E9-11707. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The existing AD currently requires a one-time inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas; and related investigative/corrective actions if necessary. This proposed AD would expand the area to be inspected and, for certain airplanes, require earlier inspections for certain inspection zones. This proposed AD results from additional detailed analysis of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines; the analysis resulted in different inspection zones, thresholds and repetitive intervals, and airplane groupings. We are proposing this AD to prevent rapid decompression of the airplane due to fatigue cracks resulting from scribe lines on pressurized fuselage structure.

DATE:

We must receive comments on this proposed AD by July 6, 2009.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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. You may review copies of the referenced 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.

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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

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

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2009-0452; Directorate Identifier 2007-NM-326-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

On March 20, 2006, we issued AD 2006-07-12, amendment 39-14539 (71 FR 16211, March 31, 2006), for all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That AD requires a one-time inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas; and related investigative/corrective actions if necessary. That AD resulted from reports of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines. Scribe line damage can also occur at many other locations, including butt joints, external doublers, door scuff plates, the wing-to-body fairing, and areas of the fuselage where decals have been applied or removed. We issued that AD to prevent rapid decompression of the airplane due to fatigue cracks resulting from scribe lines on pressurized fuselage structure.

Related ADs

This proposed AD is similar to AD 2007-19-07, amendment 39-15198 (72 FR 60244, October 24, 2007), which applies to all Boeing Model 757-200, -200PF, and -200CB series airplanes. That AD requires inspections to detect scribe lines in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas; and related investigative/corrective actions if necessary. Those actions resulted from reports of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines.

Actions Since Existing AD Was Issued

AD 2006-07-12 cites Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, as the appropriate source of service information for the scribe line inspection. Since we issued that AD, Boeing issued Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008. Revisions to the service bulletin were based on additional detailed analysis that indicated the need to inspect some affected areas of the skin. In addition, based on the additional analysis, the service bulletin establishes two new inspection zones, Zone 4 and Zone 5, with thresholds of 50,000 and 60,000 flight cycles, respectively, since first scribe opportunity. The revised service bulletin designated certain areas of fuselage skin into other inspection zones, and some of those areas might now require inspections earlier than required by the existing AD. These areas are to be inspected within 4,500 flight cycles from the effective date of the new AD or prior to the revised zonal threshold, whichever is later.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2006-07-12 and retain the requirements of the existing AD, require inspection of newly added Zones 4 and 5, reduce certain compliance thresholds, and require inspection results to be sent to Boeing.

In addition, we have moved the content of paragraph (p)(4) of AD 2006-07-12 (from its location under the “Alternative Methods of Compliance” heading) to new paragraph (w) in this NPRM. New paragraph (w) specifies that a repair plan approved by a Boeing Company Authorized Representative or Designated Engineering Representative is acceptable for compliance with certain repair requirements of the proposed AD (provided certain conditions have been met). The provisions in paragraph (w) are considered a different repair method—not an alternative method of compliance (AMOC), which can be issued only after an AD has been issued.

Differences Between Proposed AD and Service Bulletin

Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, specifies to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing those conditions in one of the following ways:

• Using a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make those findings.

Costs of Compliance

There are about 2,685 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs, including the costs for the new proposed inspection areas in Zones 4 and 5, for U.S. operators to comply with this proposed AD.

Estimated Costs Required by AD 2006-07-12

Zone	Action	Work hours	Average labor rate per hour	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
1	Sealant removal	66	$80	$5,280	787	$4,155,360
	Inspection	4	80	320	787	251,840
2	Sealant removal	38	80	3,040	787	2,392,480
	Inspection	29	80	2,320	787	1,825,840
3	Sealant removal	88	80	7,040	787	5,540,480
	Inspection	38	80	3,040	787	2,392,480

Estimated Costs Required by New Actions of This AD

Zone	Action	Work hours	Average labor rate per hour	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
4	Sealant removal	15	$80	$1,200	787	$944,400
	Inspection	1	80	80	787	62,960
5	Sealant removal	31	80	2,480	787	1,951,760
	Inspection	2	80	160	787	125,920

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 proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the 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 proposed 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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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 39-14539 (71 FR 16211, March 31, 2006) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2009-0452; Directorate Identifier 2007-NM-326-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by July 6, 2009.

Affected ADs

(b) This AD supersedes AD 2006-07-12.

Applicability

(c) This AD applies to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category.

Subject

(d) Air Transport Association (ATA) of America Code 53: Fuselage.

Unsafe Condition

(e) This AD results from reports of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines. Scribe line damage can also occur at many other locations, including butt joints, external doublers, door scuff plates, the wing-to-body fairing, and areas of the fuselage where decals have been applied or removed. We are issuing this AD to prevent rapid decompression of the airplane due to fatigue cracks resulting from scribe lines on pressurized fuselage structure.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Restatement of Requirements of AD 2006-07-12

Inspection

(g) Do a detailed inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, except as provided by paragraphs (h), (k), (l), (m), (n), and (o) of this AD. Except as required by paragraph (q) of this AD, do the actions at the time specified in paragraph 1.E., “Compliance,” of the service bulletin, except as required by paragraph (j) of this AD. Acceptable inspection exemptions are described in paragraph 1.E.1. of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004.

(1) If no scribe line is found, no further work is required by this paragraph.

(2) If any scribe line is found: Do all applicable investigative and corrective actions at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, by doing all applicable actions specified in the service bulletin, except as required by paragraph (h) of this AD.

Note 1:

A detailed inspection is defined in Note 10 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, under paragraph 3.A., “General Information.” Specific magnification requirements may be specified in the steps of the Work Instructions.

Exceptions to and Clarification of Service Bulletin 737-53A1262 Procedures

(h) Paragraph (g) of this AD requires accomplishment of Parts 1 through 11 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004. Parts 12 and 13 of the service bulletin may be accomplished, if applicable, to allow temporary return to service. This AD does not require accomplishment of Part 14 of the service bulletin, although the FAA-approved procedures described in Part 14 are acceptable for continued operation with scribe lines found before the applicable compliance time.

(i) If any scribe line or crack is found during any inspection required by paragraph (g) of this AD, and Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, specifies to contact Boeing for appropriate action: Before further flight, inspect or repair scribe lines and repair cracks using a method approved in accordance with the procedures specified in paragraph (x) of this AD.

(j) Where Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, specifies a compliance time after the issuance of the service bulletin, this AD requires compliance within the specified compliance time after May 5, 2006 (the effective date of AD 2006-07-12).

(k) Certain figures are incorrectly identified in Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004. The figure cited in Part 8, step 3, should be Figure 39, not Figure 38. The figure cited in Part 9, step 4, should be Figure 38, not Figure 39.

(l) If the operator's records show that the airplane has never been stripped and repainted under the dorsal fin fairing since delivery from Boeing, then this AD does not require inspections of the butt joint, lap joint, and repair, as specified in paragraph (g) of this AD, in the areas under the dorsal fin fairing.

(m) Figure 37 of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, defines “Restricted Zones” at door cutouts as the only affected structure. Paragraph (g) of this AD considers this area to also include Zone 1B.

(n) In Figure 1, sheets 2 and 3, of Boeing Service Bulletin 737-53A1262, dated December 9, 2004, the first condition for the initial compliance threshold for Areas B, C, and E is for areas where the cutout modification shown in Boeing Service Bulletin 737-53A1177 was accomplished. Paragraph (g) of this AD considers this condition to also include Zone 1B.

(o) In Figure 1, sheets 2 and 3, of Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, the second condition for the initial compliance threshold for Areas B, C, and E is for areas where the cutout modification shown in Boeing Service Bulletin 737-53A1177 was not accomplished. Paragraph (g) of this AD considers this condition to apply only to Zone 1A.

Reporting Requirement

(p) For airplanes on which inspections have been done in accordance with Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004: At the applicable time specified in paragraph (p)(1) or (p)(2) of this AD, submit a report of positive findings of cracks found during the inspection required by paragraph (g) of this AD to the Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Alternatively, operators may submit reports to their Boeing field service representatives. The report shall contain, as a minimum, the following information: airplane serial number, flight cycles at time of discovery, location(s) and extent of positive crack findings. Under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056.

(1) If the inspection was done before May 5, 2006: Send the report within 30 days after May 5, 2006.

(2) If the inspection was done after May 5, 2006: Send the report within 30 days after the inspection is done.

New Requirements of This AD

Inspection

(q) As of the effective date of this AD, the actions for Zones 1, 2, and 3, as specified in paragraph (g) of this AD, must be done in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, and at the applicable times specified in paragraph 1.E., “Compliance,” of Revision 3 of the service bulletin, except as specified in paragraph (s) of this AD.

Note 2:

Paragraph 1.E.5. of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, provides a grace period for airplanes that have exceeded the revised thresholds.

Inspection of Zones 4 and 5

(r) Do a detailed inspection for scribe lines and cracks in Zones 4 and 5 (adjacent to lap joints on skin panels that do not have bonded doublers), as specified in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008. Except as provided by paragraph (s) of this AD, do the actions in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, and at the applicable time specified in paragraph 1.E., “Compliance,” of the service bulletin, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later.

(1) If no scribe line or crack is found: No further work is required by this paragraph.

(2) If any scribe line or crack is found: Do all applicable investigative and corrective actions at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, by doing all applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, except as required by paragraph (s)(1) of this AD.

Exceptions to Specifications of Boeing Alert Service Bulletin 737-53A1262, Revision 3, Dated October 16, 2008

(s) The following exceptions to Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, apply to this AD:

(1) If any scribe line or crack is found during any inspection required by this AD, and Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, specifies to contact Boeing for appropriate action: Before further flight, inspect or repair scribe lines and repair cracks using a method approved in accordance with the procedures specified in paragraph (x) of this AD.

(2) Where Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, specifies a compliance time after the issuance of the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.

(3) If the operator's records show that the airplane has never been stripped and repainted under the dorsal fin fairing since delivery from Boeing, then this AD does not require inspections of the butt joint, lap joint, and repair, as specified in paragraphs (g), (q), and (r) of this AD, in the areas under the dorsal fin fairing.

(4) For airplanes in Groups 3 and 29, as identified in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008: At the applicable times specified in paragraphs (s)(4)(i), (s)(4)(ii), and (s)(4)(iii) of this AD, perform a detailed inspection for scribe lines and cracks on the main cargo door along the lower edge of the upper hinge, around external repairs, and around decals, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, or using a method approved in accordance with the procedures specified in paragraph (x) of this AD. If no scribe line or crack is found, no further work is required by this paragraph. If any scribe line or crack is found, do all applicable related investigative and corrective actions at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, by doing all applicable actions specified in the Accomplishment Instructions of the service bulletin, except as required by paragraphs (s)(1), (s)(2), and (s)(3) of this AD.

(i) For areas along the lower edge of the door hinge from BS 360 to BS 500, the initial compliance threshold is to be determined using Zone 1B.

(ii) For external repairs, the initial compliance threshold is to be determined using Zone 1B.

(iii) For decals, the initial compliance threshold is to be determined using Zone 2.

(5) For Group 11 airplanes, as specified in Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008: Stringer 20R between BS 727C and BS 727D+10 is in Zone 1B.

Actions Accomplished in Accordance With Previous Service Information

(t)(1) Actions accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 737-53A1262, dated December 9, 2004, are acceptable for compliance with the corresponding requirements of paragraph (q) of this AD.

(2) Actions accomplished before the effective date of this AD in accordance with the Boeing Service Bulletin 737-53A1262, Revision 1, dated March 1, 2007; or Revision 2, dated September 20, 2007; are acceptable for compliance with the corresponding requirements of paragraphs (g), (q), and (r) of this AD.

Clarification of Procedures in the Service Bulletin

(u) For airplanes on which inspections are done as of the effective date of this AD: This AD requires accomplishment of Parts 1 through 11, 15, and 16 of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008. Parts 12 and 13 of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, may be accomplished, if applicable, to allow temporary return to service. This AD does not require accomplishment of Part 14 of Boeing Alert Service Bulletin 737-53A1262, Revision 3, dated October 16, 2008, although the FAA-approved procedures described in Part 14 are acceptable for continued operation with scribe lines found before the applicable compliance time.

Report

(v) For airplanes on which inspections are done in accordance with the service information identified in Table 1 of this AD: At the applicable time specified in paragraph (v)(1) or (v)(2) of this AD, submit a report of positive findings of cracks found during the inspections required by paragraphs (q), (r), and (s)(4) of this AD to the Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Alternatively, operators may submit reports to their Boeing field service representatives. The report must contain, as a minimum, the following information: airplane serial number, flight cycles at time of discovery, location(s) and extent of positive crack findings. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056.

(1) For an inspection done before the effective date of this AD: Send the report within 30 days after the effective date of this AD.

(2) For an inspection done after the effective date of this AD: Send the report within 30 days after the inspection is done.

Table 1—Service Information

Boeing service information	Revision	Date
Alert Service Bulletin 737-53A1262	3	October 16, 2008.
Service Bulletin 737-53A1262	1	March 1, 2007.
Service Bulletin 737-53A1262	2	September 20, 2007.

Repair Plan In Lieu of Required Inspections

(w) A repair plan approved by a Boeing Company Authorized Representative or Designated Engineering Representative before the effective date of this AD is acceptable for compliance with the requirements of paragraphs (g)(2), (i), (q), (r), (s)(1), and (s)(4) of this AD, provided the approval was documented via FAA Form 8110-3 or 8100-9, and identified scribe line damage in the title of the form.

Alternative Methods of Compliance (AMOCs)

(x)(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. Send information to ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (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 (AR) 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 approval must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, WA, on May 6, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.