[Federal Register Volume 63, Number 135 (Wednesday, July 15, 1998)]
[Rules and Regulations]
[Pages 38080-38082]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-18650]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-197-AD; Amendment 39-10655; AD 98-15-04]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A320 Series 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 series airplanes, that requires 
repetitive inspections for fatigue cracking of the bottom flanges of 
the longitudinal floor beams at frame 43; and repair, if necessary. 
This amendment also requires a one-time inspection for fatigue cracking 
of the fastener holes in the longitudinal floor beams, and modification 
of the floor

[[Page 38081]]

beams, which constitutes terminating action for the repetitive 
inspections. This amendment is prompted by issuance of mandatory 
continuing airworthiness information by a foreign civil airworthiness 
authority. The actions specified by this AD are intended to prevent 
fatigue cracking on the bottom flanges of the longitudinal floor beams, 
which could result in reduced structural integrity of the airplane.

DATES: Effective August 19, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of Augut 19, 1998.

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: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2110; fax (425) 227-1149.

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 series 
airplanes was published in the Federal Register on April 14, 1998 (63 
FR 18158). That action proposed to require repetitive inspections for 
fatigue cracking of the bottom flanges of the longitudinal floor beams 
at frame 43; and repair, if necessary. That action also proposed to 
require a one-time inspection for fatigue cracking of the fastener 
holes in the longitudinal floor beams, and modification of the floor 
beams, which would constitute terminating action for the repetitive 
inspections.

Comments

    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.

Request To Allow Flight With Cracks

    One commenter requests that the proposed AD be revised to allow 
continued operation of the airplane following the detection of cracks, 
provided operators follow the defined values for follow-on inspections 
and repairs as recommended in Airbus Service Bulletin A320-53-1085. The 
commenter states that the structure of Airbus A320 series airplanes is 
classified as damage tolerant. Additionally, based on fatigue test 
results and calculations of the crack propagation rate, the 
manufacturer has defined in the service bulletin an appropriate number 
of flight cycles for continued flight with cracks, depending on the 
crack length detected. Finally, the commenter notes that the inspection 
program recommended in the service bulletin was developed in order to 
prevent the need for extensive repair of the aircraft.
    The FAA does not concur with the commenter's request to allow 
continued operation of the airplane following the detection of cracks. 
Generally, the FAA considers that damage tolerance assessment 
methodologies are effective for establishing an inspection program that 
will detect cracks before failure occurs, but they are not sufficiently 
accurate to predict precisely and reliably the rates at which 
identified cracks will propagate to failure. Additionally, the FAA 
recognizes that there are adverse human factors associated with the 
performance of repetitive inspections that may reduce safety if such 
repair deferrals are practiced routinely.
    Therefore, it is FAA policy to require repair of known cracks prior 
to further flight whether the airplane structure is classified as 
damage tolerant or not, rather than to use the principles of damage 
tolerance as a tool to manage existing cracks. There may be certain 
exceptions to this policy for cases where there is an unusual need for 
a temporary deferral of the repair, such as difficulty in acquiring 
parts to accomplish a repair in a timely manner. Since the commenter 
has not identified any unusual need that would warrant an exception to 
FAA policy in this instance, the FAA has determined that, due to the 
safety implications and consequences associated with such cracking, any 
subject bottom flange or fastener hole that is found to be cracked must 
be repaired or modified prior to further flight. No change to the final 
rule is necessary.

Conclusion

    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.

Cost Impact

    The FAA estimates that 5 airplanes of U.S. registry will be 
affected by this AD. It will take approximately 3 work hours per 
airplane to accomplish the required inspection of the bottom flanges, 
at an average labor rate of $60 per work hour. Based on these figures, 
the cost impact of the inspection required by this AD on U.S. operators 
is estimated to be $900, or $180 per airplane, per inspection cycle.
    It will take approximately 32 work hours per airplane to accomplish 
the required inspection of the fastener holes and required 
modification, at an average labor rate of $60 per work hour. Required 
parts will cost between $649 and $3,056 per airplane, depending on the 
service kit purchased. Based on these figures, the cost impact of the 
inspection of the fastener holes and modification required by this AD 
on U.S. operators is estimated to be as low as $12,845, or $2,569 per 
airplane, and as high as $24,880, or $4,976 per airplane.
    The cost impact figures discussed above are 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.

Regulatory Impact

    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

[[Page 38082]]

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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

98-15-04  Airbus Industrie: Amendment 39-10655. Docket 97-NM-197-AD.

    Applicability: Model A320 series airplanes, on which Airbus 
Modification 20904 (reference Airbus Service Bulletin A320-53-1008, 
dated March 31, 1995) has not been accomplished, 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 (c) 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 fatigue cracking on the bottom flanges of the 
longitudinal floor beams at frame 43, which could result in reduced 
structural integrity of the airplane, accomplish the following:
    (a) Prior to the accumulation of 20,000 total flight cycles, or 
within 1,000 flight cycles after the effective date of this AD, 
whichever occurs later, perform a visual inspection for fatigue 
cracking of the longitudinal floor beams at frame 43, in accordance 
with Airbus Service Bulletin A320-53-1085, dated March 31, 1995.
    (1) If no cracking is detected, repeat the visual inspection 
thereafter at intervals not to exceed 6,000 flight cycles.
    (2) If any cracking is detected, prior to further flight, repair 
in accordance with a method approved by the Manager, International 
Branch, ANM-116, FAA, Transport Airplane Directorate.
    (b) Prior to the accumulation of 32,000 total flight cycles, or 
within 1,000 flight cycles after the effective date of this AD, 
whichever occurs later, accomplish paragraphs (b)(1) and (b)(2) of 
this AD. Accomplishment of paragraphs (b)(1) and (b)(2) constitutes 
terminating action for the repetitive inspection requirements of 
this AD.
    (1) Perform a one-time eddy current (rotary probe) non-
destructive test (NDT) inspection for fatigue cracking of the 
fastener holes on the longitudinal floor beams at frame 43, in 
accordance with Airbus Service Bulletin A320-53-1008, dated March 
31, 1995. If any cracking is detected, prior to further flight, 
repair in accordance with a method approved by the Manager, 
International Branch, ANM-116.
    (2) Modify the floor beam fasteners in accordance with Airbus 
Service Bulletin A320-53-1008, dated March 31, 1995.
    (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, International Branch, ANM-116. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, International Branch, ANM-116.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

    (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.
    (e) The visual inspection shall be done in accordance with 
Airbus Service Bulletin A320-53-1085, dated March 31, 1995. The eddy 
current inspection and the modification shall be done in accordance 
with Airbus Service Bulletin A320-53-1008, dated March 31, 1995. 
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.

    Note 3: The subject of this AD is addressed in French 
airworthiness directive 96-236-089(B), dated October 23, 1996.

    (f) This amendment becomes effective on August 19, 1998.

    Issued in Renton, Washington, on July 7, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-18650 Filed 7-14-98; 8:45 am]
BILLING CODE 4910-13-P