[Federal Register Volume 59, Number 242 (Monday, December 19, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-31061]
[[Page Unknown]]
[Federal Register: December 19, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 81-ANE-03]
Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking; reopening of
comment period.
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SUMMARY: This notice revises an earlier proposed airworthiness
directive (AD), applicable to Pratt & Whitney JT8D series turbofan
engines, that would have amended an existing AD by eliminating an
optional on-wing ultrasonic inspection of the 10th stage high pressure
compressor (HPC) disk, and by including an engine model inadvertently
omitted. That proposal was prompted by a report of an uncontained
failure of a 10th stage HPC disk that was previously inspected using
the on-wing ultrasonic inspection method. This action revises the
proposed rule by removing the reference to the inadvertently omitted
engine model, as the FAA has remedied this discrepancy in an earlier
correction to the AD, and changing the proposed action from amending AD
81-08-02 R2 to superseding that AD. The actions specified by this
proposed AD are intended to prevent uncontained fractures of 9th
through 12th stage HPC disks and engine failure.
DATES: Comments must be received by February 17, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration, New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 81-ANE-03, 12 New England
Executive Park, Burlington, MA 01803-5299. 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, Technical Publications Department, M/S
132-30, 400 Main Street, East Hartford, Connecticut, 06108. This
information may be examined at the FAA, New England Region, Office of
Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA.
FOR FURTHER INFORMATION CONTACT: Mark A. Rumizen, Aerospace Engineer
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7137; 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 81-ANE-03.'' 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. 81-ANE-03, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
On February 7, 1984, the Federal Aviation Administration (FAA)
issued airworthiness directive (AD) 81-08-02 R2, Amendment No. 39-4817
(49 FR 7361; February 29, 1984), to require initial and repetitive
inspections of 9th through 12th stage high pressure compressor (HPC)
disks at the tierod holes in Pratt & Whitney (PW) JT8D series turbofan
engines. That action was prompted by cracks in the tierod holes in HPC
disks that resulted in engine failures. That condition, if not
corrected, can result in uncontained fractures of 9th through 12th
stage HPC disks and engine failure.
On August 30, 1984, the FAA issued a correction to AD 81-08-02 R2,
Amendment 39-4817 (49 FR 35618; September 11, 1984), to include an
engine model that had been inadvertently omitted from the AD.
Since issuance of AD 81-08-02 R2, the FAA received a report of an
uncontained fracture of a 10th stage HPC disk. This disk had been
subjected to three previous on-wing ultrasonic inspections prior to
fracture. This method has since been determined as inadequate for
detecting tierod hole cracking.
On May 8, 1989, the FAA issued an NPRM that was published in the
Federal Register (54 FR 22306; May 23, 1989), that would have amended
the existing AD by eliminating the optional on-wing ultrasonic
inspection of the 10th stage HPC disk, and by including an engine model
inadvertently omitted.
Since the issuance of that NPRM, the FAA has determined that the
reference to the inadvertently omitted engine model was unnecessary, as
the FAA had remedied this discrepancy in the August 30, 1984,
correction. Also, the FAA now utilizes a revised format that supersedes
existing AD's by publishing a complete document rather than only
amending applicable paragraphs of the compliance section. This
document, therefore, reprints the corrected AD compliance section text
in its entirety for clarity.
Since the FAA has changed the format of the proposed rule, the FAA
has determined that it is desirable to reopen the comment period to
provide additional opportunity for public comment.
There are approximately 200 engines which would be affected by this
AD, and the FAA has determined that eliminating the optional on-wing
ultrasonic inspection would have negligible economic impact, since most
operators use uninstalled tenth stage disk inspections.
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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Pratt & Whitney: Docket No. 81-ANE-03.
Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -7, -7A, -7B, -
9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines
installed on but not limited to Boeing 727 series and 737 series,
and McDonnell Douglas DC-9 series aircraft.
Compliance: Required as indicated, unless accomplished
previously in accordance with PW Alert Service Bulletin (ASB) No.
4723, Revision 9, dated July 13, 1983; Revision 10, dated September
15, 1986; or Revision 11, dated October 30, 1987. All inspections
subsequent to the effective date of this airworthiness directive
(AD) must be accomplished in accordance with the methods and
intervals identified in PW ASB No. 4723, Revision 12, dated March 8,
1990, except as is specified in paragraph (d) of this AD.
To prevent uncontained fractures of 9th through 12th stage high
pressure compressor (HPC) disks and engine failure, accomplish the
following:
(a) Initially inspect 9th through 12th stage HPC disks at the
tierod holes in accordance with PW ASB No. 4273, Revision 12, dated
March 8, 1990.
(b) Thereafter, inspect 9th through 12th stage HPC disks at the
tierod holes in accordance with Tables I through V and Table VIII of
PW ASB No. 4723, Revision 12, dated March 8, 1990. Disks initially
inspected prior to the first inspection limit must be reinspected
before reaching the specified reinspection interval, or before
reaching the first inspection limit, whichever is later. In no case
shall the established life limits of the disks be exceeded.
(c) Remove cracked disks from service prior to further flight,
and replace with a serviceable part. Disks may be returned to
service if repaired in accordance with Paragraph 7 of PW ASB No.
4723, Revision 12, dated March 8, 1990.
(d) For 10th stage HPC disks that were last inspected in
accordance with the on-wing ultrasonic inspection procedure
specified in AD 81-08-02 R2 prior to the effective date of this AD,
inspect as follows:
(1) Perform a magnetic particle inspection or eddy current
inspection in accordance with the procedure defined in Paragraph 6
and Appendix B of PW ASB No. 4723, Revision 12, dated March 8, 1990,
no later than 750 cycles in service (CIS) since the last on-wing
inspection.
(2) Accomplish all subsequent inspections in accordance with the
methods and intervals specified in PW ASB No. 4723, Revision 12,
dated March 8, 1990.
(e) 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.
(f) Special flight permits may be issued in accordance with
Secs. 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 December 9, 1994.
James C. Jones,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 94-31061 Filed 12-16-94; 8:45 am]
BILLING CODE 4910-13-P
