[Federal Register Volume 63, Number 168 (Monday, August 31, 1998)]
[Proposed Rules]
[Pages 46200-46202]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-23360]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-28-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 fluorescent 
penetrant inspection (FPI) of the rear skirt of the diffuser case for 
cracks, and, if necessary, blending down to minimum wall thickness to 
remove cracks and subsequent FPI to determine if cracks have been 
removed, polishing, and shotpeening. If the cracks are shown by 
subsequent FPI not to have been removed, this proposed AD would require 
removing the diffuser case from service and replace with a serviceable 
part. This proposal is prompted by a report of a diffuser case rupture 
during takeoff roll that resulted in damage to the aircraft. The 
actions specified by the proposed AD are intended to prevent diffuser 
case rupture due to cracks, which can result in an uncontained engine 
failure and damage to the aircraft.

DATES: Comments must be received by October 30, 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-28-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-28-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-28-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) received a report of a 
diffuser case rupture on a Pratt & Whitney (PW)

[[Page 46201]]

Model JT9D-7Q turbofan engine. The diffuser case rupture occurred when 
the engine was at takeoff power at the beginning of takeoff roll. As a 
result of the diffuser case rupture both engine side cowl doors, a 
precooler, and other hardware were ejected from the engine. The 
escaping gas and engine debris blew out the engine pylon access panels, 
and created holes, cracks, and other damage to the wing's leading edge, 
aileron, and flaps. The investigation revealed the diffuser case 
fracture was due to a crack that most likely developed in a toolmark in 
the case outer pressure wall in the rear skirt area, adjacent to the 
dog bone-shaped embossment at the 11 o'clock circumferential location. 
Extensive investigation could not determine the source of the 
excitation that caused the crack to progress in a high cycle fatigue 
mode. This condition, if not corrected, could result in diffuser case 
rupture due to cracks, which can result in an uncontained engine 
failure and damage to the aircraft.
    The FAA has reviewed and approved the technical contents of PW 
Service Bulletin (SB) No. JT9D-6329, dated May 20, 1998, that describes 
inspection and rework procedures for cracks.
    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 a fluorescent penetrant inspection (FPI) of 
the rear skirt of the diffuser case for cracks, and, if necessary, 
blending down to minimum wall thickness, to remove cracks, subsequent 
FPI to determine if cracks have been removed, and polishing and 
shotpeening. If the cracks are shown by subsequent FPI not to have been 
removed, this proposed AD would require removing the diffuser case from 
service for possible weld repair or replacement with serviceable parts. 
The actions would be required to be accomplished in accordance with the 
SB described previously.
    There are approximately 566 engines of the affected design in the 
worldwide fleet. The FAA estimates that 157 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 68 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 $640,560.
    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. 98-ANE-28-AD.

    Applicability: Pratt & Whitney (PW) Model JT9D-7Q, -7Q3, -59A, 
and -70A turbofan engines, with diffuser cases, part numbers (P/Ns) 
772173, 772173-001, 772173-002, 782222, 782222-001, and 782222-002, 
installed. These engines are installed on but not limited to Boeing 
747 series, McDonnell Douglas DC-10 series, and Airbus A300 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 (c) 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 diffuser case rupture due to cracks, which can result 
in an uncontained engine failure and damage to the aircraft, 
accomplish the following:
    (a) At the next piece-part exposure of the diffuser case after 
the effective date of this AD, accomplish the following in 
accordance with PW Service Bulletin (SB) No. JT9D-6329, dated May 
20, 1998:
    (1) Perform a fluorescent penetrant inspection (FPI) in 
accordance with the procedures and criteria stated in the SB of the 
areas around the dog bone-shaped bosses in the diffuser case rear 
skirt identified in the SB for cracks.
    (2) If no indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, no further action is 
required.
    (3) If indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, remove the diffuser case 
from service, replace with a serviceable part, or blend the cracks 
as needed down to the minimum wall thickness to remove cracks in 
accordance with the procedures and criteria stated in the SB.
    (4) After blending down in accordance with the procedures and 
criteria stated in the SB, perform a subsequent etch and FPI for 
cracks, as follows:
    (i) If no indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, polish and shot-peen the 
area around each dog bone boss in accordance with the procedures and 
criteria stated in the SB.
    (ii) If indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, remove the diffuser case 
from service and replace with a serviceable part.
    (b) For the purpose of this AD, piece-part exposure is defined 
as when the part is considered completely disassembled when done in 
accordance with the disassembly instructions in the engine 
manufacturer's maintenance manual, to give access to the dog bone-
shaped bosses in the diffuser case rear skirt.
    (c) 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.

    (d) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199

[[Page 46202]]

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 August 25, 1998.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 98-23360 Filed 8-28-98; 8:45 am]
BILLING CODE 4910-13-U