AD 99-24-11

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 757-200 and -300 series airplanes, that requires modification of the slide/raft evacuation system by installing a girt reinforcement chafing patch. This amendment is prompted by reports of holes in the inflatable area of the slide/raft evacuation system due to chafing against the installation support bracket. The actions specified by this AD are intended to prevent holes in the inflatable portion of the slide/raft evacuation system, which could result in the slide/raft being less effective as a raft during an emergency water landing.

Final rule

99-24-11 BOEING: Amendment 39-11435. Docket 99-NM-89-AD. \n\n\tApplicability: Model 757-200 and -300 series airplanes, equipped with Air Cruisers Company slide/raft evacuation systems having part and serial numbers identified in Table 1 of this AD; certificated in any category. \n\nTABLE 1 \nAir Cruisers Company Slide/Raft Evacuation Systems Subject to this AD \n\n\nName\nPart Number\nSerial Numbers\nAir Cruisers\n D30657 - ( )\nPrior to 1132\nAir Cruisers\n D30658 - ( )\nPrior to 0859\nAir Cruisers\nD30659 - ( )\nPrior to 0860\nAir Cruisers\n61570 - ( )\nPrior to 0321\nAir Cruisers\n61475 - ( )\nPrior to 0137\nAir Cruisers\n61475 - ( )\n0138, 0139\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 holes in the inflatable portion of the slide/raft evacuation system, which could result in the slide/raft being less effective as a raft during an emergency water landing, accomplish the following: \n\nModification \n\n\t(a)\tWithin 36 months after the effective date of this AD, modify the slide/raft evacuation system in accordance with Air Cruisers Company Service Bulletin 757-105-25-51, dated January 29, 1999. \n\nSpares\n\n\t(b)\tAs of the effective date of this AD, no person shall install a slide/raft evacuation system having a part number and serial number identified in Table 1 of this AD, on any airplane, unless that slide/raft evacuation system has been modified in accordance with Air Cruisers Company Service Bulletin 757-105-25-51, dated January 29, 1999. \n\nAlternative Methods of Compliance \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\nSpecial Flight Permits \n\n\t(d)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the FederalAviation 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\nIncorporation by Reference \n\n\t(e)\tThe modification shall be done in accordance with Air Cruisers Company Service Bulletin 757-105-25-51, dated January 29, 1999. 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 Air Cruisers Company, Technical Publications Department, P.O. Box 180, Belmar, New Jersey 07719-0180. 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 January 4, 2000.

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 757-200 and -300 series airplanes was published in the Federal Register on July 20, 1999 (64 FR 38846). That action proposed to require modification of the slide/raft evacuation system by installing a girt reinforcement chafing patch. \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\tTwo commenters support the proposed rule. One commenter states that it is not affected by the proposed rule because its airplanes are not equipped with the slide/rafts referenced in the proposal. Another commenter states that it is in the process of accomplishing the actions specified by Air Cruisers Company Service Bulletin 757-105-25-51, dated January 29, 1999. \n\nRequest to Revise the Unsafe Condition \n\n\tOne commenter suggests that the unsafe condition cited in the notice of proposed rulemaking (NPRM) be revised to state that holes caused by the slide/raft chafing on the harness bracket could result in the slide/raft being "less effective" as a raft during an emergency water landing rather than "unusable." The commenter contends that the escape slide/rafts are designed with two independent inflation chambers. Each independent chamber is capable of supporting the rated occupancy of the slide/raft, and there have been no reports of holes in both chambers. \n\n\tThe FAA concurs with the commenter's statement that the holes caused by the slide/raft chafing against the bracket could result in the slide/raft being "less effective" rather than "unusable." Based on reports that only one chamber of the slide/raft would be affected, the FAA has determined that this change is appropriate and has changed the final rule accordingly.Request to Add an Inspection Requirement \n\n\tOne commenter states that an immediate inspection of the slide/rafts is required to ensure that any slide/raft already chafed "to the point of failure" be repaired immediately. \n\n\tThe FAA does not concur that an immediate inspection of the slide/rafts is necessary. To date, the FAA has received only two reports of chafing/scuffing of the slide/rafts that have resulted in a small hole being worn through one of the two inflatable chambers. The FAA adds that such a condition would result in a slow leak that would only affect the rafting use of the escape slide/raft. In light of this, the FAA has determined that accomplishment of paragraph (a) of this AD to require modification of the slide/raft within 36 months after the effective date of this AD is adequate in ensuring operational safety. No change to the final rule is necessary in this regard. \n\nRequest to Revise Paragraph (a) of the Proposed Rule \n\n\tOne commenter questions the effectiveness of the proposed repair (modification) action of adding a chafing patch, as specified by paragraph (a) of the proposed AD, since that patch may cause wear of another component, or simply delay the onset of a hole from wear. The commenter states that "a corrective action to eliminate the interference and subsequent repetitive abrasion would seem more appropriate in order to solve this problem." \n\n\tThe FAA does not concur with the commenter's request to revise the action (modification) required by paragraph (a) of the proposed AD. Although the FAA acknowledges the concerns of the commenter regarding corrective action to eliminate damage to the slide/raft, the FAA has evaluated this modification for its wear resistance and determined that modification of the slide/raft, in accordance with the requirements of paragraph (a) of the AD, is adequate to ensure the continued safety of the affected fleet. \n\nRequest to Extend the Compliance Time in Paragraph (b) \n\n\tOne commenter requests that the compliance time in paragraph (b) of the proposed AD be extended from "As of the effective date of this AD" to "As of 30 days after the effective date of this AD." The commenter contends that the compliance time should be extended to allow additional time for obtaining the slide/raft spares and to ensure that sufficient stock levels of those parts can be maintained. \n\n\tThe FAA does not concur with the commenter's request to extend the compliance time in paragraph (b) of the proposed AD to 30 days. The FAA considers that the specified compliance time allows sufficient time for obtaining spares and maintaining stock levels. Further, the intent of that paragraph is to prohibit the installation of spares that have been determined to create an unsafe condition, and to simply require the use of one part rather than another. In general, once an unsafe condition has been determined to exist, it is the FAA's policy not to allow that condition to be introduced into the fleet. When it is determined that approved parts are immediately available to operators, the installation of unsafe parts after the effective date of the AD is prohibited. Further, the FAA considers that the period of time between publication of the final rule AD in the Federal Register and the effective date of the final rule (usually 30 days) is sufficient to provide operators with an opportunity to determine their immediate need for modified spares and to obtain them. However, in individual cases where this is not possible, every AD contains a provision that allows an operator to obtain an extension of compliance time based upon a specific showing of need. The FAA considers that this policy does increase safety and does not impose undue burdens on operators. Therefore, no change to the final rule is necessary in this regard. \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 increase the economic burden on any operator nor increase the scope of the . \n\nCost Impact \n\n\tThere are approximately 445 Model 757-200 and -300 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 310 airplanes of U.S. registry will be affected by this AD, that it will take approximately 5 work hours per airplane to accomplish the modification, and that the average labor rate is $60 per work hour. Required parts will cost approximately $145 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $137,950, or $445 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.Regulatory 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 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: