AD 2001-16-09

[Federal Register Volume 66, Number 161 (Monday, August 20, 2001)]
[Rules and Regulations]
[Pages 43471-43474]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-20700]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-342-AD; Amendment 39-12377; AD 2001-16-09]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), which is applicable to all Model A320 series airplanes, that 
currently requires repetitive measurements of the deflection of the 
elevator trailing edge; inspections of the elevator servo controls and 
their attachments; and replacement of worn or damaged parts, if 
necessary. This amendment requires periodic inspection of the elevators 
for excessive freeplay, repair of worn parts if excessive freeplay is 
detected, and modification of the elevator neutral setting. It also 
revises the applicability to include additional airplane models. This 
amendment is prompted by additional reports of severe vibration in the 
aft cabin of Model A320 series airplanes and studies that indicate that 
the primary cause is excessive freeplay in the elevator attachments. 
The actions specified by this AD are intended to prevent excessive 
vibration of the elevators, which could result in reduced structural 
integrity and reduced controllability of the airplane.

DATES: Effective September 24, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 24, 2001.

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: Tim Dulin, Aerospace Engineer, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2141; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION: The FAA issued a proposal to amend part 39 
of the Federal Aviation Regulations (14 CFR part 39) to supersede AD 
92-04-06, amendment 39-8177 (57 FR 6068, February 20, 1992). (A 
correction of AD 92-04-06 was published in the Federal Register on 
April 1, 1992 (57 FR 11137).) AD 92-04-06 is applicable to all Airbus 
Model A320 series airplanes. The proposed AD was published in the 
Federal Register on March 1, 2001 (66 FR 12913). The action proposed to 
require periodic inspection of the elevators for excessive freeplay; 
repair or replacement of worn parts, if excessive freeplay is detected; 
replacement of the elevator servo controls with modified elevator servo 
controls; and modification of the elevator neutral setting. The action 
also proposed to revise the applicability to include additional 
airplane models.

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.

Support for Proposed AD

    Several commenters, including the National Transportation Safety 
Board, support the proposed AD.

Request To Withdraw the Proposed AD

    One commenter (the manufacturer) requests that the proposed AD be 
withdrawn. The commenter asserts that there is no unsafe condition due 
to limit cycle oscillation (LCO) of the elevator. The commenter 
disagrees with the FAA's conclusion that elevator LCO could result in 
reduced structural integrity and reduced controllability of the 
airplane. The commenter notes that because LCO is a fixed-frequency 
vibration with a constant amplitude, it is therefore not a stability 
problem. The commenter contends that such a phenomenon is well 
detectable, and the flight crew can determine the significance of the 
airframe vibration and initiate appropriate corrective action. The 
commenter claims that, during the period between LCO initiation and 
uncomfortable vibration, there is no structural concern. The commenter 
adds that extensive flight tests have been conducted by the 
manufacturer, with representative backlash configurations combined with 
low hinge moment, and no adverse effect on handling qualities was 
found. The commenter considers the actions included in existing tasks 
in the aircraft maintenance manual (AMM) and service bulletins to be 
sufficient to address any possible LCO phenomenon. In addition, the 
commenter does not consider that there would be any benefit from 
imposing corrective action on an airplane with no vibration reported.
    The FAA does not concur with the request to withdraw the proposed 
AD. The FAA has determined that the A320 elevator LCO, as defined by 
Airbus, is actually an aeroelastic stability problem (i.e., self-
excited and not damped with time), which, if not addressed, could 
result in reduced structural integrity and reduced controllability of 
the airplane. The FAA is aware of all of the analytical and 
experimental investigations conducted by Airbus that have shown that 
LCO is caused by a combination of low hinge moment and elevator 
freeplay. The FAA is also aware that the amplitude of the vibration 
increases with freeplay and airspeed. The FAA disagrees with the Airbus 
contention that the vibration will be felt by the flight crew, who can 
initiate the appropriate corrective action. The FAA notes that the 
modification of the elevator neutral setting would tend to

[[Page 43472]]

mask the presence of freeplay and associated vibration, and make the 
freeplay checks even more critical. The FAA also disagrees with the 
Airbus contention that there would be no benefit from imposing these 
actions on airplanes that have not had vibration problems. To address 
potential LCO events, Airbus has revised the AMM to reduce the 
allowable freeplay limits, and issued service bulletins to recommend 
installation of improved spherical bearings to reduce the wear rate, 
and modification of the elevator neutral setting to ensure that 
elevators have sufficient hinge moment loading under most flight 
conditions. The FAA agrees with these recommendations but considers 
that these actions, except as noted below, must be mandated to ensure 
the continued safe operation of the fleet, by reducing the likelihood 
of LCO events and ensuring that the amplitude of any LCO event that 
does occur is controlled to a level that will not result in reduced 
structural integrity of the airplane.
    The FAA notes that this LCO phenomenon is not unique to Airbus 
airplanes; the actions required by this AD are consistent with actions 
taken on other airplanes. The FAA considers this final rule necessary 
to adequately address the identified unsafe condition.

