Airworthiness Directives; Aerospatiale Model ATR-42 and ATR-72 Series Airplanes

[Federal Register Volume 63, Number 78 (Thursday, April 23, 1998)]
[Rules and Regulations]
[Pages 20064-20066]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-10918]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-124-AD; Amendment 39-10497; AD 98-09-16]
RIN 2120-AA64


Airworthiness Directives; Aerospatiale Model ATR-42 and ATR-72 
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) that 
is applicable to all Aerospatiale Model ATR-42 and ATR-72 series 
airplanes. This action requires revising the Airplane Flight Manual 
(AFM) to add specific flightcrew instructions to be followed in the 
event of failure of one or both of the direct current (DC) generators. 
This amendment is prompted by issuance of mandatory continuing 
airworthiness information by a foreign civil airworthiness authority. 
The actions specified in this AD are intended to prevent failure of the 
second of two DC generators after the failure of the first generator, 
which could lead to the loss of main battery power and result in the 
loss of all electrical power, except the emergency battery supply, 
during flight.

DATES: Effective May 8, 1998.
    Comments for inclusion in the Rules Docket must be received on or 
before May 26, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-124-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    Information pertaining to this amendment may be obtained from or 
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: 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 all Aerospatiale 
Model ATR-42 and ATR-72 series airplanes. The DGAC advises that an ATR 
airplane experienced the loss of the number one direct current (DC) 
generator, followed by the loss of the number two DC generator, during 
flight. The loss of the second generator occurred following an attempt 
by the flightcrew to reset the number one generator, in accordance with 
approved procedures. After a few minutes, the airplane experienced the 
loss of main battery power. The cause of the failure of the second 
generator is currently under investigation. Such failures, if not 
corrected, could result in the loss of all electrical power, except the 
emergency battery supply, during flight.

French Airworthiness Directives

    The DGAC issued French telegraphic airworthiness directives T98-
148-076(B) and T98-149-038(B), both dated March 20, 1998, in order to 
assure the continued airworthiness of these airplanes in France. These 
French airworthiness directives require adherence to instructions 
specified in ATR AFM Chapter 5-04 in the event of one DC generator 
failure, and specify that no attempt should be made to reset the 
affected DC generator. Additionally, the French airworthiness 
directives note that, in the event of failure of both DC generators, 
resetting the generators should be attempted.

Explanation of FAA's Findings

    The current version of the FAA-approved ATR Airplane Flight Manual 
(AFM) specifies that a single failed generator is to be left in the 
``OFF'' position; however, the AFM does not explicitly prohibit an 
attempted reset of a failed generator. Moreover, for some operators, 
Flight Crew Operating Manuals may contain instructions for one attempt 
to reset a failed generator. Therefore, the FAA has determined that 
explicit instructions must be provided in the Limitations section of 
the AFM to specify that flight crews should not attempt to reset a 
single failed generator. However, in the event of dual DC generator 
failure, reset of the generators should be attempted.

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

[[Page 20065]]

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 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 failure of the 
second of two DC generators after the failure of the first generator, 
which could lead to the loss of main battery power and result in the 
loss of all electrical power, except the emergency battery supply, 
during flight. This AD requires revising the Limitations Section of the 
AFM to add specific flightcrew instructions to be followed in the event 
of failure of one or both of DC generators.

Interim Action

    This is considered to be interim action. The manufacturer has 
advised the FAA that it is currently investigating the cause of the 
dual generator failure and may develop a modification that will 
positively address the unsafe condition in this AD. Once the 
investigation is concluded, the FAA may consider further rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an 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 Docket Number 98-NM-124-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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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, 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:

98-09-16  Aerospatiale: Amendment 39-10497. Docket 98-NM-124-AD.

    Applicability: All Model ATR-42 and ATR-72 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 (b) 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 failure of the second of two direct current (DC) 
generators after the failure of the first generator, which could 
lead to the loss of main battery power and result in the loss of all 
electrical power, except the emergency battery supply, during 
flight, accomplish the following:
    (a) Within 10 flight hours after the effective date of this AD, 
revise the Limitations Section of the FAA-approved Airplane Flight 
Manual (AFM) to include the following statements. This action may be 
accomplished by inserting a copy of this AD into the AFM.
    ``<bullet> In the event of failure of either DC generator during 
flight, do not attempt to reset the affected DC generator.
    <bullet> In the event of failure of both DC generators during 
flight, one attempt to reset each of the generators may be made, as 
follows:

--If the first attempt to reset a generator is successful, do not 
attempt to reset the other generator.
--If the first attempt to reset a generator is not successful, one 
attempt to reset the other generator may be made.
--If neither attempt to reset the generators is successful, land at 
the nearest suitable airport.''

    (b) 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

[[Page 20066]]

send it to the Manager, International Branch, ANM-116.

    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.

    (c) 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 French telegraphic 
airworthiness directives T98-148-076(B) and T98-149-038(B), both 
dated March 20, 1998.

    (d) This amendment becomes effective on May 8, 1998.

    Issued in Renton, Washington, on April 20, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-10918 Filed 4-22-98; 8:45 am]
BILLING CODE 4910-13-U

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