AD 96-04-06

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A320 series airplanes, that requires replacement of the relays in the forward electronics rack of the braking system of the landing gear with new relays. This amendment is prompted by reports of loss of the systems of the braking/steering control unit (BSCU) on these airplanes due to electrical overvoltage of the relays. The actions specified by this AD are intended to prevent such electrical overvoltage of the relays, which could result in the loss of the BSCU systems, and subsequent loss of the antiskid functions and nose wheel steering of the airplane.

Final rule.

96-04-06 AIRBUS INDUSTRIE: Amendment 39-9518. Docket 95-NM-77-AD.

Applicability: Model A320 series airplanes on which Airbus Modification 23611 (reference Airbus Service Bulletin A320-32-1115) has not been installed, 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 (b) 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 an electrical overvoltage of the relays, which could result in the loss of the braking/steering control unit (BSCU) systems, and subsequent loss of the antiskid functions and nose wheel steering of the airplane, accomplish the following:

(a) Within 10 months after the effective date of this AD, replace relays 24 GG and 25 GG in the forward electronics rack 90VU of zone 120 of the braking system of the landing gear with new relays, in accordance with Airbus Service Bulletin A320-32-1115, Revision 2, dated September 21, 1994.

(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, Standardization Branch, ANM-113, 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, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(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.

(d) The replacement shall be done in accordance with Airbus Service Bulletin A320- 32-1115, Revision 2, dated September 21, 1994, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1-4, 13
2
September 21, 1994
5-12
1
April 22, 1994

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 Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(e) This amendment becomes effective on March 25, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Airbus Model A320 series airplanes was published in the Federal Register on October 20, 1995 (60 FR 54202). That action proposed to require replacement of certain relays in the forward electronics ack 90VU of the braking system of the landing gear with new relays.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the three comments received.

The commenters support the proposed rule.

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

The FAA estimates that 87 airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplaneto accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will be supplied by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $10,440, or $120 per airplane.

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

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.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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 USC 106(g), 40113, 44701.
39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: