Airworthiness Directives; Airbus Model A320-111, -211, and -231 Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-210-AD; Amendment 39-9068; AD 94-23-06]

Airworthiness Directives; Airbus Model A320-111, -211, and -231

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Airbus Model A320-111, -211, and -231 airplanes,

that requires modification of the currently installed one-stage shock

absorbers on the main landing gear to two-stage shock absorbers. This

amendment is prompted by the results of an evaluation of the air-to-

ground sensing logic relative to the operation of other airplane

systems during landing in adverse weather conditions. The actions

specified by this AD are intended to prevent a delay in sensing by the

air-to-ground logic system that the airplane is on the ground, which

could prevent the airplane from achieving the landing distances

specified in the FAA-approved Airplane Flight Manual (AFM).

DATES: Effective December 21, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of December 21, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707

Blagnac Cedex, France. This information may be examined at the Federal

Aviation Administration (FAA), Transport Airplane Directorate, Rules

Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of

the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Stephen Slotte, Aerospace Engineer, Standardization Branch, ANM-113,

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (206) 227-2797; fax (206) 227-1320.

SUPPLEMENTARY INFORMATION: 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 A320-111, -

211, and -231 airplanes was published in the Federal Register on

December 29, 1993 (58 FR 68786). That action proposed to require

modification of the currently installed one-stage shock absorbers on

the main landing gear (MLG) to two-stage shock absorbers.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the proposed rule.

One commenter opposes the proposed requirement to modify the

currently installed one-stage shock absorber on the MLG to two-stage

shock absorbers. This commenter states that the requirement is

unnecessary due to the fact that the one-stage absorbers currently

installed on Model A320 series airplanes, when operated within the

certification standards of the airplane, do not adversely affect the

airworthiness of these airplanes. This commenter contends that the

purpose of the two-stage shock absorber is solely to improve passenger

comfort. The FAA does not concur that this rulemaking action is

unnecessary. The FAA has determined that the installation of the two-

stage shock absorber will improve the airplane's ability to achieve the

landing distances specified in the FAA-approved Airplane Flight Manual

(AFM). Earlier activation of supplemental braking devices, which would

be available by installing two-stage shock absorbers, will enhance

deceleration of the airplane when necessary to meet the required

landing distances. The FAA has re-evaluated the air-to-ground sensing

logic, has reviewed all other available data, and has determined that

an unsafe condition exists with regard to the airplane failing to

achieve the landing distances specified in the FAA-approved AFM.

Further, the FAA has determined that this AD action is necessary for

airplanes of this type design that are certificated for operation in

the United States.

One commenter asserts that the FAA is taking action contrary to the

normal course of action by proposing to issue the AD, when the French

Direction Generale de l'Aviation Civile (DGAC), which is the

airworthiness authority for France, has not issued a parallel AD. From

this comment, the FAA infers that the commenter is requesting that the

rule be withdrawn or delayed until the DGAC issues a similar mandatory

action. The FAA does not concur. While the United States and France

observe the provisions of the bilateral airworthiness agreement, it

remains the responsibility of the FAA to monitor and maintain the

continuing airworthiness of U.S.-type certificated and registered

airplanes. The bilateral airworthiness agreements do not restrict the

FAA from issuing AD's based upon its own finding of an unsafe

condition, regardless of the decision made by another airworthiness

authority relative to the same subject. In that the FAA has determined

that an unsafe condition exists, and that action is necessary to

correct that condition in the fleet, the issuance of this AD is not

only appropriate, but warranted.

One commenter suggests that the issuance of this rule be delayed

until such time that a lower cost alternative can be developed by the

manufacturer. In the interim, this commenter suggests that the proposal

be revised to require a periodic inspection to be performed at 15-month

intervals. The FAA does not concur. To delay this action would be

inappropriate, since the FAA has determined that an unsafe condition

exists, a corrective modification is currently available, and the

modification must be accomplished to ensure continued safety. However,

paragraph (b) of the final rule does provide affected operators the

opportunity to obtain approval from the FAA for alternative methods of

compliance by presenting justification for those alternatives.

Two commenters request that the proposed compliance time of 12

months be extended to accomplish the proposed modification of the shock

absorbers. One of these commenters requests that the compliance time be

extended to 24 months. The other commenter requests that the compliance

time be extended to 60 months, in light of the low probability of

duplicating the combination of factors that may result in an accident.

This commenter notes that, due to the unavailability of manpower and

tooling, the proposed modification would result in a minimum of three

days of downtime per airplane. Both commenters state that the

manufacturer may be unable to provide an adequate number of MLG pistons

to accomplish the modification within the proposed 12-month compliance

time.

The FAA concurs that the compliance time may be extended somewhat.

The FAA acknowledges the low probability of duplicating all of the

factors that may result in an accident. However, in the unlikely event

that all of the factors should be duplicated, airplanes equipped with

dual stage shock absorbers would be able to activate, at an earlier

stage of the landing roll, all available braking devices, including the

deployment of ground spoilers, application of wheel brakes, and

deployment of thrust reversers. Proper activation of braking devices

would permit the airplane to land within the distances specified in the

FAA-approved AFM. In light of the potential for these airplanes to

overrun the end of the runway due to delayed onset of braking, the FAA

cannot concur with the one commenter's request to extend the compliance

time to 60 months; the FAA considers that such an extension (five times

the amount of time proposed) would adversely affect safety. However, it

was not the FAA's intent to impose an undue economic burden on

operators by requiring them to take airplanes out of service for an

extended period of time due to the problem posed by a lack of available

parts to accomplish the modification required by this AD. Although the

airframe manufacturer has indicated that ample modification parts are

currently available, the supplier of those parts has indicated that

shipping to operators may take an extended period of time. In light of

this, the FAA has determined that an extension of the compliance time

to 18 months is appropriate; it will allow sufficient time for

operators to obtain the parts necessary to accomplish the modification,

while minimizing the economic burden on operators. The FAA finds that

this extension of the compliance time will not adversely affect the

safety of the fleet. Accordingly, paragraph (a) of the final rule has

been revised to extend the compliance time to accomplish the

modification of the shock absorber to 18 months.

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 change previously

described. The FAA has determined that this change will neither

increase the economic burden on any operator nor increase the scope of

the AD.

The FAA estimates that 35 airplanes of U.S. registry will be

affected by this AD, that it will take approximately 58 work hours per

airplane to accomplish the required actions, and that the average labor

rate is $55 per work hour. Required parts will cost approximately

$16,000 per airplane. Based on these figures, the total cost impact of

the AD on U.S. operators is estimated to be $671,650, or $19,190 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-23-06 Airbus Industrie: Amendment 39-9068. Docket 93-NM-210-AD.

Applicability: Model A320-111, -211, and -231 airplanes, as

listed in Airbus Industrie Service Bulletin A320-32-1058, Revision

2, dated June 16, 1993, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent a delay in sensing by the air-to-ground logic system

that the airplane is on the ground, which could prevent the airplane

from achieving the landing distances specified in the FAA-approved

Airplane Flight Manual (AFM), accomplish the following:

(a) Within 18 months after the effective date of this AD, modify

the currently installed one-stage shock absorbers to two-stage shock

absorbers, in accordance with Airbus Industrie Service Bulletin

A320-32-1058, Revision 2, dated June 16, 1993.

(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

Secs. 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 Airbus

Industrie Service Bulletin A320-32-1058, Revision 2, dated June 16,

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 December 21, 1994.

Issued in Renton, Washington, on November 4, 1994.

S. R. Miller,

Acting Management, Transport Airplane Directorate Aircraft

Certification Service.

[FR Doc. 94-27849 Filed 11-18-94; 8:45 am]

BILLING CODE 4910-13-U