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Proposed Rule

Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP Series Airplanes

Document Details

Information about this document as published in the Federal Register.

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Start Preamble

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 747 series airplanes. The existing AD currently requires repetitive detailed inspections of the aft pressure bulkhead for indications of “oil cans” and previous oil can repairs, and corrective actions, if necessary. An oil can is an area on a pressure dome web that moves when pushed from the forward side. This proposed AD would reduce the compliance time for the initial detailed inspection and clarify the applicability. This proposed AD results from a report that cracks in oil-canned areas were found during an inspection of the aft pressure bulkhead. We are proposing this AD to detect and correct the propagation of fatigue cracks in the vicinity of oil cans on the web of the aft pressure bulkhead, which could result in rapid decompression of the airplane and overpressurization of the tail section, and consequent loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by August 18, 2008.

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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: 202-493-2251.
  • 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, P.O. Box 3707, Seattle, Washington 98124-2207.

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 800-647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Start Further Info

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 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-2008-0731; Directorate Identifier 2008-NM-058-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 July 30, 2004, we issued AD 2004-16-09, amendment 39-13765 (69 FR 48133, August 9, 2004), for all Boeing Model 747 series airplanes. That AD requires repetitive detailed inspections of the aft pressure bulkhead for indications of “oil cans” and previous oil can repairs, and corrective actions, if necessary. An oil can is an area on a pressure dome web that moves when pushed from the forward side. That AD resulted from a report indicating that a 2.1-inch long crack in the web of the aft pressure bulkhead at the perimeter of an “oil can” was found on a Model 747SR series airplane. We issued that AD to detect and correct the propagation of fatigue cracks in the vicinity of oil cans on the web of the aft pressure bulkhead, which could result in rapid decompression of the airplane and overpressurization of the tail section, and consequent loss of control of the airplane.

Actions Since Existing AD Was Issued

Since we issued AD 2004-16-09, we received a report that 9 cracks (up to 0.4-inch long in 2 oil-canned areas) were found during an inspection on the aft pressure bulkhead of a Model 747-200F series airplane with about 21,000 total flight cycles. Boeing recommends reducing the initial inspection threshold (required in paragraph (b) of AD 2004-16-09) from 30,000 total flight cycles to 20,000 total flight cycles.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2482, Revision 1, dated February 21, 2008. The service bulletin describes procedures that are the same as in Boeing Alert Service Bulletin 747-53A2482, dated October 3, 2002, except for a reduction in a compliance time and some editorial changes. Revision 1 of the service bulletin also specifies contacting Boeing for repair data if any crack is found during a detailed inspection of any previous “oil can” repair.

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 2004-16-09 and would retain the requirements of the existing AD. This proposed AD would also require accomplishing the actions specified in the service bulletin described previously at a reduced threshold, except as discussed under “Differences Between the Proposed AD and Revision 1 of the Service Bulletin.”

Differences Between the Proposed AD and Revision 1 of the Service Bulletin

The 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.

We have revised paragraph (g) of AD 2004-16-09 to allow repairs in accordance with data that conforms to an airplane's type certificate and that are approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make such findings.

Change to Existing AD

This proposed AD would retain all requirements of AD 2004-16-09. Since AD 2004-16-09 was issued, the AD format has been revised, and certain paragraphs have been rearranged. As a result, the corresponding paragraph identifiers have changed in this proposed AD, as listed in the following table:

Revised Paragraph Identifiers

Requirement in AD 2004-16-09Corresponding requirement in this proposed AD
paragraph (a)paragraph (f).
paragraph (b)paragraph (g).
paragraph (c)paragraph (h).
paragraph (d)paragraph (i).
paragraph (e)paragraph (j).
paragraph (f)paragraph (k).
paragraph (g)paragraph (l).

The cost information specified in AD 2004-16-09 inadvertently contained information on on-condition inspections. The cost information, below, has been revised to state only the work hours necessary for the initial and repetitive inspections specified in paragraph (g) of this proposed AD.

Costs of Compliance

There are about 917 airplanes of the affected design in the worldwide fleet. Start Printed Page 37902This proposed AD would affect about 165 airplanes of U.S. registry.

The actions that are required by AD 2004-16-09 and retained in this proposed AD take about 2 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the currently required actions to the U.S. operators is $26,400, or $160 per airplane, 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 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.

Start List of Subjects

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:

Start Authority

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

End Authority
[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by removing amendment 39-13765 (69 FR 48133, August 9, 2004) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2008-0731; Directorate Identifier 2008-NM-058-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by August 18, 2008.

Affected ADs

(b) This AD supersedes AD 2004-16-09.

