AD 94-26-51

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T94-26-51 that was sent previously to all known U.S. owners and operators of all McDonnell Douglas Model MD-11 series airplanes by individual telegrams. This AD requires a revision to the FAA-approved Airplane Flight Manual (AFM) to prohibit autoland operation below 100 feet above ground level (AGL), and the installation of certain flight control computer software. This AD provides for an optional terminating action for the AFM revision. This amendment is prompted by reports of a loose nut on a coaxial connector on a radio altimeter receiver/transmitter rack, and the transmittal of erroneous altitude data to the flight control computers below 100 feet AGL, which resulted in abnormal flare (pitch) control during autoland operation. The actions specified by this AD are intended to prevent abnormal flare (pitch) control, which could result in degradation of the landing capability of the airplane.\n\n\tThe incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of February 6, 1995.\n\tComments for inclusion in the Rules Docket must be received on or before March 21, 1995.

Final rule; request for comments.

94-26-51 MCDONNELL DOUGLAS: Amendment 39-9120. Docket 94-NM-234-AD.\n\n\tApplicability: All Model MD-11 series airplanes, 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 use the authority provided in paragraph (d) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.\n\n\tCompliance: Required as indicated, unless accomplished previously.\n\n\tTo prevent degradation of the landing capability of these airplanes, accomplish the following:\n\n\t(a)\tWithin 24 hours after the effective date of this AD, revise the Limitations Section of the FAA-approved MD-11 Airplane Flight Manual (AFM), page 5-3, Flight Guidance, Automatic Landing Section, to include the following restriction. This may be accomplished by inserting a copy of this AD in the AFM.\n\n\t"Autoland operation below 100 feet above ground level (AGL) is prohibited. The autopilot must be disconnected prior to descent below 100 feet AGL."\n\n\t(b)\tAccomplishment of the inspections and tests specified in paragraphs (b)(1) and (b)(2) of this AD, in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A34-57, dated December 19, 1994, constitutes terminating action for the AFM revision required by paragraph (a) of this AD. Following accomplishment of the inspections and tests, the AFM revision may be removed from the AFM.\n\n\t\t(1)\tPerform an inspection to determine if the connector nut of the four coaxial connectors on the back of the radio altimeter receiver/transmitter is loose.\n\n\t\t\t(i)\tIf no loose nut is found, prior to further flight, loosen the nut until finger tight, retorque the nut to 10 to 15 inch pounds, and mark the nut with a torque stripe. Thereafter, repeat the inspection at intervals not to exceed 500 hours time-in-service.\n\n\t\t\t(ii)\tIf any loose nut is found, prior to further flight, tighten the nut to a torque of 10 to 15 inch pounds, and mark the nut with a torque stripe. Thereafter, repeat the inspection at intervals not to exceed 500 hours time-in-service.\n\n\tNOTE 2: Retorque is not necessary during repetitive inspections if the torque stripe is in line, as specified in the alert service bulletin.\n\n\t\t(2)\tPerform a leakage indication test to verify the integrity of the radio altimeter antenna system. Prior to further flight, correct any discrepancy found. Thereafter, repeat the test at intervals not to exceed 500 hours time-in-service.\n\n\t(c)\tWithin 15 days after the effective date of this AD, install -905 flight control computer (FCC) software in accordance with McDonnell Douglas MD-11 Service Bulletin 22-14, dated November 30, 1994.\n\n\t(d)\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 3: 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(e)\tSpecial flight permits may be issued in accordance withsections 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(f)\tThe inspections, tests, and installation shall be done in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A34-57, dated December 19, 1994; and McDonnell Douglas MD-11 Service Bulletin 22-14, dated November 30, 1994. 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, P.O. Box 1771, Long Beach, California 90801-1771, Attention: Business Unit Manager, Technical Administrative Support, Dept. L51, M.C. 2-98. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 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(g)\tThis amendment becomes effective on February 6, 1995, to all persons except those persons to whom it was made immediately effective by telegraphic AD T94-26-51, issued on December 19, 1994, which contained the requirements of this amendment.

On December 19, 1994, the FAA issued telegraphic AD T94-26-51, which is applicable to all McDonnell Douglas Model MD-11 series airplanes.\n\n\tThat action was prompted by two reports of abnormal flare (pitch) control that occurred during autoland operation on McDonnell Douglas Model MD-11 series airplanes. McDonnell Douglas reported that, during one occurrence, radio altimeter #1 transmitted erroneous altitude data to the flight control computers below 100 feet above ground level (AGL). This condition caused the airplane to flare prematurely during landing. Following a subsequent occurrence of abnormal autoland operation, an operator noticed that a nut on a coaxial connector on the back of the radio altimeter receiver/transmitter rack was loose. After refastening the connector, the airplane exhibited normal flare during autoland operation.\n\n\tSubsequent investigation of these reports conducted by McDonnell Douglas revealed that signals leaked between thetransmitter and receiver of radio altimeter #1. The cause of this leakage has not yet been determined. In addition, the exact failure mode of the radio altimeter coaxial cable that can produce the leakage is unclear at this time. The manufacturer is conducting an investigation into the cause of this leakage in order to develop a corrective action.\n\n\tEarly and/or abnormal flare (pitch) control during autoland operation, if not corrected, could result in degradation of the landing capability of the airplane.\n\n\tThe FAA has reviewed and approved McDonnell Douglas MD-11 Alert Service Bulletin A34-57, dated December 19, 1994, which describes procedures for repetitive inspections to determine if the connector nut of the four coaxial connectors on the back of the radio altimeter receiver/transmitter is loose; repetitive leakage indication tests to verify the integrity of the radio altimeter antenna system; and correction of any discrepancy.\n\n\tThe alert service bulletin references McDonnell Douglas MD-11 Service Bulletin 22-14, dated November 30, 1994, which describes procedures for installation of -905 flight control computer (FCC) software. Accomplishment of this installation will provide additional protection against the effects of other discrepancies that may exist in the radio altimeter antenna system.\n\n\tSince the unsafe condition described is likely to exist or develop on other airplanes of the same type design, the FAA issued Telegraphic AD T94-26-51 to require a revision to the FAA-approved Airplane Flight Manual (AFM) to prohibit autoland operation below 100 feet AGL.\n\n\tThis AD also provides for an optional terminating action for the AFM revision. The optional terminating action consists of:\n\n\t1.\tperforming repetitive inspections to determine if the connector nut of the four coaxial connectors on the back of the radio altimeter receiver/transmitter is loose, and tightening the nut, if necessary; and\n\n\t2.\tperforming repetitive leakage indication tests to verify the integrity of the radio altimeter antenna system, and correction of any discrepancy found.\n\n\tThese actions, if accomplished, are required to be accomplished in accordance with McDonnell Douglas MD-11 Alert Service Bulletin A34-57, dated December 19, 1994, as described previously.\n\n\tThis AD also requires installation of -905 FCC software. The installation is required to be accomplished in accordance with McDonnell Douglas MD-11 Service Bulletin 22-14, as described previously.\n\n\tThis is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.\n\n\tAs a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been included in this rule to clarify this requirement.\n\n\tSince it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual telegrams issued on December 19, 1994, to all known U.S. owners and operators of McDonnell Douglas Model MD-11 series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.\n\nComments Invited\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 94-NM-234-AD." The postcard will be date stamped and returned to the commenter.\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 isdetermined 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\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment\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.\tThe authority citation for part 39 continues to read as follows:\nAuthority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.\n\n§ 39.13 - (Amended)\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: