AD 98-15-14

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 series airplanes, that currently requires a revision of the Airplane Flight Manual (AFM) to alert the flightcrew that both flight management computers (FMC's) must be installed and operational. That AD also requires an inspection to determine the serial number of the FMC's; and follow-on corrective actions, if necessary, which terminate the AFM revision. That amendment was prompted by a report indicating that, due to incorrect multiplexers that were installed in the FMC's during production, certain data busses failed simultaneously during a ground test. This amendment removes the terminating action from the existing AD. The actions specified in this AD are intended to prevent loss of airspeed and altitude indications on both primary flight displays in the cockpit, and/or loss or degradation of the autopilot functionality due to installation of incorrectmultiplexers, and consequent failure of the data busses.

Final rule; request for comments.

98-15-14 McDONNELL DOUGLAS: Amendment 39-10665. Docket 98-NM-209-AD. Supersedes AD 98-10-01, amendment 39-10512. \n\n\tApplicability: Model MD-11 series airplanes, manufacturer's fuselage numbers 0447 through 0552 inclusive, and 0554 through 0621 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 request approval for an alternative method of compliance in accordance with paragraph (b) 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 specificproposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent loss of airspeed and altitude indications on both primary flight displays in the cockpit, and/or loss or degradation of the autopilot functionality due to installation of incorrect multiplexers, and consequent failure of the data busses, accomplish the following: \n\n\t(a)\tWithin 5 days after May 20, 1998 (the effective date of AD 98-10-01, amendment 39-10512), revise Section 1, page 5-1, of the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following statement. This may be accomplished by inserting a copy of this AD into the AFM. \n\n\n\t"Prior to dispatch of the airplane, both Flight Management Computer 1 (FMC-1) and FMC-2 must be installed and operational." \n\n\t(b)\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 Operations 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(c)\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(d)\tThis amendment becomes effective on August 3, 1998.

On April 28, 1998, the FAA issued AD 98-10-01, amendment 39-10512 (63 FR 24742, May 5, 1998), applicable to certain McDonnell Douglas Model MD-11 series airplanes. That AD requires a revision of the Airplane Flight Manual (AFM) to alert the flightcrew that both flight management computers (FMC's) must be installed and operational. That AD also requires an inspection to determine the serial number of the FMC's, and follow-on corrective actions, if necessary; which terminate the AFM revision. That action was prompted by a report indicating that, due to incorrect multiplexers that were installed in the FMC's during production, certain data busses failed simultaneously during a ground test. The actions required by that AD are intended to prevent loss of airspeed and altitude indications on both primary flight displays in the cockpit, and/or loss or degradation of the autopilot functionality due to installation of incorrect multiplexers, and consequent failureof the data busses. \n\nActions Since Issuance of Previous Rule \n\n\tThe existing AD requires terminating action for only a small subgroup of affected airplanes (those with FMC multiplexers having certain part numbers). However, since the issuance of that AD, additional defective multiplexers (not previously identified) have been found. \n\n\tAirplanes having affected FMC's that have been purged of suspected defective multiplexers, in compliance with AD 98-10-01, would be considered airworthy. However, FMC's or mutliplexes may have been exchanged or replaced during routine maintenance subsequent to compliance with AD 98-10-01, and it would be impossible to determine whether units inspected in accordance with that AD may now contain suspected defective multiplexers. Therefore, the AFM revision will continue to be required until the entire fleet can be systematically inspected for suspected defective multiplexers. The AFM revision requirement will ensure the continued safe operationof the entire fleet during this interim period. \n\n\tThe AFM revision currently required by the existing AD, and retained in this new action, requires that both FMC's be installed and operational. The identified unsafe condition could not occur unless both FMC's fail. Therefore, the FAA finds that the AFM limitation adequately addresses the identified unsafe condition. \n\nInterim Action \n\n\tThis is considered to be interim action. The FAA may consider further rulemaking to require inspection of all MD-11 FMC's to detect defective multiplexers. However, the compliance time under consideration for these actions is sufficiently long so that notice and opportunity for prior public comment will be practicable. \n\nExplanation of Requirements of Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 98-10-01 to continue to require an AFM revision to alert the flightcrew that both FMC's must be installed and operational. In addition, this AD removes the terminating action required by AD 98-10-01. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-NM-209-AD." The postcard will be date stamped and returned to the commenter. \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\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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\nAir transportation, Aircraft, Aviation safety, 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 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-10512 (63 FR 24742, May 5, 1998), and by adding a new airworthiness directive (AD), amendment 39-10665, to read as follows: