[Federal Register Volume 61, Number 109 (Wednesday, June 5, 1996)]
[Proposed Rules]
[Pages 28520-28522]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-14033]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-ANE-57]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D 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 JT9D series 
turbofan engines. This proposal would require installing an improved 
design turbine exhaust case (TEC) with a thicker containment wall or 
modified TEC. This proposal is prompted by reports of 64 uncontained 
engine failures since 1972. The actions specified by the proposed AD 
are intended to prevent release of uncontained debris from the turbine 
exhaust case following an internal engine failure, which can result in 
damage to the aircraft.

DATES: Comments must be received by August 5, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 95-ANE-57, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be 
submitted to the Rules Docket by using the following Internet address: 
``[email protected]''. 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, Publications Department, Supervisor 
Technical Publications Distribution, M/S 132-30, 400 Main St., East 
Hartford, CT 06108; telephone (860) 565-7700. 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: Daniel Kerman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7130, 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

[[Page 28521]]

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 95-ANE-57.'' 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. 95-ANE-57, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has determined that the 
turbine exhaust case (TEC) on Pratt & Whitney (PW) JT9D-3, -7, -20, -
59A, -70A, -7Q, and -7R4 series turbofan engines may not be capable of 
containing a release of engine debris should an internal engine failure 
occur. The FAA has determined, based on service experience, that TEC 
penetrations have resulted from multiple internal gas path failure 
modes. Primary penetrations of the TEC have been isolated to the outer 
wall between the leading edge of the casing struts and the forward 
``P'' flange. This condition, if not corrected, could result in release 
of uncontained debris from the turbine exhaust case following an 
internal engine failure, which can result in damage to the aircraft.
    Service experience has demonstrated that there exists a need for 
out-of-plane, aft containment. The FAA has received reports of 64 
uncontained failures of the TEC since 1972.
    These TEC penetrations have resulted from a variety of failure 
modes. In some incidents, the engine failures have occurred as far 
upstream as the fan module No. 1 bearing to as far downstream as the 
sixth stage low pressure turbine blades. In all instances these 
failures have caused a balling effect in which downstream debris has 
penetrated through the TEC shell wall. As a result of these 
uncontainments, PW has refined their analytical containment model based 
on the results of ballistics testing. PW utilized this data to 
establish new casing wall thickness requirements for aft containment. 
Pratt & Whitney has developed three containment improvements: a 
redesigned, thick-wall TEC developed for all models of the JT9D engine; 
containment shields for all models of the JT9D engine; and a new TEC 
``P'' flange and case wall replacement for all models of the JT9D 
engine excluding the Model JT9D-7R4D (BG-700 series) turbofan engines.
    The FAA has reviewed and approved the technical contents of the 
following PW Service Bulletins (SB's): SB No. 6113, dated April 13, 
1993; SB No. 5977, dated December 14, 1990; SB No. JT9D-7R4-72-479, 
Revision 1, dated November 12, 1993; SB No. 6243, dated February 1, 
1996; SB No. JT9D-7R4-72-513, Revision 2, dated January 10, 1996; SB 
No. 5907, dated March 27, 1990; SB No. JT9D-7R4-72-407, Revision 1, 
dated August 16, 1990; SB No. JT9D-7R4-72-466, Revision 2, dated May 
10, 1996; SB No. 6118, Revision 3, dated January 10, 1996; and SB No. 
6157, dated February 9, 1994. These SB's describe replacing the 
previous TEC with a new, thicker case wall TEC, installing a new 
containment shield for enhanced containment capability, and replacing 
the TEC ``P'' flange and case wall with a thicker cross section.
    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 installing an improved design TEC with a 
thicker containment wall, modifying the existing TEC to incorporate a 
containment shield, or modifying the existing TEC to replace the ``P'' 
flange and case wall. The FAA has established a compliance end-date of 
48 months after the effective date of this AD based upon shop visit 
rates for hot section overhaul. The actions would be required to be 
accomplished in accordance with the service bulletins described 
previously.
    There are approximately 2,748 engines of the affected design in the 
worldwide fleet. The FAA estimates that 740 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 14 work hours per engine to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
Required parts would cost approximately $1,404 per engine. Based on 
these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $1,660,560.
    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. 95-ANE-57.

