[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]
BILLING CODE 4910-13-U