[Federal Register Volume 62, Number 61 (Monday, March 31, 1997)]
[Rules and Regulations]
[Pages 15096-15098]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-7519]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 97-NM-22-AD; Amendment 39-9974; AD 97-07-01]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A330 and A340 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Airbus Model A330 and A340 series airplanes. This 
action requires the deactivation of the avionics ground refrigeration 
unit (GRU) of the air conditioning system until a modification of 
avionics ventilation circuit and the GRU is accomplished. This 
amendment is prompted by reports of water accumulation found in the Air 
Data/Inertial Reference Unit (ADIRU) trays of the avionics rack; the 
accumulation is the result of operation of the GRU in high ambient 
humidity. The actions specified in this AD are intended to prevent 
water accumulating in this area, which could result in the failure of 
the ADIRU and consequent loss of air data and navigational information 
to the flightcrew.

DATES: Effective April 15, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 15, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before May 30, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-22-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    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 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.

FOR FURTHER INFORMATION CONTACT: Charles Huber, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2589; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION: The Direction Generale de l'Aviation Civile 
(DGAC), which is the airworthiness authority for France, recently 
notified the FAA that an unsafe condition may exist on certain Airbus 
Model A330 and A340 series airplanes. The DGAC advises that there have 
been reports of water accumulation found in the Air Data/Inertial 
Reference Unit (ADIRU) trays of the avionics racks on in-service 
airplanes. All of the airplanes on which this phenomenon occurred were 
equipped with a ground cooling system, identified as Airbus 
Modification No. 40063S10052. (This is an optional modification 
available to Model A330 and A340 series airplanes.)
    Investigation revealed that water droplets can accumulate on the 
evaporator cores of the ground refrigeration unit (GRU) as a result of

[[Page 15097]]

high ambient humidity. The water droplets are then carried within the 
airflow and accumulate in the low points of the avionics ventilation 
ducting.
    In at least two cases, this accumulation of water resulted in the 
failure of one or two ADIRU's during flight. In one of these incidents, 
both inertial reference systems on one airplane were lost, and the 
flight crew was compelled to execute an in-flight turn-back. Upon the 
subsequent approach, all instrument landing system data disappeared 
from the airplane's primary flight displays.
    Failure of the ADIRU(s) during flight, which can occur as a result 
of the consequences associated with water accumulation in the relevant 
avionics rack, could result in loss of air data and navigational 
information to the flightcrew. This could compromise the ability of the 
flight crew to maintain the safe flight and landing of the airplane.

Explanation of Relevant Service Information

    Airbus has issued All Operators Telex (AOT) 21-01, dated March 28, 
1995, which describes procedures for deactivating the avionics GRU, if 
one is installed on the airplane. The DGAC classified this AOT as 
mandatory and issued French airworthiness directives (CN) 95-089-010(B) 
(for Model A330 series airplanes) and 95-093-020(B) (for Model A340 
series airplanes), both dated May 24, 1995, in order to assure the 
continued airworthiness of these airplanes in France.
    Airbus also has issued Service Bulletin A330-21-3028, Revision 2, 
dated May 5, 1995 (for Model A330 series airplanes), and Service 
Bulletin A340-21-4046, Revision 2, dated May 5, 1995 (for Model A340 
series airplanes). These service bulletins describe procedures for 
modifying the avionics equipment ventilation system and the GRU on 
airplanes equipped with one. The modification procedures include:
    1. Air tappings for relocation of ADIRU ventilation from the lower 
to the upper side of the ventilation ducting;
    2. Installing water drains at the lower side of the ventilation 
ducting;
    3. Drilling a hole in each ADIRU tray; and
    4. On airplanes equipped with a GRU, increasing the inner diameter 
of the existing GRU drain line.
    Accomplishment of this modification will prevent water from 
accumulating in the ventilation ducting low points and subsequently 
damaging the ADIRU's. [This modification was installed during 
production on Model A330 series airplanes beginning at manufacturer's 
serial number (MSN) 107, and on Model A340 series airplanes beginning 
at MSN 114.]
    The DGAC has classified Revision 2 of Airbus Service Bulletins 
A330-21-3028 and A340-21-4046 as ``recommended.''

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 21.19) 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 the 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, this AD is being issued to prevent water from 
accumulating in the ADIRU trays of the avionics racks, which could 
result in the damage to or failure of the ADIRU(s) and consequent loss 
of air data and navigational information to the flightcrew. This AD 
requires the deactivation of the GRU on those airplanes equipped with a 
GRU. The deactivation must be accomplished in accordance with the 
Airbus AOT described previously.
    Should an operator want to reactivate the GRU, it must first modify 
the avionics equipment ventilation system in accordance with the 
procedures contained in the Airbus service bulletin, described 
previously.

Cost Impact

    None of the Model A330 and A340 series airplanes affected by this 
action are on the U.S. Register. All airplanes included in the 
applicability of this rule currently are operated by non-U.S. operators 
under foreign registry; therefore, they are not directly affected by 
this AD action. However, the FAA considers that this rule is necessary 
to ensure that the unsafe condition is addressed in the event that any 
of these subject airplanes are imported and placed on the U.S. Register 
in the future.
    Should an affected airplane be imported and placed on the U.S. 
Register in the future, it would require approximately 1 work hour to 
accomplish the deactivation of the GRU at an average labor charge of 
$60 per work hour. Based on these figures, the cost impact of this 
required action would be $60 per airplane.
    If an operator elected to the modify avionics equipment ventilation 
system so that the GRU could be reactivated, it would take 4 work hours 
to accomplish the modification, at an average labor charge of $60 per 
work hour. Required parts would be provided to operators free of charge 
by the manufacturer. Based on these figures, the cost impact of this 
optional action would be $240 per airplane.

Determination of Rule's Effective Date

    Since this AD action does not affect any airplane that is currently 
on the U.S. register, it has no adverse economic impact and imposes no 
additional burden on any person. Therefore, prior notice and public 
procedures hereon are unnecessary and the amendment may be made 
effective in less than 30 days after publication in the Federal 
Register.

Comments Invited

    Although this action is in the form of a final rule and was not 
preceded by notice and opportunity for public comment, comments are 
invited on this rule. Interested persons are invited to comment on this 
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 under the caption 
ADDRESSES. All communications received on or before the closing date 
for comments will be considered, and this rule may be amended in light 
of the comments received. Factual information that supports the 
commenter's ideas and suggestions is extremely helpful in evaluating 
the effectiveness of the AD action and determining whether additional 
rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to

[[Page 15098]]

Docket Number 97-NM-22-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 adding the following new 
airworthiness directive:

97-07-01 Airbus: Amendment 39-9974. Docket 97-NM-22-AD.

    Applicability: Model A330-301 series airplanes having 
manufacturer's serial number (MSN) 1 through 106, inclusive; and 
Model A340-211, -212, -311, and -312 series airplanes having MSN 1 
through 113, inclusive; on which Airbus Modification No. 40063S10052 
(ground cooling system) has 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 (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 water from accumulating in the Air Data/Inertial 
Reference Unit (ADIRU) trays of the avionics racks, which could 
result in the damage to or failure of the ADIRU(s) and consequent 
loss of air data and navigational information to the flightcrew, 
accomplish the following:
    (a) Within 500 hours time-in-service after the effective date of 
this AD, deactivate the avionics ground refrigeration unit (GRU) in 
accordance with Airbus All Operators Telex 21-01, dated March 28, 
1995.
    (b) Modification of the avionics equipment ventilation system in 
accordance with Airbus Service Bulletin A330-21-3028, Revision 2, 
dated May 5, 1995 (for Model A330 series airplanes); or Airbus 
Service Bulletin A340-21-4046, Revision 2, dated May 5, 1995 (for 
Model A340 series airplanes); as applicable; constitutes terminating 
action for the requirements of paragraph (a) of this AD. Once the 
modification is completed, the avionics GRU may be reactivated.
    (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. 
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.
    (e) The modification, if accomplished, shall be done in 
accordance with the following Airbus service bulletins, which 
contain the specified list of effective pages:

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      Service bulletin revision and date                     Page No.                   Revision level shown on page            Date shown on page      
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A330-21-3028, Revision 2, May 5, 1995........  1, 3-6                               2..................................  May 5, 1995.                   
                                               2, 11, 23, 24, 29-30                 1..................................  March 3, 1995.                 
                                               7-10, 12-22, 25-28                   Original...........................  January 19, 1995.              
A340-21-4046, Revision 2, May 5, 1995........  1-4,                                 2..................................  May 5, 1995.                   
                                               5-12, 14-24, 27-30                   Original...........................  January 19, 1995.              
                                               13, 25, 26, 31, 32                   1..................................  March 3, 1995.                 
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    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.
    (f) This amendment becomes effective on April 15, 1997.

    Issued in Renton, Washington, on March 19, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-7519 Filed 3-28-97; 8:45 am]
BILLING CODE 4910-13-U