AD 97-08-05

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-100, -200, and -300 series airplanes, that requires replacement of certain switches in the cabin attendant's panel at door 4 right and door 2 right with new improved switches. This amendment is prompted by reports indicating that fires have occurred on some airplanes due to the internal failure of some of these switches. The actions specified by this AD are intended to prevent the installation and use of switches that could short circuit when they fail, and consequently cause fire and smoke aboard the airplane.

Final rule

97-08-05 BOEING: Amendment 39-9993. Docket 96-NM-239-AD. \n\n\tApplicability: Model 747-100, -200, and -300 series airplanes; as listed in Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996, as revised by Boeing Notice of Status Change 747-33A2252 NSC 01, dated October 10, 1996; 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 (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 installation and use of switches in the cabin attendant's panel that could short circuit when they fail, and consequently cause fire and smoke aboard the airplane, accomplish the following: \n\n\t(a)\tWithin 10 months after the effective date of this AD, remove switches S4 and/or S5, or switches S7 and S8, that are installed in the cabin attendant's panel at door 4 right, and the equivalent switches at door 2 right, and replace them with new switches in accordance with the procedures specified in Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996, as revised by Boeing Notice of Status Change 747-33A2252 NSC 01, dated October 10, 1996.\n\n\tNOTE 2: Although the procedures in Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996, as revised by Boeing Notice of Status Change 747-33A2252 NSC 01, datedOctober 10, 1996, address replacing only the switches located at door 4, they can be used just as effectively for replacing the switches located at door 2. \n\n\t(b)\tAs of the effective date of this AD, no person shall install at door 2 right or at door 4 right of any airplane an attendant's panel having switch part numbers identified in the "Old Switch" column of any table contained in Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996, as revised by Boeing Notice of Status Change 747-33A2252 NSC 01, dated October 10, 1996. \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, 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 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(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\n\t(e)\tThe replacement shall be done in accordance with Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996, as revised by Boeing Notice of Status Change 747-33A2252 NSC 01, dated October 10, 1996. 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 May 15, 1997.

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 747-100, -200, and -300 series airplanes was published in the Federal Register as a supplemental notice of proposed rulemaking (NPRM) on January 21, 1997 (62 FR 2981). That action proposed to require removing switches S4 and/or S5, or switches S7 and S8, that are currently installed on the cabin attendant's panel at door 4 right, and the equivalent switches at door 2 right, and replacing them with new improved switches. \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\nSupport for the Proposal \n\n\tTwo commenters support the proposed rule.\n\n Request to Include A New Requirement for Doors 1 and 3 \n\n\tOne commenter requests that the proposed replacement of the switches onthe cabin attendant's panel also be accomplished at doors 1 and 3. The commenter states that doors 1 and 3 have the same switches that are subject to the addressed unsafe condition as the switches at doors 2 and 4. \n\n\tThe FAA acknowledges that the switches at doors 1 and 3 are prone to failure; however, at this time, the FAA has received no reports of fire and smoke at those locations. The FAA points out that adding a new requirement to the proposed AD would require public comment before adopting a final rule, hence a second supplemental NPRM. The FAA has considered the degree of urgency associated with addressing the identified unsafe condition at doors 2 and 4, and the amount of time that has already elapsed since issuance of the original proposed rule. In light of these items, the FAA has determined that further delay of this final rule action is not appropriate. However, the FAA is currently considering issuing a separate rulemaking action to address the identified unsafe condition at doors 1 and 3. \n\nRequest for an Alternative Method of Compliance \n\n\tOne commenter requests that the FAA revise paragraph (a) of the proposed rule to reference an alternative method of compliance for replacing the existing switches with new improved replacement switches. The commenter recommends suitable plug-in switches, in lieu of the soldered switches, as described in Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996 (which is referenced in the proposed AD as the appropriate source of service information). The commenter states that soldered switches add considerable complexity and cost to the replacement, which prevents accomplishment of the replacement on the line. The commenter notes that it has requested Boeing revise the referenced alert service bulletin to specify a suitable plug-in switch.\n\n\tThe FAA does not concur. The FAA does not consider it appropriate to include various provisions in an AD applicable to a single operator's unique use of an affected airplane. Paragraph (c) of this AD contains a provision for requesting approval of an alternative method of compliance to address these types of unique circumstances. The FAA acknowledges that a design solution that utilizes plug-in switches may cost less and may be less complex; however, the FAA does not mandate a design solution based on those criteria alone. Further, the FAA is unaware of a revision to the referenced alert service bulletin. \n\nRequest to Revise the Cost Estimate \n\n\tOne commenter questions the FAA's cost and work hour estimate in the preamble of the proposal. The commenter states that the estimated per airplane cost of $1,112, presented in the cost impact information in the preamble to the proposal, is too low. This commenter suggests that the required replacement would take approximately 10 work hours per airplane and would cost approximately $1,300 per panel (2 panels per airplane). Upon further review, the FAA concurs that the number of work hours and cost of required parts is higher than approximated previously. The FAA has revised the cost impact information, below, to include this updated information. \n\nNew Notice of Status Change \n\n\tSince issuance of the supplemental NPRM, Boeing has issued Notice of Status Change (NSC) 747-33A2252 NSC 01, dated October 10, 1996, which amends Boeing Alert Service Bulletin 747- 33A2252, dated August 1, 1996. This NSC removes airplanes that have been converted to special freighters from the effectivity listing of the alert service bulletin and makes certain editorial changes. The FAA has revised the final rule to reference this NSC as an additional source of service information. \n\nNew "NOTE 2" \n\n\tThe FAA has revised the final rule to include a new NOTE 2 to clarify that, although the procedures in Boeing Alert Service Bulletin 747-33A2252, dated August 1, 1996, address replacing only the switches located at door 4, they can be used just as effectively for replacing the switcheslocated at door 2. The FAA mentioned this clarification in the Requirements of the Revised Proposed Rule Section in the preamble of the supplemental NPRM.\n \nConclusion \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 significantly increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 648 Boeing Model 747-100, -200, and -300 series airplanes of the affected design in the worldwide fleet. Of this number, the FAA estimates that 167 airplanes of U.S. registry will be affected by this AD. \n\n\tThe required replacement of the switches will take approximately 10 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,300 perpanel (2 panels per airplane). Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $534,400, or $3,200 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\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. 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: