Airworthiness Directives: Boeing Model 747 Airplanes
Federal Register: September 23, 2008 (Volume 73, Number 185)
Proposed Rules
Page 54751-54755
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
DOCID:fr23se08-30
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration 14 CFR Part 39
Docket No. FAA-2008-0981; Directorate Identifier 2008-NM-073-AD
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747 Airplanes
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 Boeing Model 747 airplanes. The existing AD currently requires repetitive inspections of the body station (BS) 2598 bulkhead, and corrective actions if necessary. The existing AD also currently requires a terminating modification for the repetitive inspections and a post-modification inspection of the modified area. This proposed AD would continue requiring those actions with revised service information. For certain airplanes, this proposed
AD would require new repetitive inspections, an interim modification, and post-interim modification inspections. For certain airplanes, this proposed AD also would require replacing any previously repaired aft inner chord and reinstalling the terminating modification. This proposed AD results from reports of cracked aft inner chords on airplanes after certain requirements of the existing AD were done. We are proposing this AD to prevent fatigue cracking of the BS 2598 bulkhead structure, which could result in inability of the structure to carry horizontal stabilizer flight loads, and loss of controllability of the airplane.
DATES: We must receive comments on this proposed AD by November 7, 2008.
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.
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.
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-2008-0981;
Directorate Identifier 2008-NM-073-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
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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 February 22, 2006, we issued AD 2006-05-06, amendment 39-14503
(71 FR 12125, March 9, 2006), for certain Boeing Model 747 airplanes.
That AD requires repetitive inspections of the body station (BS) 2598 bulkhead, and corrective action if necessary. That AD also requires modification of the bulkhead, including a one-time inspection and corrective action if necessary, which terminates certain repetitive inspections. In addition, that AD also requires a post-modification inspection of the modified area. That AD resulted from reports of fatigue cracking on BS 2598 bulkhead. We issued that AD to prevent fatigue cracking of the BS 2598 bulkhead structure, which could result in inability of the structure to carry horizontal stabilizer flight loads, and loss of controllability of the airplane.
Actions Since Existing AD Was Issued
Since we issued AD 2006-05-06, we have received a report of a cracked aft inner chord that was completely severed and a 0.5-inch crack in the adjacent frame support on an in-service airplane. These cracks have been attributed to fatigue. The airplane had accumulated 9,988 total flight cycles and 68,081 total flight hours. A surface high frequency eddy current (HFEC) inspection had been done on the aft inner chord as required by AD 2006-05-06. In addition, we have received reports of cracked aft inner chords that had been previously repaired and not replaced before the bulkhead was modified in accordance with AD 2006-05-06. Repaired chords can have an active crack tip that may continue to propagate, even if the area has been reinforced.
Therefore, we have determined that in addition to the repetitive surface HFEC inspections required by AD 2006-05-06, repetitive open hole surface HFEC inspections are necessary to detect cracks that are beneath the surface of the aft inner chords. We also have determined that the terminating modification, if installed with a repaired aft inner chord in place as required by AD 2006-05-06, does not adequately address the identified unsafe condition, and that further rulemaking is necessary.
Relevant Service Information
We have reviewed Revision 4 of Boeing Alert Service Bulletin 747- 53A2427, dated March 6, 2008 (AD 2006-05-06 refers to Boeing Alert
Service Bulletin 747-53A2427, Revision 2, dated October 5, 2000; or
Revision 3, dated September 27, 2001; as appropriate sources of service information for accomplishing certain requirements). The repetitive surface HFEC inspections described in Revision 4 are identical to those in earlier revisions of the service bulletin. Revision 4 adds new repetitive open hole HFEC inspections to detect cracks in the bulkhead splice fitting, frame support fitting, and forward and aft inner chords on the left and right side of the BS 2598 bulkhead, and repair if necessary. Revision 4 also adds a new interim modification for the aft inner chords, which defers the repetitive surface and open hole HFEC inspections. The compliance time for accomplishing the initial open hole inspection is before 6,000 or 16,000 total flight cycles
(depending on the airplane configuration), or within 1,500 flight cycles after the date on Revision 4 of the service bulletin, whichever occurs later. The compliance time for accomplishing repetitive surface and open hole HFEC inspections is within 1,500 flight cycles after the last surface HFEC inspection of the forward side of the bulkhead or within 6,000 flight cycles after installation of the structural repair manual repair or interim modification, depending on the airplane configuration.
We also have reviewed Revision 1 of Boeing Service Bulletin 747-53- 2473, dated February 20, 2007 (AD 2006-05-06 refers to Boeing Service
Bulletin 747-53-2473, dated March 24, 2005; as an appropriate source of service information for accomplishing the terminating modification).
Revision 1 removes the option to re-install an aft inner chord that has been repaired before accomplishing the terminating modification. The modification and related investigative and corrective actions are essentially identical to those specified in Boeing Service Bulletin 747-53-2473, dated March 24, 2005.
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 develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2006-05-06 and would retain the requirements of the existing AD. This proposed AD would also require accomplishing the actions specified in service information described previously, except as discussed under ``Differences Between the Proposed AD and Service
Information.''
Differences Between the Proposed AD and Service Information
The service information described previously 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.
For certain airplanes, Boeing Service Bulletin 747-53-2473,
Revision 1, does not specify a compliance time for replacing the previously repaired aft inner chord and reinstalling the terminating modification. In developing an appropriate compliance time for these proposed actions, we considered the degree of urgency associated with the subject unsafe condition, the manufacturer's recommendation for an appropriate compliance time, and the average utilization of the affected fleet. In light of these factors, we find that a compliance time of within 3,000 flight cycles after doing the modification required by paragraph (l) of this AD, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, represents an appropriate interval of time for affected airplanes to continue to operate without compromising safety. This difference has been coordinated with Boeing.
Explanation of Change Made to Requirements of AD 2006-05-06 Retained in
This AD
We have simplified paragraphs (g), (i), and (k) of this AD by referring to the ``Alternative Methods of Compliance (AMOCs)'' paragraph of this AD for repair methods.
Costs of Compliance
There are about 998 airplanes of the affected design in the worldwide fleet. The following table provides the
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estimated costs for U.S. operators to comply with this proposed AD.
Estimated Costs
Number of
Average
U.S.-
Action
Work hours labor rate
Parts
Cost per airplane
registered
Fleet cost per hour
airplanes
Surface HFEC inspections and open
2
$80 None.................... $160, per inspection
162 $25,920, per inspection hole HFEC inspections.
cycle.
cycle.
Detailed inspections.................
2
80 None.................... $160, per inspection
162 $25,920, per inspection cycle.
cycle.
Interim modification.................
4
80 $4,000.................. $4,320.................
162 $699,840.
Replacement of Previously Repaired
2
80 None.................... $160...................
162 $25,920.
Aft Inner Chords.
Terminating modification.............
126
80 $33,716................. $43,796................
162 $7,094,952.
Post-terminating modification
4
80 None.................... $320...................
162 $51,840. inspection.
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, 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.
Sec. 39.13 [Amended] 2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by removing amendment 39-14503 (71 FR 12125, March 9, 2006) and adding the following new airworthiness directive (AD):
Boeing: Docket No. FAA-2008-0981; Directorate Identifier 2008-NM- 073-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by November 7, 2008.
Affected ADs
(b) This AD supersedes AD 2006-05-06.
Applicability
(c) This AD applies to 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, line numbers 1 through 1307 inclusive.
Unsafe Condition
(d) This AD results from reports of cracked aft inner chords on airplanes after certain requirements of the existing AD were done.
We are issuing this AD to prevent fatigue cracking of the body station (BS) 2598 bulkhead structure, which could result in inability of the structure to carry horizontal stabilizer flight loads, and loss of controllability 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.
Requirements of AD 2006-05-06
Repetitive High Frequency Eddy Current (HFEC) Inspections of the
Bulkhead Frame Supports
(f) Before the accumulation of 10,000 total flight cycles, or within 1,000 flight cycles after August 16, 2001 (the effective date of AD 2001-14-07), whichever occurs later: Do an open-hole HFEC inspection to find cracking of the bulkhead frame support under the hinge support fittings of the horizontal stabilizer on the left and right sides at BS 2598, in accordance with Figure 2 of the
Accomplishment Instructions of Boeing Service Bulletin 747-53A2449,
Revision 1, dated May 24, 2001; or Revision 2, dated March 14, 2002.
Repeat the inspection after that at intervals not to exceed 3,000 flight cycles. Inspections accomplished before August 16, 2001, per
Boeing Alert Service Bulletin 747-53A2449, dated June 8, 2000, are considered acceptable for compliance with the applicable inspection specified in this paragraph.
Repair of Any Cracked Bulkhead Frame Support
(g) If any cracking is found during any inspection required by paragraph (f) of this AD, before further flight, repair using a method approved in accordance with the
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procedures specified in paragraph (w) of this AD.
Repetitive Inspections of Inner Chords, Frame Support, and Splice
Fitting
(h) Except as provided by paragraph (n) of this AD: Do a surface
HFEC inspection of the forward and aft inner chords, the frame support, and the splice fitting of the forward inner chord of the upper corners of the station 2598 bulkhead to find cracking, in accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 747-53A2427, Revision 2, dated October 5, 2000; or
Revision 3, dated September 27, 2001; at the latest of the times specified in paragraphs (h)(1) and (h)(2) of this AD, as applicable.
Repeat the inspection after that at intervals not to exceed 1,500 flight cycles.
(1) For airplanes having line numbers 1 through 1241 inclusive:
(i) Before the accumulation of 6,000 total flight cycles.
(ii) Within 500 flight cycles after August 28, 2001 (the effective date of AD 2001-15-03).
(iii) For airplanes inspected before August 28, 2001, in accordance with Boeing Alert Service Bulletin 747-53A2427, dated
December 17, 1998 (including inspections of the splice fitting), or
Revision 1, dated October 28, 1999: Within 1,500 flight cycles after accomplishment of the last inspection done in accordance with the original service bulletin or Revision 1, as applicable.
(2) For airplanes having line numbers 1242 through 1307 inclusive:
(i) Before the accumulation of 16,000 total flight cycles.
(ii) Within 500 flight cycles after August 28, 2001.
(iii) For airplanes inspected before August 28, 2001, in accordance with Boeing Alert Service Bulletin 747-53A2427, dated
December 17, 1998 (including inspections of the splice fitting), or
Revision 1, dated October 28, 1999: Within 1,500 flight cycles after accomplishment of the last inspection done in accordance with the original service bulletin or Revision 1, as applicable.
Repair of Any Cracked Inner Chord, Frame Support, or Splice Fitting
(i) If any cracking is found during the inspections required by paragraph (h) of this AD, before further flight, repair in accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 747-53A2427, Revision 2, dated October 5, 2000; or
Revision 3, dated September 27, 2001; except as provided by paragraph (n) of this AD, and except where the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (w) of this AD.
Repetitive Detailed Inspections of BS 2598 Bulkhead
(j) Before the accumulation of 10,000 total flight cycles, or within 1,000 flight cycles after October 27, 2003 (the effective date of AD 2003-19-08), whichever is later: Do a detailed inspection of the BS 2598 bulkhead for discrepancies (cracking, elongated fastener holes) of the areas specified in paragraphs (j)(1) and
(j)(2) of this AD, in accordance with the Accomplishment
Instructions of Boeing Alert Service Bulletin 747-53A2467, dated
July 26, 2001; or Revision 1, dated April 28, 2005. Repeat the inspections after that at intervals not to exceed 3,000 flight cycles.
(1) The lower aft inner chords.
(2) The upper aft outer chords, and the diagonal brace attachment fittings, flanges, and rods.
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 mirrors, magnifying lenses, etc. may be necessary. Surface cleaning and elaborate procedures may be required.''