    Applicability: Pratt & Whitney (PW) JT9D-3, -7, -20, -59A, -70A, 
-7Q, and -7R4 series turbofan engines, installed on but not limited 
to Airbus A300 and A310 series; Boeing 747 and 767 series; and 
McDonnell Douglas DC-10 series aircraft.

    Note: 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

[[Page 28522]]

use the authority provided in paragraph (b) to request approval from 
the Federal Aviation Administration (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 release of uncontained debris from the turbine 
exhaust case (TEC) following an internal engine failure, which can 
result in damage to the aircraft, accomplish the following:
    (a) At the next removal of the TEC from the low pressure turbine 
case ``P'' flange for overhaul, where the No. 4 bearing, carbon 
seals, lubrication pressurization lines, or scavenge lines are 
removed for maintenance after the effective date of this AD, but not 
later than 48 months after the effective date of this AD, accomplish 
the following:
    (1) For PW JT9D-3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20J 
series turbofan engines, accomplish any one of the following 
actions:
    (i) Install a thicker-walled TEC, with Part Numbers (P/N's) 
listed in PW SB No. 6113, dated April 13, 1993, as applicable; or
    (ii) Install a modified TEC that incorporates a containment 
shield, with P/N's listed in PW SB No. 5907, dated March 27, 1990, 
as applicable; or
    (iii) Install a modified TEC that incorporates a replacement 
``P'' flange and case wall, with P/N's listed in PW SB No. 6118, 
Revision 3, dated January 10, 1996.
    (2) For PW JT9D-7Q and -7Q3 series turbofan engines, accomplish 
any one of the following actions:
    (i) Install a thicker-walled TEC, with P/N's listed in PW SB No. 
5977, dated December 14, 1990; or
    (ii) Install a modified TEC that incorporates a containment 
shield, with P/N's listed in PW SB No. 5907, dated March 27, 1990, 
as applicable; or
    (iii) Install a modified TEC that incorporates a replacement 
``P'' flange and case wall, with P/N's listed in PW SB No. 6157, 
dated February 9, 1994.
    (3) For PW JT9D-59A and -70A series turbofan engines, accomplish 
one of the following actions:
    (i) Install a thicker-walled TEC, with P/N's listed in PW SB No. 
6243, dated February 1, 1996; or
    (ii) Install a modified TEC that incorporates a containment 
shield, with P/N's listed in PW SB No. 5907, dated March 27, 1990, 
as applicable;
    (iii) Install a modified TEC that incorporates a replacement 
``P'' flange and case wall, with P/N's listed in PW SB No. 6157, 
dated February 9, 1994.
    (4) For PW JT9D-7R4D (BG-700 series) turbofan engines, 
accomplish either of the following actions:
    (i) Install a thicker-walled TEC, with P/N's listed in PW SB No. 
JT9D-7R4-72-479, Revision 1, dated November 12, 1993; or
    (ii) Install a modified TEC that incorporates a containment 
shield, with P/N's listed in PW SB No. JT9D-7R4-72-407, Revision 1, 
dated August 16, 1990, as applicable.
    (5) For PW JT9D-7R4D (BG-800 series), -7R4D (BG-900 series), -
7R4D1 (AI-500 series), -7R4E (BG-800 series), -7R4E (BG-900 series), 
-7R4E1 (AI-500 series), -7R4E1 (AI-600 series), -7R4E4 (BG-900 
series), -7R4G2 (BG-300 series), and -7R4H1 (AI-600 series) turbofan 
engines, accomplish any one of the following actions:
    (i) Install a thicker-walled TEC, with P/N's listed in PW SB No. 
JT9D-7R4-72-513, Revision 2, dated January 10, 1996; or
    (ii) Install a modified TEC that incorporates a containment 
shield, with P/N's listed in PW SB No. JT9D-7R4-72-466, Revision 2, 
dated May 10, 1996; or
    (iii) Install a modified TEC that incorporates a replacement 
``P'' flange and case wall, with P/N's listed in PW SB No. JT9D-7R4-
72-513, Revision 2, dated January 10, 1996.
    (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: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (c) 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 May 22, 1996.
Robert E. Guyotte,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 96-14033 Filed 6-4-96; 8:45 am]
BILLING CODE 4910-13-P