[Federal Register Volume 62, Number 34 (Thursday, February 20, 1997)]
[Rules and Regulations]
[Pages 7665-7667]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-3843]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-24-AD; Amendment 39-9933; AD 97-04-09]
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 adopts a new airworthiness directive (AD) that
is applicable to certain Aerospatiale Model ATR42-300 and ATR42-320
series airplanes. This action 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 ones and a follow-on inspection. This amendment is
prompted by reports indicating that, due to fatigue cracking in the
lower lugs of the barrel, the MLG collapsed. The actions specified in
this AD are intended to detect and correct such fatigue cracking, which
could lead to the collapse of the MLG.
DATES: Effective March 7, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of March 7, 1997.
Comments for inclusion in the Rules Docket must be received on or
before April 21, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 97-NM-24-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: Gary Lium, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-1112; 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
Aerospatiale Model ATR42-300 and ATR42-320 series airplanes. The DGAC
advises that it has received reports indicating that the main landing
gear (MLG) collapsed on two airplanes; one incident occurred during
taxi and the other during landing roll. Investigation revealed that,
following normal overhaul or repair procedures, moisture may enter the
joint between the fixed barrel and the shock absorbing portion of the
trailing arm of the MLG. Such moisture could result in corrosion and
consequent fatigue cracking in the lower lugs of the barrel of the MLG,
which is the main attachment point for the joint.
Fatigue cracking in the lower lugs of the barrel of the MLG, if not
detected and corrected in a timely manner, could lead to the collapse
of the MLG.
Explanation of Relevant Service Information
Messier-Dowty has issued Service Bulletin No. 631-32-132, dated
January 21, 1997, which describes procedures for performing repetitive
ultrasonic inspections to detect fatigue cracks of the barrel lower
lugs of MLG. The service bulletin also describes procedures for
replacement of cracked barrel lower lugs with new or serviceable ones
and a follow-on inspection. The DGAC classified this service bulletin
as mandatory and issued French airworthiness directive 96-294(B), dated
January 15, 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 is being issued to detect and correct
fatigue cracking in the lower lugs of the barrel, which could result in
collapse of the MLG. This AD requires repetitive ultrasonic inspections
to detect fatigue cracks of the lower lugs of the barrel of MLG. This
AD also requires replacement of cracked lower lugs with new or
serviceable ones and a follow-on inspection. The actions are required
to be accomplished in accordance with the service bulletin described
previously.
Interim Action
The FAA is considering further rulemaking action to supersede this
AD to require modification of the lower lugs of the barrel of the MLG,
which will constitute terminating action for the repetitive inspections
required by this AD action. However, the planned compliance time for
these actions is sufficiently long so that prior notice and time for
public comment will be practicable.
[[Page 7666]]
In addition, the FAA is continuing to investigate whether the
existing design of the lower lugs of the barrel makes overhauls or
repairs difficult to accomplish correctly. Preliminary investigation
results indicate that, following an improperly overhauled or repaired
lower lug of the barrel, moisture could enter the joint between the
fixed barrel and the shock absorbing portion of the trailing arm of the
MLG. Such moisture could result in corrosion and consequent fatigue
cracking in the lower lugs of the barrel, which may lead to the
collapse of the MLG. Once final action is identified, the FAA may
consider additional 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 97-NM-24-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 adding the following new
airworthiness directive:
97-04-09 Aerospatiale: Amendment 39-9933. Docket 97-NM-24-AD.
Applicability: Model ATR42-300 and ATR42-320 series airplanes,
on which the lower lugs of the barrel of the main landing gear (MLG)
have been overhauled or repaired, certificated in any category.
Note 1: This AD does not affect new barrel assemblies that have
never been overhauled or repaired.
Note 2: 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 fatigue cracking in the lower lugs of the barrel and
consequent collapse of the MLG, accomplish the following:
(a) Prior to the accumulation of 2 years time-in-service since
last overhaul or repair of the barrel lower lugs of the MLG, or
within 60 days after the effective date of this AD, whichever occurs
later, 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.
(1) If no echo is detected or the echo is less than 20%, repeat
the ultrasonic inspection thereafter at intervals not to exceed 700
landings.
(2) If any echo is greater than or equal to 20%, prior to
further flight, replace the barrel assembly with a new or
serviceable barrel assembly, in accordance with the service
bulletin. After replacement, prior to the accumulation of 2 years
time-in-service on that replacement part, accomplish the actions
specified in paragraph (a) of this AD.
(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, 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Standardization Branch, ANM-113.
(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.
(d) The inspections and replacement shall be done in accordance
with Messier-Dowty Service Bulletin 631-32-132, dated January 21,
1997. 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 Aerospatiale, 316 Route de
Bayonne,
[[Page 7667]]
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.
(e) This amendment becomes effective on March 7, 1997.
Issued in Renton, Washington, on February 10, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-3843 Filed 2-19-97; 8:45 am]
BILLING CODE 4910-13-U
