[Federal Register Volume 66, Number 39 (Tuesday, February 27, 2001)]
[Proposed Rules]
[Pages 12440-12442]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-4764]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-35-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D-7R4 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 (PW) JT9D-7R4 
series turbofan engines. This proposal would require initial and 
repetitive fluorescent penetrant inspection (FPI) of the high pressure 
turbine (HPT) 1st stage disk aft lugs, and if the aft lug(s) are 
cracked, replacement of the HPT 1st stage disk and HPT 1st stage 
airseals. Also, for certain configuration HPT disk assemblies, this 
proposal would require replacement of the HPT 1st stage airseals with 
newly designed airseals at the next accessibility. This proposal is 
prompted by reports of cracks in HPT 1st stage disk firtrees and 
failure of firtree lugs. The actions specified by the proposed AD are 
intended to prevent 1st stage HPT disk firtree fracture, which could 
result in an uncontained engine failure, and damage to the airplane.

[[Page 12441]]


DATES: Comments must be received by April 30, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 2000-NE-35-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: [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 action 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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NE-35-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRM's

    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. 2000-NE-35-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The FAA is aware of nine occurrences of HPT 1st stage disk firtree 
cracking, and one in-service event involving the failure of two 
adjacent firtree lugs installed on Pratt & Whitney JT9D-7R4 series 
turbofan engines, which resulted in the liberation of three HPT blades. 
Investigation and analysis have traced the cause of this disk lug 
cracking to the pre-bowing of the HPT aft 1st stage airseals. The pre-
bow can place excessive stresses on the HPT 1st stage disk lugs that 
retain the airseals, and result in fatigue cracking of the lugs. The 
manufacturer has redesigned these HPT 1st stage airseals with revised 
pre-bow and reduced weight, to lower the stresses on the HPT 1st stage 
disk lugs. Onset of this fatigue cracking is dependent upon the HPT 
disk material; powder disks (P/N 787521) experience cracking much 
sooner than Waspalloy disks (P/N 797621). Therefore, the FAA has 
determined that the HPT 1st stage airseals on disk assemblies with 
powder disks (P/N 787521) must be replaced at the next hot section shop 
visit. PW and the FAA have developed a fleet management plan requiring 
initial and repetitive fluorescent penetrant inspection of the HPT 1st 
stage disk aft lug fillet radius for cracking, and replacement of the 
HPT 1st stage airseals at next HPT shop visit for engines configured 
with powder HPT 1st stage disk assembly (P/N 787521). The actions 
specified by the proposed AD are intended to prevent 1st stage HPT disk 
firtree fracture, which could result in an uncontained engine failure, 
and damage to the airplane.

Service Information

    The FAA has reviewed the technical contents of Pratt & Whitney 
Service Bulletin (SB's): JT9D-7R4-72-566, dated May 26, 2000; JT9D-7R4-
72-567, dated May 26, 2000 and JT9D-7R4-72-568, dated May 26, 2000, 
that describe procedures for incorporation of new HPT 1st stage 
airseals, fluorescent penetrant inspection (FPI) of HPT disk rear lugs, 
and incorporation of new HPT disks and redesigned HPT 1st stage 
airseals. These documents were developed by PW and are generally 
consistent with the fleet management plan defined in this AD, and can 
be utilized for reference.

Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, this 
proposed AD would prevent HPT 1st stage disk firtree fracture by 
requiring initial and repetitive FPI of the 1st stage disk aft lug, and 
if cracked, replacement of the HPT 1st stage disk and HPT 1st stage 
airseals. In addition, the proposed AD would require replacement of HPT 
1st stage airseals with redesigned HPT 1st stage airseals for certain 
HPT disk configurations.

Cost Analysis

    There are approximately 324 engines of the affected design in the 
worldwide fleet. The FAA estimates that 47 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD. 
Although forced engine removals are not anticipated the first year as a 
result of this proposed action, a maximum of two removals will be 
assumed. It would take approximately 86 work hours per engine to 
accomplish the proposed actions, and the average labor rate is $60 per 
work hour. Based on these figures, the total labor cost impact of the 
proposed AD on U.S. operators the first year is estimated to be 
$24,520. Hardware costs the first year for HPT 1st stage airseals 
replaced by SB JT9D-7R4-72-566 are estimated to be $128,000, based on 
replacement costs of $147,110 per disk and $45,143 for sideplates, 
discounted for average \1/3\ life lost at removal. Total combined labor 
and hardware costs for the first year are therefore estimated to be 
$140,000
    The following year, it is estimated that inspections will result in 
a maximum of three engines requiring forced replacement of the HPT 1st 
stage disk and HPT 1st stage airseals due to cracking. Due to these 
forced removals, approximately \1/3\ of the disk life will be lost. The 
total combined hardware and labor cost is estimated to be approximately 
$210,000. The total cost impact of this proposal on U.S. operators in 
the first two years is expected to be approximately $350,000.

Regulatory Impact

    This proposal does not have federalism implications, as defined in 
Executive Order 13132, because it would not have a substantial direct 
effect on the States, on the relationship

[[Page 12442]]

between the national government and the States, or on the distribution 
of power and responsibilities among the various levels of government. 
Accordingly, the FAA has not consulted with state authorities prior to 
publication of this proposal.
    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:


Pratt & Whitney: Docket No. 2000-NE-35-AD.

    Applicability: This airworthiness directive (AD) is applicable 
to Pratt & Whitney (PW) JT9D-7R4E1, JT9D-7R4E4, JT9D-7R4G2, JT9D-
7R4H1 series turbofan engines which incorporate HPT 1st stage disk 
assembly P/N 787521 or HPT 1st stage disk assembly P/N 797621. These 
engines are installed on but not limited to Boeing 747 and 767 
series and Airbus A300 and 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 (e) 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: Compliance with this AD is required as indicated, 
unless accomplished previously.
    To prevent HPT disk firtree fracture, which could result in an 
uncontained engine failure, and damage to the airplane, accomplish 
the following:

HPT 1st Stage Airseal Replacement

    (a) For engines that incorporate HPT 1st stage disk assembly P/N 
787521, replace HPT 1st stage airseals with P/N 820121 at the next 
hot section shop visit. Information on replacement of the HPT 1st 
stage airseal is contained in PW service bulletin (SB) JT9D-7R4-72-
566, dated May 26, 2000.

Fluorescent Penetrant Inspection (FPI)

    (b) Inspect the HPT 1st stage disk aft lug fillet radius for 
cracks in accordance with Paragraph 4 of the Accomplishment 
Instructions of PW SB JT9D-7R4-72-567, dated May 26, 2000, and Table 
1 of this AD as follows:

                                                     Table 1
----------------------------------------------------------------------------------------------------------------
   HPT 1st stage disk assembly      HPT 1st stage disk     Initial inspection    Repetitive inspection interval
----------------------------------------------------------------------------------------------------------------
(1) P/N 787521..................  P/N 825701 or P/N      Before the latest of   Within 4,000 CSLI.
                                   827201.                4,000 CSN or 4,000
                                                          cycles since last
                                                          HPT disk lug
                                                          fluorescent
                                                          penetrant inspection
                                                          (CSLI), or 500 CIS
                                                          after the effective
                                                          date of this AD.
----------------------------------------------------------------------------------------------------------------
(2) P/N 797621..................  (i) P/N 829401 with    Before the latest of   Within 4,000 CSLI.
                                   air seals P/N's        5,000 CSN or CSLI,
                                   797355, 796760,        or 500 CIS after the
                                   803979, 797355-001     effective date of
                                   installed.             this AD.
                                  (ii) 829401 with air   Before the latest of   Within 6,000 CSLI.
                                   seals P/N 820121       5,000 CSN or 5,000
                                   installed.             CSLI, or 500 CIS
                                                          after the effective
                                                          date of this AD.
----------------------------------------------------------------------------------------------------------------

    (c) Replace any disks that have crack indications. Information 
on replacement of the disk is contained in PW SB JT9D-7R4-72-568, 
dated May 26, 2000.

Terminating Action

    (d) Installation of HPT disk P/N 820321 with redesigned HPT 1st 
stage airseal P/N 820121 is considered terminating action to the 
initial and repetitive inspection requirements of paragraph (b) this 
AD. Information on installation of the HPT disk is contained in PW 
SB JT9D-7R4-72-568, dated May 26, 2000.

Definition

    (e) For the purpose of this AD, a hot section shop visit is 
defined as any time the HPT rotor is disassembled.

Alternative Methods of Compliance

    (f) 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 (ECO). 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

Special Flight Permits

    (g) 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 February 19, 2001.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 01-4764 Filed 2-26-01; 8:45 am]
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