Airworthiness Directives; Airbus Model A300-600 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-192-AD]

Airworthiness Directives; Airbus Model A300-600 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Airbus Model A300-600

series airplanes. This proposal would require repetitive ultrasonic

inspections to detect cracks in the bolt holes inboard and outboard of

rib 9 on the bottom booms of the front and rear wing spars, and repair,

if necessary. This proposal is prompted by the discovery of fatigue

cracks that emanated from the bolt holes inboard and outboard of rib 9

in the bottom booms of the front and rear wing spars. The actions

specified by the proposed AD are intended to prevent reduced structural

integrity of a wing spar as a result of fatigue cracks in the bolt

holes.

DATES: Comments must be received by January 26, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-192-AD, 1601 Lind Avenue, SW.,

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

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: 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:

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 94-NM-192-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. 94-NM-192-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

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

airworthiness authority for France, recently notified the FAA that an

unsafe condition may exist on certain Airbus Model A300-600 series

airplanes. The DGAC advises that, during full-scale fatigue testing of

Model A300 series airplanes, fatigue cracks were found that emanated

from the bolt holes inboard and outboard of rib 9 in the bottom booms

of the front and rear wing spars. The cracks were discovered at 58,650

simulated flight cycles. Additionally, the DGAC received six reports of

cracks found in the bottom booms of the front and rear wing spars at

the rib 9 joint on an in-service Model A300-B2 series airplane. The

cracks were discovered between 19,500 and 29,700 flight cycles. Model

A300-600 series airplanes are similar in type design to Model A300

series airplanes and, therefore, are subject to the cracking that was

discovered on Model A300 series airplanes.

Fatigue cracks in the lower boom of the front and rear wing spars,

if not detected and corrected in a timely manner, could result in

reduced structural integrity of a wing spar.

Airbus has issued Service Bulletin A300-57-6037, dated August 1,

1994, which describes procedures for repetitive ultrasonic inspections

to detect cracks in the bolt holes inboard and outboard of rib 9 on the

bottom booms of the front and rear wing spars, and repair, if

necessary. The DGAC classified this service bulletin as mandatory and

issued French airworthiness directive 94-208-169(B), dated September

14, 1994, in order to assure the continued airworthiness of these

airplanes in France.

This airplane model is manufactured in France and is type

certificated or 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 require repetitive

ultrasonic inspections to detect cracks in the bolt holes inboard and

outboard of rib 9 on the bottom booms of the front and rear wing spars,

and repair, if necessary. The actions would be required to be

accomplished in accordance with the service bulletin described

previously.

As a result of recent communications with the Air Transport

Association (ATA) of America, the FAA has learned that, in general,

some operators may misunderstand the legal effect of AD's on airplanes

that are identified in the applicability provision of the AD, but that

have been altered or repaired in the area addressed by the AD. Under

these circumstances, at least one operator appears to have incorrectly

assumed that its airplane was not subject to an AD. On the contrary,

all airplanes identified in the applicability provision of an AD are

legally subject to the AD. If an airplane has been altered or repaired

in the affected area in such a way as to affect compliance with the AD,

the owner or operator is required to obtain FAA approval for an

alternative method of compliance with the AD, in accordance with the

paragraph of each AD that provides for such approvals. A note has been

included in this notice to clarify this requirement.

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

affected by this proposed AD, that it would take approximately 11 work

hours per airplane to accomplish the proposed actions, and that the

average labor rate is $60 per work hour. Based on these figures, the

total cost impact of the proposed AD on U.S. operators is estimated to

be $23,100, or $660 per airplane, per inspection cycle.

The total 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.

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 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:

Airbus Industrie: Docket 94-NM-192-AD.

Applicability: Model A300-600 series airplanes on which Airbus

Modification 10161 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 use the authority

provided in paragraph (c) to request approval from the FAA. This

approval may address either no action, if the current configuration

eliminates the unsafe condition; or different actions necessary to

address the unsafe condition described in this AD. Such a request

should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

case does the presence of any modification, alteration, or repair

remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished

previously.

To prevent reduced structural integrity of a wing spar,

accomplish the following:

(a) Perform an ultrasonic inspection to detect cracks in the

bolt holes inboard and outboard of rib 9 on the bottom booms of the

front and rear wing spars, in accordance with Airbus Service

Bulletin A300-57-6037, dated August 1, 1994, at the time specified

in paragraph (a)(1) or (a)(2) of this AD, as applicable.

(1) For airplanes on which Airbus Modification 8842 (reference

Airbus Service Bulletin A300-57-6039) has not been installed: Prior

to the accumulation of 17,000 total landings, or within 2,000

landings after the effective date of this AD, whichever occurs

later. Repeat the inspection thereafter at intervals not to exceed

9,000 landings.

(2) For airplanes on which Airbus Modification 8842 has been

installed: Prior to the accumulation of 17,000 total landings after

accomplishment of Airbus Modification 8842, or within 2,000 landings

after the effective date of this AD, whichever occurs later. Repeat

the inspection thereafter at intervals not to exceed 9,000 landings.

(b) If any crack is found, prior to further flight, repair in

accordance with Airbus Service Bulletin A300-57-6037, dated August

1, 1994. Thereafter, perform the repetitive inspections required by

paragraph (a) of this AD.

(c) 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.

(d) 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 December 9, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-30802 Filed 12-14-94; 8:45 am]

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