Repair of Any Cracked BS 2598 Bulkhead
(k) If any discrepancy is found during any inspection required by paragraph (j) of this AD: Before further flight, repair in accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 747-53A2467, dated July 26, 2001; or Revision 1, dated April 28, 2005. If the service bulletin specifies to contact
Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (w) of this AD.
Terminating Modification
(l) Except as provided by paragraphs (p) and (q) of this AD:
Before the accumulation of 20,000 total flight cycles, or within 48 months after April 13, 2006 (the effective date of AD 2006-05-06), whichever occurs later, modify the bulkhead by doing all applicable actions including surface and open-hole HFEC inspections for cracking of the upper forward inner chords, aft inner chords, upper splice fittings, and frame support fittings, as specified in the
Accomplishment Instructions of Boeing Service Bulletin 747-53-2473, dated March 24, 2005. Repair any cracks before further flight in accordance with the service bulletin. Where the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions: Before further flight, repair the cracks using a method approved in accordance with the procedures specified in paragraph (w) of this AD. Accomplishment of the modification terminates the requirements of paragraph (f), (h), and (j)(1) of this AD.
Post-Modification Inspection and Repair
(m) Within 20,000 flight cycles after the modification required by paragraph (l) of this AD, inspect the BS 2598 bulkhead for cracks, and repair any cracks before further flight, in accordance with a method approved by the Manager, Seattle Aircraft
Certification Office (ACO).
New Requirements of This AD
New Revision of Service Bulletin
(n) As of the effective date of this AD, use only the
Accomplishment Instructions of Boeing Alert Service Bulletin 747- 53A2427, Revision 4, dated March 6, 2008, to do the repetitive surface HFEC inspections required by paragraph (h) of this AD and the repair required by paragraph (i) of this AD.
Terminating Repair for Repetitive Surface HFEC Inspections
(o) As of the effective date of this AD, accomplishment of the aft inner chord repair required by paragraph (i) of this AD in accordance with the applicable structural repair manual (SRM) specified in the Accomplishment Instructions of Boeing Alert Service
Bulletin 747-53A2427, Revision 4, dated March 6, 2008, ends the repetitive surface HFEC inspections required by paragraph (h) of this AD for that side of the bulkhead only.
Replacement of Previously Repaired Aft Inner Chord and Reinstallation of Terminating Modification
(p) For airplanes on which the terminating modification required by paragraph (l) of this AD has been done before the effective date of this AD, and on which any previously repaired aft inner chord was not replaced during that terminating modification: Within 3,000 flight cycles after doing the modification, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, replace any previously repaired aft inner chord with a new aft inner chord and reinstall the terminating modification using a method approved in accordance with the procedures specified in paragraph
(w) of this AD. Accomplishment of the replacement and reinstallation of the terminating modification terminates the requirements of paragraphs (l) and (m) of this AD and repetitive inspections required by this AD, except for the inspections specified in paragraph (r) of this AD.
Revised Terminating Modification
(q) For airplanes on which the terminating modification required by paragraph (l) of this AD has not been done as of the effective date of this AD: Before the accumulation of 20,000 total flight cycles, or within 18 months after the effective date of this AD, whichever occurs later, modify and do applicable relative investigative and corrective actions by doing all the applicable actions specified in the Accomplishment Instructions of Boeing
Service Bulletin 747-53-2473, Revision 1, dated February 20, 2007; except where the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, before further flight, repair the cracks using a method approved in accordance with the procedures specified in paragraph (w) of this
AD. The applicable related investigative and corrective actions must be done before further flight. Accomplishment of the replacement and reinstallation of the terminating modification terminates the requirements of paragraphs (l) and (m) of this AD and repetitive inspections required by
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this AD, except for the inspections specified in paragraph (r) of this AD.
Post-Modification Inspection and Repair
(r) Within 20,000 flight cycles after the modification required by paragraph (p) or (q) of this AD, as applicable, inspect the BS 2598 bulkhead for cracks, and repair any crack before further flight, in accordance with a method approved by the Manager, Seattle
ACO.
Open Hole HFEC Inspection(s) and Terminating Repair
(s) For airplanes on which the terminating modification required by paragraph (l) or (q) of this AD has not been done: Do an initial open hole HFEC inspection to detect cracks in the bulkhead splice fitting, frame support fitting, and forward and aft inner chords on the left and right sides of the BS 2598 bulkhead, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2427, Revision 4, dated March 6, 2008. Do the initial inspection at the applicable time specified in Table 1 or 3 of paragraph 1.E., ``Compliance,'' of the service bulletin; except, where the service bulletin specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.
(1) If no crack is detected, repeat the open hole HFEC inspection thereafter at intervals not to exceed 1,500 flight cycles.
(2) If any crack is detected, before further flight, repair it in accordance with the service bulletin; except, where the service bulletin specifies to contact Boeing for appropriate action, before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (w) of this
AD. Accomplishment of the aft inner chord repair in accordance with the applicable SRM specified in the Accomplishment Instructions of the service bulletin ends the repetitive open hole HFEC inspections required by paragraphs (h) and (s)(1) of this AD for that side of the bulkhead only.
Interim Modification
(t) For Group 1 airplanes, as identified in Boeing Alert Service
Bulletin 747-53A2427, Revision 4, dated March 6, 2008, on which the terminating modification required by paragraph (l) or (q) of this AD has not been done: Before the accumulation of 12,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, install the interim modification for the aft inner chords, in accordance with the Accomplishment
Instructions of the service bulletin. Accomplishment of the interim modification ends the repetitive open hole and surface HFEC inspections required by paragraphs (h) and (s)(1) of this AD.
Post-Interim Modification/Repair Repetitive Surface and Open Hole HFEC
Inspections
(u) For airplanes on which the interim modification required by paragraph (t) of this AD has been done or the repair of any cracked aft inner chord has been done in accordance with the SRM specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2427, Revision 4, dated March 6, 2008, as required by paragraph (i) or (s)(2) of this AD; and on which the terminating modification required by paragraph (l) or (q) of this AD has not been done: At the applicable times specified in Table 1, 2, or 3 of paragraph 1.E., ``Compliance,'' of the service bulletin, do a surface HFEC inspection to detect cracks on the forward side
(unmodified area) of the bulkhead and open hole and surface HFEC inspections to detect cracks in the modified or repaired area, in accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 747-53A2427, Revision 4, dated March 6, 2008.
Repeat the open hole and surface HFEC inspections thereafter at intervals not to exceed 1,500 flight cycles, until the modification required by paragraph (q) of this AD is done, as applicable; except, for airplanes on which the repair of any cracked aft inner chord has been done on only one side of the bulkhead in accordance with the applicable SRM as required by paragraph (i) or (s)(2) of this AD, the repetitive open hole and surface HFEC inspections required by paragraph (h) and (s)(1) of this AD must continue to be done for the other side of the bulkhead.
Repair of Any Cracked Inner Chord, Splice Fitting, or Frame Support
Fitting
(v) If any crack is detected during any open hole or surface
HFEC inspection required by paragraph (u) of this AD, before further flight, repair any cracked inner chord, splice fitting, or frame support fitting, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2427, Revision 4, dated
March 6, 2008; except, where the service bulletin specifies to contact Boeing for appropriate action, before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (w) of this AD.
Alternative Methods of Compliance (AMOCs)
(w)(1) The Manager, Seattle ACO, FAA, ATTN: Ivan Li, Aerospace
Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917- 6437; fax (425) 917-6590; has the authority to approve AMOCs for this AD, if requested using 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, and the approval must specifically refer to this
AD.
(4) AMOCs approved previously in accordance with AD 2006-05-06 are approved as AMOCs for the corresponding provisions of this AD.
Issued in Renton, Washington, on September 11, 2008.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
FR Doc. E8-22215 Filed 9-22-08; 8:45 am
BILLING CODE 4910-13-P
