AD 94-19-51 R1 ACTIVE

This document revises and publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T94-19-51 that was sent previously to all known U.S. owners and operators of McDonnell Douglas Model MD-11 and MD-11F series airplanes by individual telegrams. This AD supersedes an existing airworthiness directive that currently requires a revision to the Airplane Flight Manual (AFM) to ensure that the flight crews verify the accuracy of data provided by the Flight Management Computer (FMC) under certain conditions. This amendment requires a revision to the AFM to ensure that the flight crews verify the accuracy of data provided by the FMC under all conditions. This amendment is prompted by a report that the "check/confirm V speed" message may be inhibited when the flaps are extended to within three degrees of the takeoff flap setting that was entered into the FMC. The actions specified by this AD are intended to prevent FMC miscalculations that may result in excessively high takeoff decision (V1) speeds, which may adversely affect accelerate-stop distances and may lead to the failure of the airplane to stop prior to departing the end of the runway during a high speed rejected takeoff. This amendment also revises the previously issued telegraphic AD by correcting a typographical error in the listing of the part numbers for the FMC's.

Final rule; request for comments.

94-19-51 R1 MCDONNELL DOUGLAS: Amendment 39-9042. Docket 94-NM-160-AD. Supersedes AD 94-08-07, amendment 39-8879. \n\n\tApplicability: Model MD-11 and MD-11F series airplanes, equipped with Honeywell Flight Management Computers having part numbers 4059050-906, -907, and -908; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent the airplane from departing the end of the runway during a high speed rejected takeoff, accomplish the following: \n\n\t(a)\tWithin 7 days after the effective date of this AD, replace the revision to the Limitations Section (Section 1) of the FAA-approved Airplane Flight Manual (AFM), page 5-1, FLIGHT GUIDANCE, Flight Management System (FMS) Section, that was required by AD 94-08-07, amendment 39-8879, with the following information. This may be accomplished by inserting a copy of this AD or an FAA-approved McDonnell Douglas AFM revision in the AFM. \n\n\t"For any approved thrust level, the FMScomputed V1, VR, and V2 speeds must be verified with AFM derived data and manually entered." \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: 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 October 24, 1994, to all personsexcept those persons to whom it was made immediately effective by telegraphic AD T94-19-51, issued on September 14, 1994, which contained the requirements of this amendment.

On April 6, 1994, the FAA issued AD 94-08-07, amendment 39-8879 (59 FR 17467, April 13, 1994), to require revising the FAA-approved Airplane Flight Manual (AFM) to ensure that the flight crews verify the accuracy of data provided by the Flight Management Computer (FMC) when the anti-ice system is turned on during flex (assumed) temperature takeoffs. That AD does not require that these procedures be followed if the runway is dry, if the field length is balanced, or if the ice protection is turned off. That action was prompted by a report that certain Honeywell FMC's provided erroneous V speed data when the anti-ice system was turned on during flex temperature takeoffs. The FAA determined that this phenomenon may occur on McDonnell Douglas Model MD-11 and MD-11F series airplanes equipped with Honeywell FMC's having part numbers 4059050-906, -907, and -908. That condition, if not corrected, could result in the airplane failing to achieve sufficient climb gradient, which may result in the airplane failing to achieve obstacle clearance. \n\n\tSince the issuance of that AD, the FAA has received a report that the "check/confirm V speed" message may be inhibited when the flaps are extended to within three degrees of the takeoff flap setting that was entered into the FMC. Under normal operating conditions, the FMC calculates V speeds based on data the pilot enters into the FMC and data the FMC receives from the aircraft sensors, including total air temperature (TAT). Investigation revealed that on hot sunny days, the TAT probe may indicate an erroneously high ambient temperature that is up to 15 degrees Celsius higher than the actual ambient temperature. The FMC, however, was supposedly designed and certified to account for this error in the actual ambient temperature by continually recalculating the V speed data and indicating a "check/confirm V speed" message when the calculations indicate that the V speeds differ by more than two knots from the V speeds entered into the FMC by the pilot. However, if the flaps are set to the takeoff position prior to the TAT probe temperature reaching the ambient temperature, that message would be inhibited and the pilot would not be notified that the indicated V speed is incorrect. The FAA has determined that such erroneous indications may result in an FMC calculation of the takeoff decision speed (V1) that is up to six knots greater than the actual V1 speed. \n\n\tFMC miscalculations that result in excessively high V1 speeds could result in accelerate- stop distances that exceed planned takeoff distances, which may lead to the airplane departing the end of the runway during a high speed rejected takeoff. \n\n\tSince the unsafe condition described is likely to exist or develop on other McDonnell Douglas Model MD-11 and MD-11F series airplanes of the same type design, the FAA issued telegraphic AD T94-19-51, on September 14, 1994, to supersede AD 94-08-07 and to require a revision to the FAA-approved AFM to ensure that the flight crews verify the accuracy of data provided by the FMC under all conditions. The AD also requires that V speeds be manually entered into the FMC. \n\n\tThis is considered to be interim action. The manufacturer of these airplanes, in concert with the manufacturer of the FMC, is currently developing new software that will address the unsafe condition addressed by this AD. Once this software is developed, approved, and available, the FAA may consider additional rulemaking. \n\n\tAdditionally, subsequent to the issuance of telegraphic AD T94-19-51, the FAA discovered that a typographical error appeared in the listing of affected part numbers for the Honeywell FMC's. The part numbers were inadvertently listed as "4059040-906, -907, and -908." The correct part numbers are "4059050-906, -907, and -908." (These correct part numbers were listed correctly in the preamble to the telegraphic AD and in the previously-issued AD 94-08-07.) \n\n\tSince itwas 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 September 14, 1994, to all known U.S. owners and operators of McDonnell Douglas Model MD-11 and MD- 11F 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. Additionally, this AD revises the telegraphic AD by correcting a typographical error in the listing of FMC part numbers. \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 ofthis 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-160-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 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\n\tAir 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\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1.\tThe authority citation for part 39 continues to read as follows: \n\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\n\t2.\tSection 39.13 is amended by removing amendment 39-8879 (59 FR 17467, April 13, 1994), and by adding a new airworthiness directive (AD), amendment 39-9042, to read as follows:

Information concerning this amendment may be obtained from or examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.\n\n\tSubmit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-160-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Thomas A. Enyart, Aerospace Engineer, Flight Test Branch, ANM-162L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California 90806-2425; telephone (310) 988-5372; fax (310) 988-5210.