[Federal Register Volume 62, Number 246 (Tuesday, December 23, 1997)]
[Rules and Regulations]
[Pages 66980-66982]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-33509]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-283-AD; Amendment 39-10262; AD 97-26-19]
RIN 2120-AA64


Airworthiness Directives; Aerospatiale Model ATR42-300 and ATR42-
320 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to all Aerospatiale Model ATR42-300 and ATR42-320 
series airplanes, that currently requires repetitive ultrasonic 
inspections to detect fatigue cracks of the lower lugs of the barrel of 
the main landing gear (MLG); and replacement of cracked lower lugs with 
new or serviceable parts, and a follow-on inspection. This amendment 
expands the applicability of the existing AD. This action also provides 
for an optional terminating action, which, if accomplished, terminates 
the repetitive inspection requirement. 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 detect and correct fatigue cracking of the lower lugs of 
the barrel of the MLG, which could lead to the collapse of the MLG.

DATES: Effective January 7, 1998.
    The incorporation by reference of Messier-Dowty Service Bulletin 
631-32-133, dated February 24, 1997, as revised by Messier-Dowty 
Service Bulletin Change Notice No. 1, dated March 18, 1997, as listed 
in the regulations, is approved by the Director of the Federal Register 
as of January 7, 1998.
    The incorporation by reference of Messier-Dowty Service Bulletin 
631-32-132, dated January 21, 1997, as listed in the regulations, was 
approved previously by the Director of the Federal Register as of March 
7, 1997 (62 FR 7665, February 20, 1997).
    Comments for inclusion in the Rules Docket must be received on or 
before January 22, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-283-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 03, 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: 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: On February 10, 1997, the FAA issued AD 97-
04-09, amendment 39-9933 (62 FR 7665, February 20, 1997), which is 
applicable to certain Aerospatiale Model ATR42-300 and ATR42-320 series 
airplanes. That AD requires repetitive ultrasonic inspections to detect 
fatigue cracks of the lower lugs of the barrel of the main landing gear 
(MLG), for airplanes on which the barrel assembly has been overhauled 
or repaired. If any lower lug is found to be cracked, the AD further 
requires replacement of the MLG barrel assembly with new or serviceable 
parts, and a follow-on inspection. That action was prompted by reports 
indicating that, due to fatigue cracking in the lower lugs of the 
barrel, the MLG collapsed. The actions required by that AD are intended 
to detect and correct such fatigue cracking, which could lead to the 
collapse of the MLG.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the Direction Generale de l'Aviation 
Civile (DGAC), which is the airworthiness authority for France, advises 
that further investigation has revealed that the fatigue cracking is 
the result of a design flaw that may also affect new barrel assemblies 
that have never been overhauled or repaired. In addition, the DGAC 
advises that the interval for the repetitive inspections may be 
extended from 700 landings to 900 landings.

Relevant Service Information

    Messier-Dowty has issued Service Bulletin 631-32-133, dated 
February 24, 1997, which describes procedures to modify the lower lugs 
of the barrel of the MLG. The modification entails reconditioning the 
lower lugs and installing new bushings on the swinging lever. 
Accomplishment of this modification will prevent failure of the lugs 
due to fatigue cracking. Accomplishment of the modification

[[Page 66981]]

eliminates the need for the repetitive visual inspections. The DGAC 
classified this service bulletin as mandatory, and issued French 
airworthiness directive 96-294(B)R1, dated September 10, 1997, 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 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 supersedes AD 97-04-09 to continue to 
require repetitive ultrasonic inspections to detect fatigue cracks of 
the lower lugs of the barrel of the main landing gear (MLG); and 
replacement of cracked lower lugs with new or serviceable parts, and a 
follow-on inspection. This AD expands the applicability of the existing 
AD to include all Model ATR42-300 and -320 series airplanes, regardless 
of whether the MLG barrel assemblies installed on those airplanes are 
new, overhauled, or repaired. Additionally, this AD extends the 
repetitive inspection interval from 700 to 900 landings.
    This AD also provides for optional modification of the lower lugs 
of the barrel of the MLG, which, if accomplished, constitutes 
terminating action for the repetitive inspection requirements of this 
AD. The modification is required to be accomplished in accordance with 
the service bulletin described previously.

