AD 99-13-05

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 777 series airplanes. This action requires repetitive inspections to detect cracking of the upper cutout and lower flange of the outboard support assembly of the flaperons on the wings; and corrective actions, if necessary. This amendment also provides an optional terminating action for the repetitive inspections. This amendment is prompted by results of flight testing conducted by the manufacturer indicating that high engine thrust conditions during takeoff cause excessive cyclic loads and could lead to fatigue cracking of the outboard support of the flaperon. The actions specified in this AD are intended to detect and correct such fatigue cracking, which could result in fracture of the flaperon support structure, loss of the flaperon, and consequent reduced controllability of the airplane.

Final rule; request for comments

99-13-05 BOEING: Amendment 39-11198. Docket 99-NM-116-AD. \n\n\tApplicability: Model 777 series airplanes, as listed in Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999; certificated in any category. \n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated,unless accomplished previously. \n\n\tTo detect and correct fatigue cracking of the outboard support of the flaperon, which could result in fracture of the flaperon support structure, loss of the flaperon, and consequent reduced controllability of the airplane; accomplish the following: \n\nRepetitive Inspections \n\n\t(a)\tPerform high frequency eddy current (HFEC) inspections to detect fatigue cracking of the upper cutout and lower flange of the outboard support assembly of the flaperons on the left and right wings, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999, at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable.\n \n\t\t(1)\tFor airplanes identified as Group 1 in the alert service bulletin: Perform HFEC inspections prior to the accumulation of 10,000 total flight cycles, or within 225 flight cycles after the effective date of this AD, whichever occurs later. Repeat the inspections thereafter at intervals not to exceed 225 flight cycles. \n\n\t\t(2)\tFor airplanes identified as Group 2 in the alert service bulletin: Perform HFEC inspections prior to the accumulation of 4,000 total flight cycles, or within 70 flight cycles after the effective date of this AD, whichever occurs later. Repeat the inspections thereafter at intervals not to exceed 70 flight cycles. \n\nCorrective Action \n\n\t(b)\tIf any fatigue cracking is detected during any inspection required by paragraph (a) of this AD: Prior to further flight, concurrently accomplish the modifications specified in Parts 2 and 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999. Accomplishment of the modifications constitutes terminating action for the repetitive inspection requirements of this AD. \n\n\t(c)\tIf any fatigue cracking is detected, and Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999, specifies that corrective actions may be accomplished in accordance with an operator's "equivalent procedure:" The actions must be accomplished in accordance with the chapter of the Boeing 777 Airplane Maintenance Manual (AMM) specified in the alert service bulletin. \n\nOptional Terminating Action \n\n\t(d)\tConcurrent accomplishment of the modifications specified in Parts 2 and 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999, constitutes terminating action for the repetitive inspections required by this AD. \n\nSpares \n\n\t(e)\tAs of the effective date of this AD, no person shall install any part identified in the "Existing Part Number" column of Section 2.E. of Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999, on any airplane. \n\nAlternative Methods of Compliance \n\n\t(f)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office(ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\n\t(g)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\n\t(h)\tThe actions shall be done in accordance with Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O.Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC. \n\n\t(i)\tThis amendment becomes effective on July 8, 1999

Results of flight testing of the Boeing Model 777 series airplane indicate that high engine thrust conditions during takeoff cause excessive cyclic loads on the flaperon support structure of the flaperons on the left and right wings. Based on engineering analysis of the flaperon support structure, it was determined that due to the reduced fatigue life of the affected parts, fatigue cracks could develop on the outboard support of the flaperons. For airplanes powered by Rolls-Royce engines, it was determined that fatigue cracks could occur prior to the accumulation of 4,000 total flight cycles; and for airplanes powered by General Electric and Pratt & Whitney engines, fatigue cracks could occur prior to the accumulation of 10,000 total flight cycles. Such fatigue cracking of the outboard support of the flaperons, if not detected and corrected, could result in fracture of the flaperon support structure, loss of the flaperon, and consequent reduced controllability of the airplane. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 777-57A0008, dated March 25, 1999, which describes procedures for accomplishment of repetitive high frequency eddy current (HFEC) inspections to detect cracking of the upper cutout and lower flange of the outboard support assembly of the flaperons on the left and right wings; and corrective actions, if necessary. The corrective actions include modification of the fairings of the outboard flaperon; modification of the lower panels of the fixed trailing edge of the outboard flaperon; replacement of the existing outboard support, the outboard support bearing block, and the upper panel bracket of the fixed trailing edge of the flaperons on each wing with new components; and an operational test to detect fuel leakage. \n\n\tIn addition, the service bulletin describes procedures for accomplishment of modification of the inboard aft fairing assembly ofthe flaperons to be accomplished concurrently with the modification of the outboard support assemblies. These procedures include modification of the aft fairing of the inboard support and replacement of the existing inboard support bearing block with a new block. \n\n\tAccomplishment of the modifications described previously eliminates the need for the repetitive inspections. \n\nExplanation of the Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to detect and correct fatigue cracking of the outboard support assembly of the flaperons on each wing, which could result in fracture of the flaperon support structure, loss of the flaperon, and consequent reduced controllability of the airplane. This AD requires accomplishment of the actions specified in the service bulletin described previously, except as discussed below. In addition, this AD provides an optionalterminating action for the repetitive inspections. \n\nDifferences Between This Rule and Alert Service Bulletin \n\n\tThe alert service bulletin specifies that the manufacturer may be contacted for disposition of certain cracking conditions, in lieu of accomplishment of the terminating action. However, if any cracking is detected, this AD requires accomplishment of the terminating action prior to further flight. \n\n\tThe alert service bulletin specifies that certain corrective actions required by this AD may be accomplished in accordance with the Airplane Maintenance Manual or an operator's "equivalent procedure." However, this AD requires that any such actions be accomplished only in accordance with the procedures specified in the Airplane Maintenance Manual. An "operator's equivalent procedure" may be used only if approved as an alternative method of compliance in accordance with the provisions of this AD. \n\nInterim Action \n\n\tThis is considered to be interim action. The FAA iscurrently considering requiring modification of the outboard and inboard support assemblies of the flaperons, as described in the alert service bulletin, which would constitute terminating action for the repetitive inspections required by this AD. However, the planned compliance time for these actions is sufficiently long so that notice and opportunity for prior public comment will be practicable. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on thisrule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.\n \n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 99-NM-116-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \n\n\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significantregulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." \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\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:\n\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: