[Federal Register Volume 60, Number 78 (Monday, April 24, 1995)]
[Rules and Regulations]
[Pages 20019-20021]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-9471]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-ANE-04; Amendment 39-9204; AD 95-08-15]
Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to Pratt & Whitney (PW) JT8D series turbofan engines.
This action requires a one-time borescope inspection of certain
combustion chamber outer cases (CCOC) installed only on McDonnell
Douglas DC-9 series and Boeing 737 series aircraft, and an ultrasonic
inspection of all affected CCOC's at every accessibility. This
amendment is prompted by reports of two CCOC ruptures in service and of
two CCOC's discovered during maintenance with intergranular cracks. The
actions specified in this AD are intended to prevent CCOC rupture,
which can result in an uncontained engine failure and damage to the
aircraft.
DATES: Effective May 9, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of May 9, 1995.
Comments for inclusion in the Rules Docket must be received on or
before June 23, 1995.
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-04, 12 New England
Executive Park, Burlington, MA 01803-5299.
The service information referenced in this AD 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; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
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: The Federal Aviation Administration (FAA)
has received reports of two uncontained engine failures on Pratt &
Whitney (PW) JT8D series turbofan engines. Investigation revealed that
the engine failures were due to combustion chamber outer case (CCOC)
ruptures that exhibited intergranular cracking. The CCOC ruptures
resulted from the low cycle fatigue (LCF) propagation of the
intergranular crack. In addition, intergranular cracking on two other
CCOC's was discovered during in-shop maintenance. The FAA has
determined that intergranular cracks may develop from an initiation
site on the case during assembly of the CCOC to the high pressure
turbine (HPT) case, or during engine operation in which an impact load
is imposed on the CCOC. During subsequent engine operation, the crack
can then propagate to failure due to normal LCF loads. Analysis of
operating experience relative to CCOC ruptures indicated that only
engines installed on McDonnell Douglas DC-9 series and Boeing 737
series aircraft have a significant risk of CCOC rupture, whereas
engines installed on other aircraft have been statistically proven to
have less risk of CCOC rupture. Therefore, the FAA has determined that
a borescope inspection of CCOC's installed only on McDonnell Douglas
DC-9 series and Boeing 737 series aircraft is required to meet safety
of flight criteria. However, the FAA has determined that an ultrasonic
inspection of all affected CCOC's during in-shop maintenance is also
required, regardless of intended aircraft installation, to meet safety
of flight criteria. This condition, if not corrected, could result in
CCOC rupture, which can 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. A6202, dated February 20, 1995, that
describes procedures for a one-time borescope inspection of certain
CCOC's installed [[Page 20020]] only on McDonnell Douglas DC-9 series
and Boeing 737 series aircraft, and an ultrasonic inspection of all
affected CCOC's at every accessibility when the ``J'' and ``K'' flanges
are separated and the outer split fan ducts are removed.
Since an unsafe condition has been identified that is likely to
exist or develop on other PW JT8D series turbofan engines of the same
type design, this AD is being issued to prevent CCOC rupture, which can
result in an uncontained engine failure and damage to the aircraft.
This AD requires a one-time borescope inspection of certain CCOC's
installed only on McDonnell Douglas DC-9 series and Boeing 737 series
aircraft, and an ultrasonic inspection of all affected CCOC's at every
accessibility when the ``J'' and ``K'' flanges are separated and the
outer split fan ducts are removed. However, performing the ultrasonic
inspection in the shop or on-wing is an acceptable alternative to
performing the borescope inspection. The actions are required to be
accomplished in accordance with the ASB described previously.
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
summarizes each FAA-public contact concerned with the substance of this
AD 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-04.'' The postcard will be date stamped and
returned to the commenter.
The regulations adopted herein will 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 final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and is not a ``significant regulatory action''
under Executive Order 12866. It has been determined further that this
action involves an emergency regulation under DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979). If it is determined
that this emergency regulation otherwise would be significant under DOT
Regulatory Policies and Procedures, a final regulatory evaluation will
be prepared and placed in the Rules Docket. A copy of it, if filed, may
be obtained from the Rules Docket at the location provided under the
caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends 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:
95-08-15 Pratt & Whitney: Amendment 39-9204. Docket 95-ANE-04.
Applicability: Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7,
-7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR
turbofan engines, with combustion chamber outer cases (CCOC) Part
Numbers (P/N) 490547, 542155, 616315, 728829, 728829-001, 730413,
730413-001, 730414, 730414-001, 767197, 767279, and 767279-001.
These engines are installed on but not limited to Boeing 737 series
and 727 series, and McDonnell Douglas DC-9 series aircraft.
Note: This 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 FAA. This approval may address either no
action, if the current configuration eliminates the unsafe
condition, or different action 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 CCOC rupture, which can result in an uncontained
engine failure and damage to the aircraft, accomplish the following:
(a) For engines installed on McDonnell Douglas DC-9 series
aircraft, perform the following:
(1) Perform a borescope inspection of the CCOC for cracking
within 1,000 cycles in service (CIS) after the effective date of
this airworthiness directive (AD), in accordance with Section 2.A of
PW Alert Service Bulletin (ASB) No. A6202, dated February 20, 1995.
(2) Remove from service CCOC's that exhibit cracking in
accordance with Section 2.A of PW ASB No. A6202, dated February 20,
1995.
(b) For engines installed on Boeing 737 series aircraft, perform
the following:
(1) Perform a borescope inspection of the CCOC for cracking
within 1,500 CIS after the effective date of this AD, in accordance
with Section 2.A of PW ASB No. A6202, dated February 20, 1995.
(2) Remove from service CCOC's that exhibit cracking in
accordance with section 2.A of PW ASB No. A6202, dated February 20,
1995.
(c) At every accessibility of the CCOC after the effective date
of this AD, perform the following:
(1) Prior to reassembly of the outer split fan ducts, perform an
ultrasonic inspection for cracking in accordance with Section 2.B of
[[Page 20021]] PW ASB No. A6202, dated February 20, 1995.
(2) Remove from service CCOC's that exhibit cracking in
accordance with Section 2.B of PW ASB No. A6202, dated February 20,
1995.
(d) Compliance with paragraph (c) of this AD is an acceptable
alternative to performing the borescope inspection required by
paragraph (a) or (b) of this AD, as applicable.
(e) For the purpose of this AD, accessibility of the CCOC is
defined as separation of the ``J'' and ``K'' flanges and removal of
the outer split fan ducts.
(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
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.
(h) The inspections of the CCOC shall be done in accordance with
the following service document:
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Document No. Pages Date
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PW ASB No. A6202......................... 1-11 Feb. 20, 1995.
Total pages: 11.
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This incorporation by reference was approved by the Director of the
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part
51. Copies may be obtained from Pratt & Whitney, 400 Main St, East
Hartford, CT 06108. Copies may be inspected at the FAA, New England
Region, Office of the Assistant Chief Counsel, 12 New England
Executive Park, Burlington, MA; or at the Office of the Federal
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(i) This amendment becomes effective on May 9, 1995.
Issued in Burlington, Massachusetts, on April 11, 1995.
James C. Jones,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 95-9471 Filed 4-21-95; 8:45 am]
BILLING CODE 4910-13-P
