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 certain Model 747 series airplanes. The existing AD currently requires repetitive inspections for cracks of the fuselage skin lap splice between body station (BS) 400 and BS 520 at stringers S-6L and S-6R, and repair if necessary. This proposed AD would shorten the interval for the repetitive inspections, require modification for certain airplanes, and require certain post-modification inspections for other airplanes. This proposed AD results from reports of multiple adjacent cracks on an airplane, and a recent fleet-wide evaluation of widespread fatigue damage of skin lap joints, which indicated the need for revised procedures and reduced compliance times. We are proposing this AD to detect and correct cracking of the fuselage skin lap splice between BS 400 and BS 520 at stringers S-6L and S-6R. Such cracking could result in sudden loss of cabin pressurization and the inability of the fuselage to withstand fail-safe loads.
DATES:
We must receive comments on this proposed AD by August 15, 2011.
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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; 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.
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.
FOR FURTHER INFORMATION CONTACT:
Bill Ashforth, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 425-917-6432; fax 425-917-6590; e-mail: bill.ashforth@faa.gov.
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-2011-0645; Directorate Identifier 2010-NM-009-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 October 1, 1990, we issued AD 90-21-17, amendment 39-6768 (55 FR 41510, October 12, 1990), for certain Model 747 series airplanes. That AD requires inspection of the fuselage skin lap splice between body station (BS) 400 and BS 520 at stringers (S) 6L or S-6R, and repair if necessary. That AD resulted from reports of multiple adjacent cracks on one airplane. We issued that AD to detect and correct such cracking, which could result in sudden loss of cabin pressurization and the inability of the airplane fuselage to withstand fail-safe loads.
Actions Since Existing AD Was Issued
Since we issued AD 90-21-17, Boeing performed a fleet-wide evaluation of the Model 747 skin lap joints for widespread fatigue damage (WFD) and concluded that the existing repetitive interval of both the pre- and post-modification inspections needs to be reduced to preclude WFD. In addition, Boeing has determined that one of the existing modification options, which allow installation of protruding head fasteners without external reinforcement, does not provide adequate durability for WFD and must be prohibited, and all previously accomplished modifications that are inadequately reinforced (i.e., lap joints that have no external reinforcement or are only partially reinforced) must be reworked.
Relevant Service Information
The appropriate source of service information for the required actions in AD 90-21-17 is Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988; and Revision 1, dated March 29, 1990. Boeing has since issued Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, which does the following:
- Shortens the interval for repetitive inspections from 5,000 to 3,000 flight cycles, with a grace period of 1,000 flight cycles after the date on Revision 2 of the service bulletin.
- Adds installation of reinforcing doublers to the upper and lower skin of the lap splice for certain modified airplanes.
- Adds post-modification inspections which are internal and external high-frequency eddy current inspections for cracking in the area of the modification.
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 90-21-17, retain its requirements, and require accomplishing the actions specified in Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, described previously.
Changes to Existing AD
We have made the following changes to the existing AD:
1. Boeing Commercial Airplanes has received an Organization Designation Authorization (ODA). We have revised paragraph (p) in this proposed AD to add delegation of authority to Boeing Commercial Airplanes ODA to approve an alternative method of compliance for any repair required by this AD.
2. Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, specifies contacting 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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) whom we have authorized to make those findings.
3. Paragraph A. of AD 90-21-17 specifies doing a “close visual” inspection. We have revised that paragraph (paragraph (g) in this NPRM) to also refer to a “detailed inspection” to correspond to the terminology used in Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009. New Note 1 in this NPRM defines a detailed inspection.
4. This proposed AD would retain the requirements of AD 90-21-17. Since that AD 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 90-21-17 | Corresponding requirement in this proposed AD |
|---|---|
| paragraph A | paragraph (g) |
| paragraph B | paragraph (h) |
| paragraph C | paragraph (i) |
| paragraph D | paragraph (j) |
| paragraph E | paragraph (k) |
Costs of Compliance
There are about 165 airplanes of the affected design in the worldwide fleet; of these, 64 are U.S.-registered airplanes. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.
Estimated Costs
| Action | Work hours | Average labor rate per hour | Parts | Cost per airplane | Fleet cost |
|---|---|---|---|---|---|
| Inspection (required by AD 90-21-17) | 8 | $85 | $0 | $680 per inspection cycle | $43,520 per inspection cycle. |
| Modification (new proposed action) | Up to 370 | 85 | Between $954 and $2,064 | Up to $33,514 | Up to $2,144,896. |
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.
2. The FAA amends § 39.13 by removing amendment 39-6768 (55 FR 41510, October 12, 1990) and adding the following new AD:
The Boeing Company: Docket No. FAA-2010-0645; Directorate Identifier 2010-NM-009-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by August 15, 2011.
Affected ADs
(b) This AD supersedes AD 90-21-17, Amendment 39-6768.
Applicability
(c) This AD applies to The Boeing Company 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 Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009.
Subject
(d) Air Transport Association (ATA) of America Code 53: Fuselage.
Unsafe Condition
(e) This AD results from reports of multiple adjacent cracks on an airplane, and a recent fleet-wide evaluation of widespread fatigue damage of skin lap joints, which indicated the need for revised procedures and reduced compliance times. The Federal Aviation Administration is issuing this AD to detect and correct cracking of the fuselage skin lap splice between body station (BS) 400 and BS 520, at stringers S-6L and S-6R. Such cracking could result in sudden loss of cabin pressurization and the inability of the fuselage to withstand fail-safe loads.
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 90-21-17, Amendment 39-6768, With Revised Service Information, Reduced Inspection Interval, and Added Note
Inspection
(g) Conduct a close visual or detailed inspection, and a high frequency eddy current (HFEC) inspection, of the fuselage skin lap splice between BS 400 and BS 520, at stringers S-6L and S-6R, for cracking, in accordance with Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988; Revision 1, dated March 29, 1990; or Revision 2, dated October 1, 2009; at the times specified in paragraph (g)(1), (g)(2), or (g)(3) of this AD. After the effective date of this AD, only Revision 2 may be used. Adequate lighting must be used for this inspection. The eddy current inspections may be conducted without removal of the paint, provided the paint does not interfere with the inspections. Paint must be removed, using an approved chemical stripper, in any situation where the inspector determines that the paint is interfering with the proper functioning of the inspection instrument.
(1) Within the next 100 landings after March 31, 1989 (the effective date of Amendment 39-6146, AD 89-05-03, which was superseded by AD 90-21-17), for airplanes that have accumulated 16,000 or more landings as of March 31, 1989, unless previously accomplished within the last 4,900 landings.
(2) Within the next 1,000 landings after March 31, 1989, or prior to the accumulation of 16,000 landings, whichever occurs first, for airplanes that have accumulated between 12,000 and 16,000 landings, as of March 31, 1989, unless previously accomplished within the last 4,000 landings.
(3) Prior to the accumulation of 13,000 landings for airplanes that have accumulated 12,000 or fewer landings as of March 31, 1989, unless previously accomplished within the last 5,000 landings.
Note 1:
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 mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”
(h) On airplanes which have been modified to the stretched-upper-deck configuration, as identified in Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988; or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; the accumulated landing threshold for compliance with paragraph (g) of this AD is measured from the time of the stretched-upper-deck modification.
(i) If no cracking is detected during the inspections required by paragraph (g) of this AD, repeat the inspections required by paragraph (g) of this AD one time at the earlier of the times specified in paragraphs (i)(1) and (i)(2) of this AD. Thereafter repeat the inspections at intervals not to exceed 3,000 landings.
(1) Within 5,000 landings after the last inspection.
(2) Within 3,000 landings after the last inspection, or within 1,000 landings after the effective date of this AD, whichever occurs later.
