# AD 98-10-01: Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes - Type: Airworthiness directive - Effective: May 20, 1998 - Published: May 5, 1998, 63 FR 24742–24744 - Issued as: Final rule; request for comments - Superseded by: Nothing supersedes this AD - Amendment: 39-10512 - Docket: 98-NM-131-AD - Official PDF: https://openairdocs.org/files/sha256/d1/60/d1602172bad56dda9dd28c71c4235c2bd85f94830dcc6f2d731340f719e92026 (from https://www.govinfo.gov/content/pkg/FR-1998-05-05/pdf/98-11808.pdf) - Federal Register: https://www.federalregister.gov/documents/1998/05/05/98-11808/airworthiness-directives-mcdonnell-douglas-model-md-11-series-airplanes - Page: https://openairdocs.org/ad/98-10-01 ## Summary This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes. This action requires a revision of the Airplane Flight Manual to alert the flightcrew that both flight management computers (FMC's) must be installed and operational. This AD also requires an inspection to determine the serial number of the FMCs, and follow-on corrective actions, if necessary. This amendment is prompted by a report indicating that, due to incorrect multiplexers that were installed in the flight management computer system (FMC'S) during production, certain data busses failed simultaneously during a ground test. 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 incorrect multiplexers, and consequent failure of the data busses. ## The airworthiness directive ### PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. ### Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: 98-10-01 McDonnell Douglas: Amendment 39-10512. Docket 98-NM-131-AD. Applicability: Model MD-11 series airplanes, manufacturer's fuselage numbers 0447 through 0552 inclusive, and 0554 through 0621 inclusive; certificated in any category. Note 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. Compliance: Required as indicated, unless accomplished previously. 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 in the flight management computer system (FMCS), accomplish the following: ### (a) (a) Within 5 days after the effective date of this AD, 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. ``Prior to dispatch of the airplane, both Flight Management Computer 1 (FMC-1) and FMC-2 must be installed and operational.'' ### (b) (b) Within 45 days after the effective date of this AD, perform a visual inspection to determine the serial number of the flight management computers (FMC), in accordance with McDonnell Douglas Alert Service Bulletin MD11-34A083, dated April 6, 1998. After this inspection is accomplished, the AFM revision required by paragraph (a) of this AD may be removed from the AFM. (1) If no affected serial number is found, no further action is required by this paragraph. (2) If any affected serial number is found, prior to further flight, perform a visual inspection to determine the part number (P/ N) of the multiplexer, in accordance with the alert service bulletin. If any affected P/N is found, prior to further flight, modify the multiplexer in accordance with the alert service bulletin. Note 2: McDonnell Douglas Alert Service Bulletin MD11-34A083, dated April 6, 1998, references Honeywell Service Bulletin 4059050-34-0011, dated March 12, 1998, as an additional source of service information. ### (c) (c) An 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. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. ### (d) (d) Special 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. ### (e) (e) Except as provided for in paragraph (a) of this AD, the actions shall be done in accordance with McDonnell Douglas Alert Service Bulletin MD11-34A083, dated April 6, 1998. 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 The Boeing Company, Douglas Products Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). 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. ### (f) (f) This amendment becomes effective on May 20, 1998. Issued in Renton, Washington, on April 28, 1998. John J. Hickey, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. ## Rule preamble ### Dates Effective May 20, 1998. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of May 20, 1998. Comments for inclusion in the Rules Docket must be received on or before July 6, 1998. ### Addresses Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-131-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. The service information referenced in this AD may be obtained from The Boeing Company, Douglas Products Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). This information may be examined 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. ### For further information contact Brett Portwood, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5350; fax (562) 627-5210. ### Supplementary information The FAA received a report indicating that, during a routine ground test on an Airbus Model A310 series airplane, which included a power-down test of the Honeywell Flight Management Computer System (FMCS), multiple ARINC 429 data busses failed simultaneously. Investigation revealed that a batch of incorrect multiplexers were installed in the FMCS during production, which can cause loading of the ARINC 429 data busses when the flight management computer (FMC) is de-energized. This condition, if not corrected, could result in loss of airspeed and altitude indications on both primary flight displays in the cockpit and/or loss or degradation of the autopilot functionality. ### Similar Airplanes The FMCS of Airbus Model A310 series airplanes is similar in design to that of McDonnell Douglas Model MD-11 series airplanes. Therefore, the FAA has determined that Model MD-11 series airplanes may be subject to the same unsafe condition. The FAA has been advised that the Direction Generale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, may consider issuing a parallel French airworthiness directive to correct the identified unsafe condition on Airbus Model A310 series airplanes. ### Explanation of Relevant Service Information The FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin MD11-34A083, dated April 6, 1998, which describes procedures for a visual inspection to determine the serial number of the FMC's, and follow-on corrective actions, if necessary. The follow-on corrective actions include, for any airplane on which an affected serial number is found, a visual inspection to determine the part number of the multiplexer, and modification of certain multiplexers. In addition, the alert service bulletin describes procedures for a functional test of the FMC in the flight compartment to determine if an incorrect multiplexer is installed, and corrective actions, if necessary. McDonnell Douglas Alert Service Bulletin MD11-34A083, dated April 6, 1998, references Honeywell Service Bulletin 4059050-34-0011, dated March 12, 1998, as an additional source of service information. ### Explanation of the Requirements of the Rule Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued 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 as a result of incorrect multiplexers installed in the FMCS. This AD requires revising the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to alert the flightcrew that, prior to dispatch, both FMC's must be installed and operational. This AD also requires accomplishment of the actions specified in the alert service bulletin described previously, except as discussed below. ### Differences Between Rule and Alert Service Bulletin Operators should note that, although the alert service bulletin describes procedures for a functional test, this AD does not require that functional test. The FAA has determined that the functional test does not positively indicate that an incorrect multiplexer is installed. ### Interim Action This is considered to be interim action. The FAA is considering further rulemaking action to supersede this AD to require modification of any FMC that does not have an affected serial number (i.e., Condition 2 of the Work Instructions in the referenced alert service bulletin). However, the planned compliance time for these actions is sufficiently long so that notice and opportunity for prior public comment will be practicable. ### Determination of Rule's Effective Date Since 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. ### Comments Invited Although 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. Comments 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. Commenters 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-131-AD.'' The postcard will be date stamped and returned to the commenter. ### Regulatory Impact The 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. The 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. ### List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. ### Adoption of the Amendment Accordingly, 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: No proposed rule in this release led to it. Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.