FR Doc E7-10025

[Federal Register: May 25, 2007 (Volume 72, Number 101)]
[Rules and Regulations]
[Page 29241-29244]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25my07-3]

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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

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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