[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]
BILLING CODE 4910-13-P