Request To Remove Requirement To Replace Elevator Servo Controls

    One commenter (the manufacturer) considers that the effect of 
replacing the elevator servo controls would merely improve the wear 
resistance of the servo control spherical bearings, and would not cure 
the root cause of the LCO phenomenon. The commenter asserts that 
mandating the servo control replacement would place an unnecessary 
financial burden on airlines. (The commenter subsequently clarified 
this comment as a request to remove this requirement from the proposed 
AD.)
    The FAA concurs. The FAA has determined that replacing the servo 
controls with new improved controls, as proposed, would provide 
improved wear resistance but would not prevent wear from occurring. 
Therefore, the FAA has determined that mandatory replacement is not 
necessary. Paragraph (c) of the proposed AD has been removed from this 
final rule. The freeplay checks and rigging change required by this AD 
will adequately address the identified unsafe condition.

Request To Revise Unsafe Condition

    One commenter (an operator) requests that the AD be revised to 
reflect the position that the identified unsafe condition is instead 
more a matter of passenger inconvenience. The operator has revised its 
airplane flight manual (AFM) to include a ``Vibration Section,'' which 
explains vibration types, methods of identifying vibrations, and 
specific reporting procedures.
    The FAA does not concur. The FAA considers the LCO to be unsafe for 
the reasons identified in response to the previous comment. No change 
to the final rule is necessary in this regard.

Request To Extend Compliance Time of the Inspection

    Two commenters request that the proposed AD be revised to extend 
the compliance time for the freeplay inspection. One commenter (an 
operator) requests that the compliance time be extended from 18 to 18.5 
months to correspond to its ``L'' check. This commenter states that the 
inspection at 18.5-month intervals has proven to be effective at 
detecting deterioration before elevator-induced vibration is reported. 
Another commenter (also an operator) reports that, based on its 
experience, it takes significantly longer than 18 months for the Airbus 
elevator system components to degrade to a level at which the trailing 
edge freeplay would fail the test. The commenter suggests that 36 
months is a more appropriate inspection interval.
    The FAA does not concur with the requests to extend the inspection 
interval. The FAA has determined that 18 months is the maximum amount 
of time allowable for these airplanes to continue to safely operate 
between inspections. The FAA finds that the 18-month compliance time is 
consistent with the maintenance schedules of most operators. Further, 
the experience of a couple operators is not sufficient to indicate that 
the interval should be increased. In the absence of data to justify a 
longer interval, the FAA finds no reason to deviate from the 18-month 
interval, as proposed, to accommodate the special maintenance schedules 
of one operator. No change to the final rule is necessary in this 
regard.

Request To Extend Compliance Time for Replacement

    One commenter (an operator) requests that the proposed AD be 
revised to extend the compliance time from 18 to 36 months to replace 
the elevator servo controls. The commenter states that the vendor 
turnaround time for nonroutine repair of the servo is 26 days, which 
does not support a servo replacement for its fleet within 18 months, 
and suggests 36 months for the compliance time for the servo 
replacement.
    As stated previously, the proposed requirement to replace the 
elevator servo controls has been removed from this final rule. 
Therefore, no change to the final rule is necessary regarding this 
comment.

Request To Provide Credit for Actions Completed

    One commenter (an operator) states that upgrading the elevator 
servo controls, uprigging the elevators, and accomplishing a trailing 
edge play check have been completed on nearly all its airplanes, and 
asserts that no value would be added by repeating the actions.
    The FAA infers that the operator requests the addition of specific 
language to provide credit for prior accomplishment of those actions. 
The FAA notes that operators are given credit for work previously 
performed by means of the phrase in the ``Compliance'' section of the 
AD that states, ``Required as indicated, unless accomplished 
previously.'' Therefore, for this AD, if the modification has been 
accomplished prior to the effective date of the AD, this AD does not 
require that the action be repeated. No change to the final rule is 
necessary in this regard.

Request To Revise Cost Estimates

    Two commenters request that the proposed AD be revised to indicate 
that required parts for elevator servo control replacement are not free 
of charge. One commenter (the manufacturer) notes that the elevator 
servo bearing replacement is free only on an attrition basis, and not 
to accommodate the required replacement on all affected airplanes. 
Another commenter (an operator) notes that removal and upgrade of the 
elevator servo controls resulted in nonroutine maintenance, costing in 
excess of $16,666 per airplane.
    As stated previously, the proposed requirement to replace the 
elevator servo controls has been removed from this final rule. 
Therefore, no change to the final rule is necessary regarding this 
comment.

Request To Allow Alternative Tooling

    Two commenters request that paragraph (a) of the proposed AD be 
revised to allow the use of ``equivalent tooling'' to perform the 
inspection for excessive elevator freeplay. One commenter (an operator) 
states that the proposed AD could be interpreted as requiring the use 
of the tooling identified in the AMM. The commenter contends that 
applying this interpretation would preclude credit for previous 
freeplay checks performed

[[Page 43473]]

with the alternative tooling, and that the AD would therefore require 
all of the operator's airplanes to be inspected within three months. 
The commenter asserts that use of a calibrated spring scale to apply 
force along with a pointer affixed to the trailing edge to measure the 
freeplay provides results equivalent to those provided by the AMM-
specified tooling.
    The commenter has correctly interpreted the AD as requiring the 
tooling specified in the AMM. The FAA does not concur with the request 
to revise the final rule to allow alternative tooling to accomplish the 
inspection. The commenter did not provide any data regarding this 
alternative tooling to substantiate that the alternative tooling would 
provide results equivalent to those intended by this AD. However, under 
the provisions of paragraph (d) of the final rule, the FAA may approve 
requests for alternative methods of compliance if data are submitted to 
substantiate that the use of such alternative tooling would provide 
equivalent results. No change to the final rule is necessary in this 
regard.

Request To Allow Alternative Materials

    One commenter (an operator) requests that the proposed AD be 
revised to allow use of 535K001/930K016A primer instead of Mastinox 
6856K primer for accomplishment of the elevator servo control 
replacement. The commenter reports that 535K001/930K016A primer was 
substituted for Mastinox 6856K primer during the modification because 
of environmental concerns.
    As stated previously, the proposed requirement to replace the 
elevator servo controls has been removed from this final rule. 
Therefore, no change to the final rule is necessary regarding this 
comment.

Request To Refer to Future Revision of CMM

    This same commenter requests that the proposed AD be revised to 
indicate a reference to a future revision of the Lucus CMM. Lucus has 
advised the commenter that CMM 34-52 misidentified the primer as 
``Mastinox 5866K'' primer, which will be corrected to ``Mastinox 
6856K'' in the next CMM revision.
    As stated previously, the proposed requirement to replace the 
elevator servo controls has been removed from this final rule. 
Therefore, no change to the final rule is necessary regarding this 
comment.

Request To Allow Previous Versions of Service Bulletin

    One commenter (an operator) requests that the proposed AD be 
revised to allow compliance with the modification requirement in 
accordance with Airbus Service Bulletin A320-27-1114, Revision 01, 
dated April 11, 1997; Revision 02, dated October 13, 1998; and Revision 
03, dated December 3, 1998. Based on experience with this type of 
vibration, the commenter reports that the elevator neutral setting 
modification has already been accomplished on numerous airplanes, in 
accordance with Revisions 01, 02, and 03 of the service bulletin. The 
commenter adds that Revisions 02, 03, and 04 all state: ``No additional 
work required for previously accomplished aircraft.''
    The FAA partially concurs with the request. (Although the commenter 
refers to ``item `C' of the Replacement section,'' the FAA infers that 
the commenter intended to refer to the ``Modification'' requirement, 
which was paragraph (d) in the proposed AD.) The FAA agrees that 
airplanes modified in accordance with Revision 01, 02, or 03 should not 
be required to repeat the modification in accordance with Revision 04. 
However, the FAA notes that, after the effective date of the AD, only 
Revision 04 may be used to ensure that the most accurate information is 
being followed. This final rule has been revised to include new Note 2, 
which provides credit for the modification in accordance with Revisions 
01, 02, and 03 of the service bulletin, if accomplished prior to the 
effective date of this AD.

Request To Allow Future Service Bulletin Revision

    One commenter requests that the proposed AD be revised to specify a 
future revision to Airbus Service Bulletin A320-27-1114 (which was 
cited at Revision 04 as the appropriate source of service information 
for accomplishment of the modification specified by paragraph (d) of 
the proposed AD). The commenter notes that Airbus has advised that an 
upcoming revision of the service bulletin will include additional 
airplanes not included in Revision 04.
    The FAA does not concur. Referring to documents that do not exist 
at the time the AD is published violates Office of the Federal Register 
(OFR) regulations regarding approval of materials ``incorporated by 
reference'' in rules. These OFR regulations require that either the 
service document be submitted for approval by the OFR as ``referenced'' 
material, in which case it may be simply called out in the text of an 
AD, or the service document contents be published as part of the actual 
AD language. An AD may reference only the specific service document 
that was submitted and approved by the OFR for ``incorporation by 
reference.'' In order for operators to use later revisions of the 
referenced document (issued after the publication of the AD), either 
the FAA must revise the AD to reference the specific later revisions, 
or operators must request the approval of their use as an alternative 
method of compliance (under the provisions of paragraph (d) of this 
AD). The FAA may consider additional rulemaking if it is determined 
that additional airplanes must be modified.

Request To Revise Repair Requirements

    One commenter (an operator) requests that paragraph (b) of the 
proposed AD be revised to require that repair be accomplished ``as 
necessary,'' rather than in accordance with specific AMM task numbers. 
The commenter notes that those AMM tasks address only the servo control 
and the elevator, not the rod end bearings. The commenter reports that, 
for almost every check that revealed freeplay outside the AMM limits, 
it was necessary to replace the rod end bearings of the servo control 
to correct the deterioration.
    The FAA partially concurs. The FAA notes that repair of rod end 
bearings is addressed under the AMM procedure referenced in the AD. 
However, the FAA agrees that the specific repair task number is not 
included in the AMM procedure. Therefore, paragraph (b) of the final 
rule has been revised to remove specific AMM task references and 
clarify that the repair must be accomplished in accordance with the AMM 
to bring freeplay within AMM-specified limits.

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 with the changes previously 
described. The FAA has determined that these changes will neither 
significantly increase the economic burden on any operator nor increase 
the scope of the AD.

Cost Impact

    Approximately 352 airplanes of U.S. registry will be affected by 
this proposed AD.
    Inspecting to detect elevator freeplay will take approximately 2 
work hours, at an average labor rate of $60 per work

[[Page 43474]]

hour. Based on these figures, the cost impact of the initial inspection 
required by this AD on U.S. operators is estimated to be $42,240, or 
$120 per airplane.
    Approximately 112 airplanes will require adjustment of the elevator 
neutral setting, which will take approximately 12 work hours, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the required adjustment on U.S. operators is estimated 
to be $80,640, or $720 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. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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 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 removing amendment 39-8177 (57 FR 
11137, April 1, 1992); and by adding a new airworthiness directive 
(AD), amendment 39-12377, to read as follows:

2001-16-09  Airbus Industrie: Amendment 39-12377. Docket 2000-NM-
342-AD. Supersedes AD 92-04-06, Amendment 39-8177.

    Applicability: All Model A319, A320, and A321 series airplanes; 
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 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 excessive vibration of the elevators, which could 
result in reduced structural integrity and reduced controllability 
of the airplane, accomplish the following:

Inspection

    (a) Within 18 months from the last inspection for excessive 
freeplay or within 3 months after the effective date of this AD, 
whichever occurs later: Inspect the elevators for excessive 
freeplay, using a load application tool and a spring scale assembly, 
in accordance with Airbus A319/A320 Aircraft Maintenance Manual 
(AMM) Task 27-34-00-200-001, including all changes through August 1, 
2000. Thereafter, repeat the inspection at intervals not to exceed 
18 months.

Repair

    (b) If any inspection required by paragraph (a) of this AD 
indicates that the freeplay in the elevator exceeds 7 millimeters: 
Prior to further flight, repair the elevator or servo controls in 
accordance with the Airbus A319/A320 Aircraft Maintenance Manual, 
including all changes through August 1, 2000, to bring elevator 
freeplay within the limits specified by the AMM.

Modification

    (c) For the airplanes listed in Airbus Service Bulletin A320-27-
1114, Revision 04, dated December 7, 1999: Within 18 months after 
the effective date of this AD, shift the elevator neutral setting to 
minus 0.5 degree, nose-up, in accordance with Airbus Service 
Bulletin A320-27-1114, Revision 04, dated December 7, 1999.

    Note 2: Accomplishment prior to the effective date of this AD of 
the modification in accordance with Airbus Service Bulletin A320-27-
1114, dated December 12, 1996; Revision 1, dated April 11, 1997; 
Revision 2, dated October 13, 1998; or Revision 3, dated December 3, 
1998; is acceptable for compliance with the requirements of 
paragraph (c) of this AD.

Alternative Methods of Compliance

    (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, International Branch, ANM-116, 
Transport Airplane Directorate, FAA. 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

Special Flight Permits

    (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.

Incorporation by Reference

    (f) The modification shall be done in accordance with Airbus 
Service Bulletin A320-27-1114, Revision 04, dated December 7, 1999. 
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.

Effective Date

    (g) This amendment becomes effective on September 24, 2001.

    Issued in Renton, Washington, on August 10, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-20700 Filed 8-17-01; 8:45 am]
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