AD 2000-07-09

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-600, -700, and -800 series airplanes. This action requires a one-time inspection to detect loose nuts installed on the bolts at each end of the input rods connected to each elevator power control unit (PCU), and corrective action, if necessary. This amendment is prompted by reports of loose nuts on the bolts that connect the lower input crank arm and the vernier adjustment input rod of the elevator PCU. The actions specified in this AD are intended to detect and correct loose nuts on the bolts of the input crank arms of the elevator PCU, which could result in the loss of pivot bolts on the PCU and consequent loss of control of the airplane during takeoff and landing.

Final rule; request for comments

2000-07-09 BOEING: Amendment 39-11663. Docket 2000-NM-84-AD. \n\n\tApplicability: Model 737-600, -700, and -800 series airplanes, line numbers 1 through 477 inclusive, 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 loss of control of the airplane during takeoff and landing due to loose nuts on the bolts of the input crank arms of the elevator power control unit (PCU), and consequent loss of pivot bolts, accomplish the following: \n\n\tNOTE 2: For the purposes of this AD, a general visual inspection is defined as: "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 under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and 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\n\t(a)\tWithin 30 days after the effective date of this AD, perform a one-time general visual inspection to determine if the nuts installed on the bolts at each end of the input rods connected to each elevator PCU are installed correctly, in accordance with Boeing Telegraphic Service Letter 737-SL-27-150, dated February 14, 2000. \n\n\t\t(1)\tIf all bolts are protruding through the nuts, no further action is required by this AD. \n\n\t\t(2)\tIf any bolt does not protrude through the nut, prior to further flight, tighten the nut in accordance with the telegraphic service letter. \n\n\t(b)\tWithin 10 days after accomplishing the inspection required by this AD; or within 10 days after the effective date of this AD if the inspection was accomplished prior to the effective date of this AD: Submit a report of any findings of loose nuts to the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; fax (425) 227-1181. The report must include the operator's name, the date the inspection was accomplished, the airplane line number, and the number of loose nuts found on that airplane. 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\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, Seattle 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 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\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 locationwhere the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\t(e)\tThe actions shall be done in accordance with Boeing Telegraphic Service Letter 737-SL-27-150, dated February 14, 2000. 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 April 25, 2000.

The FAA received several reports indicating that operators found loose nuts on the bolts that connect the lower input crank arm and the vernier adjustment input rod of the elevator power control unit (PCU). Apparently, maintenance had not been accomplished on the PCU's since delivery of the airplanes from the manufacturer. One of the loose PCU input rod nuts was found on a production airplane during a line check. The loose nuts reported had been finger tightened, but had not been properly torqued on the bolts. \n\n\tLoose nuts on the bolts of the input rod of the elevator PCU could result in the loss of pivot bolts on the crank arms of the elevator PCU's, and consequent loss of control of the airplane during takeoff and landing. \n\nExplanation of Relevant Service Information \n\tThe FAA has reviewed and approved Boeing Telegraphic Service Letter 737-SL-27-150, dated February 14, 2000, which describes procedures for a one-time visual inspection to determine if the nuts installed on the bolts at each end of the input rods connected to each elevator power control unit (PCU) are installed correctly, and tightening of any loose nut that is found. \n\nExplanation of the Requirements of the Rule \n\tSince an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 737-600, -700, and -800 series airplanes of the same type design, this AD is being issued to prevent loss of control of the airplane during takeoff and landing due to loose nuts on the bolts of the input crank arms of the elevator PCU, and consequent loss of pivot bolts on the PCU. This AD requires a one-time general visual inspection to determine if the nuts installed on the bolts at each end of the input rods connected to each elevator PCU are installed correctly, and corrective action, if necessary. The actions are required to be accomplished in accordance with the telegraphic service letter described previously. \n\n\tThis AD also requires that operators report findings of loose nuts to the FAA. \n\nDetermination of Rule's Effective Date \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\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. \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 2000-NM-84-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\tThe regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \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 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\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \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: \nPART 39 - AIRWORTHINESS DIRECTIVES \n\t1. The authority citation for part 39 continues to read as follows: \nAuthority: 49 U.S.C. 106(g), 40113, 44701.\n§ 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: