AD 99-25-02

This amendment adopts a new airworthiness directive (AD) that is applicable to all Boeing Model 737-100, -200, -300, -400, and -500 series airplanes. This action requires a one-time inspection to verify correct installation of the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank, and corrective actions, if necessary. For certain airplanes, this action requires replacement of the nut, bolt, and cotter pin that connects the input rod of the spoiler mixer mechanism to the torque tube crank with a new or serviceable nut, bolt, and cotter pin. This amendment is prompted by reports indicating numerous discrepancies in the installation of the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank. The actions specified in this AD are intended to prevent the linkage between the ratio changer input rod and the aft aileron control quadrant from becoming disconnected, which could result in reduced controllability of the airplane.

Final rule; request for comments

99-25-02 BOEING: Amendment 39-11445. Docket 99-NM-332-AD. \n\n\tApplicability: All Model 737-100, -200, -300, -400, and -500 series airplanes, 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 (c) 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 prevent the linkage between the ratio changer input rod and the aft aileron control quadrant from becoming disconnected, which could result in reduced controllability of the airplane; accomplish the following: \n\nDetailed Visual Inspection \n\n\t(a)\tWithin 90 days after the effective date of this AD, accomplish the actions required by paragraph (a)(1) or (a)(2) of this AD, as applicable, in accordance with Boeing Alert Service Bulletin 737-27A1213, Revision 1, dated May 21, 1998. \n\n\t\t(1)\tFor airplanes on which Boeing Alert Service Bulletin 737-27A1213, dated April 23, 1998, has not been accomplished: Perform a one time detailed visual inspection to verify correct installation of the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank, in accordance with Revision 1 of the alert service bulletin. \n\n\tNOTE 2: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required." \n\n\t\t\t(i)\tIf the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank is installed correctly, no further action is required by this AD.\n \n\t\t\t(ii)\tIf the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank is not installed correctly, prior to further flight, either re-install the existing fastener, or install a new or serviceable fastener, in accordance with Revision 1 of the alert service bulletin. \n\n\t\t(2)\tFor airplanes on which Boeing Alert Service Bulletin 737-27A1213, dated April 23, 1998, has been accomplished: Replace the nut, bolt, and cotter pin that connects the input rod of the spoiler mixer mechanism to the torque tube crank with a new or serviceable nut, bolt, and cotter pin in accordance with Revision 1 of the alert service bulletin. \n\nReporting Requirement \n\n\t(b)\tWithin 10 days after accomplishing the actions required by paragraph (a)(1) of this AD, submit a report of any findings of fasteners that connect the input rod of the spoiler mixer mechanism to the torque tube crank that require corrective action to the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; fax (425) 227-1181. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056. \n\nAlternative Methods of Compliance \n\n\t(c)\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, ACO. 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 3: 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(d)\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(e)\tThe actions shall be done in accordance with Boeing Alert Service Bulletin 737-27A1213, Revision, 1, dated May 21, 1998. 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(f)\tThis amendment becomes effective on December 15, 1999.

The FAA has received reports indicating numerous discrepancies in the installation of the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank on Boeing Model 737-100, -200, -300, -400, and -500 series airplanes. These discrepancies include the use of incorrect hardware, the lack of secondary means of retention, and the incorrect (inverted) installation of the bolt. Additionally, the airplane manufacturer has indicated that the torque values specified, in a previously issued service bulletin, for the nut and bolt of the fastener in the spoiler mixer mechanism were too high. The previously specified torque values could cause the nut and bolt to fail, which could result in a disconnection of the linkage between the ratio changer input rod and the aft aileron control quadrant. This condition, if not corrected, could result in reduced controllability of the airplane. \n\nExplanation of Relevant Service InformationThe FAA has reviewed and approved Boeing Alert Service Bulletin 737-27A1213, Revision 1, dated May 21, 1998, which describes procedures for a one-time visual inspection to verify correct installation of the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank, and corrective actions, if necessary. The corrective actions involve either re-installation of the existing fastener, or replacement of the fastener with a new or serviceable fastener. \n\n\tFor certain airplanes on which the initial issue of the alert service bulletin has been accomplished, the alert service bulletin describes procedures for replacement of the nut, bolt, and cotter pin that connects the input rod of the spoiler mixer mechanism to the torque tube crank with a new or serviceable nut, bolt, and cotter pin. \n\n\tAccomplishment of the actions specified in the alert service bulletin is intended to adequately address the identified unsafe condition. \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 prevent the linkage between the ratio changer input rod and the aft aileron control quadrant from becoming disconnected, which could result in reduced controllability of the airplane. The actions are required to be accomplished in accordance with the alert service bulletin described previously, except as discussed below. This AD also requires that operators report certain results of the one-time inspections to the FAA. \n\nDifferences Between AD and Alert Service Bulletin \n\n\tOperators should note that the Boeing alert service bulletin recommends that the inspection to verify correct installation of the fastener that connects the input rod of the spoiler mixer mechanism to the torque tube crank be performed at the operator's earliest maintenance opportunity. However, the FAA has determined that such an interpretive compliance time may not address the identified unsafe condition in a timely manner. In developing appropriate compliance times for this AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, the accessibility of the area to be inspected, the time necessary to accomplish the inspection (approximately 1 hour), and the time necessary to accomplish the replacement (approximately 1 hour). In light of all these factors, the FAA finds that inspecting to verify correct installation of the fastener in the spoiler mixer mechanism within a 90-day compliance time is warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety. \n\n\tOperators also should note that the Boeing alert service bulletin specifies the effectivity to be Boeing Model 737-100, -200, -300,-400, and -500 series airplanes having line numbers 1 through 2681. However, the FAA has determined that this effectivity would not address all the affected airplanes on which the identified unsafe condition is likely to exist or develop. Therefore, the applicability of this AD includes all Boeing Model 737-100, -200, -300, -400, and -500 series airplanes. \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 this rule 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.Commenters 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-332-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 "significant regulatory action" under Executive Order12866. 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\nPART 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: