AD 2008-22-17

The FAA is superseding an existing airworthiness directive (AD) that applies to certain Boeing Model 747 series airplanes. That AD currently requires repetitive inspections for cracking and corrosion of all exposed surfaces of the carriage spindles (including the inner bore and aft links) of the trailing edge flaps, and additional inspection and corrective action if necessary. That AD also currently requires repetitive overhaul of the carriage spindle and aft link, which terminates the repetitive inspections. This new AD adds a repetitive inspection to detect broken parts, and revises the overhaul threshold and repetitive intervals. This AD results from analysis that showed additional inspections should be done to prevent the loss of a flap, and that the flight-hour-based interval should be revised to a flight- cycle-based interval, because the greatest loads on the spindles happen during takeoff and landing. We are issuing this AD to detect and correct failed carriage spindles or aft links of the inboard or outboard trailing edge flaps. Such failure could cause the flap to depart the airplane, reducing the flightcrew's ability to maintain the safe flight and landing of the airplane.

Final rule.

2008-22-17 Boeing: Amendment 39-15714. Docket No. FAA-2008-0414; Directorate Identifier 2007-NM-095-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective December 19, 2008. \n\nAffected ADs \n\n\t(b) This AD supersedes AD 90-17-19. \n\nApplicability \n\n\t(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, and 747SR series airplanes, certificated in any category. \n\nUnsafe Condition \n\n\t(d) This AD results from analysis that showed that additional inspections should be done to prevent the loss of a flap, and that the flight-hour-based interval should be revised to a flight-cycle- based interval, because the greatest loads on the spindles happen during takeoff and landing. We are issuing this AD to detect and correct failed carriage spindles or aft links of the inboard or outboard trailing edge flaps. Such failure could cause the flap to depart the airplane, reducing the flightcrew's abilityto maintain the safe flight and landing of the airplane. \n\nCompliance \n\n\t(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. \n\nRequirements of AD 90-17-19 \n\nRepetitive Inspections \n\n\t(f) For all airplanes except those airplanes on which the repetitive overhauls required by paragraph B. of AD 90-17-19 are being accomplished as of the effective date of this AD: Prior to the accumulation of 30,000 flight hours or 8 years on each new or previously overhauled flap carriage spindle, whichever occurs first, remove the aft link and thrust collars from the trailing edge flaps' carriage spindles and perform a detailed inspection of all exposed surfaces of the carriage spindles, including inner bore, and aft links to detect cracking and corrosion, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989. \n\n\tNote 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.'' \n\n\t(1) If no cracking or corrosion is found, repeat the inspections required by paragraph (f) of this AD at intervals not to exceed 12 months until the carriage spindles are overhauled in accordance with paragraph (g) of this AD. \n\t(2) If a cracked carriage spindle or aft link is found, prior to further flight, replace the part(s) in accordance with the service bulletin. \n\t(3) If corrosion is found on any part of the carriage spindle/ aft link assembly, but not on the other assembly on the same flap, perform a repetitive general visual inspection in accordancewith the service bulletin at intervals not to exceed 2 months. Overhaul or replace corroded parts in accordance with the service bulletin within 36 months after detection of the corrosion. \n\t(4) If corrosion is found on any part of both carriage spindle/ aft link assemblies on the same flap, prior to further flight, overhaul or replace the part(s) in accordance with the service bulletin or repair in accordance with the procedures specified in paragraph (m) of this AD. \n\n\tNote 2: For the purposes of this AD, a general visual inspection is: "A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplightand may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.'' \n\nInitial and Repetitive Overhauls \n\n\t(g) For all airplanes: Prior to the accumulation of 8 years or 30,000 flight hours on any new or previously overhauled flap carriage spindle, whichever occurs later, remove the carriage spindle and aft link, and overhaul in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989. Repeat the overhaul thereafter at intervals not to exceed 8 years or 30,000 flight hours, whichever occurs earlier. Accomplishment of initial overhaul required by this paragraph terminates the requirements of paragraph (f) of this AD. \n\nNew Requirements of This AD \n\nTerminating Requirements \n\n\t(h) The actions specified in paragraphs (i) and (j) of this AD must be accomplished in their entirety, at the specified compliance times, to terminate the requirements of paragraphs (f) and (g) of this AD. There is no