[Federal Register Volume 59, Number 189 (Friday, September 30, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-24070]
[[Page Unknown]]
[Federal Register: September 30, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 92-ANE-33; Amendment 39-9038; AD 93-19-02R1]
Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule, request for comments.
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SUMMARY: This amendment revises an existing airworthiness directive
(AD), applicable to Pratt & Whitney (PW) JT9D series turbofan engines,
that currently requires eddy current inspection and modification of the
diffuser case rear rail, and removal, if necessary, of the diffuser
case. This amendment corrects an error in paragraph numbering in the
compliance section and allows modification of diffuser cases in
accordance with previous revisions of a PW Service Bulletin as an
alternative means of compliance. This amendment is prompted by comments
received after issuance of AD 93-19-02. The actions specified by this
AD are intended to prevent diffuser case rupture and an uncontained
engine failure.
DATES: Effective on October 17, 1994.
The incorporation by reference of certain publications listed in
the regulations was approved by the Director of the Federal Register as
of October 18, 1993 (58 FR 51212, October 1, 1993).
Comments for inclusion in the Rules Docket must be received on or
before November 29, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 92-ANE-33, 12 New England
Executive Park, Burlington, MA 01803-5299.
The service information referenced in this AD may be obtained from
Pratt & Whitney, 400 Main Street, 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: Daniel Kerman, Aerospace Engineer,
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: On September 16, 1993, the Federal Aviation
Administration (FAA) issued AD 93-19-02, Amendment 39-8695 (58 FR
51212, October 1, 1993), as a final rule with request for comments that
superseded AD 86-11-04, to define initial inspection requirements that
will allow for transition to more stringent repetitive on-wing eddy
current inspections of the diffuser case rear rail for cracking. AD 93-
19-02 also requires ultrasonic and metallographic inspections of the
shell wall, and ultrasonic inspection of the rear rail at the Boss 6
location to determine weld size. In the previous AD, 86-11-04, diffuser
cases were allowed to remain in service with weld repairs of up to 4
inches in length. In AD 93-19-02, diffuser cases with weld repairs in
the rear rail of greater than or equal to 1.5 inches in axial length at
Boss 6 must be replaced. In addition, AD 93-19-02 requires a one-time
X-ray inspection of the rear rail and sides of bosses for weld quality.
This inspection is necessary since in the last two failures, weld
defects were undetected by the inspections required by AD 86-11-04.
Also, diffuser cases with rear rails that have been weld-repaired must
incorporate the modifications described in PW SB No. 5805, Revision 6,
dated September 15, 1993. Finally, an optional terminating action to
the inspections and modifications of AD 93-19-02 is available with the
installation of a new, improved diffuser case in accordance with PW SB
No. 6105, Revision 2, dated May 14, 1993.
AD 93-19-02 was prompted by reports of 2 additional diffuser case
failures. Both failures occurred within significantly shorter time
intervals since last inspection than that specified in AD 86-11-04. In
an effort to better understand the diffuser case failure mode, a rig
test was performed. This test examined crack initiation and growth
rates in weld-repaired versus non-weld-repaired diffuser cases. Results
of the test established that cracks initiate and propagate more rapidly
in weld-repaired diffuser cases. In addition, weld repairs at the Boss
6 location were determined to have even greater potential for rapid
crack growth and resultant diffuser case failure. That condition, if
not corrected, could result in diffuser case rupture and an uncontained
engine failure.
Although AD 93-19-02 was issued as a final rule without prior
notice and an opportunity for public comment, the FAA requested comment
on the AD. Due consideration has been given to the comments received.
One commenter states that paragraph (c)(3) of AD 93-19-02 refers
incorrectly to paragraphs (d) and (f), as those paragraphs are
applicable to those diffuser cases that have been weld-repaired. The
FAA concurs. Paragraph (c)(3) of this Revision to AD 93-19-02 has been
changed to refer to paragraphs (e), (g), (h), (i), (j), (k), and (l).
These paragraphs are applicable to those diffuser cases that have not
been weld-repaired.
One commenter states that paragraph (o) of AD 93-19-02 requires
modifications to the diffuser case in accordance with PW Service
Bulletin (SB) No. 5805, Revision 6, dated September 15, 1993. The
commenter maintains that modifications performed in accordance with the
earlier revisions to this SB should be considered in compliance with
this AD. The FAA concurs. All previous revisions of PW SB No. 5805
differ from Revision 6 only in editorial clarifications or corrections
of typographical errors and do not impact the intent of the document.
Modifications performed to the diffuser case in accordance with the
previous revisions of PW SB No. 5805 constitute an acceptable alternate
means of compliance to paragraph (o) of this AD.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the revision of the rule with the changes described
previously. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
The FAA has reviewed and approved the technical contents of PW SB
No. 5805, Revision 6, dated September 15, 1993, that describes
procedures for modification of the rear rail by detaching the diffuser
case rear rail from the strut boss, thus extending the serviceable life
of the diffuser case by reducing crack initiation and propagation
rates; PW Alert Service Bulletin (ASB) No. 6076, Revision 1, dated
August 20, 1992, that describes ultrasonic and metallographic
inspection of the shell wall, and ultrasonic inspection of the rear
rail at the Boss 6 location to determine weld size; PW SB No. 6088,
dated August 5, 1992, that describes an X-ray inspection of the rear
rail and sides of bosses for detection of poor weld quality; PW SB No.
5591, Revision 7, dated August 25, 1992, that describe initial and
repetitive on-wing eddy current inspections of the diffuser case rear
rail; and PW SB No. 6105, Revision 2, dated May 14, 1993, that
describes installation of a new, improved diffuser case.
Additional information regarding weld repair requirements for the
diffuser case rear rail is contained in PW JT9D Engine Manual, Part
Number 686028, dated September 1, 1993.
Since an unsafe condition has been identified that is likely to
exist or develop on other PW JT9D series turbofan engines of this same
type design, this AD revises AD 93-19-02 to correct an error in
paragraph numbering in the compliance section and allow modification of
diffuser cases in accordance with previous revisions of PW SB No. 5805
as an alternative means of compliance to paragraph (o) of this AD. The
actions are required to be accomplished in accordance with the service
bulletins 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 92-ANE-33.'' 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 removing Amendment 39-8695 (58 FR
51212, October 1, 1993) and by adding a new airworthiness directive,
Amendment 39-9038, to read as follows:
93-19-02 R1 Pratt & Whitney: Amendment 39-9038. Docket 92-ANE-33.
Revises AD 93-19-02, Amendment 39-8695.
Applicability: Pratt & Whitney (PW) JT9D-3A, -7, -7H, -7A, -7AH,
-7F, -7J, -20, and -20J turbofan engines installed on but not
limited to Boeing 747 series, Airbus A300 series, and McDonnell
Douglas DC-10 series aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent diffuser case rupture and an uncontained engine
failure, accomplish the following:
(a) For those diffuser cases that have not been inspected in
accordance with PW Alert Service Bulletin (ASB) No. 6076, Revision
1, dated August 20, 1992, initially inspect the diffuser case for
cracks in accordance with the intervals and requirements described
in paragraphs (d), (f), (g), (i), (j), (k), or (l) of this AD, as
applicable.
(b) For those diffuser cases that have not been inspected in
accordance with PW ASB No. 6076, Revision 1, dated August 20, 1992,
inspect the diffuser case rear rail along the shell wall at Boss 6
for weld repair size in accordance with PW ASB No. 6076, Revision 1,
dated August 20, 1992, at the next M flange separation of the high
pressure turbine case after the effective date of this AD. Diffuser
cases with weld repairs in the rear rail along the shell wall of
axial length greater than or equal to 1.5 inches at Boss 6 must not
be returned to service. If the weld length is less than 1.5 inches,
inspect in accordance with the new criteria, improved technique,
intervals, and requirements defined in the Accomplishment
Instructions of PW Service Bulletin (SB) No. 5591, Revision 7, dated
August 25, 1992.
Note: Additional information regarding weld repair requirements
for the diffuser case rear rail is contained in PW JT9D Engine
Manual, Part Number 686028, dated September 1, 1993.
(c) For those diffuser cases that have been inspected in
accordance with PW ASB No. 6076, Revision 1, dated August 20, 1992,
accomplish the following:
(1) For diffuser cases that have weld repairs in the rear rail
along the shell wall at Boss 6 of axial length greater than or equal
to 1.5 inches, remove from service and replace with a serviceable
part prior to further flight.
(2) For diffuser cases that have weld repairs in the rear rail
along the shell wall at Boss 6 of axial length less than 1.5 inches,
initially inspect the diffuser case for cracks in accordance with
the intervals and requirements described in paragraphs (d), (f),
(g), (i), (j), (k), or (l) of this AD, as applicable.
(3) For diffuser cases that have no weld repairs in the rear
rail along the shell wall at Boss 6, initially inspect the diffuser
case for cracks in accordance with the intervals and requirements
described in paragraphs (e), (g), (h), (i), (j), (k), or (l) of this
AD, as applicable.
