The Direction G n rale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, notified the FAA that an unsafe condition may exist on certain Airbus Model A319, A320, and A321 series airplanes. The DGAC advises that, during testing and analysis, logic errors, i.e., software anomalies, occurred on certain Rockwell Collins radio altimeters. Investigation revealed that, under certain conditions, the software anomalies cause the radio altimeter to display erroneous information to the flight crew with no alarm detection. This condition, if not corrected, could result in an increased risk of collision with the terrain.
Explanation of Relevant Service Information
The manufacturer has issued Airbus A319/A320/A321 Airplane Flight Manual (AFM) Temporary Revision (TR) 2.05.00/43, dated September 16, 1999. The temporary revision provides information for the flight crew concerning the use of the radio altimeter of the flight management guidance system (FMGS) during the approach phase of flight. The TR revises the AFM to limit the use of the automatic flight system for certain types of instrument landing system (ILS) approaches. The DGAC classified this TR as mandatory and issued airworthiness directive 2000-004-142(B), dated January 12, 2000, in order to assure the continued airworthiness of these airplanes in France.
Airbus also has issued Service Bulletin A320-31-1106, Revision 04, dated December 21, 1999, which describes procedures for modification of the flight warning computers (FWC). The modification involves incorporating software changes into the onboard replaceable modules of the FWC's. Accomplishment of the modification would terminate the requirement for the AFM temporary revision.
FAA's Conclusions
These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the DGAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DGAC, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.
Explanation of Requirements of Rule
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to prevent erroneous display of decision height information to the flight crew during final approach, which could result in an increased risk of collision with the terrain. This AD requires a revision to the Limitations and Normal Procedures Sections of the FAA-approved AFM to limit the use of the radio altimeter of the FMGS during the approach phase of flight. Thisaction also provides for an optional terminating modification, which would eliminate the need for the AFM revision. The optional terminating modification is to be accomplished in accordance with the service bulletin described previously.
Interim Action
This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.
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 2000-NM-51-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.
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 thisaction 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:
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.
39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: