[Federal Register Volume 64, Number 107 (Friday, June 4, 1999)]
[Proposed Rules]
[Pages 29965-29966]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14128]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 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.
 
 ========================================================================
 

  Federal Register / Vol. 64, No. 107 / Friday, June 4, 1999 / Proposed 
Rules  

[[Page 29965]]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-06-AD]
RIN 2120-AA64


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 JT9D-7R4 series 
turbofan engines. This proposal would require initial and repetitive 
inspections of certain High Pressure Turbine (HPT) stage 1 and stage 2 
disks utilizing an improved ultrasonic method when the disks are 
exposed during a shop visit, and if a subsurface anomaly is found, 
removal from service and replacement with a serviceable part. This 
proposal is prompted by the results of a stage 1 HPT disk fracture 
investigation which has identified a population of HPT stage 1 and 2 
disks that may have subsurface anomalies formed during the forging 
process. The actions specified by the proposed AD are intended to 
prevent HPT disk fracture, which could result in an uncontained engine 
failure, damage to the aircraft, and an in-flight engine shutdown.

DATES: Comments must be received by July 6, 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-06-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) 565-6600, 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: Peter White, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7128, 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-06-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-06-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) received a report of an 
uncontained high pressure turbine (HPT) disk failure on an 
International Aero Engines (IAE) V2500-A1 series turbofan engine. The 
investigation into the cause of that failure revealed that certain HPT 
stage 1 and stage 2 disks were manufactured using a process that 
resulted in a subsurface defect in the disk material. The subsurface 
defect, called a ``clean linear'' anomaly, was formed during a specific 
forging process also used for HPT stage 1 and stage 2 disks for the 
JT9D-7R4 series engines. The anomaly may not have been detected during 
ultrasonic inspection during manufacture due to its orientation and 
shape. The disk failure occurred as a result of a crack that initiated 
at the anomaly site. An improved ultrasonic inspection has been 
developed which is more capable of detecting anomalies, or cracks that 
originate from the sites of anomalies, prior to disk failure. V2500-A1, 
PW2000 and JT9D-7R4 1st and 2nd stage HPT disks manufactured using this 
same material and forging process are affected. There are approximately 
131 JT9D-7R4 HPT stage 1 and stage 2 disks that were manufactured using 
this material and forging process, and those disks have been identified 
by serial number in Pratt & Whitney (PW) Service Bulletin JT9D-7R4-72-
553, Revision 1, dated February 17, 1999. This condition, if not 
corrected, could result in an HPT disk fracture, which could result in 
an uncontained engine failure, damage to the aircraft, and an in-flight 
engine shutdown.
    The FAA has reviewed and approved the technical contents of PW 
Service Bulletin (SB) JT9D-7R4-72-553, Revision 1, dated February 17, 
1999, that describes inspection procedures and criteria for certain 
stage 1 and 2 HPT disks.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same

[[Page 29966]]

type design, the proposed AD would require initial and repetitive 
inspections of certain stage 1 and stage 2 HPT disks using an improved 
ultrasonic method whenever the disk is exposed during a shop visit. If 
a subsurface anomaly is found, the disk must be removed from service 
and replaced with a serviceable part. The actions would be required to 
be accomplished in accordance with the SB described previously.
    There are approximately 131 affected disks installed in engines in 
the worldwide fleet. The FAA estimates that 25 engines on aircraft of 
U.S. registry would be affected by this proposed AD. The FAA estimates 
that the shipping cost per disk to the facility which will inspect the 
disk and its return will be approximately $250 per disk, that no 
engines will require an unplanned HPT module disassembly/assembly, that 
the inspection would take approximately 8 work hours per disk to 
accomplish the proposed actions, and that the average labor rate is $60 
per work hour. Some disks will require multiple inspections during 
their service life. Based on these figures, the total cost impact of 
the proposed AD on U.S. operators is estimated to be $88,000. The 
manufacturer has advised the FAA that the all costs relative to the 
inspection will be reimbursed to the operator.
    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.


39.13  [Amended]

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

99-XX-XX  Pratt & Whitney: Docket No. 99-NE-06-AD.

    Applicability: Pratt & Whitney JT9D-7R4 Series Turbofan Engines, 
installed on but not limited to Boeing 747, Airbus A300 and Airbus 
A310 series airplanes.

    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 high pressure turbine (HPT) disk fracture, which 
could result in an uncontained engine failure and damage to the 
aircraft, accomplish the following:
    (a) For engines with a HPT stage 1 or Stage 2 disk installed 
that has a serial number listed in the Accomplishment Instructions 
section of PW SB JT9D-7R4-72-553, Revision 1, dated February 17, 
1999, perform initial and repetitive ultrasonic inspections in 
accordance with the Accomplishment Instructions section of PW SB 
JT9D-7R4-72-553, Revision 1, dated February 17, 1999, as follows:
    (1) Perform an initial ultrasonic inspection at the next HPT 
disk piece part accessibility after the effective date of this AD.
    (2) Thereafter, perform an ultrasonic inspection at each HPT 
disk piece part accessibility after the initial inspection performed 
in accordance with paragraph (a)(1) of this AD.
    (3) For the purpose of this AD, piece part accessibility is 
defined as removal of the blades from the disk.
    (b) Remove from service those HPT disks found with a crack 
indicating a subsurface anomaly and replace with a serviceable part.
    (c) For engines that do not have a HPT stage 1 or Stage 2 disk 
installed that has a serial number listed in the Accomplishment 
Instructions section of PW SB JT9D-7R4-72-553, Revision 1, dated 
February 17, 1999, no inspections are required.
    (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 
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 27, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-14128 Filed 6-3-99; 8:45 am]
BILLING CODE 4910-13-P