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Proposed Rule

Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes

Document Details

Information about this document as published in the Federal Register.

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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 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. This proposed AD would require repetitive high frequency eddy current inspections for cracks of the fuselage skin at stringer 5 left and right between stations 340 and 350, and corrective actions if necessary. This proposed AD results from reports of fatigue cracks in the fuselage skin near stringer 5 between stations 340 and 350. We are proposing this AD to detect and correct fatigue cracking of the fuselage skin near stringer 5. Cracks in this area could join together and result in in-flight depressurization of the airplane.

DATES:

We must receive comments on this proposed AD by April 20, 2007.

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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.
  • 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.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for the service information identified in this proposed AD.

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FOR FURTHER INFORMATION CONTACT:

Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437; fax (425) 917-6590.

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SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2007-27359; Directorate Identifier 2006-NM-042-AD” at the beginning 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 received 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 may 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 Docket Management System receives them.

Discussion

We have received a report indicating that, during inspections on certain Boeing Model 747 airplanes, four operators found fatigue cracks in the fuselage skin at stringer 5, between stations 340 and 350. The airplanes had flown 18,000 to 20,000 total flight cycles. The cracks that were found ranged in length from a single crack of 0.25 inch to multiple cracks that were equivalent to a 10-inch long crack. Skin cracks in this area could join together and result in in-flight depressurization of the airplane.

Other Relevant Rulemaking

On January 16, 1990, we issued AD 90-06-06, amendment 39-6490 (55 FR 8374, March 7, 1990), for certain Boeing Model 747 series airplanes. That AD requires the incorporation of certain structural modifications (reference Boeing Service Bulletin 747-53-2272, Revision 12, dated December 22, 1988, identified in Boeing Document No. D6-35999). We issued that AD to prevent structural failure of the affected airplanes. One of the required modifications of AD 90-06-06 ends the repetitive inspections of certain structures that would also be required by this proposed AD.

On April 1, 2005, we issued AD 2005-08-01, amendment 39-14053 (70 FR 18290, April 11, 2005), for certain Boeing Model 747 series airplanes. That AD requires repetitive inspections; repetitive external detailed inspections for cracks or loose or missing fasteners of certain body skin on the left and right sides of the airplane; an internal detailed inspection for cracking of certain left- and right-side frames and adjacent skin; repetitive high-frequency eddy current (HFEC) inspections of certain body frames between certain body stations; and repairs if necessary. We issued that AD to detect and correct fatigue cracks in the body frames, skin, and other internal structures in fuselage section 41, which could lead to rapid decompression and loss of the structural integrity of the airplane. Paragraph (s) of AD 2005-08-01 refers to Boeing Service Bulletin 747-53-2272, dated January 12, 1987, and any revision through Revision 18, dated May 16, 2002, as the appropriate source of service information for accomplishing the terminating action described in that AD. That terminating action ends the repetitive inspections of certain structures that would also be required by this proposed AD.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2542, dated February 16, 2006 (referred to hereafter as “the alert service bulletin”). For airplanes that do not have external skin doublers installed around the left- and right-side Number 3 flight deck windows in accordance with Boeing Service Bulletin 747-53-2272, the alert service bulletin describes procedures for repetitive HFEC inspections for cracks of the external surface of the fuselage skin at stringer 5 left and right, between stations 340 and 350. The alert service bulletin specifies that the HFEC inspections be done at the compliance times specified in the following table.

Compliance Times for HFEC Inspections

Airplane groupAirplane conditionInitial compliance time (whichever occurs later)Repetitive interval (not to exceed)
Group 1Fewer than 16,000 total flight cyclesBefore accumulating 16,000 total flight cycles or within 2,000 flight cycles 14,000 flight cycles.
16,000 or more total flight cyclesBefore accumulating 18,000 total flight cycles or within 250 flight cycles 1None.
Group 2Fewer than 20,000 total flight cycleBefore accumulating 20,000 total flight cycles or within 2,000 flight cycles 14,000 flight cycles.
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20,000 or more total flight cyclesBefore accumulating 22,000 total flight cycles or within 250 flight cycles 1None.
1 After the date on the alert service bulletin.

The alert service bulletin also describes corrective actions to be done if any crack is found. If the total length of all cracks found is less than 1.0 inch, corrective actions include stop drilling the crack or cracks; and, either installing external skin doublers around the Number 3 flight deck window, or installing a temporary external structural repair manual (SRM) skin repair. If the total length of all cracks found is 1.0 inch or longer, corrective actions include trimming the cracked area of skin and installing a filler; and, either installing external skin doublers around the Number 3 flight deck window and installing a tripler, or installing a temporary external SRM skin repair. The alert service bulletin specifies that the corrective actions should be done before further flight. The alert service bulletin refers to Boeing Service Bulletin 747-53-2272 (currently at Revision 18, dated May 16, 2002) as an additional source of service information for installing the external skin doublers around the left- and right-side Number 3 flight deck windows.

For Group 2 airplanes only: The alert service bulletin describes installing external skin doublers around the left- and right-side Number 3 flight deck windows before accumulating 24,000 total flight cycles or within 250 flight cycles after the effective date of the alert service bulletin, whichever occurs later. This constitutes terminating action for the repetitive HFEC inspections specified in this NPRM.

For Group 1 airplanes only: AD 90-06-06 requires installation of external skin doublers around the Number 3 flight deck windows in accordance with Boeing Service Bulletin 747-53-2272, Revision 12, dated December 22, 1988, at or before 20,000 total flight cycles. This constitutes terminating action for the repetitive HFEC inspections specified in this NPRM.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

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. For this reason, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the Proposed AD and Alert Service Bulletin.”

Difference Between the Proposed AD and Alert Service Bulletin

The alert service bulletin 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.

Clarification of Reporting

Although the alert service bulletin discusses reporting inspection results, the Accomplishment Instructions of the alert service bulletin do not specify sending such a report to Boeing. This proposed AD would not require such reporting.

Costs of Compliance

There are about 281 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 92 airplanes of U.S. registry. The proposed inspection would take about 4 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed inspection for U.S. operators is $29,440, or $320 per airplane, per inspection cycle.

For Group 2 airplanes (about 4 of U.S. registry), the mandatory terminating action for the repetitive inspections would take about 1,240 work hours, at an average labor rate of $80 per work hour. The manufacturer states that it will supply required parts to the operators at no cost. Based on these figures, the estimated cost of the terminating action for U.S. operators is $396,800, or $99,200 per airplane.

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.

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List of Subjects in 14 CFR Part 39

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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:

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

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[Amended]

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

Boeing: Docket No. FAA-2007-27359; Directorate Identifier 2006-NM-042-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by April 20, 2007.

Affected ADs

(b) AD 90-06-06, amendment 39-6490, paragraph A., requires installation of external skin doublers in the area near the flight deck windows for Group 1 airplanes, which ends the repetitive high-frequency eddy current (HFEC) inspections required by this AD only for those airplanes. Installing external skin doublers as required by paragraph (g) of this AD ends certain repetitive inspections of the fuselage skin required by paragraph (f) of AD 2005-08-01, amendment 39-14053, only for the area near the flight deck windows modified by the external skin doublers.

Applicability

(c) This AD applies to Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2542, dated February 16, 2006.

Unsafe Condition

(d) This AD results from reports of fatigue cracks in the fuselage skin near stringer 5 between body stations 340 and 350. We are issuing this AD to detect and correct fatigue cracking of the fuselage skin near stringer 5. Cracks in this area could join together and result in in-flight depressurization 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.

Inspections and Corrective Actions

(f) For any airplane that has not had external skin doublers installed around the left- or right-side Number 3 flight deck window in accordance with Boeing Service Bulletin 747-53-2272, Revision 18, dated May 16, 2002, or an earlier revision: Do the applicable actions described in paragraphs (f)(1) and (f)(2) of this AD. Do all the actions in and in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2542, dated February 16, 2006. Do the actions at the compliance times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2542, dated February 16, 2006, on the side(s) of the airplane on which the doubler installation has not been done; except where the service bulletin specifies compliance times after the date on the service bulletin, this AD requires compliance times after the effective date of this AD. Installing external skin doublers around the left- or right-side Number 3 flight deck windows in accordance with Boeing Service Bulletin 747-53-2272, Revision 18, or an earlier revision; ends the repetitive HFEC inspections required by this paragraph on the side of the airplane on which the doubler is installed. After the effective date of this AD, only Boeing Service Bulletin 747-53-2272, Revision 18, may be used to install the external skin doublers around the left- and right-side Number 3 flight deck windows.

(1) Do a HFEC inspection for cracks of the fuselage skin at stringer 5, between body stations 340 and 350; and do all applicable corrective actions before further flight.

(2) Repeat the HFEC inspection thereafter at the applicable interval specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2542.

Terminating Action

(g) For Group 2 airplanes only: Before accumulating 24,000 total flight cycles, or within 250 flight cycles after the effective date of the AD, whichever occurs later, install external skin doublers around the left- and right-side Number 3 flight deck windows; in accordance with Boeing Service Bulletin 747-53-2272, Revision 17, dated November 18, 1999; or Revision 18, dated May 16, 2002. After the effective date of this AD, only Boeing Service Bulletin 747-53-2272, Revision 18, may be used to accomplish the doubler installation around the left- and right-side Number 3 flight deck windows. Accomplishing this action ends the repetitive inspections required by paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office (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 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.

Start Signature

Issued in Renton, Washington, on February 23, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. E7-3842 Filed 3-5-07; 8:45 am]

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