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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-54-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

                        This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Airbus Model A300, A300-600, and A310 series airplanes. This proposal would require replacement of the transformer rectifier units (TRU) in the avionics compartment with new, improved TRU's. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority.                               ( print page 20923)                            The actions specified by the proposed AD are intended to prevent failure of the TRU's. Failure of multiple TRU's could result in loss of the thrust reversers, autothrottle, flaps, and various systems (wing/cockpit window anti-ice, trim tank pumps, and windshield wipers) on the airplane; or incorrect information displayed to the flight crew.                     

# DATES:

Comments must be received by May 19, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-54-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. 

The service information referenced in the proposed rule may be obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. 

# FOR FURTHER INFORMATION CONTACT:

Norman B. Martenson, Manager, International Branch, ANM-116, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149. 

# SUPPLEMENTARY INFORMATION:

## Comments Invited 

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. 

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. 

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-54-AD.” The postcard will be date stamped and returned to the commenter. 

## Availability of NPRMs 

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-54-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

                    The Direction Ge                                        ne                                        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 A300, A300-600, and A310 series airplanes. The DGAC advises that it has received reports of failures in operation of the direct current (DC) electrical power transformer rectifier units (TRU). Investigation of these failures revealed that the temperature level that triggers the fan may lead to the overheat and failure of one or more TRU's. Failure of multiple TRU's, if not corrected, could result in loss of the thrust reversers, autothrottle, flaps, and various systems (wing/cockpit window anti-ice, trim tank pumps, and windshield wipers) on the airplane; or incorrect information displayed to the flight crew.                 

## Explanation of Relevant Service Information 

The manufacturer has issued Airbus Service Bulletin A300-24-0089, dated March 4, 1998 (for Model A300 series airplanes), A300-24-6068, dated January 28, 1998 (for Model A300-600 series airplanes), and A310-24-2077, dated January 21, 1998 (for Model A310 series airplanes). These service bulletins describe procedures for replacement of the TRU's in the avionics compartment with new, improved TRU's. The new TRU's utilize a reduced working temperature, thus improving the reliability of the TRU's. The DGAC classified these service bulletins as mandatory and issued French airworthiness directive 1999-435-296(B), dated November 3, 1999, in order to assure the continued airworthiness of these airplanes in France. 

The Airbus service bulletins reference AUXILEC Service Bulletin F11QB3121-24-007, dated February 2, 1998, as an additional source of service information for accomplishing the replacement proposed by this AD. 

## 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 Proposed 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, the proposed AD would require replacement of the TRU's in the avionics compartment with new, improved TRU's. The actions would be required to be accomplished in accordance with the service bulletins described previously, except as discussed below. 

## Differences Between Proposed Rule and Foreign Airworthiness Directive 

The proposed rule would differ from the French airworthiness directive in that it would require accomplishment of the replacement described previously, within 6 months after the effective date of this AD. The parallel French airworthiness directive specifies accomplishment of the replacement prior to September 30, 2001 (18 months after the effective date). In developing an appropriate compliance time for this AD, the FAA considered not only the DGAC's and the manufacturer's recommendations, but the degree of urgency associated with addressing the subject unsafe condition and the average utilization of the affected fleet. In light of these factors, the FAA finds a 6-month compliance time for the required actions to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety. 

## Cost Impact 

                    The FAA estimates that 122 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per airplane to accomplish the proposed replacement, and that the average labor rate is $60 per work hour. Required                           ( print page 20924)                        parts would be provided by the manufacturer at no cost to the operators if modification of the TRU's is accomplished at the vendor's (AUXILEC) facilities, otherwise the required parts would cost approximately $253 per TRU. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be between $120 and $1,132 per airplane.                 

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. 

## Regulatory Impact 

The regulations proposed herein would 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 proposal would not have federalism implications under Executive Order 13132. 

                    For the reasons discussed above, I certify that this proposed 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption                     **ADDRESSES.**

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Safety

## The Proposed Amendment 

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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 

2. Section 39.13 is amended by adding the following new airworthiness directive: 

**Airbus Industrie:**                                 Docket 2000-NM-54-AD.                            

*Applicability:*                                 Model A300, A300-600, and A310 series airplanes; certificated in any category; equipped with AUXILEC transformer rectifier units (TRU) having part number (P/N) F11QB3121.                             

# 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 failure of multiple TRU's, which could result in loss of the thrust reversers, autothrottle, flaps, and various systems (wing/cockpit window anti-ice, trim tank pumps, and windshield wipers) on the airplane; or incorrect information displayed to the flight crew; accomplish the following: 

## Replacement 

(a) Within 6 months after the effective date of this AD, replace the TRU's in the avionics compartment with new, improved TRU's, in accordance with Airbus Service Bulletins A300-24-0089, dated March 4, 1998 (for Model A300 series airplanes); A300-24-6068, dated January 28, 1998 (for Model A300-600 series airplanes); or A310-24-2077, dated January 21, 1998 (for Model A310 series airplanes); as applicable. 

# Note 2:

The Airbus service bulletins reference AUXILEC Service Bulletin F11QB3121-24-007, dated February 2, 1998, as an additional source of service information for accomplishing the replacement required by this AD. 

## Alternative Methods of Compliance 

(b) 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, International Branch, ANM-116, 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, International Branch, ANM-116. 

# Note 3:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, International Branch, ANM-116. 

## Special Flight Permits 

(c) 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. 

# Note 4:

The subject of this AD is addressed in French airworthiness directive 1999-435-296(B), dated November 3, 1999.

Issued in Renton, Washington, on April 13, 2000. 

Charles D. Huber, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-9822 Filed 4-18-00; 8:45 am] 

BILLING CODE 4910-13-U