AD 96-10-16

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 series airplanes, that requires inspections to detect damage of the sidewall vent box diaphragms, and repair, if necessary. This amendment also requires the eventual installation of stops on the vent box diaphragm, which terminates the inspection requirements of the AD. This amendment is prompted by reports of damage to sidewall vent box diaphragms, which can result in non-functional diaphragms during a rapid decompression. The actions specified by this AD are intended to prevent buckling of the floor beams due to insufficient air flow of the cabin sidewall vent box diaphragms during rapid decompression, and consequent reduction in the controllability of the airplane.

Final rule.

96-10-16 MCDONNELL DOUGLAS: Amendment 39-9623. Docket 95-NM-191-AD. \n\n\tApplicability: Model MD-11 series airplanes, as listed in McDonnell Douglas Alert Service Bulletin MD11-25A181, dated September 28, 1995; 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 buckling of the floor beams due to insufficient air flow of the cabin sidewall vent box diaphragms during rapid decompression, and subsequent loss of airplane control capabilities, accomplish the following: \n\n\t(a)\tWithin 90 days after the effective date of this AD, perform an inspection to detect damage of the sidewall vent box diaphragms, in accordance with McDonnell Douglas Alert Service Bulletin MD11-25A181, dated September 28, 1995. Based on the findings of the initial inspection, or any repetitive inspection, accomplish the requirements of paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable: \n\n\t\t(1)\tCondition 1. If no damage is detected: Repeat the inspection at intervals not to exceed 90 days. \n\n\t\t(2)\tCondition 2. If damage is detected, but the number of damaged sidewall vent box assemblies does not exceed the applicable allowable number specified in Table 1 of the alert service bulletin: Repeat the inspection at intervals not to exceed 90 days. \n\n\t\t(3)\tCondition 3. If damage is detected, and the number of damaged vent box assemblies exceeds the applicable number specified in Table 1 of the alert service bulletin: Prior to further flight, install stops on and re-identify as many damaged sidewall vent box assemblies as necessary so that the total number of damaged vent box assemblies does not exceed the applicable allowable number specified in Table 1 of the alert service bulletin. Accomplish the installation of the stops and reidentification of the assemblies in accordance with the alert service bulletin. The installation of stops on and reidentification of an assembly constitutes terminating action for the repetitive inspections of that assembly only. All other assemblies must continue to be inspected thereafter at intervals not to exceed 90 days. \n\n\t(b)\tWithin 30 months after the effective date of this AD, install stops on and reidentify all sidewall ventbox assemblies that do not already have stops installed and have not been reidentified in accordance with McDonnell Douglas Alert Service Bulletin MD11-25A181, dated September 28, 1995. Accomplishment of this action constitutes terminating action for the inspection requirements of this AD. \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, Los Angeles 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, Los Angeles 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 Los Angeles 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 inspections and installations shall be done in accordance with McDonnell Douglas Alert Service Bulletin MD11-25A181, dated September 28, 1995. 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 McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood, California; 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 June 20, 1996.

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 McDonnell Douglas Model MD-11 series airplanes was published in the Federal Register on February 21, 1996 (61 FR 6581). That action proposed to require repetitive inspections to detect damage of the sidewall vent box assemblies. Initially, that action proposed to permit continued flight if only a certain number of assemblies are found to be damaged. However, once that number is exceeded, the damaged assemblies would be required to be modified, prior to further flight, until the remaining number of damaged assemblies does not exceed a certain number. That amendment also proposed to require the eventual installation of stop pads for all vent box diaphragms and reidentification of the assemblies, which, when accomplished, terminates the requirement for the repetitive inspections. \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the two comments received. \n\n\tBoth commenters support the proposed rule. \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 as proposed. Cost Impact \n\n\tThere are approximately 123 Model MD-11 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 39 airplanes of U.S. registry will be affected by this AD. \n\n\tTo accomplish the required inspections will take approximately 2 work hours per airplane, per inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the required inspections on U.S. operators is estimated to be $4,680, or $120 per airplane, per inspection cycle. \n\n\tTo accomplish the required installation and reidentification will take a total of approximately 270 work hours per airplane. This figure represents 3 work hours per vent box, and up to a maximum of 90 vent boxes on an airplane. The average labor rate is $60 per work hour. The cost of required parts will be negligible; the parts may be fabricated locally. Based on these figures, the cost impact of the required installation on U.S. operators is estimated to be $631,800, or $16,200 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. \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\n\t1. The authority citation for part 39 continues to read as follows: \n\nAuthority: 49 USC 106(g), 40113, 44701. \n\n§ 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: