame that, combined with cracking of the skin lap splice above stringer 10, could result in rapid decompression of the airplane.

DATES:

This AD becomes effective February 27, 2009.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of February 27, 2009.

ADDRESSES:

For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1, fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (telephone [phone]) is the Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT:

Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a supplemental 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, -800 and -900 series airplanes. That supplemental NPRM was published in the Federal Register on August 19, 2008 (73 FR 48307). That supplemental NPRM proposed to require a one-time general visual inspection of frames between body station (BS) 360 and BS 907 to determine if certain support brackets of the air conditioning (A/C) outlet extrusions are installed; medium- and high-frequency eddy current inspections for cracking of the frames around the attachment holes of the subject brackets; and repair if necessary. That supplemental NPRM also proposed to require installing new, improved fittings for all support brackets of the A/C outlet extrusions between BS 360 and BS 907.

Comments

We provided the public the opportunity to participate in the development of this AD. We have considered the comments received.

Request To Revise “Estimated Costs” Table

Boeing requests that we revise the “Estimated Costs” table in the Cost of Compliance paragraph of the supplemental NPRM to match the information specified in Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008. Boeing states that the parts cost in the supplemental NPRM reflects a price range between $56,095 and $81,339, while the price range specified in the Boeing special attention service bulletin is between $19,854 and $28,789. We referred to the Boeing special attention service bulletin as the appropriate source of service information for doing the actions specified in the supplemental NPRM.

We agree with the commenter's request to revise the parts cost to match the information specified in Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008. We have revised the parts cost to specify “between $19,854 and $28,789” and we have revised the corresponding “Cost per Airplane” and “Fleet Cost” columns in the “Estimated Costs” table of this AD.

Request To Clarify the References to the Boeing Special Attention Service Bulletin

Boeing requests that we clarify the references to Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008, in paragraphs (g), (g)(2), and (h) of the supplemental NPRM. Boeing states that the supplemental NPRM reads “* * * in accordance with Part 2 of the service bulletin * * *” when the reference is meant to be “* * * in accordance with Part 2 of the accomplishment instructions of the service bulletin. * * *” Boeing further states the service bulletin is divided into three parts with Part 3 being the accomplishment instructions. Boeing notes that the accomplishment instructions are further divided into four parts, which are referenced in the supplemental NPRM.

We agree to clarify the references to Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008. However, we had already included the phrase “Accomplishment Instructions” in paragraph (f) of the supplemental NPRM as part of the definition of “service bulletin.” Paragraph (f) of the supplemental NPRM states that “the term ‘service bulletin,' as used in this AD, means the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008.”

To avoid any confusion as to which part of the service bulletin we are referring to in the AD, we have removed paragraph (f) of the supplemental NPRM from this AD and revised the subsequent paragraph identifiers accordingly. We have also included the phrase “Accomplishment Instructions” in the references to the service bulletin in paragraphs (f), (f)(2), and (g) of this AD.

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 1,679 airplanes of the affected design in the worldwide fleet. This AD affects about 626 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this AD, at an average labor rate of $80 per work hour. Operators should note that special cold working tools and sleeves will be needed if any repair is required, which may increase costs.

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Fleet cost
General visual inspection	1	No parts required	$80	$50,080.
MFEC and HFEC inspections	Between 170 and 216	No parts required	Between $13,600 and $17,280	Up to $10,817,280.
Replace support fittings	Between 258 and 346	Between $19,854 and $28,789	Between $40,494 and $56,469	Up to $35,349,594.

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):

2009-01-02 Boeing: Amendment 39-15780. Docket No. FAA-2007-28283; Directorate Identifier 2006-NM-254-AD.

Effective Date

(a) This AD becomes effective February 27, 2009.

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 737-25-1544, Revision 1, dated January 16, 2008.

Unsafe Condition

(d) This AD results from numerous reports of multiple cracks in the frame around the attachment holes of the support bracket of the air conditioning (A/C) outlet extrusion. We are issuing this AD to prevent frame cracking, which, if not corrected, could lead to a severed frame that, combined with cracking of the skin lap splice above stringer 10, 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.

Inspections

(f) Before the accumulation of 36,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, except as required by paragraph (h) of this AD: Do a general visual inspection to determine if the support brackets of the A/C outlet extrusions between body station (BS) 360 and BS 907 have two-rivet attachment fittings in accordance with Part 2 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008 (“the service bulletin”), except at the locations identified in the notes of Step 3.B.1 of Part 1 of the Accomplishment Instructions of the service bulletin.

(1) For any support bracket attached with three or more rivets: No further action is required by paragraph (f) of this AD.

(2) For any subject support bracket having a two-rivet attachment fitting: Before the accumulation of 36,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, except as required by paragraph (h) of this AD, do medium- and high-frequency eddy current inspections for cracking of the frame around the attachment holes of the support bracket, in accordance with Part 2 of the Accomplishment Instructions of the service bulletin. If any cracking is discovered, before further flight, repair the cracking in accordance with Part 3 of the Accomplishment Instructions of the service bulletin.

Modification

(g) Except as required by paragraph (h) of this AD: Before the accumulation of 36,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, replace the support fittings of all A/C outlet extrusions between BS 360 and BS 907 with new, improved support fittings, in accordance with Part 4 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008.

Compliance Time for Certain Airplanes

(h) For airplanes on which Boeing Business Jet (BBJ) lower cabin altitude modification is incorporated in accordance with Supplemental Type Certificate ST01697SE: Before the accumulation of 18,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, do the actions specified in paragraphs (f) and (g) of this AD.

Actions Accomplished According to Previous Issue of Service Bulletin

(i) Actions accomplished before the effective date of this AD according to Boeing Special Attention Service Bulletin 737-25-1544, dated October 4, 2006, are considered acceptable for compliance with the corresponding actions specified in this AD.

Alternative Methods of Compliance (AMOCs)

(j)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]; has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(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

(k) You must use Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008, to perform the actions that are required by this AD, unless the AD specifies otherwise.

(1) 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.

(2) Contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1, fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com, for a copy of this service information.

(3) You may review copies of the service information that is incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152.

(4) You may also review copies of the service information at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

Issued in Renton, Washington, on December 18, 2008.

Stephen P. Boyd,

Assistant Manager, Transport Airplane Directorate, Aircraft Certification Service.