[Federal Register Volume 63, Number 88 (Thursday, May 7, 1998)]
[Proposed Rules]
[Pages 25179-25180]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-12062]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 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. 88/ Thursday, May 7, 1998 / Proposed 
Rules  

[[Page 25179]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-21-AD]
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 certain Pratt & Whitney (PW) JT9D 
series turbofan engines. This proposal would require a one-time acid 
etch inspection of the turbine exhaust case (TEC) wall between and on 
either side of the ``R'' and ``S'' rails in the engine mount lug area 
(top quadrant of the case) for the presence of weld material, and if 
weld material is detected, removal from service and replacement with 
serviceable parts. This proposal is prompted by reports of weld rework 
performed in the outer case wall of the TEC, in the mount lug fillet 
area, during original production to address local under minimum wall 
thickness conditions which have left the TEC's structural capability 
compromised. The actions specified by the proposed AD are intended to 
prevent TEC structural failure under abnormal operating conditions, 
which could result in reduced main mount load capability, which could 
result in an engine separating from the wing and subsequent loss of 
control of the aircraft.

DATES: Comments must be received by July 6, 1998.

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-21-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: Tara Goodman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7130, 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-21-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-21-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received reports of 
weld rework performed in the outer case wall of the turbine exhaust 
case (TEC), in the mount lug fillet area, during original production to 
address local under minimum wall thickness conditions which have left 
the TEC's structural capability compromised on certain Pratt & Whitney 
(PW) Models JT9D-7, -7A, -7H, -7AH, -7F, -7J, -20, -20J, -7Q, -7Q3, -
59A, -70A, and -7R4D turbofan engines. The investigation identified 24 
TECs as having a weld rework performed to the case wall during original 
production to address local under minimum wall thickness conditions. 
Rework procedure authorization did not limit welding locations on the 
circumference of the case wall and permitted welding either on the 
inner diameter or the outer diameter of the part. A weld rework may or 
may not have been performed in the mount area on the 24 turbine exhaust 
cases, only 11 of which have been identified by serial number (S/N). 
The FAA has determined that possibly other TECs that had the welding 
rework procedure have a quality review order (QRO) number marked on it 
next to the part. At this time one of the 24 turbine exhaust cases (S/N 
JC4708) has been located and removed from service. Engine manual repair 
allowances were never intended to authorize welding in the vicinity of 
the engine mount lugs due to structural concerns for engine mount 
integrity under abnormal engine operating conditions. The FAA believes 
that the majority of these parts have been installed in engines; 
however, there may be some that are presently not installed. The 
manufacturer regards weld repairs in the turbine exhaust case wall on 
either side of the ``R'' and ``S'' rails in the engine mount lug area 
unacceptable and does not authorize or accept case wall weld repairs in 
the

[[Page 25180]]

engine mount lug area. This condition, if not corrected, could result 
in TEC structural failure under abnormal operating conditions, which 
could result in reduced main mount load capability, which could result 
in an engine separating from the wing and subsequent loss of control of 
the aircraft.
    The FAA has reviewed and approved the technical contents PW Alert 
Service Bulletin (ASB) No. JT9D-A6322, Revision 1, dated March 19, 
1998, and ASB No. JT9D-7R4-A72-546, Revision 1, dated March 19, 1998, 
that describe procedures for acid etch inspections of the TEC wall 
between and on either side of the ``R'' and ``S'' rails in the engine 
mount lug area (top quadrant of the case) for the presence of weld 
material, and if that material is detected, removal from service and 
replacement with serviceable parts.
    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, at the next removal of the TEC from the low 
pressure turbine case ``P'' flange for maintenance after the effective 
date of this AD, a one-time acid etch inspection of TEC wall between 
and on either side of the ``R'' and ``S'' rails in the engine mount lug 
area (top quadrant of the case) for the presence of weld material, and 
if that material is detected, removal from service and replacement with 
serviceable parts. The actions would be required to be accomplished in 
accordance with the ASBs described previously.
    There are approximately 2,720 engines of the affected design in the 
worldwide fleet. The FAA estimates that 1,125 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 1.4 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 $94,500.
    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. 98-ANE-21-AD.

    Applicability: Pratt & Whitney (PW) Models JT9D-7, -7A, -7H, -
7AH, -7F, -7J, -20, -20J, -7Q, -7Q3, -59A, -70A, and -7R4D turbofan 
engines. These engines are installed on but not limited to Boeing 
747 and 767 series, McDonnell Douglas DC-10 series, and Airbus 
Industrie A300 and A310 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 (b) 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 turbine exhaust case (TEC) structural failure under 
abnormal operating conditions, which could result in reduced main 
mount load capability, which could result in an engine separating 
from the wing and subsequent loss of control of the aircraft, 
accomplish the following:
    (a) At the next removal of the TEC from the low pressure turbine 
case ``P'' flange for maintenance after the effective date of this 
AD, accomplish the following in accordance with PW Alert Service 
Bulletin (ASB) No. JT9D-A6322, Revision 1, dated March 19, 1998, or 
ASB No. JT9D-7R4-A72-546, Revision 1, dated March 19, 1998, as 
applicable:
    (1) Perform a one-time acid etch inspection of TEC wall between 
and on either side of the ``R'' and ``S'' rails in the engine mount 
lug area (top quadrant of the case) for the presence of weld 
material.
    (2) If weld material is found, remove from service the TEC and 
replace with a serviceable part.
    (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. 
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.

    (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 inspection requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on April 29, 1998.
Thomas A. Boudreau,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 98-12062 Filed 5-6-98; 8:45 am]
BILLING CODE 4910-13-P