[Federal Register Volume 59, Number 171 (Tuesday, September 6, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-21869]


[[Page Unknown]]

[Federal Register: September 6, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-ANE-08]

 

Airworthiness Directives; Turbomeca Arriel 1 Series Turboshaft 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to Turbomeca Arriel 1 series 
turboshaft engines, that currently requires repetitive checks for 
engine rubbing noise during gas generator shutdown, and for free 
rotation of the gas generator by rotating the compressor manually after 
the last flight of the day. This action would continue to require these 
checks, but eliminates the reference to the Turbomeca service bulletin, 
allows the pilot to perform all the checks required in this proposed 
rule, clarifies the inspection interval requirement for daily checks, 
and specifies terminating action for the repetitive checks required by 
this AD. In addition, this action would allow the check for engine 
rubbing noise to be performed during engine motoring, and specifies 
that the engine turbine (T4) temperature must be below 150 degrees 
Centigrade when performing the check for free rotation. This proposal 
is prompted by comments submitted by operators of the affected engines 
in response to the existing AD and the availability of an improved 
design 2nd stage nozzle guide vane. The actions specified by the 
proposed AD are intended to prevent engine failure due to rubbing of 
the 2nd stage turbine disk on the 2nd stage turbine nozzle guide vane, 
which could result in complete engine failure and damage to the 
aircraft.

DATES: Comments must be received by November 7, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 94-ANE-08, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, 
except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Turbomeca, 64511 Bordes Cedex - France. This information 
may be examined at the FAA, New England Region, Office of the Assistant 
Chief Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Mark Rumizen, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7137, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 94-ANE-08.'' The postcard will be date-stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 94-ANE-08, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    On November 19, 1993, the Federal Aviation Administration (FAA) 
issued airworthiness directive (AD) 93-23-09, Amendment 39-8745 (58 FR 
63061, November 30, 1993), applicable to Turbomeca Arriel 1 series 
turboshaft engines, to require repetitive checks for engine rubbing 
noise during gas generator shutdown, and for free rotation of the gas 
generator by rotating the compressor manually after the last flight of 
the day. That action was prompted by a report of a Turbomeca Arriel 1B 
engine failure, which resulted in the crash of an Aerospatiale AS350B 
helicopter. That condition, if not corrected, could result in engine 
failure due to rubbing of the 2nd stage turbine disk on the 2nd stage 
turbine nozzle guide vane, which could result in complete engine 
failure and damage to the aircraft.
    Since the issuance of that AD, the FAA has received a significant 
number of comments from operators of the affected engines indicating 
that the performance of the checks required by this AD are within the 
capabilities of the pilot. The FAA has also determined that 
instructions contained in the AD are adequate for performance of 
required actions, and the Turbomeca Service Bulletin (SB) No. 72 292 
0181 need not be incorporated by reference. Other comments indicated 
that the interval specified in the existing AD, ``after the last flight 
of the day,'' is not consistent with operating and maintenance 
schedules for operators who typically operate ``around the clock'' on a 
24 hours per day basis, such as medevac or police operators. In 
response to these comments, a ``daily'' interval has been specified for 
this check.
    In addition, operators reported difficulty in listening for rubbing 
noises during engine shutdown, and that this check could be 
accomplished during engine motoring. The FAA has also determined that 
the check for free rotation must be accomplished on a cold engine due 
to the variation of rotating component clearances with engine 
temperature. Finally, the manufacturer has completed testing and 
analysis, and has accumulated sufficient field experience to 
substantiate the design of the improved 2nd stage nozzle guide vane. 
This AD would require installation of modification TU 202, which 
incorporates an improved 2nd stage nozzle guide vane manufactured from 
a new material that is more resistant to fatigue cracking, at the next 
engine overhaul after the effective date of this AD, but not later than 
December 31, 1999, as terminating action for the repetitive checks. 
This calendar end-date is based upon parts availability.
    Turbomeca has issued SB No. 292 72 0150, dated April 10, 1992, that 
specifies installing an improved design 2nd stage nozzle guide vane.
    This engine 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 in effect at the time 
of type certification. The Direction Generale de L'Aviation Civile 
(DGAC), which is the airworthiness authority for France, 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 an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 93-23-09 to continue to require 
repetitive checks for engine rubbing noise during gas generator 
shutdown, and for free rotation of the gas generator by rotating the 
compressor manually at a daily interval until installation of the 
improved 2nd stage nozzle guide vane.
    This proposed AD would allow pilots to perform all the required 
checks. This action does not require special training beyond that 
already incurred by pilots of the aircraft having affected engines, or 
the use of tools or special measuring equipment, or reference to 
technical data. Accordingly, the FAA has determined that pilots may 
perform all the checks required by this proposed rule as an exception 
to Sec. 43.3 of the Federal Aviation Regulations (14 CFR 43.3) 
regarding the performance of maintenance.
    The FAA estimates that 160 engines installed on aircraft of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 0.2 work hours per engine to accomplish the proposed 
actions, and that the average labor rate is $55 per work hour. Required 
parts would cost approximately $8,000 per engine. Based on an assumed 
utilization rate and an assumed modification rate, the total cost 
impact of the proposed AD on U.S. operators over the five year 
compliance period is estimated to be $3,101,600.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13   [Amended]

    2. Section 39.13 is amended by removing amendment 39-8745 (58 FR 
63061, November 30, 1993) and by adding a new airworthiness directive 
to read as follows:

    Turbomeca: Docket No. 94-ANE-08. Supersedes AD 93-23-09, 
Amendment 39-8745.

    Applicability: Turbomeca Arriel turboshaft engines Models 1B 
that do have modification TU 76 but do not have modification TU 197 
or TU 202; Arriel Models 1D and 1D1 that do not have modification TU 
197 or TU 202; Arriel Models 1A, 1A1, 1A2 that have had modification 
TU 76 but do not have modification TU 197 or TU 202; and Arriel 
Models 1C, 1C1, and 1C2 that do not have TU 197 or TU 202. These 
engines are installed on but not limited to Aerospatiale Models 
AS350B, SA365, and AS565 helicopters.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent engine failure due to rubbing of the 2nd stage 
turbine disk on the 2nd stage turbine nozzle guide vane, which could 
result in engine failure and damage to the aircraft, accomplish the 
following:
    (a) For Turbomeca Arriel turboshaft engines Models 1B that have 
modification TU 76 but do not have modification TU 197 or TU 202; 
and Arriel Models 1D and 1D1 that do not have modification TU 197 or 
TU 202; accomplish the following:
    (1) Perform a daily check for unusual engine rubbing noises 
during gas generator shutdown or as engine gas generator speed 
decreases after completion of engine motoring.
    (2) Perform a daily check for free rotation of the gas 
generator, when T4 temperature is below 150 degrees Centigrade, by 
rotating the compressor manually.
    (3) While checking for free rotation of the gas generator, 
perform a check for engine rubbing noise.
    (b) For Turbomeca Arriel turboshaft engines Models 1A, 1A1, 1A2 
that have modification TU 76 but do not have modification TU 197 or 
TU 202; and Arriel Models 1C, 1C1, and 1C2 that do not have 
modification TU 197 or TU 202; accomplish the following:
    (1) Within 50 hours time in service (TIS) after the effective 
date of this AD, perform a check for unusual engine rubbing noise 
during gas generator shutdown or within 5 seconds after engine 
motoring.
    (2) Thereafter, at intervals not to exceed 50 hours TIS since 
the last check, perform a check for unusual engine rubbing noise 
during gas generator shutdown or within 5 seconds after engine 
motoring.
    (3) Perform a daily check for free rotation of the gas generator 
when T4 temperature is below 150 degrees C, by rotating the 
compressor manually.
    (4) While checking for free rotation of the gas generator, 
perform a check for engine rubbing noise.
    (c) If any engine rubbing noise is detected during the checks 
required by paragraphs (a) and (b) of this AD, prior to further 
flight replace gas generator module M03 with a serviceable module.
    (d) Install the improved 2nd stage nozzle guide vane, 
modification TU 202, at the next engine overhaul after the effective 
date of this AD, but not later than December 31, 1999, in accordance 
with Turbomeca Service Bulletin 292 72 0150, dated April 10, 1992. 
Installation of this hardware constitutes terminating action to the 
checks required by this AD.
    (e) The checks required by paragraphs (a) and (b) of this AD may 
be performed by the pilot holding at least a private pilot 
certificate as an exception to the requirements of part 43 of the 
Federal Aviation Regulations (14 CFR part 43). The checks must be 
recorded in accordance with Sections 43.9 and 91.417(a)(2)(v) of the 
Federal Aviation Regulations (14 CFR 43.9 and 14 CFR 
91.417(a)(2)(v)), and the records must be maintained as required by 
the applicable Federal Aviation Regulation.
    (f) 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, Engine Certification Office. The 
request should be forwarded through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Engine Certification Office.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (g) 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 aircraft to a location where 
the requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on August 24, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 94-21869 Filed 9-2-94; 8:45 am]
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