[Federal Register Volume 61, Number 59 (Tuesday, March 26, 1996)]
[Proposed Rules]
[Pages 13111-13113]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-7244]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-ANE-01]
Airworthiness Directives; AlliedSignal, Inc. AL5512 Series
Turboshaft Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to AlliedSignal, Inc. (formerly
Textron Lycoming) AL5512 series turboshaft engines. This proposal would
require a one-time eddy current inspection of the second stage turbine
disk, reduced service lives for the second, third, and fourth stage
turbine disks, reduced service lives for the first and third through
seventh stage compressor rotor disks, and a reduced service life for
the gas producer turbine spacer. This proposal would also require a
new, more conservative minor cycle counting factors table for
repetitive heavy lift operations, and provides a method for prorating
past utilization for all gas producer and compressor components based
on the new cycle counting factors. For those components that exceed
their new published life limits, this proposal would implement a
drawdown for safe removal of time-expired components. This proposal is
prompted by reports of cracks in certain AlliedSignal, Inc. ALF502R
series turbofan engine disks, which are identical in design and
construction to those within the AlliedSignal, Inc. AL5512 series
turboshaft engines. The actions specified by the proposed AD are
intended to prevent disk failure, which could result in an uncontained
engine failure, inflight shutdown, or possible damage to the
rotorcraft.
DATES: Comments must be received by May 28, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 95-ANE-01, 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 AlliedSignal, Inc., 550 Main St., Stratford, CT 06497-
7593. 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: Daniel Kerman, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA
[[Page 13112]]
01803-5299; telephone (617) 238-7130, 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 95-ANE-01.'' 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. 95-ANE-01, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received reports of
cracks found in certain disks returned from service to the manufacturer
and in certain factory tested disks installed on AlliedSignal, Inc.
(formerly Textron Lycoming) ALF502R series turbofan engines. While no
cracks have been found in AlliedSignal, Inc. AL5512 series turboshaft
engine components, certain disks are identical in design and
construction to those utilized in the ALF502R engine. The cracks in the
ALF502R engines have been found in the bolt hole area of several second
stage turbine disks. Cracks have also been discovered in the rim
dovetail area of several first and third through seventh stage
compressor rotor disks in the ALF502R engines. Subsequent analysis and
testing of the current design of first and third through seventh stage
compressor rotor disks; second, third, and fourth stage turbine disks;
and the gas producer spacer have revealed a lower fatigue life than
originally calculated. In addition, the FAA has determined the need to
require a special, one-time eddy current inspection of the second stage
turbine disk to discover possible bolt hole cracking. This condition,
if not corrected, could result in disk failure, which could result in
an uncontained engine failure, inflight shutdown, or possible damage to
the rotorcraft.
The FAA has reviewed and approved the technical contents of Textron
Lycoming Service Bulletin (SB) No. AL5512-0002, Revision 5, dated
December 16, 1993, that describes reduced service lives for first and
third through seventh stage compressor rotor disks; second, third, and
fourth stage turbine disks; and the gas producer spacer. In addition
this SB describes factors to be used for cyclic computation of
components utilized in repetitive heavy lift (RHL) operation, and
provides a method for prorating past component utilization based on the
new cycle counting factors.
The FAA has also reviewed and approved the technical contents of
the following SB's: Textron Lycoming SB No. AL5512-0041, dated December
16, 1993, and Textron Lycoming SB No. AL5512-0046, dated April 4, 1994.
These SB's describe drawdown schedules for those components that exceed
their new life limits.
In addition, the FAA has reviewed and approved the technical
contents of Textron Lycoming SB No. AL5512-0042, dated December 16,
1993, that describes procedures for a one-time eddy current inspection
of the second stage turbine disk bolt holes.
Since an unsafe condition has been identified that is likely to
exist or develop on other engines of this same type design, the
proposed AD would require a one-time eddy current inspection of the
second stage turbine disk, reduced service lives for the second, third,
and fourth stage turbine disks, reduced service lives for the first and
third through seventh stage compressor rotor disks, and a reduced
service life for the gas producer turbine spacer. This proposal would
also require a new, more conservative minor cycle counting factors
table for RHL operation and provides a method for prorating past
utilization for all gas producer and compressor components based on the
new cycle counting factors. For those components that exceed their new
published life limits, this proposal would implement a drawdown for
safe removal of time-expired components. The actions would be required
to be accomplished in accordance with the service bulletins described
previously.
There are approximately 33 engines of the affected design in the
worldwide fleet. The FAA estimates that 20 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, that
it would take approximately 60 work hours per engine to disassemble,
assemble, and test each engine, that each engine would consume $2,000
per engine of fuel and disposable hardware, and that the average labor
rate is $60 per work hour. The prorated life-expired components
replacement cost would be approximately $74,530 per engine. Based on
these figures, the cost impact of performing the actions described in
Textron Lycoming SB No. AL5512-0002, Revision 5, dated December 16,
1993, is estimated to be $1,602,600.
In addition, the FAA also estimates that it would take
approximately 16 work hours to perform a one-time eddy current
inspection of the second stage turbine disk. The cost impact of
performing the actions described in Textron Lycoming SB No. AL5512-
0042, dated December 16, 1993, is estimated to be $19,200. Therefore,
the total cost impact of the proposed AD on U.S. operators is estimated
to be $1,621,800.
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.
[[Page 13113]]
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 USC 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
AlliedSignal, Inc.: Docket No. 95-ANE-01.
Applicability: AlliedSignal, Inc. (formerly Textron Lycoming)
AL5512 series turboshaft engines, installed on but not limited to
Boeing Helicopter Model 234 rotorcraft.
Note: This AD applies to each engine 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 engines 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 engine from the
applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent disk failure, which could result in an uncontained
engine failure, inflight shutdown, or possible damage to the
rotorcraft, accomplish the following:
(a) Within 30 days after the effective date of this
airworthiness directive (AD), conduct a revised operating cycle
count (prorate) of all gas producer and compressor components in
accordance with paragraph 2.D of Textron Lycoming Service Bulletin
(SB) No. AL5512-0002, Revision 5, dated December 16, 1993.
(b) After the effective date of this AD, utilize the new, more
conservative minor cycle counting methodology for repetitive heavy
lift operation described in Textron Lycoming SB No. AL5512-0002,
Revision 5, dated December 16, 1993
(c) Following implementation of the revised operating cycle
count methodology (prorate) specified in paragraph (a) of this AD,
replace those components that exceed their new life limits in
accordance with the component removal schedules defined in Textron
Lycoming SB No. AL5512-0041, dated December 16, 1993, and SB No.
AL5512-0046, dated April 4, 1994, as applicable. Replacement
components must have cyclic accumulation no greater than the reduced
life limits as defined in Textron Lycoming SB AL5512-0002, Revision
5, dated December 16, 1993.
(d) Following implementation of the revised operating cycle
count methodology (prorate) specified in paragraph (a) of this AD,
installation of those components that exceed their life limit on the
effective date of this AD is prohibited.
(e) Perform a one-time eddy current inspection of installed
second stage turbine rotor disk, part number 2-121-058-18, bolt
holes at the next shop visit that the disk assembly is removed from
the engine or module after the effective date of this AD and after
the part has accrued a minimum of 5,000 cycles in service, in
accordance with the Accomplishment Instructions of Textron Lycoming
SB No. AL5512-0042, dated December 16, 1993. Prior to further
flight, remove from service disks that do not meet the return to
service limits defined in the SB, and replace with serviceable
parts.
(f) Prior to installation, but after accruing a minimum of 5,000
cycles in service, perform a one-time eddy current inspection of
uninstalled second stage turbine rotor disk, part number 2-121-058-
18, bolt holes in accordance with the Accomplishment Instructions of
Textron Lycoming SB No. AL5512-0042, dated December 16, 1993.
Installation of disks that do not meet the return to service limits
defined in the SB is prohibited.
(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, 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.
(h) 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 March 11, 1996.
James C. Jones,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 96-7244 Filed 3-25-96; 8:45 am]
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