The Direction Generale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, notified the FAA of numerous reports of the intermittent interruption of the electrical power supply. The power interruption has been attributed to arcing of the electrical harness of the integrated drive generator (IDG) at the pin-to-socket connector at the firewall. The affected IDG connectors are installed on Airbus Model A319, A320, and A321 series airplanes equipped with International Aero Engines (IAE) Model V2500. In most of the incidents, the generator control unit (GCU) detected the arcing and shut down the associated IDG with only minor consequences. However, in some cases, the GCU--because of intermittent arcing--did not shut down the IDG. Investigation revealed that the arcing is due to fretting corrosion between the Cannon connector installed on the nacelle side of the firewall and the Souriau connector installed on the pylon side of the firewall.The following events have occurred or could occur during flight as a result of the intermittent loss of electrical power supply:
Flickering cabin lights;
Flickering primary flight and navigation displays;
Transient disconnection of several systems (autopilot, yaw damper, auto throttle), triggering warnings from the electronic centralized aircraft monitoring (ECAM) displays and prompting diversions to the nearest available airport; and
Loss of IDG power supply on the affected engine.
These conditions, if not corrected, could result in reduced ability of the flightcrew to cope with adverse flight conditions.
Relevant Service Information
Airbus has issued Temporary Revision (TR) 4.02.00/20 to the A318/319/320/321 Airplane Flight Manual (AFM). The TR, dated May 3, 2004, provides background information and operational recommendations regarding the intermittent interruption of electrical power supply.
Airbus has also issued Service Bulletin A320-71-1030, dated February 27, 2003. The service bulletin describes procedures for replacing the IDG harness on the nacelle side of the firewall to eliminate the pin-to-socket arcing. Specifically, harnesses having Cannon connectors are replaced with harnesses having Souriau connectors. The Souriau connector provides a better connection of the IDG electrical harness at the firewall. Airbus Service Bulletin A320-71-1030 refers to International Aero Engines Information Bulletin V2500-NAC-70-0736, dated January 28, 2003, as an additional source of information for the IDG harness/connector replacement.
The DGAC approved these service documents. The DGAC has issued French airworthiness directive F-2004-074, dated May 26, 2004, to ensure the continued airworthiness of these airplanes in France.
FAA's Determination and Requirements of This AD
These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of section 21.29 ofthe 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. We have examined the DGAC's findings, evaluated all pertinent information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.
Therefore, we are issuing this AD to prevent transient loss of the systems connected to the affected arcing connector and consequent reduced ability of the flightcrew to cope with adverse flight conditions. This AD requires revising the AFM to advise the flightcrew of procedures associated with the intermittent interruption of the electrical power. Under certain conditions, this AD also requires inspecting for signs of arcing and performing any necessary corrective actions. This AD also provides for optional terminating action for the requirements of the AD. The actions must be done in accordance with the service information described previously, except as described below.
Differences Between FAA and DGAC Airworthiness Directive
The following differences have been coordinated between the FAA and the DGAC.
The French airworthiness directive does not require inspecting an IDG that has been shut down in accordance with the TR or that has been shut down automatically. We have determined that investigative and corrective actions (including an inspection for signs of arcing, and repair or replacement of any discrepant IDG harness/connector with a new harness/connector) are necessary due to the severity of the problem to prevent the unsafe condition from recurring. The inspections and corrective actions must be done in accordance with a method approved by the FAA.
The French airworthiness directive applies to all Model A319, A320, and A321 series airplanes equipped with IAE V2500 series engines--regardless of the type of connector installed. This AD, however, applies to only those airplanes having Cannon connectors on the nacelle side of the firewall and Souriau connectors on the pylon side of the firewall. There have been no reported problems on airplanes equipped with Souriau connectors on both sides of the firewall. Therefore, the applicability of this AD excludes production airplanes that have been equipped with Souriau connectors on both sides of the firewall on both engines (accomplished via Airbus Modification 32943). This AD also includes a provision for replacing, on both engines, the IDG harnesses having Cannon connectors with IDG harnesses having Souriau connectors; this replacement would terminate the requirements of this AD.
Interim Action
We consider this AD interim action. We may consider further rulemaking at a later date to mandate replacement of the subject connectors, as specified in Airbus Service Bulletin A320-71-1030.
FAA's Determination of the Effective Date
An unsafe condition exists that requires the immediate adoption of this AD; therefore, providing notice and opportunity for public comment before the AD is issued is impracticable, and good cause exists to make this AD effective in less than 30 days.
Comments Invited
This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "Docket No. FAA-2004-18681; Directorate Identifier 2004-NM-56-AD" at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the AD in light of those comments.
We will post all comments we receive, without change, to http://dms.dot.gov , including anypersonal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of our docket Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.
We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications with you. You can get more information about plain language at http://www/faa.gov/language and http://www.plainlanguage.gov.
Regulatory Findings
We have determined that this AD will not have federalismimplications under Executive Order 13132. This AD 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.
For the reasons discussed above, I certify that the regulation:
1. Is not a "significant regulatory action" under Executive Order 12866;
2. Is not a "significant rule" under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
We prepared a regulatory evaluation of the estimated costs to comply with this AD. See the ADDRESSES section for a location to examine the regulatory evaluation.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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. The FAA amends 39.13 by adding the following new airworthiness directive (AD):