[Federal Register Volume 63, Number 244 (Monday, December 21, 1998)]
[Proposed Rules]
[Pages 70352-70353]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-33747]
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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. 63, No. 244 / Monday, December 21, 1998 /
Proposed Rules
[[Page 70352]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-ANE-31-AD]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Pratt & Whitney (PW) JT9D
series turbofan engines. This proposal would require initial and
repetitive in-shop eddy current and on-wing ultrasonic inspections of
the Combustion Chamber Outer Casing (CCOC) forward flange (L flange)
fillet radius for cracking, and replacing cracked L flanges with
serviceable parts. Replacement with an improved L flange constitutes
terminating action to the repetitive inspections. This proposal is
prompted by reports of CCOC rupture due to cracking in the L flange
fillet radius. The actions specified by the proposed AD are intended to
prevent CCOC rupture due to cracking, which could result in an
uncontained engine failure and damage to the aircraft.
DATES: Comments must be received by February 19, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 98-ANE-31-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``9-ad-
[email protected]''. Comments sent via the Internet must contain the
docket number in the subject line. 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, 400 Main St., East Hartford, CT 06108;
telephone (860) 565-6600, fax (860) 565-4503. This information may be
examined at the FAA, New England Region, Office of the Regional
Counsel, 12 New England Executive Park, Burlington, MA.
FOR FURTHER INFORMATION CONTACT: Peter White, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (781)
238-7128, fax (781) 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 98-ANE-31-AD.'' 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 Regional Counsel,
Attention: Rules Docket No. 98-ANE-31-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received seven
reports of combustion chamber outer casing (CCOC) cracking in revenue
service on certain Pratt & Whitney (PW) JT9D series turbofan engines.
The investigation revealed that the first failure was associated with
an under-minimum radius at the forward flange (``L'' flange) fillet. A
fleet-wide inspection campaign found no other discrepant CCOCs. Six
subsequent forward flange cracks were found to have initiated and
propagated in low cycle fatigue (LCF); 3 of these cracks transitioned
to rapid tensile failure during takeoff, resulting in aborted takeoffs,
stalls, inflight engine shutdowns or metal in the tailpipe. The FAA
determined that these failures were not special cases, but were
associated with the design of this part operated in this application.
All reports of large cracking have been found to have initiated at the
4:00 position. This condition, if not corrected, could result in CCOC
rupture due to cracking, which could result in an uncontained engine
failure and damage to the aircraft.
The FAA has reviewed and approved the technical contents of PW
Alert Service Bulletin (ASB) No. A6343 Revision 1, dated October 8,
1998, that describes procedures for initial and repetitive on-wing
ultrasonic inspections of CCOC L flange fillet radius for cracking;
JT9D Engine Manual (Part Number P/N 646028, P/N 770407, P/N 770408, as
appropriate) Revision No. 104 (or Temporary Revision No. 72-6517,
Temporary Revision No. 72-6334, or Temporary Revision No. 72-6206,
which were superseded by manual Revision No. 104), that describes
procedures for in-shop eddy current inspections of the L flange; and PW
SB No. 4482, Revision 1, dated July 8, 1976, that describes procedures
for installation of replacement L flanges.
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 in-shop and on-wing
inspections of the CCOC L flange fillet radius for cracking, and
[[Page 70353]]
replacement of cracked L flanges with serviceable parts. Installation
of an improved L flange constitutes terminating action to the
repetitive inspections. The actions would be required to be
accomplished in accordance with the service documents described
previously.
There are approximately 950 engines of the affected design in the
worldwide fleet. The FAA estimates that 500 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, that
it would take approximately 2 work hours to perform the inspection and
45.4 work hours per engine to replace the forward flange if cracked,
and that the average labor rate is $60 per work hour. Required parts
would cost approximately $6,376 per engine. Based on current usage
rates, each engine should undergo approximately 1 inspection per year.
To date, approximately 4% of cases have been found with cracking. Based
on these figures, the total annual cost impact of the proposed on U.S.
operators is estimated to be $242,000.
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), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Pratt & Whitney: Docket No. 98-ANE-31-AD.
Applicability: Pratt & Whitney (PW) JT9D-3A, -7, -7H, 7A, -7AH,
-7F, -7J, -20, and -20J series turbofan engines, with Combustion
Chamber Outer Casing (CCOC), part numbers (P/Ns) 644801, 693294,
709016, 729237, 729238, and 729239, installed. These engines are
installed on but not limited to certain models of Boeing 747, Airbus
A300, and McDonnell Douglas DC-10 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 (g) 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 CCOC rupture due to cracking, which could result in
an uncontained engine failure and damage to the aircraft, accomplish
the following:
(a) Perform initial on-wing ultrasonic inspections of the CCOC
forward flange (L flange) fillet radius for cracking in accordance
with PW Alert Service Bulletin (ASB) No. A6343 Revision 1, dated
October 8, 1998, as follows:
(1) For engines that have not had the L Flange fillet radius
eddy current inspected using the JT9D Engine Manual (P/N 646028, P/N
770407, P/N 770408, as appropriate) Revision No. 104; or Temporary
Revision No. 72-6517, Temporary Revision No. 72-6334, or Temporary
Revision No. 72-6206, all of which were superseded by manual
Revision No. 104; at the last shop visit, inspect within 250 cycles
in service (CIS) after the effective date of this AD, or the next
shop visit, whichever occurs first.
(2) For engines that did have the L Flange fillet radius eddy
current inspected using the JT9D Engine Manual (P/N 646028, P/N
770407, P/N 770408, as appropriate) Revision No. 104; or Temporary
Revision No. 72-6517, Temporary Revision No. 72-6334, or Temporary
Revision No. 726206, all of which were superseded by manual Revision
No. 104; at the last shop visit, inspect within 2,000 CIS, or the
next shop visit after the effective date of this AD, whichever
occurs first.
(b) Thereafter, ultrasonically inspect on-wing at intervals not
to exceed 500 CIS since last on-wing inspection in accordance with
PW Alert Service Bulletin (ASB) No. A6343 Revision 1, dated October
8, 1998, or 2000 cycles in service(CIS) since last in-shop ECI
inspection, whichever occurs later.
(c) If a crack is found during on-wing inspection, remove the
part from service, and replace with a serviceable part as follows:
(1) For cracks found to be over the inspection threshold limit,
but less than 2 inches, remove within 5 CIS.
(2) For cracks found to be over the inspection threshold limit
and equal to or greater than 2 inches, remove prior to further
flight.
(d) If a crack in the L flange fillet radius of the CCOC is
found during in-shop inspection, remove the CCOC and replace with a
serviceable part, or replace the flange in accordance with PW SB No.
4482, Revision 1, dated July 8, 1976. Installation of an improved L
flange in accordance with this SB constitutes terminating action to
the repetitive inspection requirements of this AD.
(e) Inspect the CCOC L flange fillet radius during every CCOC
shop visit in accordance JT9D Engine Manual (P/N 646028, P/N 770407,
P/N 770408, as appropriate) Revision No. 104 (or Temporary Revision
No. 72-6517, Temporary Revision No. 72-6334, or Temporary Revision
No. 72-6206, which were superseded by manual Revision No. 104); that
details eddy current inspection procedures for the L flange fillet
radius.
(f) For the purpose of this AD, a shop visit is defined as
anytime the L flange is separated in the process of performing
engine repair.
(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.
Operators shall submit their request 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.
(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 December 15, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 98-33747 Filed 12-18-98; 8:45 am]
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