[Federal Register Volume 60, Number 199 (Monday, October 16, 1995)]
[Proposed Rules]
[Pages 53556-53557]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25566]



-----------------------------------------------------------------------


DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-ANE-51]


Airworthiness Directives; Pratt & Whitney JT9D-7R4 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 Pratt & Whitney (PW) JT9D-7R4 
series turbofan engines. This proposal would require replacement of 
3rd, 4th, and 5th stage low pressure turbine (LPT) vane retention bolts 
and nuts, and the removal of the 5th stage vane configuration which 
includes an electro-discharge machined (EDM) slot and replacement with 
a cast slot configuration. This proposal is prompted by reports of LPT 
failures that resulted in uncontained engine failures. The actions 
specified by the proposed AD are intended to prevent LPT vane failures, 
which can result in uncontained engine failure, fire, 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. 94-ANE-51, 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, 400 Main St., 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 94-ANE-51.'' 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. 94-ANE-51, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received five reports 
of low pressure turbine (LPT) failures on Pratt & Whitney (PW) JT9D-7R4 
series turbofan engines, three of which resulted in uncontained engine 
failures. These LPT failures have been attributed to the following two 
root causes. The FAA's investigation revealed that certain 4th stage 
LPT vane retention bolts fractured due to the application of uncured 
anti-gallant compound on vane retention bolts. Also, the investigation 
revealed that certain 5th stage vanes failed due to inclusion of an 
electro-discharge machined (EDM) slot, which is prone to high stress 
concentrations in the outer platform slot. These conditions, if not 
corrected, could result in LPT vane failures, which can result in 
uncontained engine failure, fire, and possible damage to the aircraft.
    The FAA has reviewed and approved the technical contents of PW 
Service Bulletin (SB) No. JT9D-7R4-72-473, Revision 2, dated February 
8, 1993, that describes procedures for identification 

[[Page 53557]]
of EDM slot 5th stage LPT vanes and cast slot 5th stage LPT vanes; PW 
Alert Service Bulletin (ASB) No. JT9D-7R4-72-480, dated April 20, 1993, 
that describes procedures for replacement of vane clusters that have 
machined slots in the front face of the outer platform; PW ASB No. 
JT9D-7R4-72-481, dated April 20, 1993, that describes procedures for 
replacement of vane retention bolts and nuts; and PW SB No. JT9D-7R4-
72-484, Revision 1, dated October 9, 1993, that describes procedures 
for replacement or modification to the 3rd, 4th, and 5th stage LPT air 
sealing ring stop assemblies and the turbine case heat shield 
assemblies, and installation of new bolts.
    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 replacement of 3rd, 4th, and 5th stage LPT 
vane retention bolts and nuts and the removal of the 5th stage vane 
configuration which includes an EDM slot, and replacement with a cast 
slot configuration. In addition, the proposed AD would prohibit use of 
uncured anti-gallant compound on the bolts or nuts, as uncured anti-
gallant compound was a contributor to the unsafe condition. The actions 
would be required to be accomplished in accordance with the service 
bulletins described previously.
    The FAA estimates that 600 engines installed on aircraft of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 22 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 $792,000.
    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), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Pratt & Whitney: Docket No. 94-ANE-51.

    Applicability: Pratt & Whitney (PW) JT9D-7R4 series turbofan 
engines, installed on but not limited to Airbus A300 and A310 
series, and Boeing 747 and 767 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 (e) 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 low pressure turbine (LPT) vane failures, which can 
result in uncontained engine failure, fire, and possible damage to 
the aircraft, accomplish the following:
    (a) Remove electro-discharge machined (EDM) slot 5th stage LPT 
vane cluster segments, Part Numbers (P/N) 787885 or 787885-001, and 
replace with the cast pocket vane configuration, P/N 796985, 795175, 
796985-001, 808875, 811985, or 811985-001, at the next shop visit, 
but not later than 5,000 cycles in service (CIS) after the effective 
date of this AD, in accordance with PW Alert Service Bulletin (ASB) 
No. JT9D-7R4-72-480, dated April 20, 1993. NOTE: Pratt & Whitney SB 
No. JT9D-7R4-72-473, Revision 2, dated February 8, 1993, may be used 
to segregate EDM slot from cast pocket 5th stage LPT vane clusters 
sharing the same P/N 787885 and 787885-001.
    (b) For LPT modules that have been previously disassembled, 
perform either paragraph (b)(1) or (b)(2) of this AD at the next 
shop visit, but not later than 5,000 CIS after the effective date of 
this AD.
    (1) Install new 3rd, 4th, and 5th stage LPT vane bolts and nuts, 
in accordance with PW ASB No. JT9D-7R4-72-481, dated April 20, 1993. 
Do not use uncured anti-gallant compound on the bolts or nuts.
    (2) Install new 3rd, 4th, and 5th stage LPT vane bolts and nuts, 
and install heat shield assemblies and air sealing ring stop 
assemblies in accordance with PW SB No. JT9D-7R4 72-484, Revision 1, 
dated October 9, 1993. Do not use uncured anti-gallant compound on 
the bolts or nuts.
    (c) For LPT modules that have never been disassembled, perform 
either paragraph (b)(1) or (b)(2) of this AD at the first LPT module 
disassembly. Do not use uncured anti-gallant compound on the bolts 
or nuts.
    (d) For the purpose of this AD, a shop visit is defined as the 
induction of an engine into a maintenance facility for the purpose 
of either:
    (1) Separation of pairs of major mating engine flanges; or
    (2) The removal of an engine disk, hub, or spool.
    (e) 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.

    (f) 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. 95-25566 Filed 10-13-95; 8:45 am]
BILLING CODE 4910-13-P