Airworthiness Directives; Eurocopter France Model SA-365N, SA- 365N1, and SA-366G1 Helicopters

[Federal Register Volume 63, Number 25 (Friday, February 6, 1998)]
[Rules and Regulations]
[Pages 6069-6071]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-2969]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-23-AD; Amendment 39-10313; AD 97-15-15]
RIN 2120-AA64


Airworthiness Directives; Eurocopter France Model SA-365N, SA-
365N1, and SA-366G1 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 97-15-15, which was sent 
previously to all known U.S. owners and operators of Eurocopter France 
Model SA-365N, SA-365N1, and SA-366G1 helicopters by individual 
letters. This AD requires an inspection of the main gearbox magnetic 
plug (magnetic plug) and the main gearbox oil filter (oil filter) for 
ferrous chips; vibration measurements, if necessary; and replacement of 
the main gearbox if a specified quantity of ferrous chips are 
discovered, or if abnormal vibrations are identified at a certain 
frequency. This amendment is prompted by two recent reports of cracks 
found in planetary gear shafts (gear shafts) in main gearboxes that 
have not been modified in accordance with MOD 077244. The actions 
specified by this AD are intended to detect cracks in the gear shaft 
which could lead to failure of the gear shaft, failure of the 
transmission, and subsequent loss of control of the helicopter.

DATES: Effective February 23, 1998, to all persons except those persons 
to whom it was made immediately effective by priority letter AD 97-15-
15, issued on July 18, 1997, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before April 7, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 97-SW-23-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr. Shep Blackman, Aerospace Engineer, 
Rotorcraft Standards Staff, Rotorcraft Directorate, FAA, 2601 Meacham 
Blvd., Fort Worth, Texas 76137, telephone (817) 222-5296, fax (817) 
222-5961.

SUPPLEMENTARY INFORMATION: On July 18, 1997, the FAA issued priority 
letter AD 97-15-15, applicable to Eurocopter France Model SA-365N, SA-
365N1, and SA-366G1 helicopters, which requires an inspection of the 
magnetic plug and the oil filter for ferrous chips; vibration 
measurements, if necessary; and replacement of the main gearbox if a 
specified quantity of ferrous chips are discovered, or if abnormal 
vibrations are identified at a certain frequency.
    That action was prompted by two recent reports of cracks found in 
gear shafts in main gearboxes, part number (P/N) 365A32-6000-00, 
365A32-6000-02, 365A32-6001-00, or 366A32-0001-00, that have not been 
modified in accordance with MOD 077244. Upon inspection, the 
manufacturer discovered that 13 main gearbox epicyclic modules were 
assembled at the factory with mismatched planetary gear tooth to ring 
gear radii. This produces higher than normal gear tooth loading 
stresses which substantially reduce the fatigue life of the gear shaft. 
This condition, if not corrected, could result in cracks in the gear 
shaft, failure of the transmission, and subsequent loss of control of 
the helicopter.
    Eurocopter France has issued Telex Service No. 0035/00188/97, dated 
July 7, 1997, and Telex Service No. 00037/00190/97, dated July 9, 1997, 
which specify checks of the oil filter after the last flight of each 
day for cracks; and also specify performing vibration measurements if 
metal chips are found on the magnetic plug or in the oil filter, or if 
abnormal vibrations are reported by the crew. The DGAC classified these 
service telexes as mandatory, and issued AD 97-145-042(AB), dated July 
10, 1997, and AD 97-164-020(AB), dated July 16, 1997.
    These helicopter 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 Direction

[[Page 6070]]

Generale de L'Aviation Civile (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.
    Since the unsafe condition described is likely to exist or develop 
on other Eurocopter France Model SA-365N, SA-365N1, and SA-366G1 
helicopters of the same type design, the FAA issued priority letter AD 
97-15-15 to detect cracks in the gear shaft which could lead to failure 
of the gear shaft, failure of the transmission, and subsequent loss of 
control of the helicopter. The AD requires an inspection of the 
magnetic plug for ferrous chips after each flight when the main rotor 
is stopped, and an inspection of the oil filter for ferrous chips after 
the last flight of each day or at intervals not to exceed 12 hours 
time-in-service, whichever occurs first. If ferrous chips are 
discovered as a result of either inspection, or if abnormal vibrations 
are reported by the flight crew, then vibration measurements must be 
performed on the ground. If vibration levels above the helicopter's 
basic data are identified at a frequency of 26.07 HZ, or if an 
accumulation of ferrous chips found on the magnetic plug and in the oil 
filter is equal to or greater than an area of 0.08 in\2\ (50 mm\2\), 
removal of the main gearbox before further flight and replacement with 
an airworthy main gearbox is required.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on July 18, 1997 to all known U.S. owners and operators of 
Eurocopter France Model SA-365N, SA-365N1, and SA-366G1 helicopters. 
These conditions still exist, and the AD is hereby published in the 
Federal Register as an amendment to section 39.13 of the Federal 
Aviation Regulations (14 CFR 39.13) to make it effective to all 
persons.

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 should 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 No. 97-SW-23-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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 a new airworthiness directive 
to read as follows:

AD 97-15-15  Eurocopter France: Amendment 39-10313. Docket No. 97-
SW-23-AD.

    Applicability: Model SA-365N, SA-365N1, and SA-366G1 
helicopters, with main gearbox, part number (P/N) 365A32-6000-00, 
365A32-6000-02, 365A32-6001-00, or 366A32-0001-00, installed, but 
not modified in accordance with MOD 077244, certificated in any 
category.

    Note 1: This AD applies to each helicopter 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 helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (g) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect cracks in the gear shaft which could lead to failure 
of the gear shaft, failure of the transmission, and subsequent loss 
of control of the helicopter, accomplish the following:
    (a) Following each flight, when the main rotor is stopped, 
inspect the main gearbox magnetic plug (magnetic plug) for ferrous 
chips.
    (b) Following the last flight of each day, or at intervals not 
to exceed 12 hours time-in-service, whichever occurs first, inspect 
the main gearbox oil filter (oil filter) for ferrous chips.
    (c) If the total surface area covered by ferrous chips on the 
magnetic plug and in the oil filter is equal to or greater than 0.08 
in\2\

[[Page 6071]]

(50mm\2\), remove the main gearbox before further flight and replace 
with an airworthy main gearbox.
    (d) If the inspections specified in paragraph (a) or (b) of this 
AD reveal the presence of any ferrous chips on either the magnetic 
plug or in the oil filter, or if abnormal vibrations are reported by 
the flight crew, then perform main gearbox vibration measurements on 
the ground.

    Note 2: MET work card CT 05.53.00.221 describes an appropriate 
main gearbox vibration measurement technique for model SA-365N and 
SA-365N1 helicopters. MET work card CT 05.53.00.220 is applicable 
for model SA-366G1 helicopters.

    (e) If vibration levels above the helicopter's basic data are 
identified at a frequency of 26.07HZ, replace the main gearbox with 
an airworthy gearbox before further flight.

    Note 3: Interpretation of results is made by comparing the 
reading with previously obtained data when the aircraft vibration 
level was acceptable (i.e., reading performed upon aircraft 
acceptance or when main gearbox was installed).

    (f) Installation of MOD 077244 constitutes terminating action 
for the requirements of this AD.
    (g) 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, Rotorcraft Standards Staff, 
Rotorcraft Directorate, FAA. Operators shall submit their requests 
through an FAA Principal Maintenance Inspector, who may concur or 
comment and then send it to the Manager, Rotorcraft Standards Staff.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Rotorcraft Standards Staff.

    (h) Special flight permits will not be issued.
    (i) This amendment becomes effective on February 23, 1998, to 
all persons except those persons to whom it was made immediately 
effective by Priority Letter AD 97-15-15, issued July 18, 1997, 
which contained the requirements of this amendment.

    Note 5: The subject of this AD is addressed in Direction 
Generale de L'Aviation Civile (France) AD 97-145-042(AB), dated July 
10, 1997, and AD 97-164-020(AB), dated July 16, 1997.

    Issued in Fort Worth, Texas, on January 30, 1998.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Office.
[FR Doc. 98-2969 Filed 2-5-98; 8:45 am]
BILLING CODE 4910-13-P

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