[Federal Register Volume 61, Number 206 (Wednesday, October 23, 1996)]
[Proposed Rules]
[Pages 54963-54965]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27121]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-11-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A320 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 A320-
111, -211, and -231 series airplanes, that currently requires replacing 
the existing standby generator control unit (GCU) with a new improved 
standby GCU. That action was prompted by reports of improper 
functioning of the standby GCU. This new proposed action would require 
the replacement of the GCU on addition affected airplanes. For some 
airplanes, it would require that a wiring modification be accomplished 
prior to replacement of the GCU. The actions specified by the proposed 
AD are intended to prevent such improper functioning of the GCU, which 
could result in the loss of the standby emergency generation system.

DATES: Comments must be received by December 2, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-11-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: Tim Backman, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2797; fax (206) 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

[[Page 54964]]

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 96-NM-11-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-103, Attention: Rules 
Docket No. 96-NM-11-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 28, 1991, the FAA issued AD 91-01-01, amendment 39-6845 
(55 FR 51895, December 18, 1990), applicable to certain Airbus Model 
A320-111, -211, and -231 series airplanes, to require replacement of 
the existing standby generator control unit (GCU) with a new improved 
standby GCU. That action was prompted by reports of improper 
functioning of the standby GCU. The requirements of that AD are 
intended to prevent loss of the standby emergency generation system, 
which provides necessary back-up capability when both main generators 
fail.

Actions Since Issuance of Previous Rule

    Since issuance of that AD, the Direction Generale de l'Aviation 
Civile (DGAC), which is the airworthiness authority for France, has 
advised the FAA that additional airplanes have been identified that are 
subject to the same unsafe condition addressed by AD 91-01-01.

Explanation of Relevant Service Information

    Airbus has issued Revision 2 of Service Bulletin A320-24-1035, 
dated June 2, 1994. This revision of the service bulletin describes 
procedures for replacement of the GCU and for follow-on operational 
testing. The procedures described in this revision are essentially 
identical to those described in Revision 1 of the service bulletin, 
which was referenced in AD 91-01-01 as the appropriate source of 
service information. (Both revisions of this service bulletin refer to 
Vickers Service Bulletin No. 520754-24-01 as an additional source of 
service information.)
    Revision 2 of the service bulletin differs from Revision 1 in that 
its effectivity listing includes additional airplanes that are subject 
to the addressed unsafe condition.
    Airbus has also issued Service Bulletin A320-24-1022, Revision 1, 
dated February 27, 1990. This service bulletin describes procedures for 
modifying the wiring associated with the GCU assembly (wiring in relay 
box 103VU, the wiring in power center AC/DC emergency 106VU, and the 
wiring between 103VU and 106VU). This wiring modification must be 
accomplished prior to replacing the GCU. The procedures described in 
this service bulletin are applicable to certain airplanes on which the 
wiring modification was not accomplished prior to delivery.
    The DGAC classified these service bulletins as mandatory and issued 
French airworthiness directive 89-198-004(B)R1, dated May 27, 1992, in 
order to assure the continued airworthiness of these airplanes in 
France.

FAA's Conclusions

    This airplane model is manufactured in France and is 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 91-01-01 to 
continue to require replacement of the existing standby GCU with an 
improved standby GCU. The proposed AD also would require the identical 
replacement to be accomplished on additional airplanes. For some 
airplanes, a wiring modification would be required prior to replacement 
of the GCU. The actions would be required to be accomplished in 
accordance with the service bulletins described previously.

Cost Impact

    There are approximately 106 Airbus Model A320 series airplanes of 
U.S. registry that would be affected by this proposed AD. Of this 
number, 18 currently are subject to the requirements of AD 91-01-01, 
and the remaining 88 are the airplanes that would be added to the AD 
applicability by this proposed action.
    The replacement of the GCU that would be required by this AD takes 
approximately 1.5 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $450 per airplane. Based on these figures, the cost 
impact of this proposed action on U.S. operators is estimated to be 
$57,240 for the entire affected fleet (or $540 per airplane). However, 
based on the effective date and the compliance time established by AD 
91-01-01, the FAA assumes that the 18 airplanes that are currently 
subject to that AD already have completed the required replacement of 
the GCU. Therefore, the future cost impact of the replacement action is 
only $47,520 (for the 88 airplanes that would be added to the 
applicability of the AD).
    For airplanes on which the modification of the wiring assembly is 
required, it would take approximately 8.5 work hours to accomplish, at 
an average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this proposed action on U.S. operators of those 
airplanes is estimated to be $510 per airplane.

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 Flexibility Act. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket.

[[Page 54965]]

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 39-6845 (55 FR 
51895, December 18, 1990), and by adding a new airworthiness directive 
(AD), to read as follows:

Airbus Industrie: Docket 96-NM-11-AD. Supersedes AD 91-01-01, 
Amendment 39-6845.

    Applicability: Model A320 series airplanes; on which a generator 
control unit (GCU) having part number (P/N) 520915 has not been 
installed, or on which Airbus Modification 21052 (reference Airbus 
Service Bulletin A320-24-1022) and Airbus Modification 21736 
(reference Airbus Service Bulletin A320-24-1035) have not been 
accomplished; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent loss of the standby emergency generation system, 
which provides necessary back-up capability when both main 
generators fail, accomplish the following:

    Note 2: Airbus Service Bulletin A320-24-1035 and Airbus Service 
Bulletin A320-24-1022 refer to Vickers Service Bulletin No. 520754-
24-01 as an additional source of specific procedural information.

    (a) For Model A320-111, -211, and -231 series airplanes; having 
serial numbers 003 through 058, inclusive, 060 through 067, 
inclusive, 069 through 072, inclusive, 074 through 083, inclusive, 
and 085: Within 150 days after January 28, 1991 (the effective date 
of AD 91-01-01, amendment 39-6845), remove one generator control 
unit (GCU) identified as 1XE part number (P/N) 520754, and install a 
modified GCU identified as 1XE, P/N 520915, in accordance with 
Airbus Service Bulletin A320-24-1035, Revision 1, dated February 27, 
1990, or Revision 2, dated June 24, 1994. Following installation, 
perform an operational test of the emergency generation system, 
emergency GCU from the centralized fault display system, and the 
static inverter, in accordance with the service bulletin.
    (b) For airplanes not subject to paragraph (a) of this AD: 
Within 150 days after the effective date of this AD, accomplish 
either paragraph (b)(1) or (b)(2) of this AD, as applicable.

    Note 4: Replacement of the GCU accomplished prior to the 
effective date of this AD in accordance with Airbus Service Bulletin 
A320-24-1035, Revision 1, dated February 27, 1990, is considered 
acceptable for compliance with the actions specified in this 
paragraph.

    (1) For airplanes equipped with GCU 1XE having P/N 520754: 
Replace the GCU 1XE, having P/N 520754, in zone 125 of the avionics 
compartment, with a modified GCU 1XE, having P/N 520915, in 
accordance with Airbus Service Bulletin A320-24-1035, Revision 2, 
dated June 24, 1994. Prior to further flight following 
accomplishment of the replacement, perform an operational test of 
the affected components in accordance with that service bulletin.
    (2) For airplanes equipped with GCU 1XE having P/N 520738: 
Accomplish the requirements of paragraphs (b)(2)(i) and (b)(2)(ii) 
of this AD:
    (i) Modify the wiring in relay box 103VU, the wiring in power 
center AC/DC emergency 106VU, and the wiring between 103VU and 
106VU, in accordance with Airbus Service Bulletin A320-24-1022, 
dated June 16, 1989.
    (ii) After modifying the wiring, replace the GCU 1XE, having P/N 
520738, located in the nose gear well in zone 125, with a modified 
GCU 1XE, having P/N 520915, in accordance with Airbus Service 
Bulletin A320-24-1035, Revision 2, dated June 24, 1994. Prior to 
further flight following accomplishment of the replacement, perform 
an operational test of the affected components in accordance with 
that service bulletin.
    (c) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Standardization Branch, ANM-113, 
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, 
Standardization Branch, ANM-113.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (d) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on October 16, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27121 Filed 10-22-96; 8:45 am]
BILLING CODE 4910-13-P