[Federal Register Volume 63, Number 83 (Thursday, April 30, 1998)]
[Proposed Rules]
[Pages 23690-23692]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-11435]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-310-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A310 and A300-600 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Airbus Model A310 
and A300-600 series airplanes, that currently requires, among other 
things, repetitive inspections to ensure correct synchronization of the 
hydraulic control valves of the trimmable horizontal stabilizer (THS) 
actuator; replacement of the horizontal stabilizer actuator motors with 
new or serviceable motors and resynchronization of the valves, or 
adjustment of the synchronization, if necessary; and a functional test 
of the THS. This proposed AD would add a requirement to replace the 
hydraulic motor of the THS with an improved motor, which would 
constitute terminating action for the repetitive inspections. This 
proposal also would expand the applicability to include additional 
airplanes. This proposal is prompted by the issuance of mandatory 
continuing airworthiness information by a foreign civil airworthiness 
authority. The actions specified by the proposed AD are intended to 
prevent desynchronization of the hydraulic control valves, which could 
result in runaway of the horizontal stabilizer to its full up or down 
position, subsequent reduced maneuvering capability, and potential 
pitch upset.

DATES: Comments must be received by June 1, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-310-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 
Blagnac Cedex, France. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: 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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-310-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 97-NM-310-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 12, 1996, the FAA issued AD 96-01-52, amendment 39-9491 
(61

[[Page 23691]]

FR 2697, January 29, 1996), applicable to certain Airbus Model A310 and 
A300-600 series airplanes. That AD requires, among other things, 
repetitive inspections to ensure correct synchronization of the 
hydraulic control valves of the trimmable horizontal stabilizer (THS) 
actuator; replacement of the horizontal stabilizer actuator motors with 
new or serviceable motors and resynchronization of the valves, or 
adjustment of the synchronization, if necessary; and a functional test 
of the THS. That action was prompted by a report of desynchronization 
of the hydraulic control valves that direct fluid to the horizontal 
stabilizer actuator motors, which resulted in uncommanded movement of 
the THS. The actions specified by that AD are intended to prevent such 
desynchronization, which could lead to runaway of the horizontal 
stabilizer to its full up or down position, subsequent reduced 
maneuvering capability, and potential pitch upset.

Actions Since Issuance of Previous Rule

    In the preamble to AD 96-01-52, the FAA specified that the actions 
required by that AD were considered ``interim action.'' The FAA 
indicated that it might consider further rulemaking action once a final 
action was identified. The manufacturer now has developed a 
modification of the hydraulic motor of the THS that includes an 
improved camplate retention device and pin. The FAA has determined that 
further rulemaking action is indeed necessary in order to address the 
unsafe condition and ensure the continued safe operation of the 
affected airplanes; this proposed AD follows from that determination.

Explanation of Relevant Service Information

    Airbus has issued Service Bulletins A310-27-2081 (for Model A310 
series airplanes) and A300-27-6035 (for Model A300-600 series 
airplanes), both dated November 26, 1996. These service bulletins 
describe procedures for the installation of a modified hydraulic motor 
that includes an improved camplate retention device and pin. The 
effectivity of these service bulletins includes the airplanes affected 
by the service bulletins that are required by the existing AD, and 
includes additional airplanes. Accomplishment of the actions specified 
in the service bulletins is intended to adequately address the 
identified unsafe condition. The Direction Generale de l'Aviation 
Civile (DGAC), which is the airworthiness authority for France, 
classified these service bulletins as mandatory and issued French 
airworthiness directive 97-081-217(B), dated March 12, 1997, in order 
to assure the continued airworthiness of these airplanes in France.

FAA's Conclusions

    These airplane models are manufactured in France and are type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the DGAC has kept the FAA informed 
of the situation described above. The FAA has examined the findings of 
the DGAC, reviewed all available information, and determined that AD 
action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, the proposed AD would supersede AD 96-01-52 to 
continue to require, among other things, repetitive inspections to 
ensure correct synchronization of the hydraulic control valves of the 
THS actuator; replacement of the motors of the horizontal stabilizer 
actuator with new or serviceable motors and resynchronization of the 
valves, or adjustment of the synchronization, if necessary; and a 
functional test of the THS. This proposed AD would add a requirement to 
replace the THS actuator hydraulic motor with an improved motor. 
Accomplishment of this replacement would constitute terminating action 
for the repetitive inspection requirements. This proposed AD also would 
expand the applicability of the existing AD to include additional 
airplanes. The replacement of the motor with an improved motor would be 
required to be accomplished in accordance with the service bulletins 
described previously.

Difference Between the Proposed Rule and the French AD

    Operators should note that, although the parallel French 
airworthiness directive recommends accomplishing the modification by 
August 31, 1998 (providing a compliance time of approximately 17 
months), the FAA has determined that a 17-month compliance time would 
not address the identified unsafe condition in a timely manner. In 
developing an appropriate compliance time for this AD, the FAA 
considered not only the recommendations by the DGAC, but the degree of 
urgency associated with addressing the subject unsafe condition, the 
average utilization of the affected fleet, and the time necessary to 
accomplish the modification. In light of all of these factors, the FAA 
finds a 12-month compliance time for accomplishment of the modification 
to be warranted.

Cost Impact

    There are approximately 88 airplanes of U.S. registry that would be 
affected by this proposed AD.
    The inspection currently required by AD 96-01-52, and retained in 
this proposed AD, takes approximately 1 work hour per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the requirements of the existing AD 
on U.S. operators is estimated to be $5,280, or $60 per airplane, per 
inspection cycle.
    The new actions that are proposed in this AD action would take 
approximately 4 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would be provided by 
the manufacturer at no cost to the operators. Based on these figures, 
the cost impact of the new actions proposed by this AD on U.S. 
operators is estimated to be $21,120, or $240 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
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 proposed herein would not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, will not have a significant economic impact, 
positive or negative, on a substantial number of small entities under 
the criteria of the Regulatory

[[Page 23692]]

Flexibility Act. A copy of the draft regulatory evaluation prepared for 
this action is contained in the Rules Docket. A copy of it may be 
obtained by contacting the Rules Docket at the location provided under 
the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9491 (61 FR 
2697, anuary 29, 1996), and by adding a new airworthiness directive 
(AD), to read as follows:

    Airbus: Docket 97-NM-310-AD. Supersedes AD 96-01-52, Amendment 
39-9491.

    Applicability: Model A310 and A300-600 series airplanes on which 
Airbus Modification 11607 has not been installed, certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 (e) 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 desynchronization of the hydraulic control valves, 
which could result in runaway of the horizontal stabilizer to its 
full up or down position, subsequent reduced maneuvering capability, 
and potential pitch upset, accomplish the following:

RESTATEMENT OF REQUIREMENTS OF AD 96-01-52:

    (a) Within 12 days after February 5, 1996 (the effective date of 
AD 96-01-52, amendment 39-9491), perform an inspection to ensure 
correct synchronization of the hydraulic control valves of the 
trimmable horizontal stabilizer (THS) actuator, in accordance with 
paragraph 4.2.2.1 of Airbus All Operators Telex (AOT) 27-21, 
Revision 1, dated January 5, 1996.
    (1) If the actuator is synchronized correctly, prior to further 
flight, perform a functional test of the THS in accordance with 
paragraph 4.2.2.1 of the AOT. Thereafter, repeat the inspection 
required by paragraph (a) of this AD at intervals not to exceed 500 
hours time-in-service.
    (2) If the actuator is desynchronized slightly, as specified in 
the AOT, prior to further flight, adjust the synchronization, and 
perform a functional test of the THS, in accordance with paragraph 
4.2.2.2 of the AOT. Thereafter, repeat the inspection required by 
paragraph (a) of this AD at intervals not to exceed 500 hours time-
in-service.
    (3) If the actuator is desynchronized significantly, as 
specified in the AOT, prior to further flight, accomplish either 
paragraph (a)(3)(i) or (a)(3)(ii) of this AD. Prior to further 
flight following the accomplishment of either of those paragraphs, 
adjust the synchronization, and perform a functional test of the 
THS, in accordance with paragraph 4.2.2.3 of the AOT. Thereafter, 
repeat the inspection required by paragraph (a) of this AD at 
intervals not to exceed 500 hours time-in-service.
    (i) Remove and replace the hydraulic motors of the horizontal 
stabilizer actuator (HSA) with new or serviceable motors in 
accordance with procedures specified in the Airplane Maintenance 
Manual. Or
    (ii) Remove the hydraulic motors of the HSA and perform the 
various follow-on actions specified in paragraph 4.2.2.4 of the AOT, 
in accordance with that paragraph. (The follow-on actions include 
checking the motors and the cam seats, assembling the motors, and 
metal stamping the modification plate of the motors.) If any 
discrepancy is found during the check, prior to further flight, 
repair in accordance with paragraph 4.2.2.4 of the AOT.
    (b) For airplanes on which any maintenance action relating to a 
hydraulic motor or a hydraulic valve block of the HSA has occurred 
since the airplane was new: Within 12 days after February 5, 1996, 
accomplish either paragraph (b)(1) or (b)(2) of this AD.
    (1) Replace both hydraulic motors of the HSA with new or 
serviceable motors in accordance with the procedures specified in 
the Airplane Maintenance Manual. Adjust the synchronization, and 
perform a functional test of the THS in accordance with paragraph 
4.2.2.3 of Airbus AOT 27-21, Revision 1, dated January 5, 1996. 
Thereafter, perform the repetitive inspections required by paragraph 
(a) of this AD at intervals not to exceed 500 hours time-in-service. 
Or
    (2) Remove the hydraulic motors of the HSA and perform the 
various follow-on actions specified in paragraph 4.2.2.4 of the AOT, 
in accordance with that paragraph of the AOT. Adjust the 
synchronization, and perform a functional test of the THS in 
accordance with paragraph 4.2.2.3 of the AOT. (The follow-on actions 
include checking the motors and the cam seats, assembling the 
motors, and metal stamping the modification plate of the motors.) If 
any discrepancy is found during the check, prior to further flight, 
repair in accordance with paragraph 4.2.2.4 of the AOT. Thereafter, 
perform the repetitive inspections required by paragraph (a) of this 
AD at intervals not to exceed 500 hours time-in-service.

NEW REQUIREMENTS OF THIS AD:

    (c) Within 1 year after the effective date of this AD, replace 
the hydraulic motors of the THS actuator with improved motors, in 
accordance with Airbus Service Bulletin A310-27-2081 (for Model A310 
series airplanes) or A300-27-6035 (for Model A300-600 series 
airplanes), both dated November 26, 1996, as applicable. 
Accomplishment of this action constitutes terminating action for the 
repetitive inspection requirements of this AD.
    (d) As of the effective date of this AD, no person shall install 
on any airplane a THS actuator having part number 47142-201/-203.
    (e)(1) 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, FAA, 
Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Maintenance Inspector, 
who may add comments and then send it to the Manager, International 
Branch, ANM-116.
    (e)(2) Alternative methods of compliance, approved previously in 
accordance with AD 96-01-52, amendment 39-9491, are approved as 
alternative methods of compliance with paragraphs (a) and (b) of 
this AD.

    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.

    (f) 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.

    Note 3: The subject of this AD is addressed in French 
airworthiness directive 97-081-217(B), dated March 12, 1997.

    Issued in Renton, Washington, on April 23, 1998.
Gary L. Killion,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-11435 Filed 4-29-98; 8:45 am]
BILLING CODE 4910-13-U