AD 99-06-18

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400, -400D, and -400F series airplanes, that requires modification of the P212 and P213 panels of the cabin pressure control system. For certain airplanes, this amendment also requires modification of the P5, P6, and P7 panels, and the W4701, W4703, and W4908 wire bundles, as applicable. This amendment is prompted by a report of in-flight loss of cabin pressurization control due to a single failure of the auxiliary power unit (APU) battery. The actions specified by this AD are intended to prevent loss of control of the cabin pressurization system, which could result in rapid depressurization of the airplane. Such rapid depressurization could result in deleterious physiological effects on the passengers and crew; and airplane diversions, which represent an increased risk to the airplane, passengers, and crew.

Final rule.

99-06-18 BOEING: Amendment 39-11082. Docket 96-NM-171-AD. \n\n\tApplicability: Model 747-400, -400D, and -400F series airplanes; as identified in Boeing Alert Service Bulletin 747-21A2381, dated June 27, 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 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 cabin pressurization system, which could result in rapid depressurization of the airplane and consequent deleterious physiological effects on the passengers and crew; and airplane diversions, which represent an increased risk to the airplane, passengers, and crew, accomplish the following: \n\n\t(a)\tWithin 12 months after the effective date of this AD: Modify the P212 and P213 panels of the cabin pressure control system as specified in paragraph (a)(1) or (a)(2) of this AD, as applicable, in accordance with Boeing Alert Service Bulletin 747-21A2381, dated June 27, 1996. \n\n\t\t(1)\tFor Groups 1 through 7 airplanes, as identified in the alert service bulletin: Change the wiring in the P212 and P213 panels; replace the existing two-pole relays with new four-pole relays; and perform a test of both panels. \n\n\t\t(2)\tFor Group 8 airplanes, as identified in the alert service bulletin: Change the wiring in the P212 panel; replace the existing two-pole relays with new four-pole relays; replace the existing P213 panel with a new P213 panel; and perform a test of both panels. \n\n\t(b)\tFor airplanes having line positions 696 through 1021 inclusive: Within 12 months after the effective date of this AD, accomplish paragraphs (b)(1) and (b)(2), as applicable, of this AD; in accordance with Boeing Service Bulletin 747-24-2193, dated January 26, 1995; as revised by Notices of Status Change (NSC) 747-24-2193 NSC 1, dated April 13, 1995, 747-24-2193 NSC 2, dated October 5, 1995, 747-24-2193 NSC 3, dated November 22, 1995, 747-24-2193 NSC 4, dated December 21, 1995, 747-24-2193 NSC 5, dated May 2, 1996, and 747-24-2193 NSC 6, dated March 13, 1997; or Alert Service Bulletin 747-24A2193, Revision 1, dated June 19, 1997. \n\n\t\t(1)\tFor all airplanes: Modify the wiring of the P5, P6, and P7 panels; modify the wiring in the W4701 and W4908 wire bundles; and install diodes in the P6 panel.(2)\tFor Groups 1 and 2 airplanes identified in paragraph I. of the Accomplishment Instructions of the service bulletin or alert service bulletin: Modify the wiring in the W4703 wire bundle. \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 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(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 actions shall be done in accordance with Boeing Alert Service Bulletin 747-21A2381, dated June 27, 1996; and Boeing Service Bulletin 747-24-2193, dated January 26, 1995; as revised by Notices of Status Change (NSC) 747-24-2193 NSC 1, dated April 13, 1995, 747-24-2193 NSC 2, dated October 5, 1995, 747-24-2193 NSC 3, dated November 22, 1995, 747-24-2193 NSC 4, dated December 21, 1995, 747-24-2193 NSC 5, dated May 2, 1996, and 747-24-2193 NSC 6, dated March 13, 1997; or Boeing Alert Service Bulletin 747-24A2193, Revision 1, dated June 19, 1997. 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 26, 1999.

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 747-400, -400D, and -400F series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on May 12, 1998 (63 FR 26100). That action proposed to require modification of the P212 and P213 panels of the cabin pressure control system. For certain airplanes, that action also proposed to require modification of the P5, P6, and P7 panels, and the W4701, W4703, and W4908 wire bundles, as applicable. \n\nComments \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\tOne commenter supports the proposed rule. Another commenter offers no comments to the proposed rule, because it does not own or operate the subject airplanes. \n\nRequests to Extend Compliance Time \n\n\tOne commenter requests that the FAA extend the proposed compliance time for the modification from 180 days after the effective date of this AD to 18 months after the effective date of this AD, to reduce the impact on its operations and the cost associated with accomplishment of the proposed actions. The commenter states that the proposed 180-day compliance time would make it necessary to schedule approximately five of its airplanes for special maintenance visits, which the commenter estimates would cost $60,000 per airplane. The commenter states that an 18-month compliance time would allow the modifications proposed in the supplemental NPRM to be accomplished during a regularly scheduled "C" check. \n\n\tThe FAA partially concurs with the commenter's request to extend the compliance time. The FAA has determined that the compliance time may be extended somewhat. The FAA finds that extending the compliance time from 180 days after the effective date of this AD to 12 months after the effective date of this AD will not adversely affect safety and will allow the modifications to be performed, in the majority of cases, during a regularly scheduled maintenance visit. Therefore, paragraphs (a) and (b) of the final rule have been revised to specify a compliance time of 12 months after the effective date of this AD. However, with regard to the commenter's cost estimate, the FAA points out that operators may take advantage of special maintenance visits to accomplish other deferred maintenance tasks, which would reduce the time necessary to accomplish those deferred tasks during regularly scheduled checks. The commenter's estimate of additional costs associated with special visits does not take this into account.\n\n\tAnother commenter also requests that the FAA extend the proposed compliance time for accomplishment of the actions to 18 months after the effective date of this AD. The commenter states that Boeing Service Bulletin 747-21-2268 should be accomplished prior to the accomplishment of Boeing Alert Service Bulletin 747-21A2381, dated June 27, 1996 (which was referenced as an appropriate source of service information in the supplemental NPRM). The commenter states that Boeing Alert Service Bulletin 747-21A2381 can be accomplished within the 180-day compliance time proposed in the supplemental NPRM only if Boeing Service Bulletin 747-21-2268 has already been accomplished. The commenter requests that the compliance time be extended to provide for accomplishment of both Boeing Service Bulletin 747-21-2268 and Boeing Alert Service Bulletin 747-21A2381. \n\n\tThe FAA does not concur that Boeing Service Bulletin 747-21-2268 must be accomplished prior to accomplishment of Boeing Alert Service Bulletin 747-21A2381. The FAA has determined that Boeing Alert Service Bulletin 747-21A2381 provides specific instructions on how to accomplish the actions specified in the alert service bulletin both withand without prior incorporation of the actions specified in Boeing Service Bulletin 747-21-2268. In addition, the FAA does not require accomplishment of Boeing Service Bulletin 747-21-2268. Therefore, the FAA finds that it is not necessary to extend the compliance time to allow for accomplishment of Boeing Service Bulletin 747-21-2268. However, as stated previously, the compliance time for the actions required by this final rule has been extended to 12 months after the effective date of this AD to allow for accomplishment of the required actions during regularly scheduled maintenance visits. \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 described previously. 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 Cost Impact \n\n\tThere are approximately 351 Model 747-400, -400D, and -400F series airplanes of the affected design in the worldwide fleet. The FAA estimates that 43 airplanes of U.S. registry will be affected by this AD. \n\n\tFor all airplanes, it will take approximately 8 work hours per airplane to accomplish the required modification of the P212 and P213 panels, at an average labor rate of $60 per work hour. Required parts will cost approximately $389 per airplane. Based on these figures, the cost impact of this modification required by this AD on U.S. operators is estimated to be $37,367, or $869 per airplane. \n\n\tFor certain airplanes, it will take approximately 47 work hours per airplane to accomplish the required modification of the P5, P6, and P7 panels, and the W4701, W4703, and W4908 wire bundles, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,529 per airplane. Based on these figures, the cost impact of this modification required by this AD on U.S. operators is estimated to be $4,349 per airplane. \n\n\tThe cost impact figures discussed above are 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. \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\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: