E7-1396. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 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 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD requires repetitive inspections to detect cracks in the vertical beam webs of the body station (BS) 178 bulkhead, and corrective actions if necessary. This AD also requires a terminating modification for the repetitive inspections. This AD results from reports of numerous cracks in the vertical beam webs. We are issuing this AD to prevent fatigue cracks in certain vertical beam webs, which could result in loss of structural integrity of the BS 178 bulkhead, and consequently could impair the operation of the control cables for the elevators, speed brakes, and landing gear, or could cause the loss of cabin pressure.

DATES:

This AD becomes effective March 7, 2007.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of March 7, 2007.

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, P.O. Box 3707, Seattle, Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT:

Howard Hall, 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:

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 737-100, -200, -200C, -300, -400, and -500 series airplanes. That NPRM was published in the Federal Register on April 18, 2006 (71 FR 19835). That NPRM proposed to require repetitive inspections to detect cracks in the vertical beam webs of the body station (BS) 178 bulkhead, and corrective actions if necessary. That NPRM also proposed to require a terminating modification for the repetitive inspections.

Comments

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

Request To Extend Compliance Time Threshold

Continental Airlines (Continental) requests that the threshold for the compliance times specified in Table 1 of the NPRM be aligned with the compliance times specified in ADs 2000-05-29, amendment 39-11639 (65 FR 14834, March 20, 2000), and 2001-02-01, amendment 39-12085 (66 FR 7576, January 24, 2001). Continental states that this will reduce the economic impact on operators from doing early inspections and will encourage operators to terminate those ADs at 20,000 total flight cycles as opposed to doing repetitive inspections.

We do not agree. Continental provided no technical justification for revising the inspection threshold. In developing an appropriate compliance time for this action, we considered the safety implications and normal maintenance schedules for the timely accomplishment of the inspections. In consideration of these items, as well as the reports of numerous cracks in the vertical beam webs in service, we have determined that the compliance times specified in Table 1 of this AD will ensure an acceptable level of safety and allow the inspections to be done during scheduled maintenance intervals for most affected operators. However, according to the provisions of paragraph (m) of the AD, we may approve requests to adjust the compliance time if the request includes data that substantiate that the new compliance time would provide an acceptable level of safety.

Request To Include an Additional Grace Period

The Air Transport Association (ATA), on behalf of one of its members, United Airlines (United), requests that the compliance time specified in paragraph (f)(2) of the NPRM be revised to reflect the intention of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005 (referred to in the NPRM as the appropriate source of service information for accomplishing the repetitive inspections and terminating preventative modification). United proposes that all airplanes should have a minimum of 4,500 flight cycles after the effective date of the AD to do the initial inspection required by paragraph (f) of the NPRM. United also states that Boeing Service Bulletin 737-53A1225, dated October 19, 2000, specifies an interval of 12,000 flight cycles for the repetitive high frequency eddy current (HFEC) inspections. Without a grace period, United points out that operators doing those inspections would be grounded as of the effective date of the AD.

We agree and have revised paragraph (f)(2) of this AD to provide a grace period of 4,500 flight cycles after the effective date of this AD.

Request To Include Certain Airplanes in Compliance Time Table

Boeing requests that we revise Table 1, “Compliance Times,” of the NPRM to address airplanes inspected in accordance with Boeing Service Bulletin 737-53A1225, Revision 1.

We do not agree. Operators are given credit for actions previously done by means of the phrase in paragraph (e) of this AD that states, “unless the actions have already been done.” Therefore, in the case of this AD, if the required inspection specified in Boeing Service Bulletin 737-53A1225, Revision 1, has been done before the effective date of this AD, this AD does not require that it be repeated. In addition, if the required inspection specified in Boeing Service Bulletin 737-53A1225, Revision 1, has not been done before the effective date of this AD, this AD requires that inspection to be done at the applicable time specified in Table 1. We have made no change to the final rule in this regard.

Requests To Allow the Use of Boeing BOECOM M-7200-01-00546

KLM Engineering & Maintenance (KLM), Southwest Airlines (Southwest), and United request that the procedures specified in Boeing BOECOM M-7200-01-00546, dated March 1, 2001 (referred to in paragraph (j) of the NPRM) be allowed to be used after the effective date of the AD as an acceptable method of compliance with the preventative modification specified in paragraph (i) of the NPRM. Southwest states that BOECOM M-7200-01-00546 describes procedures for fabricating replacement parts, which would result in a significant cost savings to operators. United states that it has modified the majority of its fleet using instructions equivalent to those contained BOECOM M-7200-01-00546. KLM states that it has modified a majority of its fleet using Boeing Service Bulletin 737-53A1173, Revision 4, dated September 19, 2002 (Revision 3 of Boeing Service Bulletin 737-53A1173 is referred to in paragraph (k) of the NPRM as the appropriate source of service information for accomplishing the preventative modification), together with the instructions specified in BOECOM M-7200-01-00546. United and KLM would like to continue modifying their fleets using the same instructions. In addition, Boeing requests that the description of acceptable actions in paragraph (j) of the NPRM be revised to include procedures done in accordance with Boeing BOECOM M-7200-01-00546 and approved by Boeing and the FAA after March 1, 2001.

We partially agree. We agree that doing the replacement or modification specified in Boeing BOECOM M-7200-01-00546, dated March 1, 2001, may be an acceptable means of compliance with the requirements of paragraph (j) of this AD. However, it is not likely that replacement or modification in accordance with BOECOM M-7200-01-00546 can be done without deviations that require further FAA approval. It has been our experience that work done in accordance with BOECOM M-7200-01-00546 has nearly always required deviations. As noted in BOECOM M-7200-01-00546, to obtain approval for using the BOECOM, the operator must provide an Authorized Representative (AR) for the Boeing Commercial Airplanes Delegation Option Authorization Organization with the airplane identification, the details of the proposed replacement, and any deviations. Therefore, we have determined that operators who use the BOECOM procedures after the effective date of this AD must get them approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (m) of this AD. We have made no change to the final rule in this regard.

Request To Remove Option To Repair

Boeing requests that the word “repair” in paragraph (i) of the NPRM and in the “Relevant Service Information” section of the NPRM be deleted. Boeing did not provide a justification.

We agree. We have re-reviewed Boeing Service Bulletin 737-53A1225, Revision 1. In several places in Parts II through IV of the Accomplishment Instructions, the service bulletin states, “Repair or change the vertical beam * * * Refer to Figure 25 * * *.” Figure 25 refers to “replacement” procedures; however, it does not refer to a repair procedure. Therefore, we have deleted “repair or” in paragraph (i) of this AD. We have made no change to the AD in regard to the “Relevant Service Information” section, because that section of the NPRM does not reappear in the final rule.

Request To Allow Repair Plans Approved Previously

Southwest requests that paragraph (j) of the NPRM be revised to allow certain repair plans approved by an AR for the Boeing Commercial Airplanes Delegation Option Authorization Organization or a Boeing Designated Engineering Representative (DER) before the release of Boeing BOECOM M-7200-01-00546, dated March 1, 2001, as an acceptable method of compliance with the preventative modification specified in paragraph (i) of the NPRM. Southwest states that it has installed thicker vertical beam webs with such approval on some of its airplanes before the issuance of Boeing BOECOM M-7200-01-00546, dated March 1, 2001.

We do not agree with Southwest to revise paragraph (j) of this AD. Southwest did not provide sufficient data for us to determine if these earlier repairs are equivalent to those specified in Boeing BOECOM M-7200-01-00546, dated March 1, 2001. It is possible that the review and approval of earlier repairs may not have taken into account the latest information that was used to develop the BOECOM. However, if a particular repair is shown to be equivalent to that specified in the BOECOM, paragraph (m) of the AD provides operators the opportunity to apply for an AMOC to address this type of repair.

Request for Clarification

Southwest requests that paragraph (j) of the NPRM be revised to clarify that it is not necessary to replace certain stiffeners per step 4 of Boeing BOECOM M-7200-01-00546, if the existing holes can be oversized and a new identical fastener can be installed with an acceptable edge distance. Step 4 indicates that certain stiffeners must be replaced because they are offset by the thickness of the new webs. Southwest believes that the intent of that step is to eliminate detrimental fastener over-sizing and short edge distances that can result from the offset.

We do not agree with Southwest to revise paragraph (j) of this AD. Southwest did not provide any specific limits nor define any acceptable combinations of maximum over-sizing of fasteners and/or minimum fastener edge distance. Therefore, we are unable to provide approval at this time. However, under the provisions of paragraph (m) of this AD, we may consider requests for approval of an AMOC if sufficient data are submitted to substantiate that such a design change would provide an acceptable level of safety.

Request To Delete Concurrent Requirements

Delta Air Lines (Delta) requests that the concurrent requirements of paragraphs (k) and (l) of the NPRM be deleted, and to continue to allow the requirements specified in paragraph (c) of ADs 2000-05-29 and 2001-02-01 to be done separately. Delta notes that the “Effect of Accomplishing Concurrent Requirements” section in the preamble of the NPRM states, “We realize that the concurrent requirements of this proposed AD will force some operators to do the preventative modifications required by AD 2001-02-01 early and to do the optional preventative modification specified in AD 2000-05-29. However, accomplishing the applicable preventative modifications together is necessary to avoid repeated disassembly and re-assembly of common parts, which increases the likelihood of additional assembly errors.” Delta states that the timing of doing the preventative modification is an economic and operational decision, which is properly at the discretion of the operators, not a subject for an AD.

We partially agree. We do not agree with Delta that the concurrent requirements be deleted. We determined that mandating the previous optional preventative modification specified in AD 2000-05-29 in this AD will better ensure long-term continued operational safety of the affected airplanes by removing the source of the problem, rather than by repetitive inspections. Long-term inspections may not provide the degree of safety necessary for the affected airplanes. This, coupled with our understanding of the human factor errors associated with numerous repetitive inspections, has led us to consider placing less emphasis on special procedures and more emphasis on design improvements. The preventative modification required by paragraph (l) of this AD is consistent with these considerations. Additionally, accomplishing the modifications concurrently provides the most effective installation of these modifications and will avoid repeated disassembly and re-assembly of common parts of critical structure, which increases the likelihood of additional assembly errors. Boeing also has provided us with data supporting our determination.

We somewhat agree with Delta to allow the requirements specified in paragraph (c) of ADs 2000-05-29 and 2001-02-01 to be done separately. It is acceptable to do the preventative modifications required by AD 2001-02-01 before the requirements of paragraph (i) of this AD. However, paragraphs (k) and (l) of the NPRM state, “Concurrently with the requirements of paragraph (i) of this AD * * *.” Therefore, we have revised those paragraphs to clarify that the concurrent requirements must be done “before or concurrently with the requirements of paragraph (i) of this AD.” For clarification purposes, we also removed the phrase “unless already done before the effective date of this AD” from paragraph (k) of this AD.

Request To Supersede AD 2000-05-29

The ATA, on behalf of one of its members, Delta, requests that AD 2000-05-29 be superseded or revised to avoid conflicting requirements. Delta states that this should be done if its request in the “Request To Delete Concurrent Requirements” section of this AD is not feasible.

We do not agree. Paragraph (k) of this AD mandates the previously optional preventative modification specified in paragraph (c) of AD 2000-05-29. A mandatory requirement takes precedence over an optional action. Therefore, we find that no conflict exists between the requirements of this AD and AD 2000-05-29.

In addition, we considered superseding ADs 2000-05-29 and AD 2001-02-01 when developing the NPRM. We determined that doing so would have made this AD more complex and would have increased the consequent workload associated with revising maintenance record entries, because this AD does not affect all requirements of those ADs. This AD only affects paragraph (c) of those ADs. Therefore, we determined that a less burdensome approach for operators was not to supersede those existing ADs.

Request To Address Certain Airplanes

If the concurrent requirements of the NPRM are kept, Delta further requests that Boeing be tasked to address airplanes on which the replacement of the forward pressure bulkhead web has been done and on which the modification of the vertical beam has not been done.

We do not agree. We have determined that the procedures specified in the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005, adequately address all affected airplanes. Although the information mentioned by Delta may be helpful, the procedures specified in the service bulletin are adequate. Therefore, we find it inappropriate to task Boeing to revise the service bulletin and to delay the issuance of this AD. However, if additional data are presented that would justify additional actions, we may consider further rulemaking on this issue.

Requests To Allow AMOCs Approved Previously

Southwest requests that paragraphs (k) and (l) of the NPRM be revised to allow AMOCs approved previously in accordance with ADs 2000-05-29 and 2001-02-01, respectively. Southwest wants to avoid any issues as to whether or not those AMOCs must be resubmitted to us for approval.

Continental requests that paragraph (k) of the NPRM be revised to refer to Boeing Service Bulletin 737-53A1173, Revision 4, dated September 19, 2002. Continental states that Revision 4 included several corrections and work flow improvements.

We partially agree with both Southwest and Continental. We agree that approved AMOCs to paragraph (c) of ADs 2000-05-29 and 2001-02-01 that are done before or concurrently with the requirements of paragraph (i) of this AD are acceptable as AMOCs for the corresponding provisions of paragraphs (k) and (l) of this AD, respectively. Boeing Service Bulletin 737-53A1173, Revision 4, is one of those AMOCs. We do not agree with the commenters that the paragraphs (k) and (l) should be revised in regard to AMOCs. The appropriate paragraph to revise is paragraph (m) of this AD, which is the AMOC paragraph. Therefore, we have revised paragraph (m) accordingly.

Request To Revise AMOC Paragraph

Boeing requests that paragraph (m)(3) of the NPRM be changed to allow AR approval of modifications as well as repairs.

We agree and have revised paragraph (m)(3) of this AD accordingly.

Requests To Revise Costs of Compliance

The ATA, on behalf of two of its members, U.S. Airways and United, requests that the Costs of Compliance section in the preamble of the NPRM account for the work required to gain access, reassemble, complete post-modification checkouts, close access, etc. associated with the proposed inspection and preventative modification. U.S. Airways states that these actions represent an increase of almost 40 percent above and beyond the 240 work hours specified in the NPRM. United states that the proposed inspection and preventative modification are not normally accessed at any routine maintenance visit.

We do not agree. The Costs of Compliance section describes only the direct costs of the specific actions required by this AD. Based on the best data available, the manufacturer provided the number of work hours (240 for preventative modification; 4 for each inspection) necessary to do the required actions. This number represents the time necessary to perform only the actions actually required by this AD. We recognize that, in doing the actions required by an AD, 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 access and close up, 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. Therefore, we have made no change to this AD in this regard.

Request To Correct Typographical Error

Boeing requests that a typographical error be fixed in paragraph (h) of the NPRM. The reference to “paragraph (1) of this AD” should be changed to “paragraph (m) of this AD.”

We agree and have changed paragraph (h) of this AD accordingly.

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 3,132 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, per inspection cycle	4	$80	None	$320, per inspection cycle	1,172	$375,040, per inspection cycle.
Preventative modification	240	80	Between $960 and $13,620, depending on kit purchased	Between $20,160 and $32,820, depending on configuration	1,172 (720 airplanes have had the preventative modification incorporated)	Between $9,112,320 and $14,834,640.

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):

2007-03-03 Boeing: Amendment 39-14914. Docket No. FAA-2006-24496; Directorate Identifier 2005-NM-141-AD.

