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Proposed Rule

Airworthiness Directives; Boeing Model 747-100, 747SP, and 747SR Series Airplanes

Document Details

Information about this document as published in the Federal Register.

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-100, 747SP, and 747SR series airplanes. This proposal would require repetitive inspections to find fatigue cracking between the seal ribs of the front spar web of the wing, and repair of cracked structure. This proposal also provides for an optional modification of a certain area. This action is necessary to find and fix such fatigue cracking, which could result in fuel leakage into the area of the inboard engines, and consequent increased risk of a fire. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by March 21, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-178-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-178-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, PO Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

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FOR FURTHER INFORMATION CONTACT:

Tamara L. Anderson, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6421; fax (425) 917-6590.

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SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

  • Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
  • For each issue, state what specific change to the proposed AD is being requested.
  • Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-178-AD.” The postcard will be date stamped and returned to the commenter. Start Printed Page 5611

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-178-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report indicating that an operator found a 24-inch crack in the front spar web of the right wing between front spar station inboard (FSSI) 637 through 662 on a Boeing Model 747-100 series airplane having accumulated 14,830 total flight cycles and 85,116 total flight hours. Metallurgical analysis of the cracked section of the web revealed three cracks originating from a hole common to a rib post located on the front spar at FSSI 656 (wing station 642). The cracks were initiated by fatigue at the hole and were spread by fatigue for a short distance; then the cracks separated by a combination of fatigue and ductile separation. The cracks resulted in a fuel leak which was found after post-flight inspection revealed fire damage to the exhaust sleeve of the inboard engine turbine. Another operator reported finding a crack in the web at approximately FSSI 694, just outboard of a web section recently replaced per AD 99-10-09, amendment 39-11162 (64 FR 25194, June 15, 1999). Such fatigue cracking, if not found and fixed, could result in fuel leakage into the area of the inboard engines and consequent increased risk of a fire.

Related Rulemaking

This AD is related to the following rulemaking actions, which require the actions in the related service bulletins specified in Boeing Special Attention Service Bulletin 747-57-2313, Revision 1, including Appendices A and B, dated February 21, 2002:

  • AD 95-10-16, amendment 39-9233 (60 FR 27008, June 21, 1995). That AD references Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994, as the appropriate source of service information for accomplishment of the modification of the nacelle strut and wing structure. That AD is applicable to certain Boeing Model 747 series airplanes equipped with Pratt & Whitney Model JT9D series engines (excluding Model JT9D-70 engines). The AD requires modification of the nacelle strut and wing structure, inspections and checks to detect discrepancies, and correction of discrepancies. The modification specified in the AD also constitutes terminating action for the repetitive inspections required by certain other ADs, including AD 98-15-21, amendment 39-10672 (63 FR 39487, July 23, 1998), which references Boeing Service Bulletin 747-57A2266 as the appropriate source of service information for accomplishment of the specified actions; and AD 90-17-18, amendment 39-6702 (55 FR 33279, August 15, 1990), which references Boeing Service Bulletin 747-57A2259 as the appropriate source of service information for accomplishment of the specified actions.
  • AD 99-10-09, amendment 39-11162. That AD references Boeing Service Bulletin 747-57A2303, Revision 1, dated September 25, 1997, as the appropriate source of service information for accomplishment of the actions specified. That AD is applicable to certain Boeing Model 747-100, -200, and 747-SP series airplanes and military type E-4B airplanes, and requires repetitive inspections to detect cracking of the wing front spar web, and repair of cracked structure. That AD also provides for optional terminating action for the repetitive inspections.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Special Attention Service Bulletin 747-57-2313, Revision 1, including Appendices A and B, dated February 21, 2002. The service bulletin describes procedures for repetitive inspections to find fatigue cracking of the front spar web of the wing, and repair of cracked structure, as follows:

  • For airplanes on which the optional modification specified in AD 99-10-09 has not been done, the affected area is divided into two zones (A and B). Zone A is the area previously modified per the requirements specified in AD 95-10-16 for the wing front spar; and Zone B is the remaining area between FSSI 628 and 711.
  • For airplanes on which the optional modification specified in AD 99-10-09 has been done, the affected area is divided into three zones (A, B, and C). Zone A is the area previously modified per the requirements specified in AD 95-10-16 for the wing front spar, and is not affected by the requirements specified in AD 99-10-09; Zone C is the area affected by AD 99-10-09; and Zone B is the remaining area between FSSI 628 and 711.
  • The inspection specified in Part 1 of the service bulletin is for Zone A, B, or C, as applicable. If no cracking is found, the inspections are repeated at the intervals specified in Figure 1 of the service bulletin. If cracking is found, the inspections are also repeated at the intervals specified in Figure 1 after the cracking is repaired.
  • The modification specified in Part 2 of the service bulletin is for Zone B only. The modification includes removing the existing fasteners of the web to chord, web to rib post, and web to stiffener; straightening the holes; and doing an open-hole rotating probe high frequency eddy current inspection for cracking in the web. If no cracking is found, the service bulletin directs oversizing the holes and installing tension type fasteners in the holes; if any cracking is found, the service bulletin specifies contacting the manufacturer for repair instructions.

The service bulletin recommends prior or concurrent accomplishment of Boeing Service Bulletins 747-57A2259, 747-57A2266, and 747-54A2159. Those service bulletins are referenced in the related rulemaking described previously.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletin described above, except as discussed below.

Difference Between Service Information and Proposed Rule

Although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions to be done per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

Cost Impact

There are approximately 109 airplanes of the affected design in the worldwide fleet. The FAA estimates that 59 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 25 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $88,500, or $1,500 per airplane, per inspection cycle.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD Start Printed Page 5612action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Should an operator elect to do the optional modification of Zone B, it would take approximately 480 work hours to accomplish at an average labor rate of $60 per work hour. Parts cost would be approximately $16,652. Based on these figures, the cost impact of the proposed modification is estimated to be $45,452 per airplane.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

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List of Subjects in 14 CFR Part 39

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The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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:

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

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[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2001-NM-178-AD.

Applicability: Model 747-100, 747SP, and 747SR series airplanes, as listed in Boeing Special Attention Service Bulletin 747-57-2313, Revision 1, including Appendices A and B, dated February 21, 2002; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To find and fix fatigue cracking between the seal ribs of the front spar web of the wing, which could result in fuel leakage into the area of the inboard engines, and consequent increased risk of a fire; accomplish the following:

Compliance Times

(a) Where the compliance times in the service bulletin specify a compliance time interval calculated “after the release of this service bulletin,” this AD requires compliance within the interval specified in the service bulletin “after the effective date of this AD.” In addition, where the compliance time for the initial inspection in Tables 1 through 3 of Figure 1 of the service bulletin specifies “flight hours,” this AD requires a compliance time of “total flight hours.”

Initial and Repetitive Inspections

(b) Do detailed, high frequency eddy current and ultrasonic inspections to find cracking of the front spar web of the wing as specified in paragraphs (b)(1) and (b)(2) of this AD, per the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-57-2313, Revision 1, including Appendices A and B, dated February 21, 2002.

(1) Do the applicable initial or post-modification inspection at the times specified for the inspections in Tables 1 through 3 of Figure 1 of the Accomplishment Instructions or Appendix A of the service bulletin.

(2) After doing the applicable initial or post-modification inspection specified in paragraph (b)(1) of this AD: Repeat that inspection within the applicable intervals specified in Tables 1 through 3 of Figure 1 of the Accomplishment Instructions or Appendix A of the service bulletin.

Repair

(c) If any cracking is found during any inspection required by this AD: Before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, the approval must specifically reference this AD.

Optional Modification

(d) Accomplishment of the modification of Zone B per Part 2 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-57-2313, Revision 1, including Appendices A and B, dated February 21, 2002, would extend the threshold recommended in Tables 1 through 3 of Figure 1 of the Accomplishment Instructions or Appendix A of the service bulletin for the repetitive inspections of Zone B, to the new threshold specified in Tables 1 through 3 of Figure 1 of the service bulletin.

Previously Accomplished Inspections and Modifications

(e) Inspections and modifications done before the effective date of this AD per Boeing Special Attention Service Bulletin 747-57-2313, including Appendices A and B, dated April 19, 2001, are considered acceptable for compliance with the applicable actions specified in this AD.

Note 2:

Boeing Special Attention Service Bulletin 747-57-2313, Revision 1, including Appendices A and B, dated February 21, 2002, recommends prior or concurrent accomplishment of Boeing Service Bulletins 747-57A2259; 747-57A2266; and 747-54A2159. The modifications in those service bulletins are required by AD 95-10-16, amendment 39-9233.

Alternative Methods of Compliance

(f) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 3:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permit

(g) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

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Start Printed Page 5613

Issued in Renton, Washington, on January 29, 2003.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 03-2495 Filed 2-3-03; 8:45 am]

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