[Federal Register Volume 72, Number 101 (Friday, May 25, 2007)]
[Rules and Regulations]
[Pages 29241-29244]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-10025]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24983; Directorate Identifier 2005-NM-196-AD; 
Amendment 39-15068; AD 2007-11-11]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A318, A319, A320, and A321 
Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD), which applies to all Airbus Model A318, A319, A320, and A321 
airplanes. That AD currently requires a one-time inspection to 
determine the serial number of both main landing gear (MLG) sliding 
tubes, repetitive detailed inspections for cracking of the affected MLG 
sliding tubes, and corrective actions if necessary. This new AD retains 
these inspections and adds new repetitive inspections for cracking of 
the MLG sliding tubes. This AD also requires eventual replacement of 
both MLG shock absorbers. Doing this replacement terminates the 
repetitive inspection requirements of this AD. This AD results from a 
determination that additional inspections and mandatory replacement of 
the MLG shock absorbers are necessary. We are issuing this AD to detect 
and correct cracking in an MLG sliding tube, which could result in 
failure of the sliding tube, loss of one axle, and consequent reduced 
controllability of the airplane.

DATES: This AD becomes effective June 29, 2007.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of June 29, 
2007.
    On June 23, 2004, (69 FR 31867, June 8, 2004), the Director of the 
Federal Register approved the incorporation by reference of Airbus All 
Operators Telex A320-32A1273, Revision 01, dated May 6, 2004.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
Room PL-401, Washington, DC.
    Contact Airbus, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, 
France, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Tim Dulin, Aerospace Engineer, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
227-2141; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at http://dms.dot.gov or in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that supersedes AD 2004-11-13, amendment 
39-13659 (69 FR 31867, June 8, 2004). The existing AD applies to all 
Airbus Model A318, A319, A320, and A321 airplanes. That NPRM was 
published in the Federal Register on June 12, 2006 (71 FR 33658). That 
NPRM proposed to retain the inspections required by the existing AD and 
add new repetitive inspections for cracking of the MLG sliding tubes. 
That NPRM also proposed to require eventual replacement of both MLG 
shock absorbers, which would terminate the repetitive inspection 
requirements proposed by that NPRM.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
received on the NPRM.

[[Page 29242]]

Support for the NPRM

    Airbus concurs with the contents of the NPRM.

Request To Retain Inspection in Existing AD

    The Air Transport Association (ATA) on behalf of its members United 
Airlines (UAL), Northwest Airlines (NWA), and U.S. Airways (USAir), 
requests that we retain the 10-day inspection required by AD 2004-11-
13. The commenters state that they consider the current 10-day visual 
inspection to be the most effective and appropriate inspection method 
to check and recheck in-service parts for a crack, because that 
inspection emulates the process which identified the first and only 
crack found on the transition area of the main landing gear (MLG) 
sliding tube after an overweight/heavy landing.
    We agree with the commenters that the visual inspection is 
currently the most effective method of detecting cracks in the high 
stress transition area. As the 10-day visual inspection required by AD 
2004-11-13 is retained in this AD, it is not necessary to change the AD 
in this regard.

Request To Change Magnetic Particle Inspection (MPI) Interval

    The same commenters request that we change the interval for 
repeating the MPI from intervals not to exceed 1200 flight cycles to 
intervals not to exceed 2500 flight cycles or the gear overhaul cycle. 
NWA asserts that an MPI is most effective when applied in a shop 
environment, as the MPI could yield false readings that require 
removing the protective coating from the MLG sliding tube and re-
inspecting to prove that no crack exists. NWA asserts that the effort 
to locally remove the protective coating could lead to damage of the 
MLG sliding tube and introduce a further unsafe condition. NWA 
recommends that the MPI remain at an overhaul interval schedule instead 
of the in situ interval proposed by the NPRM. UAL asks that we change 
the MPI repetitive interval to 2,500 flight cycles or a less intrusive 
interval that corresponds with a heavy maintenance check, and that we 
change the MPI inspection area to the high stress area. NWA notes that, 
according to Airbus, the 1,200 flight cycle MPI interval is based on 
the highest stress areas, which are specifically excluded from the MPI 
inspection areas and are subject only to the detailed visual 
inspection. NWA further notes that, according to Airbus, the remaining 
axle stresses are not significant enough for a crack to reach critical 
size within one overhaul interval of 10 years or 20,000 flight cycles, 
and that utilizing a safety factor of 3 yields the required interval of 
6,666 flight cycles.
    We partially agree. We have determined that an MPI interval that 
corresponds with a gear overhaul interval of 10 years or 20,000 flight 
cycles would not provide an adequate level of safety. Further, the 
highest stress areas described by NWA have highly contoured geometries 
that cannot be reliably inspected with MPIs. However, we agree that the 
MPI and applicable corrective actions should be performed during 
scheduled heavy maintenance when these actions could be done properly. 
Therefore, we have revised the repetitive interval in paragraph (h) of 
the AD to read ``not to exceed 2,500 flight cycles or 21 months, 
whichever occurs earlier.''

Request for Alternative Terminating Action

    The same commenters request that we consider other methods of 
terminating action. UAL asserts that the acoustic resonance inspection 
system (ARIS) and phased array eddy current methods of non-destructive 
testing are able to detect subsurface flaws in complex geometries and, 
therefore, offer much more precise test results than the MPI. UAL 
states that the ARIS, which uses an electromagnetic acoustic transducer 
(EMAT), exploits the unique physical properties of ultrasonic resonance 
to produce constant sound waves of controllable depth and length that 
change only if an anomaly is scanned in the material under test. UAL 
also asserts that the phased array eddy current method, developed by 
Iowa State University with FAA funding, has proved effective in 
inspections for cracking of MLG cylinders required by AD 2005-19-08, 
amendment 39-14273, which is applicable to DC-9 series airplanes.
    We disagree. The commenters have not provided any data to 
demonstrate that these two methods will conclusively and positively 
identify subsurface flaws. Further, Airbus has investigated and 
determined that these two inspection methods would not reliably 
demonstrate the presence of any subsurface flaws. Therefore, we have 
not changed the AD in this regard. However, any operator may request an 
alternative method of compliance (AMOC) in accordance with the 
procedures in paragraph (m) of the AD, provided that sufficient data 
are submitted to substantiate that the proposed AMOC would provide an 
acceptable level of safety.

Request To Withdraw MPI and Mandatory Shock Absorber Replacement

    The same commenters request that the mandatory terminating action 
be removed from the NPRM. UAL accepts the requirement for the initial 
and repetitive detailed inspections, but asserts that the risk of MLG 
failure is so small that the expense of the MPI inspection and the 
mandatory shock absorber replacement is not justified. The commenters 
note that, in 2003, Airbus determined that the frequency of occurrence 
of the subject failure was one event in 1.33 billion component hours; 
and that, since then, the fleet has continued to operate with no 
incidents of MLG failure. Further, UAL notes that the root cause of the 
event was determined to be a manufacturing process condition that could 
be random within the volume of the part and asserts, therefore, that 
volumetric analysis would be more appropriate. Finally, UAL notes that, 
although the MPI increases the chances of identifying the surface 
indication of a crack, the areas to be inspected are not in the 
transitional area of the MLG sliding tube where the initial crack 
occurred. NWA asserts that the MPI is unable to detect subsurface flaws 
or inspect complex geometrical contours and might not be able to detect 
the most critical flaws, which could give a false sense of security. 
The commenters request, therefore, that the requirements for the MPI 
and mandatory shock absorber replacement be removed.
    We do not agree. As the probability of manufacturing flaws can not 
be precisely determined and an MLG collapse at high speed could be 
catastrophic, the absence of a completely reliable method of finding 
subsurface flaws requires that we use the best methods currently 
available to detect surface cracks until the affected MLG shock 
absorbers are replaced. As such, the MPI provides additional capability 
to detect surface cracks and, therefore, supplements the detailed 
inspections. We have not changed the AD in this regard.

Request To Make Terminating Action Optional

    The same commenters request that, if not removed, the terminating 
action be made optional. UAL asserts that operators should have the 
choice to continue repeating the required inspections indefinitely or 
to replace the affected MLG sliding tubes. UAL contends that Airbus and 
Messier-Dowty have not justified that sufficient

[[Page 29243]]

need exists to require replacing the MLG sliding tubes by a certain 
date.
    We do not agree. According to FAA policy, design changes should be 
implemented to remove the source of a problem, rather than relying on 
inspections to ensure the problem does not occur, especially when the 
results could be catastrophic and the inspection is difficult, as in 
this case. We have not changed the AD in this regard.

Clarification of AMM

    To prevent confusion, we have revised paragraph (i) of the AD to 
clarify that the Airbus A318/A319/A320/A321 aircraft maintenance 
manual, chapter 32-11-13, page block 401, describes one approved method 
of removing and replacing the MLG shock absorbers.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been received, and determined that air safety and 
the public interest require adopting the AD with the changes described 
previously. We have determined that this change will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    This AD affects about 720 airplanes of U.S. registry. The following 
table provides the estimated costs for U.S. operators to comply with 
this AD at an estimated labor rate of $80 per work hour. Operators 
should note that, although all U.S.-registered airplanes are subject to 
the requirements of the existing AD, there are only 297 possible 
affected MLG sliding tubes in the worldwide fleet. We have no way of 
knowing how many affected MLG sliding tubes, if any, are installed in 
U.S.-registered airplanes. Therefore, the estimated costs to perform 
the new requirements of this AD apply only to individual sliding tubes; 
no fleet cost can be determined for these actions.

                                            Estimated Costs To Perform Requirements of Existing AD 2004-11-13
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                                                                                                                             Cost per
                     Action                        Work hours                             Parts                              airplane       Fleet cost
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General visual inspection to determine serial                 1  None...................................................             $80         $57,600
 number.
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                                                 Estimated Costs to Perform New Requirements of This AD
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                 Action                    Work hours                         Parts                                    Cost per sliding tube
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Detailed inspection....................               1  None...........................................  $80, per inspection cycle.
Detailed inspection and magnetic                      9  None...........................................  $720, per inspection cycle.
 particle inspection.
Replacement of sliding tube............               8  $38,278 to $45,310.............................  $39,918 to $45,950.
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect 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.
    For the reasons discussed above, I certify that this AD:
    (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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD and placed it in the AD docket. See the ADDRESSES 
section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-13659 (69 FR 31867, June 8, 2004) and adding the 
following new airworthiness directive (AD):

2007-11-11 Airbus: Amendment 39-15068. Docket No. FAA-2006-24983; 
Directorate Identifier 2005-NM-196-AD.

Effective Date

    (a) This AD becomes effective June 29, 2007.

Affected ADs

    (b) This AD supersedes AD 2004-11-13.

Applicability

    (c) This AD applies to all Airbus Model A318, A319, A320, and 
A321 airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from a determination that additional 
inspections and mandatory replacement of the main landing gear (MLG) 
shock absorbers are necessary. We are issuing this AD to detect and 
correct cracking in an MLG sliding tube, which could result in

[[Page 29244]]

failure of the sliding tube, loss of one axle, and consequent 
reduced controllability of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Service Information References

    (f) The term ``service information,'' as used in this AD, means 
Airbus All Operators Telex (AOT) A320-32A1273, Revision 01, dated 
May 6, 2004; or the Accomplishment Instructions of Airbus Service 
Bulletin A320-32A1273, Revision 02, including Appendix 01, dated May 
26, 2005. After the effective date of this AD, only Airbus Service 
Bulletin A320-32A1273, Revision 02, may be used.

    Note 1: Airbus AOT A320-32A1273, Revision 01, and Airbus Service 
Bulletin A320-32A1273, Revision 02, refer to Messier-Dowty Service 
Bulletin 201-32-43, Revision 1, dated May 1, 2005; and Messier-Dowty 
Service Bulletin 200-32-286, Revision 1, dated March 1, 2005, as 
additional sources of service information for accomplishing the 
detailed inspections and magnetic particle inspections (MPI).

Restatement of Certain Requirements of AD 2004-11-13

Serial Number (S/N) Identification

    (g) For all airplanes: Within 30 days after June 23, 2004 (the 
effective date of AD 2004-11-13), do a one-time general visual 
inspection to determine the S/N of both MLG sliding tubes, in 
accordance with the service information. Instead of inspecting the 
MLG sliding tubes, reviewing the airplane maintenance records is 
acceptable if the S/N of the MLG sliding tubes can be positively 
determined from that review.
    (1) If the S/N of the MLG sliding tube is not listed in the 
service information: No further action is required by this paragraph 
for that sliding tube.
    (2) If the S/N of the MLG sliding tube is listed in the service 
information: Do the actions in paragraph (g)(2)(i) or (g)(2)(ii) of 
this AD, as applicable.
    (i) For any MLG not inspected before June 23, 2004: Before 
further flight, do a detailed inspection of the MLG for cracking in 
accordance with the service information.
    (A) If no cracking is found in any MLG sliding tube: Repeat the 
detailed inspection thereafter at intervals not to exceed 10 days, 
until the MLG replacement specified by paragraph (g)(2)(i)(B), (h), 
or (i) of this AD has been accomplished.
    (B) If any cracking is found in any MLG sliding tube: Before 
further flight replace the part with a new or serviceable part in 
accordance with a method approved by either the FAA or the Direction 
Generale de l'Aviation Civile (DGAC) (or its delegated agent). 
Chapter 32 of the Airbus A318/A319/A320/A321 Aircraft Maintenance 
Manual (AMM) is one approved method. Installing an MLG sliding tube 
having an S/N that is not listed in the service information 
terminates the repetitive inspections required by paragraph (h) of 
this AD for that MLG sliding tube only.
    (ii) For any MLG that has been inspected before June 23, 2004: 
Within 10 days after that inspection, do the detailed inspection 
required by paragraph (g)(2)(i) of this AD.

New Requirements of This AD

Detailed Inspection and Magnetic Particle Inspection (MPI)

    (h) For any airplane equipped with any MLG having a sliding tube 
installed that is identified with a S/N listed in the service 
information: Within 500 flight cycles after the effective date of 
this AD, perform a detailed inspection and an MPI of the MLG sliding 
tube for cracking in accordance with the service information. Repeat 
these inspections thereafter at intervals not to exceed 2,500 flight 
cycles or 21 months, whichever occurs earlier, until paragraph (i) 
of this AD has been accomplished. If any cracking is discovered 
during any inspection required by this paragraph, before further 
flight, replace the cracked sliding tube with a new or serviceable 
sliding tube in accordance with the service information. Replacing 
the MLG sliding tube with a sliding tube having a S/N not listed in 
the service information terminates the repetitive inspection 
requirements of this paragraph and paragraph (g)(2)(i)(A) of this AD 
for that sliding tube only.

Terminating Action

    (i) Within 41 months after the effective date of this AD, 
replace all MLG shock absorbers equipped with sliding tubes having 
S/Ns listed in the service information with new or serviceable MLG 
shock absorbers equipped with sliding tubes having S/Ns not listed 
in the service information, using a method approved by either the 
Manager, International Branch, ANM-116, Transport Airplane 
Directorate, FAA; or the DGAC (or its delegated agent). Airbus A318/
A319/A320/A321 AMM 32-11-13, page block 401, is one approved method. 
Replacing the MLG shock absorbers in accordance with this paragraph 
terminates all repetitive inspections required by this AD.

Submission of Cracked Parts Not Required

    (j) The service information has instructions to send any cracked 
part to Messier-Dowty. This AD does not include such a requirement.

Reporting Requirement

    (k) Prepare a report of any crack found during any inspection 
required by paragraph (g) or (h) of this AD. Submit the report to 
Airbus Customer Services, Engineering and Technical Support, 
Attention: M.Y. Quimiou, SEE33, fax +33+ (0) 5.6193.32.73, at the 
applicable time specified in paragraph (k)(1) or (k)(2) of this AD. 
The report must include the MLG sliding tube P/N and S/N, date of 
inspection, a description of any cracking found, the airplane serial 
number, and the number of flight cycles on the MLG at the time of 
inspection. Under the provisions of the Paperwork Reduction Act of 
1980 (44 U.S.C. 3501 et seq.), the Office of Management and Budget 
(OMB) has approved the information collection requirements contained 
in this AD and has assigned OMB Control Number 2120-0056.
    (1) For any inspection done after June 23, 2004, but before the 
effective date of this AD: Within 30 days after the inspection or 30 
days after the effective date of this AD, whichever comes first.
    (2) For any inspection done after the effective date of this AD: 
Within 30 days after the inspection.

Parts Installation

    (l) As of the effective date of this AD, no person may install, 
on any airplane, any sliding tube, or MLG shock absorber having a 
sliding tube installed, if the sliding tube has a S/N identified in 
the service information, unless the sliding tube has been inspected, 
and any applicable corrective actions have been done, in accordance 
with paragraph (g)(2)(i), (h), or (i) of this AD.

Alternative Methods of Compliance (AMOCs)

    (m)(1) The Manager, International Branch, ANM-116, has the 
authority to approve AMOCs for this AD, if requested using the 
procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Related Information

    (n) French airworthiness directive F-2005-115, dated July 6, 
2005, also addresses the subject of this AD.

Material Incorporated by Reference

    (o) You must use Airbus All Operators Telex A320-32A1273, 
Revision 01, dated May 6, 2004, and Airbus Service Bulletin A320-
32A1273, Revision 02, including Appendix 01, dated May 26, 2005; as 
applicable; to perform the actions that are required by this AD, 
unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of Airbus Service Bulletin A320-32A1273, 
Revision 02, including Appendix 01, dated May 26, 2005, in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) On June 23, 2004 (69 FR 31867, June 8, 2004), the Director 
of the Federal Register approved the incorporation by reference of 
Airbus All Operators Telex A320-32A1273, Revision 01, dated May 6, 
2004.
    (3) Contact Airbus, 1 Rond Point Maurice Bellonte, 31707 Blagnac 
Cedex, France, for a copy of this service information. You may 
review copies at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Renton, Washington, on May 15, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-10025 Filed 5-24-07; 8:45 am]
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