terminating action for the requirements of paragraphs (i) and (j) of this AD. \n\nRepetitive Inspection for Broken Parts \n\n\t(i) For all airplanes: Within 12 months or 400 flight cycles after the effective date of this AD, whichever occurs later, do a general visual inspection of all eight carriage spindles and aft links to detect a broken carriage spindle or broken aft link, and do all applicable corrective actions before further flight. Repeat the inspection thereafter at intervals not to exceed 400 flight cycles. Do all actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. For airplanes identified in Note (d) of Table 1 in paragraph 1.E., "Compliance,'' of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008, the initial compliance time and repetitive interval for a flap may be extended to 1,000 flight cycles when new carriages are installed at both the inboard and outboard carriage locations on the flap. \n\nRepetitive Overhauls \n\n\t(j) For all airplanes: At the later of the times specified in paragraph (j)(1) or (j)(2) of this AD, remove the carriage spindle and aft link, and overhaul in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. Repeat the overhaul thereafter at the applicable repeat interval specified in paragraph 1.E., "Compliance,'' of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. \n\t(1) The applicable threshold specified in paragraph 1.E. "Compliance,'' of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. \n\t(2) Within 48 months after the effective date of this AD. \n\nOptional Terminating Action \n\n\t(k) For Groups 1 and 3 airplanes identified in Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008: Replacing the existing 4340M aft linkwith a new corrosion resistant steel (CRES) aft link in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2371, dated December 20, 2000, or with an aft link specified in paragraph 3.B.5. of the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008, terminates the repetitive inspection requirements of paragraph (f) of this AD, and the repetitive overhaul requirements of paragraphs (g) and (j) of this AD for that aft link only. The repetitive inspections for broken parts required by paragraph (i) of this AD cannot be terminated. \n\nCredit for Actions Done Using Previous Revision of Service Bulletin \n\n\t(l) Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 747-27-2280, Revision 4, dated April 26, 2001, are acceptable for compliance with the corresponding requirements of paragraphs (f) and (g) of this AD. Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 747-27-2280, Revision 5, dated April 5, 2007, are acceptable for compliance with the corresponding requirements of paragraphs (i) and (j) of this AD. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(m)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Gary Oltman, Aerospace Engineer, Airframe Branch, ANM- 120S, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6443; fax (425) 917-6590; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. \n\t(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. \n\t(3) AMOCs approved previously in accordance with AD 90-17-19 are approved as AMOCs for the corresponding provisions of this AD. \n\t(4) Adjustments to the compliance times approved previously in accordance with AD 90-17-19 are not approved for the corresponding provisions of this AD. \n\t(5) 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. \n\nMaterial Incorporated by Reference \n\n\t(n) You must use the applicable service information identified in Table 1 of this AD to perform the actions that are required by this AD, unless the AD specifies otherwise. \n\nIf you accomplish the optional terminating actions specified by this AD, you must use the service information identified in Table 2 of this AD to perform those actions, unless the AD specifies otherwise. \n\nTable 1--Material Incorporated by Reference for Actions Required in this AD\n\n\nService Bulletin\nRevision Level\nDate\nBoeing Service Bulletin 747-27-2280\n3\nNovember 30, 1989\nBoeing Service Bulletin 747-27-2280\n6\nFebruary 14, 2008\n\n\tBoeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989, contains the following effective pages: \n\n\nPage No.\nRevision level shown on page\nDate shown on page\n1-26\n3\nNov. 30, 1989.\n27-29\n2\nMar. 23, 1989\n\nTable 2--Material Incorporated by Reference for the Optional Terminating Action in this AD\n\n\nService Bulletin\nRevision Level\nDate\nBoeing Service Bulletin 747-27-2280\n6\nFebruary 14, 2008\nBoeing Service Bulletin 747-27-2371\nOriginal\nDecember 20, 2000\n \n\t(1) The Director of the Federal Register approved the incorporation by reference of these documents in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. \n\t(2)Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207; telephone 206-544-9990; fax 206-766-5682; e- mail DDCS@boeing.com; Internet https://www.myboeingfleet.com; for a copy of this service information. \n\t(3) You may review copies of the service information that is incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_ regulations/ibr_locations.html.

Discussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that supersedes AD 90-17-19, amendment 39- 6705 (55 FR 33280, August 15, 1990). The existing AD applies to certain Boeing Model 747 series airplanes. That NPRM was published in the Federal Register on April 28, 2008 (73 FR 22845). That NPRM proposed to retain the requirements of the existing AD but to add a repetitive inspection to detect broken parts, and revise the overhaul threshold and repetitive intervals. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments that have been received on the NPRM. \n\nSupport for the NPRM \n\n\tBoeing has reviewed the NPRM and concurs with the contents of the proposed rule. Northwest Airlines (NWA) has no technical objection to the AD. \n\nRequests To Revise Inspection Threshold \n\n\tThe Hong Kong Civil Aviation Department, and AirTransport Association (ATA), on behalf of its member NWA, request that we revise the inspection threshold for the inspection for broken parts proposed in paragraph (i) of the NPRM. The commenters point out that the NPRM stated the first inspection should be done at the earlier of 12 months or 400 flight cycles after the effective date of the AD; however, Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008, specifies doing that inspection at the later of those two times. \n\tWe agree with the commenters. It was our intent that the compliance threshold should match that of the Boeing Service Bulletin 747-27-2280, Revision 6. We have revised paragraph (i) of the AD as requested. \n\nRequest To Clarify Compliance Times \n\n\tATA on behalf of NWA, requests that we revise paragraph (j), "Repetitive Overhauls,'' of the NPRM to clarify the compliance threshold for the initial overhaul for carriage assemblies previously overhauled in accordance with the requirements of AD 90-17-19. NWA requests that we specify that the compliance threshold is measured from the completion of the overhaul mandated by AD 90-17-19 for carriages/ assemblies previously overhauled. \n\tWe agree that the compliance times can be clarified, although we do not agree that it is necessary to change the AD in this regard. Paragraph (j) of the NPRM specifies doing the initial overhaul at the later of the applicable thresholds specified in paragraph 1.E., "Compliance,'' of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008; or 48 months after the effective date of the AD. Paragraph 1.E. of the service bulletin includes notes (a) and (e). Note (a) states, "Compliance Time and Repeat Interval applies to each new or overhauled carriage or aft link from the time it enters service, regardless of whether the part is removed and installed on another airplane.'' Note (e) states, "The initial overhaul must be accomplished prior to terminating the repetitive overhauls at the compliance times specified in FAA AD 90-17-19.'' These notes provide the information requested by the commenter. It is the intent of this new AD that if the initial or repetitive overhaul required by AD 90-17- 19 is due prior to "48 months after the effective date of this AD,'' the compliance time for the initial carriage overhaul will not be affected by the new requirements of this AD. However, if the initial or repetitive carriage overhaul required by AD 90-17-19 is due subsequent to "48 months after the effective date of this AD,'' the required carriage overhauls are governed by the new compliance times of this AD. Specifically, the compliance time for carriages with sleeved journals is to accomplish the initial overhaul within 6000 flight cycles or 8 years, whichever occurs first, since new or since completion of the overhaul mandated by AD 90-17-19; and the compliance time for carriages with chrome-plated forward and aft journals is to accomplish the initial overhaul within 9000 flight cycles or 8 years, whichever occurs first, since new or since completion of the overhaul mandated by AD 90- 17-19. We have not changed the AD in this regard. \n\nRequest To Revise Optional Terminating Action \n\n\tJapan Airlines (JAL) requests that we refer to the latest aft links. JAL explains that the latest aft links do not require a repeat overhaul, and points out that the latest aft links are not shown in Boeing Service Bulletin 747-27-2371, dated December 20, 2000 (we referred to this service bulletin in paragraph (k) of the NPRM as the source of service information for the optional terminating action of replacing the existing 4340M aft link with a new corrosion resistant steel (CRES) aft link). JAL states that the latest aft links are shown in paragraph 3.B.5. of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. \n\tWe agree that the newest aft links do not require a repeat overhaul and that a note in paragraph 3.B.5. of Boeing Service Bulletin 747-27-2280, Revision 6, refers to these links. Therefore, we have revised paragraph (k) of this AD to state that replacing the existing 4340M aft link with a new CRES aft link in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2371, dated December 20, 2000, or with an aft link specified in paragraph 3.B.5. of the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008, terminates the repetitive inspection requirements of paragraph (f) of this AD and the repetitive overhaul requirements of paragraphs (g) and (j) of this AD for that aft link only. \n\nRequest To Revise Repetitive Intervals \n\n\tAll Nippon Airways (ANA) requests that we use the results of a Boeing analysis, using ANA flight data as a basis, to change intervals in the NPRM for Boeing Model 747-400D series airplanes, or provide the intervals as an alternative method of compliance (AMOC). ANA states that it operates five Boeing Model 747-400 seriesairplanes, for which the maximum takeoff weight (MTOW) is 899,600 pounds, and 11 Boeing Model 747-400D series airplanes for which the MTOW is 599,600 pounds. ANA believes that the loads on the spindles must be smaller for the Model 747-400D series airplanes because of the difference between the takeoff and landing weights. ANA requests that Boeing develop for Model 747-400D series airplanes different repetitive intervals for the flap carriage overhaul and the general visual inspection. ANA makes this request because the repetitive flap carriage overhaul must be done every two to three C- checks (3 to 4.5 years) and the general visual inspection must be done every 2 months, thus requiring a lot of manpower and costs. ANA provided no analysis to justify this requested increase. \n\tWe disagree with the request to change the AD to include revised intervals for Boeing Model 747-400D series airplanes. The intervals for inspection proposed in the NPRM were based on analysis provided by the manufacturer. In the absence of any analysis showing the differences in landing weights for these spindles, there is no evidence that increasing the intervals would provide an acceptable level of safety. However, as ANA noted, under the provisions of paragraph (m) of the AD, we will consider requests for approval of an AMOC if sufficient data are submitted to substantiate that the change to the intervals would provide an acceptable level of safety. We have not changed the AD in this regard. \n\nConclusion \n\n\tWe reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that these changes will not increase the economic burden on any operator or increase the scope of the AD. \n\nCosts of Compliance \n\n\tThere are about 925 airplanes of the affected design in the worldwide fleet, which includes 160 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this AD. The average labor rate is $80 per work hour. \n\n\tEstimated Costs\n\n\nAction\nWork hours\nParts\nCost per airplane\nFleet cost\nInspection and overhaul (required by AD 90-17-19)\nBetween 120 and 140, per flap per cycle\n$0\nBetween $9,600 and $11,200, per flap per overhaul cycle\nBetween $1,536,000 and $1,792,000, per flap per cycle\nRepetitive inspection for broken parts (new action)\n2, per inspection cycle\n$0\n$160, per inspection cycle\n$25,600, per inspection cycle\n\nAuthority for This Rulemaking \n\n\tTitle 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. \n\tWe are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, "General requirements.'' Under thatsection, 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. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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. \n\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a "significant regulatory action'' under Executive Order 12866; \n\t(2) Is not a "significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\t(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. \n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\nAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by removing amendment 39-6705 (55 FR 33280, August 15, 1990) and by adding the following newairworthiness directive (AD):