(j) If cracks are detected during the inspections required by paragraph (g) of this AD, accomplish the repair or preventive modification of the affected lap splice, in accordance with Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988; or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; prior to further pressurized flight. After the effective date of this AD, only Revision 2 may be used. If cracks are repaired in local areas without accomplishing preventive modification of the entire affected lap area, continue inspections of the unmodified and unrepaired areas of the affected lap splice in accordance with paragraph (i) of this AD.
(k) For airplanes incorporating the preventive modification, as described in Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988; or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; accomplish the inspections required by paragraph (g) of this AD prior to the accumulation of 10,000 landings after the modification and thereafter at intervals not to exceed 5,000 landings. If cracks are found, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, prior to further pressurized flight.
New Requirements of This AD
Post-Modification Inspections
(l) For airplanes on which a protruding head fastener modification has been done in accordance with Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988; or Revision 1, dated March 29, 1990: Within 10,000 flight cycles after modification, or within 500 flight cycles after the effective date of this AD, whichever occurs later, do an external HFEC inspection for cracking in the skin around the fasteners in the upper row of the lap joint, in accordance with Part 5 of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009 (“the service bulletin”). If any crack is found, before further flight repair in accordance with the service bulletin (except as required by paragraph (o) of this AD), or do the modification specified in paragraph (n) of this AD. Repeat the inspection in affected uncracked areas at intervals not to exceed 500 flight cycles, until the modification specified in paragraph (n) of this AD is done.
(m) For airplanes on which an external doubler repair has been installed as a modification that was done in accordance with a method other than that specified in Boeing 747 SRM 53-30-03, Figure 19, 25, 28 or 34: Within 10,000 flight cycles after modification, or within 500 flight cycles after the effective date of this AD, whichever occurs later, do an internal HFEC inspection for cracking in the skin around the fasteners in the upper row of the lap joint, in accordance with Part 5 of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009 (“the service bulletin”). If any crack is found, before further flight, repair in accordance with the service bulletin (except as required by paragraph (o) of this AD), or do the modification specified in paragraph (n) of this AD. Repeat the inspection in affected uncracked areas at intervals not to exceed 500 flight cycles, until the modification specified in paragraph (n) of this AD is done.
External Doubler Modification
(n) For airplanes on which no previous modification or repair has been installed in the affected area or on which a protruding head fastener modification or a Boeing 747 SRM 53-30-03 repair or modification has been installed that is not per Figure 19, 25, 28, or 34 of the Boeing 747 SRM for the full length of the lap splice: Within 14,000 flight cycles after the first repair or modification was done, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later, modify the skin, and do all post-modification inspections and repairs, in accordance with Part 3 of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, except as required by paragraph (o) of this AD. Do the post-modification inspection within 10,000 flight cycles after installation of the modification. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles. All applicable repairs must be done before further flight.
Exception to Service Bulletin Specification
(o) Where Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (p) of this AD.
Alternative Methods of Compliance (AMOCs)
(p)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD. Information may be e-mailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) or other person 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.
(4) AMOCs approved previously in accordance with AD 90-21-17 are approved as AMOCs for the corresponding provisions of paragraphs (g) and (i) of this AD. AMOCs approved previously in accordance with AD 90-21-17 are approved as AMOCs for the corresponding provisions of paragraphs (j) and (n) of this AD only if the repair or preventive modification of the affected lap splice was done in accordance with Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009 (“the service bulletin”), including Boeing Designated Engineering Representative (DER) or Airworthiness Representative (AR) approvals of deviations to Revision 2 of the service bulletin.
Related Information
(q) For more information about this AD, contact Bill Ashforth, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 425-917-6432; fax 425-917-6590; e-mail: bill.ashforth@faa.gov.
(r) 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 206-544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; 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.
Issued in Renton, Washington, on June 17, 2011.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2011-16370 Filed 6-28-11; 8:45 am]
BILLING CODE 4910-13-P