Interim Action

    This is considered to be interim action. The FAA is currently 
considering requiring the modification of the lower lugs of the barrel 
of the MLG. However, the planned compliance time for the installation 
of the modification is sufficiently long so that prior notice and time 
for public comment will be practicable.

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 97-NM-283-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, 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 39-9933 (62 FR 
7665, February 20, 1997), and by adding a new airworthiness directive 
(AD), amendment 39-, to read as follows:

97-26-19  Aerospatiale: Amendment 39-10262. Docket 97-NM-283-AD. 
Supersedes AD 97-04-09, Amendment 39-9933.

    Applicability: All Model ATR42-300 and ATR42-320 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 
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.


[[Page 66982]]


    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct fatigue cracking in the lower lugs of the 
barrel of the main landing gear (MLG), and consequent collapse of 
the MLG, accomplish the following:
    (a) Perform an ultrasonic inspection to detect fatigue cracks of 
the lower lugs of the barrel of the MLG, in accordance with Messier-
Dowty Service Bulletin 631-32-132, dated January 21, 1997, at the 
time specified in paragraph (a)(1) or (a)(2) of this AD, as 
applicable:
    (1) Within 2 years after the last overhaul or repair of the 
lower lugs of the barrel of the MLG, or within 60 days after March 
7, 1997 (the effective date of AD 97-04-09, amendment 39-9933), 
whichever occurs later; or
    (2) Within 5 years after the installation of a new MLG barrel 
assembly, or within 60 days after the effective date of this AD, 
whichever occurs later.
    (b) If, during any inspection required by this AD, no echo is 
detected, or if the echo is less than 20%, repeat the ultrasonic 
inspection thereafter at intervals not to exceed 900 landings.
    (c) If, during any inspection required by this AD, the echo is 
greater than or equal to 20%, prior to further flight, replace the 
MLG barrel assembly with a new or serviceable MLG barrel assembly, 
in accordance with the service bulletin.
    (1) If the damaged barrel assembly is replaced with an 
overhauled or repaired assembly, within 2 years after installation 
of that overhauled or repaired part, accomplish the actions 
specified in paragraph (a) of this AD.
    (2) If the damaged barrel assembly is replaced with a new barrel 
assembly, within 5 years after installation of that new part, 
accomplish the actions specified in paragraph (a) of this AD.
    (d) Modification of the lower lugs of the barrel of the MLG in 
accordance with Messier-Dowty Service Bulletin 631-32-133, dated 
February 24, 1997, as revised by Messier-Dowty Service Bulletin 
Change Notice No. 1, dated March 18, 1997, constitutes terminating 
action for the repetitive inspection requirements of this AD.
    (e) 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.

    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.
    (g) The actions shall be done in accordance with Messier-Dowty 
Service Bulletin 631-32-133, dated February 24, 1997, as revised by 
Messier-Dowty Service Bulletin Change Notice No. 1, dated March 18, 
1997; and Messier-Dowty Service Bulletin 631-32-132, dated January 
21, 1997.
    (1) The incorporation by reference of Messier-Dowty Service 
Bulletin 631-32-133, dated February 24, 1997, as revised by Messier-
Dowty Service Bulletin Change Notice No. 1, dated March 18, 1997, is 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51.
    (2) The incorporation by reference of Messier-Dowty Service 
Bulletin 631-32-132, dated January 21, 1997, was approved previously 
by the Director of the Federal Register as of March 7, 1997 (62 FR 
7665, February 20, 1997).
    (3) Copies may be obtained from Aerospatiale, 316 Route de 
Bayonne, 31060 Toulouse, Cedex 03, 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.

    Note 3: The subject of this AD is addressed in French 
airworthiness directive 96-294(B)R1, dated September 10, 1997.

    (h) This amendment becomes effective on January 7, 1998.

    Issued in Renton, Washington, on December 15, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-33509 Filed 12-22-97; 8:45 am]
BILLING CODE 4910-13-U