AD 95-12-27

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes, that currently requires a revision to the input wiring for the flap control unit (FCU). This amendment requires a new systems test for the wiring of the trailing edge flap, and also expands the applicability of the existing AD to include additional airplanes. This amendment is prompted by a report indicating that a wiring error was not detected by the system test required by the existing AD. The actions specified by this AD are intended to prevent the possibility of an all-flaps-up landing due to the loss of control of all flap operations.

Final rule

95-12-27 BOEING: Amendment 39-9280. Docket 94-NM-251-AD. Supersedes AD 94-14-21, Amendment 39-8970. \n\n\tApplicability: Model 747-400 series airplanes having line numbers 696 through 1036 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 use the authority provided in paragraph (d) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.\n \n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tNOTE 2: Paragraph (a) of this AD merely restates the requirements of paragraph (a) of AD 94-14-21, amendment 39-8970. As allowed by the phrase, "unless accomplished previously," if those requirements of AD 94-14-21 have already been accomplished, this AD does not require that those actions be repeated. \n\n\tTo prevent the possibility of an all-flaps-up landing due to the loss of control of flap operations, accomplish the following: \n\n\t(a)\tFor airplanes having line numbers 696 through 1019 inclusive, and 1021 through 1026 inclusive: Within 30 days after August 10, 1994 (the effective date of AD 94-14-21, amendment 39- 8970), revise the input wiring for the flap control unit (FCU) in accordance with Boeing Service Bulletin 747-27A2346, Revision 1, dated May 19,1994, or Revision 2, dated January 12, 1995. \n\n\t(b)\tFor airplanes having line numbers 1020, and 1027 through 1036 inclusive: Within 30 days after the effective date of this AD, revise the input wiring for the FCU in accordance with Boeing Service Bulletin 747-27A2346, Revision 2, dated January 12, 1995. \n\n\t(c)\tFor airplanes having line numbers 696 through 1036 inclusive: Within 120 days after the effective date of this AD, perform the additional systems test for the wiring of the trailing edge flap in accordance with Boeing Service Bulletin 747-27A2346, Revision 2, dated January 12, 1995. \n\n\t(d)\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 Aircraft 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\n\t(e)\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\n\t(f)\tThe wire systems test and wiring revision shall be done in accordance with Boeing Service Bulletin 747-27A2346, Revision 1, dated May 19, 1994, and Boeing Service Bulletin 747-27A2346, Revision 2, dated January 12, 1995. The incorporation by reference is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. The incorporation by reference of Boeing Service Bulletin 747-27A2346, Revision 1, dated May 19, 1994, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of August 10, 1994 (59 FR 35240, July 11, 1994). 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(g)\tThis amendment becomes effective on July 31, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 94-14-21, amendment 39-8970 (59 FR 35240, July 11, 1994), which is applicable to certain Boeing Model 747-400 series airplanes, was published in the Federal Register on February 15, 1995 (60 FR 8591). The action proposed to continue to require a revision of the input wiring for the flap control unit (FCU), but would include the addition of a new systems test for the wiring of the trailing edge flap. The action also proposed to expand the applicability of the existing AD to include additional airplanes. \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\tThe manufacturer states that the numbers referred to as "serial numbers" in paragraphs (a), (b), and (c) of the proposal are designated incorrectly, and requests that the numbers be referredto as "line numbers." The FAA concurs and has revised paragraphs (a), (b), and (c) of the final rule to reflect this change. \n\n\tOne commenter requests that the additional systems test for the wiring, as proposed in paragraph (c) in the AD, be deleted. The commenter states that this testing is unnecessary because the specific procedures provided by Boeing Service Bulletin 747-27A2346, Revision 1, dated May 19, 1994 (which is the appropriate source of service information for existing AD 94-14-21), ensure that the wires are installed in the correct pin locations. The FAA does not concur. This AD was prompted by a report from an operator indicating that a wiring error of the landing gear module was discovered after the accomplishment of the wiring systems check required by AD 94-14-21. The FAA has determined that the wiring systems check required by that AD does not provide adequate verification that the wiring modification was made correctly. Therefore, the additional systems check as specified in paragraph (c) of the final rule is required. \n\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\n\tThere are approximately 310 Model 747-400 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 36 airplanes of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,080, or $30 per airplane. \n\n\tThe total 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\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 FlexibilityAct. 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\n List 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.\tThe authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. § 39.13 - (Amended) \n\n\t2.\tSection 39.13 is amended by removing amendment 39-8970 (59 FR 35240, July 11, 1994), and by adding a new airworthiness directive (AD), amendment 39-9280, to read as follows: