[Federal Register Volume 61, Number 88 (Monday, May 6, 1996)]
[Proposed Rules]
[Pages 20192-20194]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-11171]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-ANE-69]


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 initial and repetitive 
eddy current inspections (ECI) of 14th and 15th stage high pressure 
compressor (HPC) disks for cracks, and removal of cracked disks and 
replacement with serviceable parts. This proposal is prompted by a 
report of a 14th stage HPC disk bore found cracked during a shop 
inspection. The actions specified by the proposed AD are intended to 
prevent 14th and 15th stage HPC disk rupture, which could result in an 
uncontained engine failure and damage to the aircraft.

DATES: Comments must be received by July 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-69, 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 Engineers, 
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 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-69.'' 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-69, 12 New

[[Page 20193]]

England Executive Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) received a report of 
finding during a shop inspection a cracked 14th stage high pressure 
compressor (HPC) disk installed on a Pratt & Whitney (PW) Model JT9D-
7R4D turbofan engine. The investigation revealed that the 14th and 15th 
stage disk bores can crack due to a fatigue strength debit associated 
with large unrecrystallized grain microstructure. This material 
phenomenon results in an associated debit to the 14th and 15th stage 
HPC disk low cycle fatigue life. This condition, if not corrected, 
could result in 14th and 15th stage HPC disk rupture, which could 
result in an uncontained engine failure and damage to the aircraft.
    The FAA has reviewed and approved the technical contents of Non-
Destructive Inspection Procedure No. 858 (NDIP-858), dated November 7, 
1995, attached to PW Alert Service Bulletin (ASB) No. JT9D-7R4-A72-524, 
dated December 13, 1995, and ASB No. A6232, Revision 1, dated January 
11, 1996. That NDIP describes procedures for eddy current inspections 
(ECI) of 14th and 15th stage HPC disks 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 initial and repetitive ECI of 14th and 15th 
stage HPC disks for cracks, and removal of cracked disks and 
replacement with serviceable parts. The actions would be required to be 
accomplished in accordance with the ASB's described previously.
    There are approximately 1,100 engines of the affected design in the 
worldwide fleet. The FAA estimates that 170 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD. The 
initial and repetitive ECI would take place during regularly scheduled 
maintenance, and would therefore require no additional costs to perform 
the actions required by this proposed AD.
    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 USC 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-69.

    Applicability: Pratt & Whitney (PW) Model JT9D-7R4 series, -59A, 
-70A, -7Q, and -7Q3 turbofan engines, with the following 14th and 
15th stage high pressure compressor (HPC) disk installed: part 
numbers (P/N's) 5000814-01, 790014, 789914, 790114, 5000815-01, 
5000815-021, 704315, 704315-001, 786215, 786215-001, 704314, 789814, 
and 790214. These engines are 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 use the 
authority provided in paragraph (f) 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 14th and 15th stage HPC disk rupture, which could 
result in an uncontained engine failure and damage to the aircraft, 
accomplish the following:
    (a) Inspect 14th stage HPC disks, P/N 5000814-01, in accordance 
with Non-Destructive Inspection Procedure No. 858 (NDIP-858), dated 
November 7, 1995, attached to PW Alert Service Bulletin (ASB) No. 
JT9D-7R4-A72-524, dated December 13, 1995, as follows:
    (1) Perform an initial ECI for cracks as follows:
    (i) For disks with 7,000 or more cycles since new (CSN), and 
3,000 or more cycles in service (CIS) since last shop visit, on the 
effective date of this AD, inspect within the next 1,000 CIS after 
the effective date of this AD, or at the next shop visit, whichever 
occurs first.
    (ii) For disks with 7,000 or more CSN, and less than 3,000 CIS 
since last shop visit, on the effective date of this AD, inspect 
within 4,000 CIS since the last shop visit, or at the next shop 
visit, whichever occurs first.
    (iii) For disks with less than 7,000 CSN on the effective date 
of this AD, inspect at the next shop visit after the effective date 
of this AD, but before exceeding 4,000 CIS since last shop visit, or 
8,000 CSN, whichever occurs later.
    (iv) For uninstalled disks on or after the effective date of 
this AD, inspect prior to installation.
    (2) Thereafter, perform ECI for cracks at intervals not to 
exceed 4,000 CIS since last ECI.
    (3) Prior to further flight, remove cracked disks and replace 
with serviceable parts.
    (b) Inspect 14th stage HPC disks, P/N's 790014, 789914, 790114, 
and 15th stage HPC disks, P/N's 5000815-01, 5000815-021, 704315, 
704315-001, 786215, and 786215-001, in accordance with NDIP-858, 
dated November 7, 1995, attached to PW ASB No. JT9D-7R4-A72-524, 
dated December 13, 1995, or PW ASB No. A6232, Revision 1, dated 
January 11, 1996, as applicable, as follows:
    (1) Perform an initial ECI for cracks as follows:
    (i) For disks with 6,500 or more CSN, and 3,000 or more CIS 
since last shop visit, on the effective date of this AD, inspect 
within the next 1,000 CIS after the effective date of this AD, or at 
the next shop visit, whichever occurs first.
    (ii) For disks with 6,500 or more CSN, and less than 3,000 CIS 
since last shop visit, on the effective date of this AD, inspect 
within 4,000 CIS since the last shop visit, or at the next shop 
visit, whichever occurs first.
    (iii) For disks with less than 6,500 CSN on the effective date 
of this AD, inspect at the next shop visit after the effective date 
of this AD, but before exceeding 4,000 CIS since last shop visit, or 
7,500 CSN, whichever occurs later.

[[Page 20194]]

    (iv) For uninstalled disks on or after the effective date of 
this AD, inspect prior to installation.
    (2) Thereafter, perform ECI for cracks at intervals not to 
exceed 4,000 CIS since last ECI.
    (3) Prior to further flight, remove cracked disks and replace 
with serviceable parts.
    (c) Inspect 14th stage HPC disks, P/N's 704314, 789814, and 
790214, in accordance with NDIP-858, dated November 7, 1995, 
attached to PW ASB No. A6232, Revision 1, dated January 11, 1996, as 
follows:
    (1) Perform an initial ECI for cracks as follows:
    (i) For disks with 2,000 or more CSN, and 2,000 or more CIS 
since last shop visit, on the effective date of this AD, inspect 
within the next 1,000 CIS after the effective date of this AD, or at 
the next shop visit, whichever occurs first.
    (ii) For disks with 2,000 or more CSN, and less than 2,000 CIS 
since last shop visit, on the effective date of this AD, inspect 
within 3,000 CIS since the last shop visit, or at the next shop 
visit, whichever occurs first.
    (iii) For disks with 2,000 or more CSN, and no previous shop 
visits, inspect within 3,000 CIS after the effective date of this 
AD, or at the next shop visit, whichever occurs first.
    (iv) For disks with less than 2,000 CSN on the effective date of 
this AD, inspect at the next shop visit after the effective date of 
this AD, but before exceeding 3,000 CSN.
    (v) For uninstalled disks on or after the effective date of this 
AD, inspect prior to installation.
    (2) Thereafter, perform ECI for cracks at intervals not to 
exceed 3,000 CIS since last ECI.
    (3) Prior to further flight, remove cracked disks and replace 
with serviceable parts.
    (d) Within 30 days of inspection, report inspection results on 
the form labeled ``14th and 15th Stage HPC Disk Inspection Report,'' 
attached to PW NDIP-858, dated November 7, 1995, attached to PW ASB 
No. A6232, Revision 1, dated January 11, 1996, and PW ASB No. JT9D-
7R4-A72-524, dated December 13, 1995, to the office and fax number 
listed on that form. Reporting requirements have been approved by 
the Office of Management and Budget and assigned OMB control number 
2120-0056.
    (e) For the purpose of this AD, a shop visit is defined as 
separation of the ``N'' flange.
    (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. 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.

    (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 April 18, 1996.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 96-11171 Filed 5-3-96; 8:45 am]
BILLING CODE 4910-13-U