Applicability

(c) This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from a report that cracks in oil-canned areas were found during an inspection of the aft pressure bulkhead. We are issuing this AD to detect and correct the propagation of fatigue cracks in the vicinity of oil cans on the web of the aft pressure bulkhead, which could result in rapid decompression of the airplane and overpressurization of the tail section, and consequent loss of control 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.

Note 1:

This AD refers to certain portions of a Boeing service bulletin for inspections and repair information. In addition, this AD specifies requirements beyond those included in the service bulletin. Where the AD and the service bulletin differ, the AD prevails.

Service Bulletin References

(f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2482, dated October 3, 2002; or Boeing Alert Service Bulletin 747-53A2482, Revision 1, dated February 21, 2008. After the effective date of this AD, Revision 1 must be used.

Requirements of AD 2004-16-09, With Reduced Threshold

Initial and Repetitive Inspections

(g) At the earlier of the times specified in paragraphs (g)(1) and (g)(2) of this AD, perform a detailed inspection of the aft pressure bulkhead for indications of oil cans and previous oil can repairs, in accordance with the service bulletin.

(1) Prior to the accumulation of 30,000 total flight cycles, or within 1,000 flight cycles after September 13, 2004 (the effective date of AD 2004-16-09), whichever is later.

(2) Prior to the accumulation of 20,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

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.”

(h) If no indication of an oil can is found and no indication of a previous oil can repair is found during the detailed inspection required by paragraph (g) of this AD, repeat the detailed inspection thereafter at intervals not to exceed 2,000 flight cycles.

Indication of Oil Can

(i) If any indication of an oil can is found during the detailed inspection required by paragraph (g) or (h) of this AD, before further flight, perform an eddy current inspection of the web around the periphery of the oil can indication for cracks, as shown in Figure 3 of the service bulletin.

(j) If no crack is found during the eddy current inspection required by paragraph (i) of this AD, do the actions specified in paragraph (j)(1) or (j)(2) of this AD, as applicable.

(1) For the oil can that meets the allowable limits specified in the service bulletin: Repeat the eddy current inspection specified in paragraph (i) of this AD thereafter at intervals not to exceed 1,000 flight cycles. As an option, repair the oil can in accordance with paragraph (j)(2) of this AD.

(2) For the oil can that does not meet the allowable limits specified in the service bulletin: Before further flight, repair the oil can in accordance with the service bulletin. If the repair eliminates the oil can, accomplishment of this repair constitutes terminating action for the repetitive eddy current inspection requirements of paragraph (j)(1) of this AD for that location only. However, the repetitive detailed inspection required by paragraph (h) of this AD is still required. If any oil can remains after the repair, repeat the eddy current inspection specified in paragraph (i) of this AD thereafter at intervals not to exceed 1,000 flight cycles.Start Printed Page 37903

Indication of Previous Oil Can Repairs

(k) If any previous oil can repair is found during the detailed inspection required by paragraph (g) or (h) of this AD, before further flight, do a detailed inspection of the web for cracks and oil cans, as shown in Figure 4 or Figure 5 of the service bulletin, as applicable.

(1) If no crack and no oil can are found, repeat the detailed inspection in accordance with paragraph (h) of this AD.

(2) If any oil can is found, before further flight, do the eddy current inspection for cracks, as shown in Figure 3 of the service bulletin. If no crack is found during the eddy current inspection required by this paragraph, do the actions specified in paragraph (j)(1) or (j)(2) of this AD, as applicable, at the time specified in the applicable paragraph.

Repair of Cracks

(l) If any crack is found during any inspection required by this AD, before further flight, repair in accordance with the service bulletin. If any crack or damage exceeds limits specified in the service bulletin and the service bulletin specifies to contact Boeing for appropriate action: 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; or using a method approved in accordance with the procedures specified in paragraph (n) of this AD. For a repair method to be approved, the approval must specifically reference this AD.

New Requirements of This AD

(m) As of the effective date of this AD, if any crack or damage is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-53A2482, Revision 1, dated February 21, 2008, specifies to contact Boeing for appropriate action (repair data): Before further flight, repair the crack or damage using a method approved in accordance with the procedures specified in paragraph (n) of this AD.

Alternative Methods of Compliance (AMOCs)

(n)(1) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(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 appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(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.

(4) AMOCs approved previously in accordance with AD 2004-16-09 are not approved as AMOCs for the corresponding provisions of paragraph (g) of this AD. They are approved as AMOCs for the corresponding provisions of paragraphs (h), (i), (j), (k), (l), and (m) of this AD.

Start Signature

Issued in Renton, Washington, on June 24, 2008.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. E8-14974 Filed 7-1-08; 8:45 am]

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