On August 6, 2003, the FAA issued AD 2003- 16-15, amendment 39-13268 (68 FR 49340, August 18, 2003), applicable to certain Airbus Model A300 B4-600, B4-600R, and F4-600R (collectively called A300-600) series airplanes, and Airbus Model A310 series airplanes. That AD requires replacement of Honeywell inertial reference units (IRU) with new or modified Honeywell IRUs. For certain airplanes, that AD also requires replacement of Litton IRUs, mode selector units (MSU), and an inertial sensor display unit (ISDU) with new Honeywell IRUs, MSUs, and a new ISDU. That action was prompted by notification from the Direction Generale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, that an operator reported loss of positioning data and the display of incorrect attitude data shortly after take-off because the airplane was moved on the ground before the IRU alignment procedure had been completed. The actions required by that AD are intended to prevent loss of positioning data and a display of incorrect attitude data.
Related Rulemaking
It should be noted that the FAA previously issued AD 2001-13-24, amendment 39-12306 (66 FR 35532, July 6, 2001), applicable to certain Airbus Model A300-600 and A310 series airplanes. The DGAC notified the FAA that an unsafe condition may exist on certain Airbus Model A310 series airplanes and certain Airbus Model A300-600 series airplanes with certain Honeywell IRUs. The DGAC advised that an operator reported the loss of positioning data and the display of incorrect attitude data shortly after take-off, because the aircraft had been moved on the ground before the end of the IRU alignment procedure. This condition, if not corrected, could result in the loss of positioning data and a display of incorrect attitude data, which could compromise the ability of the flightcrew to maintain the safe flight and landing of the airplane. AD 2001-13-24 requires revisions to the Normal Procedures section of the airplane flight manual to prohibit movement of the airplane during IRU alignment and to provide instructions to the flightcrew to check the navigational display system to ensure correct display of all primary attitude and heading information prior to flight. That action is intended to address the identified unsafe condition.
Actions Since Issuance of Previous Rule
Since the issuance of AD 2003-16-15, we reviewed the requirements of that AD and noted incorrect information concerning the removal and replacement of certain Litton IRU equipment. The applicability section of AD 2003-16-15 states that that AD is applicable to certain Airbus Model A300-600 and A310 series airplanes equipped with certain Honeywell IRU part numbers. Therefore, Airbus Model A300-600 and A310 series airplanes equipped with Litton IRUs are not subject to the requirements of AD 2003-16-15.
The procedures for performing the actions required by AD 2003-16-15 are stated in Airbus Service Bulletins A300-34-6135, Revision 01 (for Model A300-600 series airplanes); and A310-34-2158, Revision 01 (for Model A310 series airplanes); both dated September 10, 2001. These service bulletins describe procedures for replacement of Honeywell IRUs with new or modified Honeywell IRUs, and were identified as mandatory service bulletins in French airworthiness directive 2001-303(B), dated July 25, 2001. Airbus Service Bulletins A300-34-6135, Revision 01; and A310-34-2158, Revision 01; specify prior or concurrent accomplishment of Airbus Service Bulletins A300-34-6082, Revision 05, dated February 13, 1998; and A310-34-2104, dated May 12, 1995; as applicable. Service Bulletins A300-34-6082 and A310-34-2104 both include provisions for those operators who have previously replaced Litton IRUs with Honeywell IRUs. For several specific aircraft these service bulletins specify the replacement of Litton IRUs with Honeywell IRUs as required changes associated with mandatory service bulletins. As a result, the replacement of certain Litton IRUs with certain Honeywell IRUs was incorrectly identified as a requirement in paragraphs (c) and (d) of AD 2003-16-15.
Therefore, one of the purposes of this AD is to remove that requirement to replace certain Litton IRUs with certain Honeywell IRUs. The Litton IRUs are designed to provide clear indication to the flightcrew if the aircraft has been moved during IRU alignment, and are not subject to the unsafe condition addressed in AD 2003-16-15.
In addition, we have removed paragraph (e), Parts Installation, of AD 2003-16-15, which prohibits the installation of certain Litton and Honeywell IRU part numbers. As stated previously, the Litton IRUs are not subject to the unsafe condition addressed by this AD. Paragraph (e)(1) of AD 2003-16-15 requires that, as of September 22, 2003 (the effective date of that AD), operators no longer install Honeywell IRUs having part numbers HG1050BD02 and HG1050BD05. The actions required by AD 2003-15-16 are specified in Airbus Service Bulletins A300-34-6135, Revision 01; and A310-34-2158, Revision 01; both dated September 10, 2001. These bulletins state that "it is impossible to mix old P/Ns with new P/Ns." Therefore it is necessary for the operators to replace or modify all three IRUs installed on each aircraft simultaneously. It is the understanding of the FAA that operators often only stock one spare unit in each field spares location. In order to adequately prepare for the possibility of IRU failures in the field after the effective date of that AD, each operator would have to replace their current spare IRUs with three updated IRUs, thus increasing their allotment of spares threefold. It is unlikely that Honeywell will be able to distribute the necessary number of IRUs to the operators' field spares locations prior to the effective date of this AD. It is likely that delay of delivery of these replacement IRUs would result in flight delays and/or cancellations. Continued compliance with AD 2001-13-24, described previously, provides adequate assurance that safety will not be compromised by continued use of the subject Honeywell IRUs until the parts replacement requirements of this AD are accomplished. Therefore, we have determined that a Parts Installation paragraph is not required in this AD.
FAA's Determination
In light of the above, we have determined that it is necessary to issue this supersedure AD to ensure the continued operational safety of the fleet.
U.S. Type Certification of the Airplanes
These airplane models are manufactured in France and are type- certificated for operation in the United States under the provisions of Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement.
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 supersedes AD 2003-16-15 to continue to require replacement of Honeywell IRUs with new or modified Honeywell IRUs. This AD removes all references to the replacement of Litton IRUs, MSUs, and a new ISDU with Honeywell IRUs, MSUs, and a new ISDU. This AD also removes paragraph (e), Parts Installation, of AD 2003-16-15, and allows the use of certain Honeywell IRUs as spare parts until the final compliance date of this AD. The actions are required to be accomplished in accordance with Airbus Service Bulletin A300-34-6135, Revision 01 (for Model A300-600 series airplanes); and Airbus Service Bulletin A310-34-2158, Revision 01 (for Model A310 series airplanes); both dated September 10, 2001.
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.
Submit comments using the following format:
Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
For each issue, state what specific change to the AD is being requested.
Include justification (e.g., reasons or data) for each request.
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 2003-NM-206-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 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:
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 removing amendment 39-13268 (68 FR 49340, August 18, 2003), and by adding a new airworthiness directive (AD), amendment 39-13319, to read as follows: