[Federal Register Volume 60, Number 210 (Tuesday, October 31, 1995)]
[Proposed Rules]
[Pages 55337-55339]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-26942]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-ANE-45]
Airworthiness Directives; Pratt & Whitney JT3D 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) JT3D series
turbofan engines. This proposal would require inspection of steel high
pressure compressor (HPC) disks for corrosion, recoating or replating
those disks, or replacing those disks as necessary. This proposal is
prompted by reports of a failure of a PW JT8D steel HPC disk, which is
similar in design to the PW JT3D steel HPC disks. The actions specified
by the proposed AD are
[[Page 55338]]
intended to prevent steel HPC disk failure due to corrosion, which
could result in an uncontained engine failure and damage to the
aircraft.
DATES: Comments must be received by January 2, 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-45, 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, 400 Main St., East Hartford, CT 06108.
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: Barbara Caufield, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7146, 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-45.'' 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-45, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received a report of
an uncontained failure of a Pratt & Whitney (PW) JT8D steel high
pressure compressor (HPC) disk due to corrosion. Investigation revealed
that fatigue can originate from a corrosion pit and progress to disk
failure. Corrosion is more apt to occur if the steel HPC disk is not
recoated or replated during its life span and retains the original
production protective coating or plating. This proposed rule,
applicable to PW JT3D series turbofan engines, is prompted by the
similarity between the PW JT8D and JT3D disk design. This condition, if
not corrected, could result in steel HPC disk failure due to corrosion,
which could result in an uncontained engine failure and damage to the
aircraft.
The FAA has reviewed and approved the technical contents of PW
Alert Service Bulletin (ASB) No. A6208, Revision 2, dated July 7, 1995,
that describes procedures for inspection of steel HPC disks, stages 10-
15, for corrosion, recoating or replating those disks, or replacing
those disks as necessary.
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 inspection of steel HPC disks, stages 10-15,
for corrosion, recoating or replating those disks, or replacing those
disks as necessary. Disks have different initial inspection threshholds
and repetitive inspection intervals based on the type of coating or
plating and the calendar time since new or since last recoating or
replating. Pratt & Whitney conducted analytical studies of operator
experience. Over 150 PW JT3D and JT8D HPC disks were analyzed for
corrosion pit depth, and were correlated with disk history, utilization
rates, and coating or plating replacement. The actions would be
required to be accomplished in accordance with the ASB described
previously.
There are approximately 2,000 engines of the affected design in the
worldwide fleet. The FAA estimates that 1,000 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, that
it would take approximately 16 work hours per engine to accomplish the
proposed actions, and that the average labor rate is $60 per work hour.
Required parts would cost approximately $75,000 per engine. Based on
these figures, the total cost impact of the proposed AD on U.S.
operators is estimated to be $75,960,000 over a 13-year period.
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), 40101, 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-45.
Applicability: Pratt & Whitney (PW) Models JT3D-1, -1A, -3, -3B,
-3C, -1-MC6,
[[Page 55339]]
-1A-MC6, -1-MC7, -1A-MC7, -7, -7A turbofan engines, installed on but
not limited to Boeing 707 and 720 series aircraft and McDonnell
Douglas DC-8 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 (b) 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 steel high pressure compressor (HPC) disk failure due
to corrosion, which could result in an uncontained engine failure
and damage to the aircraft, accomplish the following:
(a) Inspect steel HPC disks, stages 10-15, for corrosion, recoat
or replate, or replace as necessary, in accordance with PW Alert
Service Bulletin (ASB) No. A6208, Revision 2, dated July 7, 1995,
and the following schedule:
(1) For disks coated with PW110 Aluminide (AL), and for disks
with unknown coating or plating, as follows:
(i) Initially inspect, recoat or replate, or replace as
necessary, 11 years since new or since last recoat or replate, or 24
months after the effective date of this AD, whichever occurs later.
(ii) Thereafter, inspect, recoat or replate, or replace as
necessary, at intervals not to exceed 11 years since new or last
coating, if AL protective coating is applied, or not to exceed 13
years since new or last plating, if Nickel Cadmium (NI-CAD) plating
is applied.
(2) For disks plated with NI-CAD, as follows:
(i) Initially inspect, recoat or replate, or replace as
necessary, 13 years since new or since last replate, or 24 months
after the effective date of this AD, whichever occurs later.
(ii) Thereafter, inspect, recoat or replate, or replace as
necessary, at intervals not to exceed 11 years since new or last
coating, if AL protective coating is applied, or not to exceed 13
years since new or last plating, if NI-CAD plating is applied.
(3) For disks with unknown history and unknown coating or
plating, as follows:
(i) Initially inspect, recoat or replate, or replace as
necessary, 24 months after the effective date of this AD.
(ii) Thereafter, inspect, recoat or replate, or replace as
necessary, at intervals not to exceed 11 years since new or last
coating, if AL protective coating is applied, or not to exceed 13
years since new or last plating, if NI-CAD plating is applied.
(b) 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.
(c) 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 October 18, 1995.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 95-26942 Filed 10-30-95; 8:45 am]
BILLING CODE 4910-13-U
