Airworthiness Directives; Airbus Model A320 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 95-NM-216-AD]

Airworthiness Directives; Airbus Model A320 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Airbus Model A320

series airplanes, that currently requires a one-time inspection to

detect cracking of the floor beams and the side box-beams between

frames 42 and 43, and repair of cracks. It also requires modification

of the pressure floor. That AD was prompted by the results of a full-

scale fatigue test. This action would add a new improved modification

requirement for the pressure floor at section 15 of the fuselage. The

actions specified by the proposed AD are intended to prevent reduced

structural integrity of the fuselage.

DATES: Comments must be received by May 28, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 95-NM-216-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056. Comments may be inspected at this

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location between 9:00 a.m. and 3:00 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: Tim Backman, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-2797; fax (206) 227-1149.

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 95-NM-216-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-103, Attention: Rules

Docket No. 95-NM-216-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion -

On July 9, 1993, the FAA issued AD 93-14-04, amendment 39-8628 (58

FR 39440, July 23, 1993), applicable to certain Airbus Model A320

series airplanes, to require a one-time inspection to detect cracking

of the floor beams and the side box-beams between frames 42 and 43, and

repair of cracks. It also requires modification of the pressure floor.

That action was prompted by the results of a full-scale fatigue test,

which indicated that fatigue cracking can occur in those areas. The

requirements of that AD are intended to prevent reduced structural

integrity of the fuselage due to problems associated with fatigue

cracking. -

Since the issuance of that AD, Airbus has issued Revision 1 of

Service Bulletin A320-53-1024, dated March 31, 1994. This service

bulletin is essentially identical to the original version of the

service bulletin (which was referenced in AD 93-14-04), but contains

certain editorial changes. This service bulletin permits further flight

with cracks in various areas around the fastener/bolt holes, provided

that those cracks do not exceed certain limits. The Direction Generale

de l'Aviation Civile (DGAC), which is the airworthiness authority for

France, classified this service bulletin as mandatory and issued French

airworthiness directive 92-205-033(B)R1, dated June 22, 1994, in order

to assure the continued airworthiness of these airplanes in France. -

In addition, Airbus has issued Revision 3 of Service Bulletin A320-

53-1023, dated March 18, 1994. This service bulletin describes new

improved procedures for modification of the pressure floor at section

15 of the fuselage. The modification involves the following actions: -

1. Removing components of the free-fall extension system of the

main landing gear and removing specified fasteners from various areas;

2. Cleaning the fastener holes;

3. Performing an eddy current (rotary probe) non-destructive test

inspection of the fastener holes;

4. Drilling/Reaming the fasteners holes;

5. Cold expanding the crack-free fastener holes;

6. Installing new fittings with the oversize fasteners; and

7. Installing the bell crank assembly and the pulley of the free-

fall extension system of the main landing gear.

Implementation of the new improved modification will positively

address the unsafe condition identified as reduced structural integrity

of the fuselage.

This airplane model is manufactured in France and is 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.

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 supersede AD 93-14-04 to

continue to require a one-time eddy current and detailed visual

inspection to detect cracks of various areas around the fastener/bolt

holes of the pressure floor. However, this proposal would add a new

improved modification of the pressure floor at section 15 of the

fuselage. The actions would be required to be accomplished in

accordance with the service bulletins described previously.

Operators should note that, unlike the procedures described in

Airbus Service Bulletin A320-53-1024, Revision 1, dated March 31, 1994,

this proposed AD would not permit further flight with cracking detected

in various areas around the fastener/bolt holes. The FAA has determined

that, due to the safety implications and consequences associated with

such cracking, all areas around the fastener/bolt holes that are found

to be cracked must be repaired prior to further flight. The repair

would be required to be accomplished in accordance with a method

approved by the FAA.

Furthermore, the FAA has determined that long term continued

operational safety will be better assured by design changes to remove

the source of the problem, rather than by repetitive inspections. Long

term inspections may not be providing the degree of safety assurance

necessary for the transport airplane fleet. This, coupled with a better

understanding of the human factors associated with numerous continual

inspections, has led the FAA to consider placing less emphasis on

inspections and more emphasis on design improvements. The proposed

modification requirement is in consonance with these considerations.

There are approximately 24 Airbus Model A320 series airplanes of

U.S. registry would be affected by this proposed AD.

The inspections that are currently required by AD 93-14-04 take

approximately 37 work hours per

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airplane to accomplish, at an average labor rate of $60 per work hour.

Based on these figures, the cost impact on U.S. operators of the

inspections currently required is estimated to be $53,280, or $2,220

per airplane.

The new modification that is proposed in this AD action would take

approximately 241 work hours per airplane to accomplish, at an average

labor rate of $60 per work hour. Required parts would cost

approximately $5,603 per airplane. Based on these figures, the cost

impact on U.S. operators of the proposed modification requirements of

this AD is estimated to be $481,512, or $20,063 per airplane.

The cost impact figures discussed above are based on assumptions

that no operator has yet accomplished any of the current or proposed

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted.

The regulations proposed herein would 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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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 USC 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-8628 (58 FR

39440, July 23, 1993), and by adding a new airworthiness directive

(AD), to read as follows:

Airbus Industrie: Docket 95-NM-216-AD. Supersedes AD 93-14-04,

Amendment 39-8628.

Applicability: Model A320 series airplanes, manufacturer's

serial numbers 002 through 008 inclusive, 010 through 078 inclusive,

and 080 through 107 inclusive; certificated in any category.

Note 1: This AD applies to each airplane identified in the

preceding applicability provision, regardless of whether it has been

otherwise 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 (d) 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 reduced structural integrity of the fuselage,

accomplish the following:

(a) Prior to the accumulation of 12,000 total landings, or 6

months after August 23, 1993 (the effective date of AD 93-14-04,

amendment 39-8628), whichever occurs later, accomplish the

requirements of paragraphs (a)(1) and (a)(2) of this AD, in

accordance with Airbus Industrie Service Bulletin A320-53-1024,

dated September 23, 1992, or Revision 1, dated March 31, 1994. As of

the effective date of this new AD, only Revision 1 of this service

bulletin shall be used.

(1) Conduct an eddy current inspection to detect cracking around

the fastener/bolt holes at the top horizontal flange of the floor

beams and side box-beams, at the two sides of the pressure floor,

and at the vertical integral stiffener of the side box-beams; and

(2) Conduct a detailed visual inspection to detect cracking

around the fastener/bolt holes at the fillet radius and riveted area

of the top outboard flange of the side box-beams, and at the flange-

corner radius of the slanted inboard flange of the side box-beam and

fittings.

(b) If any crack is detected during the inspections required by

paragraph (a) of this AD, prior to further flight, repair the crack

in accordance with a method approved by the Manager, Standardization

Branch, ANM-113, FAA, Transport Airplane Directorate.

(c) Modify the pressure floor at section 15 of the fuselage in

accordance with Airbus Service Bulletin A320-53-1023, Revision 3,

dated March 18, 1994, at the time specified in either paragraph

(c)(1) or (c)(2) of this AD, as applicable. Accomplishment of the

modification terminates the requirements of this AD.

(1) For airplanes on which the modification specified in Airbus

Service Bulletin A320-53-1023, dated September 23, 1992, as amended

by Service Bulletin Change Notice 0A, dated January 20, 1993;

Revision 1, dated March 23, 1993; or Revision 2, dated October 22,

1993; has been accomplished: Modify prior to the accumulation of

24,000 total landings, or 6 months after the effective date of this

AD, whichever occurs later.

(2) For all other airplanes not subject to paragraph (c)(1) of

this AD: Modify prior to the accumulation of 18,000 total landings,

or 6 months after the effective date of this AD, whichever occurs

later.

(d) 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.

(e) 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.

Issued in Renton, Washington, on April 9, 1996.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 96-9235 Filed 4-12-96; 8:45 am]

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