E9-18419. 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 superseding an existing airworthiness directive (AD) that applies to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That AD currently requires repetitive inspections of the intercostal webs, attachment clips, and stringer splice channels for cracks; and corrective action if necessary. This new AD reduces the repetitive inspection intervals from 25,000 flight cycles to 6,000 flight cycles, and expands the inspection area for Model 737-200C series airplanes to include the area aft of the forward entry door. This AD results from additional reports of fatigue cracks. We are issuing this AD to detect and correct fatigue cracking of the intercostals on the forward and aft sides of the forward entry door, which could result in loss of the forward entry door and rapid decompression of the airplane.

DATES:

This AD becomes effective September 9, 2009.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of September 9, 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:

Alan Pohl, 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 notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that supersedes AD 2005-20-03, amendment 39-14296 (70 FR 56361, September 27, 2005). The existing AD applies to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That NPRM was published in the Federal Register on November 17, 2008 (73 FR 67815). That NPRM proposed to continue to require repetitive inspections of the intercostal webs, attachment clips, and stringer splice channels for cracks, at repetitive inspection intervals reduced from 25,000 flight cycles to 6,000 flight cycles; and corrective action if necessary. That NPRM also proposed to expand the inspection area for Model 737-200C series airplanes to include the area aft of the forward entry door.

Comments

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

Request to Increase Grace Period

US Airways requests that we increase the threshold grace period from 3,000 flight cycles after the effective date of this AD to 4,500 flight cycles. US Airways states that the new grace period it requests would allow operators to schedule more airplanes into appropriate maintenance tasks. US Airways explains that the inspection would affect its operation by requiring additional maintenance that is not presently scheduled.

We do not agree with the commenter's request. In developing an appropriate compliance time for this AD, we considered not only the safety implications, but the manufacturer's recommendations, and the practical aspect of accomplishing the modification within an interval of time that corresponds to typical scheduled maintenance for affected operators. However, under the provisions of paragraph (m) of this AD, we may consider requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety. We have not changed this AD in this regard.

Explanation of Additional Changes to the AD

We have clarified paragraphs (h), (i), and (l) of this AD to include the full citation for the service information referenced in those paragraphs. We made this change to ensure that it is clear which service information operators must use for a specific action.

We have changed paragraph (j) of this AD to remove the reference to “Part 4 of the Work Instructions of Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003,” because that service bulletin does not contain a Part 4. Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007, does include Part 4 to provide procedures related to inspections and corrective actions for the intercostal webs and attachment clips located aft of the forward entry door. Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003, does not include any actions for this area of the airplane.

Conclusion

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We also determined that these changes will not increase the economic burden on any operator or 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	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspection of areas forward of the aft entry door (required by AD 2005-20-03)	2	$80	$160 per inspection cycle	876	$140,160 per inspection cycle.
Inspection of areas aft of the forward entry door for Model 737-200C series airplanes (new action)	1	80	80 per inspection cycle	19	1,520 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 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 removing amendment 39-14296 ( 70 FR 56361, September 27, 2005) and by adding the following new airworthiness directive (AD):

2009-16-14 Boeing: Amendment 39-15987. Docket No. FAA-2008-1213; Directorate Identifier 2007-NM-092-AD.

Effective Date

(a) This AD becomes effective September 9, 2009.

Affected ADs

(b) This AD supersedes AD 2005-20-03.

Applicability

(c) This AD applies to Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007.

Unsafe Condition

(d) This AD results from reports of fatigue cracks. We are issuing this AD to detect and correct fatigue cracking of the intercostals on the forward and aft sides of the forward entry door, which could result in loss of the forward entry door and 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 Compliance Time

(f) For all Model 737-100, -200, -200C, -300, -400, and -500 series airplanes: Before the accumulation of 15,000 total flight cycles, or within 4,500 flight cycles after November 1, 2005 (the effective date of AD 2005-20-03), whichever occurs later: Do the inspections required by paragraphs (h) and (i) of this AD.

(g) For all Model 737-200C series airplanes: 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: Do the inspection required by paragraph (j) of this AD.

Initial Inspection for Passenger Configuration Airplanes

(h) For Group 1 passenger airplanes identified in Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007: Perform a detailed inspection for cracking of the intercostal web, attachment clips, and stringer splice channels; and a high frequency eddy current inspection for cracking of the stringer splice channels located forward and aft of the forward entry door; and do all applicable corrective actions before further flight; in accordance with Parts 1 and 2 of the Work Instructions of Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007. After the effective date of this AD, only Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007, may be used.

Initial Inspection for Cargo Configuration Airplanes (Forward of the Forward Entry Door)

(i) For Group 2 cargo airplanes identified in Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007: Perform a detailed inspection for cracking of the intercostal webs and attachment clips located forward of the forward entry door, and do all applicable corrective actions before further flight, in accordance with Part 3 of the Work Instructions of Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007. After the effective date of this AD, only Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007, may be used.

Initial Inspection for Cargo Configuration Airplanes (Aft of the Forward Entry Door)

(j) For Group 2 cargo airplanes identified in Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007: Perform a detailed inspection for cracking of the intercostal webs and attachment clips located aft of the forward entry door, and do all applicable corrective actions before further flight, in accordance with Part 4 of the Work Instructions of Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007.

Repeat Inspections

(k) Repeat the inspections required by paragraphs (h), (i), and (j) of this AD thereafter at intervals not to exceed 6,000 flight cycles after the previous inspection, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later.

Exceptions

(l) Do the actions required by this AD by accomplishing all the applicable actions specified in the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007; except as provided by paragraphs (l)(1) and (l)(2) of this AD. After the effective date of this AD, only Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007, may be used.

(1) Where Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007; specifies to contact Boeing for repair instructions: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (m) of this AD.

(2) Where Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007; specifies a compliance time relative to the date of a service bulletin, this AD requires compliance relative to the effective date of this AD. Where Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007; specifies a compliance time relative to the date of the initial release of the service bulletin, this AD requires compliance relative to the effective date of AD 2005-20-03 (November 1, 2005).

Alternative Methods of Compliance (AMOCs)

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

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

(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.

(4) AMOCs approved previously in accordance with AD 2005-20-03 are approved as AMOCs for the corresponding provisions of this AD, provided the repetitive inspection intervals (if any) do not exceed 6,000 flight cycles.

(5) AMOCs approved previously in accordance with AD 2005-20-03 are not approved as AMOCs for the provisions of paragraph (j) or (k) of this AD.

Material Incorporated by Reference

(n) You must use Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007; as applicable; to do the actions required by this AD, unless the AD specifies otherwise.

(1) The Director of the Federal Register approved the incorporation by reference of Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007, under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) 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.

(3) You may review copies of the service information 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 that is incorporated by reference 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 July 23, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.