AD 98-03-20

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 757 series airplanes, that requires one-time inspections to verify proper installation and to detect chafing and/or damage of certain rerouted wire bundles; to verify if certain protective grommets are installed properly and to detect missing grommets; and various follow-on actions. This amendment is prompted by a report of smoke and fire in the lower left-hand side of the E1-1 rack of the electrical equipment bay due to chafing of wire bundles as a result of missing protective grommets. The actions specified by this AD are intended to prevent chafing of wire bundles, which could result in smoke and fire at the E1-1 rack of the electrical equipment bay.

Final rule

98-03-20 BOEING: Amendment 39-10312. Docket 96-NM-222-AD. \n\n\tApplicability: Model 757 series airplanes, on which Boeing Alert Service Bulletin 757-24A0025, dated May 10, 1985, and/or Boeing Service Bulletin 757-24A0025, Revision 1, dated December 17, 1987, has been accomplished; excluding variable numbers NA003, NA004, NA007, NA009, NA010, NA012 through NA016 inclusive, and NA021; 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 otherwise 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 (b) 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 chafing of wire bundles, which could result in smoke and fire at the E1-1 rack of the electrical equipment bay, accomplish the following: \n\n\t(a)\tWithin 6 months after the effective date of this AD, accomplish paragraphs (a)(1), (a)(2), and (a)(3) of this AD. \n\n\t\t(1)\tPerform a one-time inspection to verify proper installation and to detect chafing and/or damage of the wire bundles, having part numbers (P/N) W4508, W2608, and W2604. Pay particular attention to the area where the wire bundles are routed through the web supports and the area over the edge of intercostal R-23L. \n\n\t\t\t(i)\tIf the wire bundles are installed properly and no chafing or damage is detected, no further action is required by this paragraph. \n\t\t\t(ii)\tIf any chafing or damage is detected, prior to further flight, repair it in accordance with Boeing Standard Wiring Practices Manual 20-10-13 (not dated). \n\t\t\t(iii)\tIf any wire bundle is installed improperly, prior to further flight, loosen the wire bundle clamps, adjust the wire bundles to achieve proper clearances, and retighten the wire bundle clamps, in accordance with Boeing Standard Wiring Practices Manual 20-10-11 (not dated). \n\n\t\t(2)\tPerform a one-time inspection to verify if all protective grommets identified in Boeing Alert Service Bulletin 757-24A0025, dated May 10, 1985, are installed properly and to detect missing grommets. If any grommet is improperly installed or missing, prior to further flight, replace the grommet with a new grommet or install a new grommet, as applicable, in accordance with the alert service bulletin. \n\n\t\t(3)\tPerform a one-time inspection to determine if a protective grommet is installed on the upper edge of intercostal R-23L at approximately station450 between the intercostal and wire bundles having P/N's W2608 and W4508. If no protective grommet is installed, prior to further flight, install one between the wire bundles and intercostal, in accordance with Boeing Production Installation Drawing 288N4329, Revision H, Sheets 1 and 2 (undated)\n\n\t(b)\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\n\t(c)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\n\t(d)\tCertain actions shall be done in accordance with Boeing Alert Service Bulletin 757-24A0025, dated May 10, 1985, Boeing Production Installation Drawing 288N4329, Revision H, Sheets 1 and 2 (not dated), Boeing Standard Wiring Practices Manual 20-10-11 (not dated), and Boeing Standard Wiring Practices Manual 20-10-13 (not dated). 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(e)\tThis amendment becomes effective on March 18, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Boeing Model 757 series airplanes was published in the Federal Register on April 17, 1997 (62 FR 18726). That action proposed to require one-time inspections to verify proper installation and to detect chafing and/or damage of certain rerouted wire bundles; to verify if certain protective grommets are installed properly and to detect missing grommets; and various follow-on actions. \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\n\tSeveral commenters support the proposed rule. \n\nRequest for Clarification \n\n\tOne commenter suggests that the FAA provide clear and objective criteria in the proposed AD for determining if the wire bundle is too tight or too slack. The commenter states that sufficient clearance is very important when determining the length of a wire bundle. The FAA finds that clarification of this point is necessary. The FAA's intent was that operators refer to Boeing Standard Wiring Practices Manual 20-10-11 (undated) for these procedures. Therefore, the FAA has revised paragraph (a)(1)(iii) of the final rule to include a reference to this manual as the appropriate source of service information for correction of discrepancies. \n\nConclusion \n\n\tAfter careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the change previously described. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 62 Boeing Model 757 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 28 airplanesof U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. The cost of required parts will be nominal. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $3,360, or $120 per airplane. \n\n\tThe cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. \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\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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 FederalAviation 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: