[Federal Register Volume 62, Number 6 (Thursday, January 9, 1997)]
[Proposed Rules]
[Pages 1298-1299]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-469]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 62, No. 6 / Thursday, January 9, 1997 /
Proposed Rules
[[Page 1298]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-ANE-32]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT8D 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 JT8D-1, -1A, -1B,
-7, -7A, -7B, -9, -9A, -11, -15, - 17, and -17R series turbofan
engines. This proposal would require initial and repetitive fluorescent
penetrant and eddy current inspections of 4th stage low pressure
turbine (LPT) hubs for cracks, and, if necessary, replacement with
serviceable parts. This proposal is prompted by a report of an
uncontained 4th stage LPT blade release. The actions specified by the
proposed AD are intended to prevent a 4th stage LPT blade release due
to hub cracking, which can result in an uncontained engine failure and
damage to the aircraft.
DATES: Comments must be received by March 10, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 96-ANE-32, 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 Pratt & Whitney, Publication Department, Supervisor
Technical Publications Distribution, M/S 132-30, 400 Main St., East
Hartford, CT 06108; telephone (860) 565-7700, fax (860) 565-4503. 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: Diane Cook, Aerospace Engineer, Engine
Certification Office, FAA, Engine and Propeller Directorate, 12 New
England Executive Park, Burlington, MA 01803-5299; telephone (617) 238-
7134, 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 96-ANE-32.'' 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. 96-ANE-32, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received a report of
an uncontained engine failure on a Pratt & Whitney (PW) JT8D-15
turbofan engine. On January 30, 1996, this engine, installed on a
Boeing Model 727-200 aircraft, experienced an uncontained 4th stage low
pressure turbine (LPT) blade release during takeoff roll. The aircraft
sustained damage to the vertical stabilizer and the engine cowling.
Inspection of the engine revealed that the LPT blade release resulted
from a radial fracture of the 4th stage LPT hub. The investigation
determined that the failure was due to a crack which initiated in and
propagated in low cycle fatigue from an inclusion located in the hub
bore. This condition, if not corrected, could result in a 4th stage LPT
blade release due to hub cracking, which can result in an uncontained
engine failure and damage to the aircraft.
Further investigation revealed that a certain population of PW JT8D
4th stage LPT hubs may contain inclusions of aluminum/titanium
carbonitrides rich in cerium and lanthanum in the hub bore that may
initiate a crack in the bore, and if undetected, may propagate,
resulting in a hub fracture and LPT blade release. The cause of the
inclusion occurred during the material melting process where a small
amount of slag created during the desulfurization/deoxidization process
of the vacuum induction melt survived a subsequent melt and was not
detected by the required nondestructive test inspections for this
material/part. The FAA has determined that material produced prior to
April 31, 1983, has more susceptibility to inclusions, whereas
subsequent to that date process improvements have been implemented to
produce material that is less susceptible to inclusions. Due to these
process improvements, the FAA has identified certain 4th stage LPT hubs
produced prior to April 1983 that have a greater potential for
contamination. Prior to the uncontained engine failure on January 30,
1996, the FAA received reports of two previous incidents of cracks in
the 4th stage LPT hub due to inclusions that were discovered during
routine shop visits.
The FAA has reviewed and approved the technical contents of PW
Alert Service Bulletin (ASB) No. A6274,
[[Page 1299]]
Revision 1, dated December 9, 1996, that identifies by serial number
(S/N) affected 4th stage LPT hubs, and describes procedures for
fluorescent penetrant inspection (FPI) and eddy current inspection
(ECI) of 4th stage LPT hubs for cracks.
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 require initial and repetitive FPI and ECI of
affected 4th stage LPT hubs for cracks, and, if necessary, replacement
with serviceable parts. The actions would be required to be
accomplished in accordance with the ASB described previously.
The FAA estimates that 381 engines installed on aircraft of U.S.
registry would be affected by this proposed AD, that it would take
approximately 6 work hours per engine to accomplish the proposed
actions, and that the average labor rate is $60 per work hour. Based on
these figures, the total cost impact of the proposed AD on U.S.
operators is estimated to be $137,160.
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 USC 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Pratt & Whitney: Docket No. 96-ANE-32.
Applicability: Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7,
-7A, -7B, 9, -9A, -11, -15, -17, and -17R turbofan engines, with 4th
stage low pressure turbine (LPT) hubs identified by serial number
(S/N) in Table A of PW Alert Service Bulletin (ASB) No. A6274,
Revision 1, dated December 97, 1996. These engines are installed on
but not limited to Boeing 727 and 737 series, and McDonnell Douglas
DC-9 series aircraft.
Note 1: This airworthiness directive (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 request
approval for an alternative method of compliance in accordance with
paragraph (b) of this AD. The request should include an assessment
of the effect of the modification, alteration, or repair on the
unsafe condition addressed by this AD; and, if the unsafe condition
has not been eliminated, the request should include specific
proposed actions to address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent 4th stage LPT blade failure due to hub cracking,
which can result in an uncontained engine failure and damage to the
aircraft, accomplish the following:
(a) Perform fluorescent penetrant inspection (FPI) and eddy
current inspection (ECI) of affected 4th stage LPT hubs for cracks,
in accordance with Paragraph 2A of PW ASB No. A6274, Revision 1,
dated December 9, 1996, as follows:
(1) Inspect at the next time after the effective date of this AD
that the hub is removed from the module and has been debladed.
(2) Thereafter, inspect each time the hub is removed from the
module and has been debladed.
(3) Remove from service any cracked 4th stage LPT hub and
replace with a serviceable part.
(b) 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 2: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Engine Certification Office.
Issued in Burlington, Massachusetts, on January 2, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 97-469 Filed 1-8-97; 8:45 am]
BILLING CODE 4910-13-U
