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Proposed Rule

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

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This proposed AD would require the following: Repetitive eddy current inspections for cracks of the countersunk rivet holes in the lower lobe, adjacent to the radio altimeter cutouts; additional inspections, for certain airplanes, for cracks and/or corrosion; and further investigative and corrective action if any crack is found. This proposed AD also would provide an optional terminating action for the repetitive inspections. This proposed AD was prompted by reports of cracks in the fuselage skin of the lower lobe. We are proposing this AD to detect and correct fatigue cracks of the countersunk rivet holes, which could result in cracks of the fuselage skin of the lower lobe, and consequent rapid depressurization of the cabin.

DATES:

We must receive comments on this proposed AD by May 2, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590. Start Printed Page 12983
  • By fax: (202) 493-2251.
  • Hand Delivery: room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You can get the service information identified in this proposed AD from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You can examine the contents of this 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., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2005-20627; the directorate identifier for this docket is 2004-NM-39-AD.

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FOR FURTHER INFORMATION CONTACT:

Sue Lucier, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6438; fax (425) 917-6590.

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SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-20627; Directorate Identifier 2004-NM-39-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

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 DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received a report indicating that five operators have found seven cracks in the lower lobe fuselage skin on Boeing Model 737-200 series airplanes. All cracks originated at the countersunk rivet holes adjacent to the radio altimeter cutouts at body stations (BSs) 430 and 450, and were located at buttock line (BL) 0. The cracks were from 0.375 inch to 5.25 inches in length. One operator reported two cracks on the same airplane: a 2-inch crack running aft of BS 431, and a 2.125-inch crack running forward of BS 449. The two cracks were growing toward each other from two adjacent cutouts. The cracks propagate by normal fatigue due to operating loads (pressure). Cracking of the countersunk rivet holes, if not detected and corrected, could result in cracks in the lower lobe fuselage skin reaching critical length for residual strength, and consequent rapid depressurization of the cabin.

The fuselage skin configuration on certain Model 737-200 series airplanes is almost identical to that on certain Model 737-100, -200C, -300, -400, and -500 series airplanes. Therefore, all of these models may be subject to the same unsafe condition.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-53-1230, dated June 13, 2002. This service bulletin describes procedures for doing an eddy current inspection for cracks of the surface area around the countersunk rivet holes in the lower lobe, adjacent to the radio altimeter cutouts at BL 0, between BS 390 and BS 450. This inspection is done with the fasteners installed.

If no crack is found during the eddy current inspection, the service bulletin describes options for repeating the eddy current inspection (with fasteners installed), or for doing a preventive modification that would eliminate the need for the repetitive inspections.

For operators that choose to do the optional preventive modification, the service bulletin describes procedures for an additional eddy current inspection for cracks of the satellite holes with the fasteners removed.

If no crack is found during the additional eddy current inspection, the service bulletin gives procedures for fabricating and installing the preventive modification doublers. The service bulletin states that a preventive modification doubler is not needed at BS 390 if the doubler has been previously installed in accordance with Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989. For these airplanes, the preventive modification is removing the ten fasteners around the altimeter cutout at BS 390, doing an eddy current inspection of the satellite holes, and installing oversize fasteners.

If any crack is found during the additional eddy current inspection, the service bulletin specifies to discontinue the preventive modification and repair the affected area, as described below. Repair of the affected area eliminates the need for the repetitive inspections.

If any crack is found during any eddy current inspection, the service bulletin describes procedures for repair, which includes further investigative and corrective actions. The corrective actions included in the repair are cutting out the crack if it is within the allowable cutout repair zone, and fabricating and installing a repair doubler and spacer ring. The further investigative actions included in the repair are an eddy current inspection of the edge of the cutout area, an eddy current inspection of the satellite holes (with fasteners removed) for additional cracking, and a visual inspection for corrosion of the area under the previously repaired area. If any crack is outside the allowable cutout repair zone, or if any corrosion is detected, the service bulletin specifies to contact Boeing for repair instructions.

Accomplishing the actions specified in Special Attention Service Bulletin 737-53-1230 will address the identified unsafe condition adequately.

This special attention service bulletin refers to Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989, as an additional source of service information for repairing certain affected airplanes.

Concurrent Service Bulletin for Certain Airplanes

Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989, must be accomplished before or at the same time as the repair procedures in Boeing Special Attention Service Bulletin 737-53-1230 for any airplane that meets all three of the following conditions: Start Printed Page 12984

1. The airplane is specified as belonging in Group 1, 2, 3, 4, or 5 as listed in Boeing Special Attention Service Bulletin 737-53-1230;

2. The airplane has a skin crack at the cutout at BS 390; and

3. The airplane has not had an external repair doubler installed previously in accordance with Boeing Service Bulletin 737-53-1117. The repair in Service Bulletin 737-53-1117 includes further investigative and corrective actions, which are an additional inspection and repair of any crack by stop-drilling the cracks and installing an external repair doubler.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require you to accomplish the actions specified in Special Attention Service Bulletin 737-53-1230, except as discussed under “Differences Between the Proposed AD and the Service Bulletins.” This proposed AD also would provide for optional terminating action for the repetitive inspections.

This proposed AD would allow repetitive inspections to continue in lieu of the terminating action. In making this determination, we considered that long-term continued operational safety in this case would be adequately ensured by repetitive inspections to detect cracks before they represent a hazard to the airplane.

Differences Between the Proposed AD and the Service Bulletins

For airplanes designated as Groups 1, 2, 3, 4, and 5 that have a skin crack at BS 390, Part III of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1230 specifies additional actions in accordance with Boeing Service Bulletin 737-53-1117. These additional actions are a detailed inspection and repair, if necessary, of an adjacent equipment cooling duct cutout just forward of BS 390. The repair in Boeing Service Bulletin 737-53-1117 allows for repair of any crack by stop-drilling and installing an external repair doubler. This repair doubler reinforces the equipment cooling duct cutout and the BS 390 cutout. This proposed AD also would allow operators the option to do an eddy current inspection and repair in accordance with Figure 17 of Boeing Special Attention Service Bulletin 737-53-1230.

Special Attention Service Bulletin 737-53-1230 specifies that you may contact the manufacturer for instructions for certain repair instructions. However, rather than contacting the manufacturer, and for instructions for repairing any crack that is 3 inches in length or greater that is found during the inspection specified in Service Bulletin 737-53-1117, this proposed AD would require you to do these repairs in one of the ways listed in the bullets below.

  • 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 Delegation Option Authorization Organization who has been authorized by the FAA to make those findings.

Clarification of Inspection Language

Both Boeing Service bulletins request that operators “visually inspect” for certain conditions. This proposed AD defines this inspection in Boeing Service Bulletin 737-53-1117 as a “detailed inspection,” and in Boeing Special Attention Service Bulletin 737-53-1230 as a “general visual inspection.” These inspections are defined in Note 1 and Note 2 of this proposed AD.

Costs of Compliance

This proposed AD would affect about 3,132 airplanes worldwide. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

ActionWork hoursAverage labor rate per hourPartsCost per airplaneNumber of U.S.- registered airplanesFleet cost
Inspection3$65No parts required$1951,004$195,780

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. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

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

Boeing: Docket No. FAA-2005-20627; Directorate Identifier 2004-NM-39-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by May 2, 2005.

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 Special Attention Service Bulletin 737-53-1230, dated June 13, 2002.

Unsafe Condition

(d) This AD was prompted by reports of cracks in the lower lobe fuselage skin of the affected airplanes. We are issuing this AD to detect and correct fatigue cracks of the countersunk rivet holes, which could result in cracks of the fuselage skin of the lower lobe, and consequent rapid depressurization of the cabin.

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.

Service Bulletin Reference

(f) The term “special attention service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1230, dated June 13, 2002.

Repetitive Inspections

(g) Before the airplane accumulates 20,000 total flight cycles, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later: Do an eddy current inspection for cracks of the surface area around the satellite holes of the radio altimeter cutouts at buttock line 0, between body station (BS) 390 and BS 450. Do the inspection with the fasteners installed. Repeat the inspection at intervals not to exceed 4,500 flight cycles. Do all inspections in accordance with the special attention service bulletin.

Repair

(h) If any crack is found during any eddy current inspection required by this AD: Before further flight, repair the area by doing all applicable corrective and further investigative actions in accordance with the special attention service bulletin. Accomplishment of the repair terminates the repetitive inspection requirements of paragraph (g) of this AD for the repaired area. Where the special attention service bulletin specifies to contact Boeing for appropriate action or for instructions about how to repair certain conditions: Before further flight, repair in accordance with 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 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.

Additional Inspection and Repair for Certain Airplanes

(i) For the following airplanes, before or at the same time as the repair in paragraph (h) of this AD, inspect in accordance with Table 1 of this AD: Any airplane in Group 1, 2, 3, 4, or 5 of the special attention service bulletin; any airplane that has a skin crack at the cutout at BS 390 found during any inspection required by paragraphs (g) and (h) of this AD; and any airplane that has not had an external repair doubler installed in accordance with Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989.

Table 1.—Service Information

Inspect in accordance with either—
The Accomplishment Instructions of Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989—Figure 17 of the special attention service bulletin—
A detailed inspection for cracks in the fuselage lower skin in the area of the electronics bay cooling duct cutoutAn eddy current inspection for cracks of the exhaust port duct cutout edge and the 6 fastener locations; An eddy current and open-hole probe inspection for cracks of the satellite holes; and
A general visual inspection for corrosion of the area under the repair.

(1) If any crack at the equipment cooling duct cutout is found that is less than 3 inches in length: Before further flight, stop-drill the crack or cracks and install an external repair doubler in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989; or repair in accordance with Part III of the special attention service bulletin. Accomplishment of the repair terminates the repetitive inspection requirements of paragraph (g) of this AD for the repaired area.

(2) If any corrosion is found, or if any crack is found that is 3 inches in length or greater: Before further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the certification basis of the airplane approved by an Authorized Representative for the Boeing 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 specifically reference this AD.

Note 1:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Note 2:

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 mirrors magnifying lenses, etc. may be necessary. Surface cleaning and elaborate procedures may be required.”

Optional Terminating Action

(j) Installing preventive modification doublers in accordance with the special attention service bulletin, including the additional eddy current inspection with the fasteners removed (with no crack finding), terminates the repetitive inspection requirements of paragraph (g) of this AD. If any crack is found during the eddy current inspection specified by this paragraph: Before further flight, discontinue the preventive modification and do the applicable actions in paragraph (h) of this AD. Start Printed Page 12986

Alternative Methods of Compliance

(k)(1) In accordance with 14 CFR 39.19, the Manager, Seattle Aircraft Certification Office (SACO), is authorized to approve alternative methods of compliance (AMOCs) for this AD.

(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 Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings.

Start Signature

Issued in Renton, Washington, on March 8, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 05-5296 Filed 3-16-05; 8:45 am]

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