AD 94-24-07

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A320 series airplanes, that requires modification of the brake steering control unit (BSCU). This amendment is prompted by reports that the BSCU on these airplanes allowed a 90-degree rotation of the nose gear after landing, which resulted in significant damage to the wheels. The actions specified by this AD are intended to prevent failure of the nose gear tires and wheels and the loss of directional control of the airplane while it is on the ground.

Final rule.

94-24-07 AIRBUS INDUSTRIE: Amendment 39-9080. Docket 92-NM-217-AD.

Applicability: Model A320 series airplanes equipped with twin wheel main landing gears (MLG) on which Airbus Industrie Service Bulletin A320-32-1094 or Airbus Industrie Modification 22990 has not been accomplished; and Model A320 series airplanes equipped with bogie MLG's on which Airbus Industrie Service Bulletin A320-32-1100 or Airbus Industrie Modification 23106 has not been accomplished; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the nose gear tires and wheels and the loss of directional control, accomplish the following:

(a) Within 6 months after the effective date of this AD, modify the brake steering control unit (BSCU) in accordance with Airbus Industrie Service Bulletin A320-32-1094, Revision 2, dated November 25, 1992; or Revision 3, dated June 24, 1993 (for airplanes equipped with twin wheel MLG's); or in accordance with Airbus Industrie Service Bulletin A320-32-1100, Revision 1, dated November 9, 1993 (for airplanes equipped with bogie MLG's); as applicable.

(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: 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 modification shall be done in accordance with the following Airbus Industrie service bulletins, as applicable, which contain the following list of effective pages:

Service Bulletin
Referenced and Date

Page Number
Revision Level
Shown on Page
Date
Shown on Page
A320-32-1094,
Revision 2,
November 25, 1992
1, 7
2-6
8-11
2
1
Original
November 25, 1992
May 26, 1992
March 25, 1992
A320-32-1094,
Revision 3,
June 24, 1993
1, 3, 6
2, 4, 5
7
8-11
3
1
2
Original
June 24, 1993
May 26, 1992
November 25, 1992
March 25, 1992
A320-32-1100,
Revision 1,
November 9, 1993
1, 3-7
2
Original
1
June 18, 1993
November 9, 1993

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 January 6, 1995.

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 April 16, 1993 (58 FR 19787). That action proposed to require modification of the brake steering control unit (BSCU) for certain airplanes equipped with twin wheel main landing gears (MLG).

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

Both commenters support the proposed rule.

Since the issuance of the proposed rule, Airbus issued Service Bulletin A320-32-1100, Revision 1, dated November 9, 1993, which describes procedures for modification of the BSCU on certain Model A320 series airplanes equipped with bogie MLG's. The modification involves upgrading the currently installed standard 3 BSCU functional software to a new standard 3.1 BSCU, which includes reprogramming of certain software for each system of the BSCU. Accomplishment of the modification will allow activation of the nose wheel steering at main gear touchdown on these airplanes, and authorization of rudder pedal action that would allow progressive amplitude authority from 130 to 40 knots. The Direction G n rale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, classified this service bulletin as mandatory and issued French Airworthiness Directive 92-117-025(B)R1, dated August 18, 1993, in order to assure the continued airworthiness of these airplanes in France.

The FAA finds that Model A320 series airplanes equipped with bogie MLG's are subject to the same unsafe condition that is addressed by this rule. In light of this, the FAA has revised the applicability of the final rule to include these airplanes. However, there currently are no Model A320 series airplanes equipped with bogie MLG's on the U.S. Register; therefore, no additional U.S. airplanes are affected directly by this AD action. The FAA considers that the revision to the applicability of the rule is necessary in order to ensure that the unsafe condition is addressed in the event that these specific airplanes are imported and placed on the U.S. Register in the future.

In addition, the FAA has revised paragraph (a) of the final rule to cite the appropriate service information for modification of the BSCU on airplanes equipped with bogie MLG's.

Since the issuance of the proposed rule, Airbus also has issued Service Bulletin A320-32-1094, Revision 3, dated June 24, 1993. Revision 3 of the service bulletin is essentially identical to Revision 2 (which was cited in the proposal as the appropriate source of service information), but revises the effectivity listing to include one additional airplane. The FAA has determined that this additional airplane is operated currently by a non-U.S. operator under foreign registry; therefore, this airplane is not affected directly by this AD action. The FAA has revised paragraph (a) of the final rule to cite Revision 3 of the service bulletin as an additional source of service information for accomplishment of the required modification.

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 with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any U.S. operator nor increase the scope of the AD.

The FAA estimates that 52 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $55 per work hour. Required parts will be supplied by the vendor at no cost to operators. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $2,860, or $55 per airplane.

The total 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 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.
39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: