[Federal Register Volume 60, Number 199 (Monday, October 16, 1995)]
[Proposed Rules]
[Pages 53554-53556]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25565]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-ANE-37]
Airworthiness Directives; Pratt & Whitney PW2000 Series Turbofan
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 Pratt & Whitney PW2000 series
turbofan engines. This proposal would require a reduction in the cyclic
service life limit for hubs, disks, airseals, blade retaining plates,
and airsealing ring supports on certain high pressure turbines (HPT)
and low pressure turbines (LPT), and provide for optional inspections
for cracks or rework of certain HPT and LPT hardware in order to retain
the original, higher cyclic service life limit for these components.
This proposal is prompted in part by new temperature data from engine
testing, which were used in recalculating stress levels, and resulted
in a change to the calculated cyclic service life limit. The actions
specified by the proposed AD are intended to prevent HPT or LPT
failure, which may result in an uncontained engine failure and possible
damage to the aircraft.
DATES: Comments must be received by December 15, 1995.
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-37, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at
this location between 8 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 Pratt & Whitney, Technical Publications Department, M/S
132-30, 400 Main Street, East Hartford, CT 06108. 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: John Fisher, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7149, 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-37.'' 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-37, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received updated high
pressure turbine (HPT) and low pressure turbine (LPT) life limited part
data for Pratt & Whitney PW2000 series turbofan engines, derived from
the manufacturer's review of turbine temperature data. The updated data
and resulting part life analysis indicate that the service cyclic life
limits must be reduced for certain HPT and LPT hubs, disks, airseals,
blade retaining plates, and airsealing ring supports. This condition,
if not corrected, could result in HPT or LPT failure, which may result
in an uncontained engine failure and possible damage to the aircraft.
The FAA has reviewed and approved the technical contents of Pratt &
Whitney PW2000 Engine Manual, Part Number (P/N) 1A6231, Sections 72-52-
00, 72-53-00, and 05-10-00, which lists the reduced service cyclic life
limits for affected parts identified by P/N, and describes procedures
for optional inspections for cracks or rework of certain HPT and LPT
hardware in order to retain the original, higher cyclic service life
limit for these components; PW Service Bulletin (SB) No. 72-82,
Revision 4, dated June 18, 1987, that describes rework and
reidentification of the 1st stage HPT blade retaining plates to extend
part life from 5,000 total part cycles (TPC) to 15,000 TPC; PW Alert
Service Bulletin (ASB) No. 72-228, Revision 4, dated November 9, 1988,
that describes inspections and rework of the 2nd stage HPT blade
retaining plates in order to attain their respective published part
lives; PW Alert SB No. 72-450, Revision 5, dated May 28, 1994, that
describes inspections, rework, and reidentification of the 2nd stage
HPT hubs to extend part life from 6,000 TPC to 15,000 TPC; PW SB No.
72-501, dated September 30, 1993, that describes inspections, rework,
and reidentification of the 2nd stage HPT blades and inspection and
reidentification of 2nd stage HPT hubs to extend hub life from 7,500
TPC to 15,000 TPC; PW ASB No. 72-220, Revision 4, dated September 20,
1989, that describes rework of the HPT lenticular seal to extend part
life from 4,000 TPC to 15,000 TPC; and PW SB No. 72-233, Revision 3,
dated May 30, 1989, that describes rework and identification of the HPT
lenticular seal to extend part life from 4,000 TPC to 15,000 TPC.
Since an unsafe condition has been identified that is likely to
exist or
[[Page 53555]]
develop on other engines of this same type design, the proposed AD
would require a reduction in the cyclic service life limit for hubs,
disks, airseals, blade retaining plates, and airsealing ring supports
on certain HPT and LPT, and provide for optional inspections for cracks
or rework of certain HPT and LPT hardware in order to retain the
original, higher cyclic service life limit for these components.
There are approximately 650 engines of the affected design in the
worldwide fleet. The FAA estimates that 600 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, and
that no additional labor costs would be incurred by the fleet since
inspection and replacement intervals fall within the normal overhaul
periods. Therefore, the FAA has determined that there would be no
additional cost impact on U.S. operators due to sufficient time to
schedule shop visits.
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. 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Pratt & Whitney: Docket No. 95-ANE-37.
Applicability: Pratt & Whitney Models PW2037, PW2037(M), PW2040,
PW2240, and PW2337 turbofan engines installed on but not limited to
Boeing 757 series and Ilyushin IL96 series aircraft.
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 (o) 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 high pressure turbine (HPT) or low pressure turbine
(LPT) failure, which may result in an uncontained engine failure and
possible damage to the aircraft, accomplish the following:
(a) Remove from service 1st stage HPT disks, Part Number (P/N)
1A5301, prior to exceeding 5,000 total part cycles (TPC), if
installed with blade retaining plate, P/N 1A6998, and replace with
serviceable parts. If blade retaining plate, P/N 1A6998, has not
been installed on disk, P/N 1A5301, the disk may accumulate 15,000
TPC prior to removal from service.
(b) Remove from service 1st stage HPT blade retaining plates, P/
N 1A6998, prior to exceeding 5,000 TPC, and replace with serviceable
parts. If rework is accomplished prior to exceeding 5,000 TPC in
accordance with the Accomplishment Instructions of PW Service
Bulletin (SB) No. 72-82, Revision 4, dated June 18, 1987, and
reidentified as assembly P/N 1B2373, the blade retaining plate may
accumulate 15,000 TPC prior to removal from service.
(c) Remove from service 2nd stage HPT blade retaining plates, P/
N 1B0450, prior to exceeding 7,000 TPC, and replace with serviceable
parts.
(d) Remove from service 2nd stage HPT blade retaining plates, P/
N 1B0945 (assembly P/N 1B0947), and replace with serviceable parts,
in accordance with the Accomplishment Instructions of PW Alert
Service Bulletin (ASB) No. 72-228, Revision 4, dated November 9,
1988, as follows:
(1) Prior to exceeding 5,000 TPC, for retaining plates that have
not been inspected in accordance with the Accomplishment
Instructions of the above ASB prior to 3,000 TPC.
(2) Prior to exceeding 8,000 TPC, for retaining plates that have
been inspected in accordance with the Accomplishment Instructions of
the above ASB prior to 3,000 TPC.
(e) Remove from service 2nd stage HPT hubs, P/N's 1A8302,
1B1002, 1B1202, and 1B4902 prior to exceeding 6,000 TPC, and replace
with serviceable hubs. Hubs may accumulate 15,000 TPC prior to
removal from service if they are inspected at intervals that are not
more than 6,000 TPC, in accordance with the Accomplishment
Instructions of PW Alert SB No. 72-450, Revision 5, dated May 28,
1994.
(f) Remove from service 2nd stage HPT hubs, P/N 1B6602, prior to
exceeding 7,500 TPC, and replace with serviceable hubs. Hubs may
accumulate 15,000 TPC prior to removal from service if hub
assemblies are inspected prior to 7,500 TPC to verify scarf cut
blades are installed and to inspect the blade platform rail fillet
radii dimensions, in accordance with the Accomplishment Instructions
of PW SB No. 72-501, dated September 30, 1993. Hub assemblies found
with non-scarf cut blades must be reinspected at intervals not to
exceed 6,000 TPC since last inspection. Blades found with under
minimum radii dimensions must be scrapped.
(g) Remove from service HPT lenticular airseal, P/N 1A8209,
prior to exceeding 4,000 TPC, and replace with serviceable airseals.
Airseals may accumulate 15,000 TPC prior to removal from service if:
(1) Inspected prior to exceeding 4,000 TPC, and thereafter
inspected at intervals not to exceed 250 cycles in service since
last inspection, in accordance with Compliance Paragraph E of the
Accomplishment Instructions of PW ASB No. 72-220, Revision 4, dated
September 20, 1989; or
(2) The 2nd stage HPT case and vane assembly is reworked (pre-
trench) and reidentified prior to exceeding 4,000 TPC in accordance
with the Accomplishment Instructions of PW SB No. 72-233, Revision
3, dated May 30, 1989.
(h) For PW2037, PW2037(M), and PW2337 model engines, remove from
service 4th stage LPT disks, P/N's 8A1024, 8A1534, and 8A2137 prior
to exceeding 17,000 TPC, and replace with serviceable disks.
(i) For PW2040 and PW2240 model engines, remove from service 4th
stage LPT disks, P/N's 8A1534 or 8A2137, prior to exceeding 15,000
TPC, and replace with serviceable disks.
(j) Remove from service 3rd stage LPT airsealing ring supports,
P/N 8A1783, and replace with serviceable parts, as follows:
(1) For PW2040 and PW2240 model engines, prior to exceeding
15,000 TPC.
(2) For PW2037, PW2037(M), and PW2337 model engines, prior to
exceeding 17,000 TPC. Airsealing ring supports may accumulate 20,000
TPC prior to removal from
[[Page 53556]]
service if they were fluorescent penetrant inspected in accordance with
PW2000 Engine Manual, P/N 1A6231.
(k) For PW2037, PW2037(M), and PW2337 model engines, remove from
service prior to exceeding 17,000 TPC, and replace with serviceable
parts, as follows:
(1) 4th stage LPT airseal, P/N's 8A1014 and 8A1805.
(2) 5th stage LPT airseal, P/N's 8A1015 and 8A1806.
(3) 7th stage LPT airseal, P/N's A8A1017, A8A1808, 8A2097, and
A8A2097.
(l) Parts listed in paragraph (k) of this AD may accumulate
20,000 TPC prior to removal from service if they were fluorescent
penetrant inspected for cracks between 12,000 TPC and 17,000 TPC in
accordance with Section 72-53-00 of PW2000 Engine Manual, P/N
1A6231.
(m) For PW2040 and PW2240 model engines, remove from service
prior to exceeding 15,000 TPC, and replace with serviceable parts,
as follows:
(1) 4th stage LPT airseal, P/N's 8A1014 and 8A1805.
(2) 5th stage LPT airseal, P/N's 8A1015 and 8A1806.
(3) 7th stage LPT airseal, P/N's A8A1017, A8A1808, 8A2097, and
A8A2097.
(n) Parts listed in paragraph (m) of this AD may accumulate the
following TPC prior to removal from service if they were fluorescent
penetrant inspected for cracks between 10,000 TPC and 15,000 TPC in
accordance with Section 72-53-00 of PW2000 Engine Manual, P/N
1A6231.
(1) 4th stage LPT airseal, P/N's 8A1014 and 8A1805, prior to
exceeding 18,000 TPC.
(2) 5th stage LPT airseal, P/N's 8A1015 and 8A1806, prior to
exceeding 19,000 TPC.
(3) 7th stage LPT airseal, P/N's A8A1017, A8A1808, 8A2097, and
A8A2097, prior to exceeding 20,000 TPC.
(o) 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.
(p) 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 October 3, 1995.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 95-25565 Filed 10-13-95; 8:45 am]
BILLING CODE 4910-13-U