Effective Date

(a) This AD becomes effective March 7, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005.

Unsafe Condition

(d) This AD results from reports of numerous cracks in the vertical beam webs. We are issuing this AD to prevent fatigue cracks in certain vertical beam webs, which could result in loss of structural integrity of the body station (BS) 178 bulkhead, and consequently could impair the operation of the control cables for the elevators, speed brakes, and landing gear, or could cause the loss of cabin pressure.

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.

Repetitive Inspections

(f) At the applicable times specified in Table 1 of this AD, do a high frequency eddy current (HFEC) inspection and detailed inspection to detect cracks in the BS 178 vertical beam webs, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005.

Table 1.—Compliance Times

For airplanes on which—	Inspect—	And repeat the HFEC and detailed inspections thereafter at—
(1) An HFEC or a detailed inspection specified in Boeing Service Bulletin 737-53A1225, dated October 19, 2000, has not been done as of the effective date of this AD	Before the accumulation of 15,000 total flight cycles, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later	Intervals not to exceed 6,000 flight cycles.
(2) An HFEC or detailed inspection specified in Boeing Service Bulletin 737-53A1225, dated October 19, 2000, has been done before the effective date of this AD	Within 6,000 flight cycles since the last HFEC inspection, within 1,200 flight cycles since the last detailed inspection, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later	Intervals not to exceed 6,000 flight cycles.

Corrective Actions

(g) If any crack is detected during any inspection required by paragraph (f) of this AD, before further flight, repair or replace the vertical beam web and associated parts with a new vertical beam web, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005, except as provided by paragraph (h) of this AD.

(h) If any damage is beyond the scope of the service bulletin or structural repair manual, before further flight, repair the damaged vertical beam web in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or using a method approved in accordance with paragraph (m) of this AD.

Terminating Preventative Modification

(i) Before the accumulation of 50,000 total flight cycles, or within 25,000 flight cycles after the effective date of this AD, whichever occurs later, replace the vertical beams at buttock lines (BL) 5.7 and 17.0 of the BS 178 bulkhead, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005. Accomplishing the replacement ends the repetitive inspections required by paragraph (f) of this AD.

(j) Actions done before the effective date of this AD in accordance with Boeing BOECOM M-7200-01-00546, dated March 1, 2001, are acceptable for compliance with the requirements of paragraph (i) of this AD.

Prior to or Concurrent Requirements

(k) For Group 1 airplanes identified in Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005: Before or concurrently with the requirements of paragraph (i) of this AD, do the preventative modifications of the center web, vertical chords, and side chord areas, including the side chord areas at water line 207, of the forward pressure bulkhead, specified in paragraph (c) of AD 2000-05-29, amendment 39-11639 (reference Boeing Alert Service Bulletin 737-53A1173, Revision 3, dated May 6, 1999).

(l) For Group 2 airplanes identified in Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005: Before or concurrently with the requirements of paragraph (i) of this AD, but no later than the time specified in AD 2001-02-01, amendment 39-12085, do the preventative modifications of the vertical and side chord areas of the forward pressure bulkhead required by paragraph (c) of AD 2001-02-01 (reference Boeing Alert Service Bulletin 737-53A1208, dated May 6, 1999).

Alternative Methods of Compliance (AMOCs)

(m)(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) 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.

(3) An AMOC that provides an acceptable level of safety may be used for any replacement or 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 replacement or repair method to be approved, the replacement or repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(4) Approved AMOCs to paragraph (c) of AD 2000-05-29 done before or concurrently with the requirements of paragraph (i) of this AD are approved as AMOCs for the corresponding provisions of paragraph (k) of this AD.

(5) Approved AMOCs to paragraph (c) of AD 2001-02-01 done before or concurrently with the requirements of paragraph (i) of this AD are approved as AMOCs for the corresponding provisions of paragraph (l) of this AD.

Material Incorporated by Reference

(n) You must use Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 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 January 19, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.