[Federal Register Volume 64, Number 207 (Wednesday, October 27, 1999)]
[Proposed Rules]
[Pages 57810-57811]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-28087]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NE-04-AD]
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 certain Pratt & Whitney (PW) JT8D
series turbofan engines. This proposal would require recalculation of
cyclic life limits for certain compressor and turbine disks installed
on engines with hush kits (Stage III noise reduction systems) installed
in accordance with PW Service Bulletin No. 5947, removal from service
of disks that exceed the new, lower cyclic life limits, and replacement
with serviceable parts. This proposal is prompted by reports that
compressor and turbine disks have higher rotor speeds on engines with
hush kits that result in lower cyclic lives. The actions specified by
the proposed AD are intended to prevent compressor and turbine disk
failure due to reduced cyclic lives, which could result in an
uncontained engine failure and damage to the airplane.
DATES: Comments must be received by December 27, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 99-NE-04-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``9-ane-
[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) 565-8770, 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: James Rosa, Aerospace Engineer,
Certification Office, FAA, Engine and Propeller Directorate, 12 New
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7152, 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 99-NE-04-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. 99-NE-04-AD, 12 New
[[Page 57811]]
England Executive Park, Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received reports of
higher than normal rotor speeds on certain compressor and turbine disks
installed on Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -
9A, -11, -15, -15A, -17, and -7A series turbofan engines with hush kits
(Stage III noise reduction systems) installed in accordance with PW
Service Bulletin (SB) No. 5947. Analysis indicates that higher rotor
speeds result in reduced cyclic lives for affected disks. This
condition, if not corrected, could result in compressor and turbine
disk failure due to reduced cyclic lives, which could result in an
uncontained engine failure and damage to the airplane.
The FAA has reviewed and approved the technical contents of PW
Alert Service Bulletin (ASB) No. A6340, dated June 25, 1998, that
identifies affected compressor and rotor disks by part number (P/N),
and describes formulae for recalculating cyclic disk lives.
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 recalculation of cyclic life limits for
certain compressor and turbine disks installed on engines with hush
kits installed in accordance with PW SB No. 5947, removal from service
of disks that exceed the new, lower cyclic life limits, and replacement
with serviceable parts. The actions would be required to be
accomplished in accordance with the ASB described previously.
There are approximately 2,872 engines of the affected design in the
worldwide fleet. The FAA estimates that 2,585 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, and
that the prorated life reduction would cost approximately $5,700 per
engine over the life of the engine. Based on these figures, the total
cost impact of the proposed AD on U.S. operators is estimated to be
$14,734,500.
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. 99-NE-04-AD.
Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A,
-7B, -9, -9A, -11, -15, -15A, -17, and -17A series turbofan engines
with hush kits (Stage III noise reduction systems) installed in
accordance with PW Service Bulletin (SB) No. 5947. These engines are
installed on but not limited to Boeing 727 and 737 series aircraft,
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 (d) 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 compressor and turbine disk failure due to reduced
cyclic lives, which could result in an uncontained engine failure
and damage to the airplane, accomplish the following:
(a) Within twenty five (25) cycles-in-service after the
effective date of this AD, recalculate the cyclic life limits of
affected compressor and turbine disks listed by part number (P/N) in
PW Alert Service Bulletin (ASB) No. A6340 dated June 25, 1998, in
accordance with the formulae described in the Accomplishment
Instructions of the ASB.
(b) After recalculating the new cyclic life limits in accordance
with paragraph (a) of this AD, but prior to further flight, remove
from service affected compressor and turbine disks that exceed the
new, lower cyclic life limits calculated in accordance with
paragraph (a) of this AD, and replace with serviceable parts.
(c) Except as provided in paragraph (d) of this AD, this AD
established new, lower cyclic life limits for affected compressor
and turbine disks installed on engines with hush kits.
(d) 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.
(e) Special flight permits may be issued in accordance with
Secs. 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 21, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 99-28087 Filed 10-26-99; 8:45 am]
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