(d) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,
that contained rear rails with no cracks at any boss location at the
last ECI, and have a weld repair in the rear rail along the shell
wall at Boss 6, perform an initial ECI of the diffuser case rear
rail for cracks in accordance with the new criteria and improved
technique defined in the Accomplishment Instructions of PW SB No.
5591, Revision 7, dated August 25, 1992, as follows:
(1) For diffuser cases with greater than 275 cycles in service
(CIS) since the last ECI performed in accordance with PW SB No.
5591, Revision 4, dated March 6, 1986, on the effective date of this
AD, perform an ECI in accordance with the new criteria and improved
technique defined in the Accomplishment Instructions PW SB No. 5591,
Revision 7, dated August 25, 1992, prior to accumulating 500 CIS
since the last ECI performed in accordance with PW SB No. 5591,
Revision 4, dated March 6, 1986, or prior to accumulating 75 CIS
after the effective date of this AD, whichever occurs first.
(2) For diffuser cases with less than or equal to 275 CIS since
the last ECI performed in accordance with PW SB No. 5591, Revision
4, dated March 6, 1986, on the effective date of this AD, perform an
ECI in accordance with the new criteria and improved technique
defined in the Accomplishment Instructions of PW SB No. 5591,
Revision 7, dated August 25, 1992, prior to accumulating 350 CIS
since the last ECI performed in accordance with PW SB No. 5591,
Revision 4, dated March 6, 1986.
(e) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,
that contained rear rails with no cracks at any boss location at the
last ECI, and have no weld repairs in the rear rail along the shell
wall at Boss 6, perform an ECI of the diffuser case rear rail for
cracks in accordance with the new criteria and improved technique
defined in the Accomplishment Instructions of PW SB No. 5591,
Revision 7, dated August 25, 1992, prior to accumulating 500 CIS
since the last ECI performed in accordance with PW SB No. 5591,
Revision 4, dated March 6, 1986.
(f) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,
that contained rear rails with ``A'' cracks at Boss 6 at the last
ECI, and have a weld repair in the rear rail along the shell wall at
Boss 6, perform an ECI of the diffuser case rear rail for cracks in
accordance with the new criteria and improved technique defined in
the Accomplishment Instructions of PW SB No. 5591, Revision 7, dated
August 25, 1992, prior to accumulating 300 CIS since the last ECI
performed in accordance with PW SB No. 5591, Revision 4, dated March
6, 1986, or prior to accumulating 60 CIS after the effective date of
this AD, whichever occurs first.
(g) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,
that contained rear rails with ``A'' cracks at any boss location
other than at Boss 6 at the last ECI, with or without weld repairs
in the rear rail along the shell wall at Boss 6, perform an ECI of
the diffuser case rear rail for cracks in accordance with the new
criteria and improved technique defined in the Accomplishment
Instructions of PW SB No. 5591, Revision 7, dated August 25, 1992,
prior to accumulating 300 CIS since the last ECI performed in
accordance with PW SB No. 5591, Revision 4, dated March 16, 1986.
(h) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,
that contained rear rails with ``A'' cracks at Boss 6 at last ECI,
and have no weld repairs at Boss 6, perform an ECI of the diffuser
case rear rail for cracks in accordance with the new criteria and
improved technique defined in the Accomplishment Instructions of PW
SB No. 5591, Revision 7, dated August 25, 1992, prior to
accumulating 300 CIS since the last ECI performed in accordance with
PW SB No. 5591, Revision 4, dated March 6, 1986.
(i) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986, and
contained rear rails with ``B'' cracks at Boss 6 at last ECI, with
or without weld repairs in the rear rail along the shell wall at
Boss 6, remove from service and replace with a serviceable part
prior to accumulating 5 CIS after the effective date of this AD.
(j) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986, and
contained rear rails with ``B'' cracks at any boss location other
than Boss 6 at last ECI, with or without weld repairs in the rear
rail along the shell wall at Boss 6, perform an ECI of the diffuser
case rear rail for cracks in accordance with the new criteria and
improved technique defined in the Accomplishment Instructions of PW
SB No. 5591, Revision 7, dated August 25, 1992, prior to
accumulating 75 CIS since the last ECI performed in accordance with
PW SB No. 5591, Revision 4, dated March 6, 1986.
(k) For those diffuser cases that have been inspected in
accordance PW SB No. 5591, Revision 4, dated March 6, 1986, and
contained rear rails with ``C'' cracks at Boss 6 at last ECI, with
or without weld repairs in the rear rail along the shell wall at
Boss 6, remove from service and replace with a serviceable part
prior to further flight.
(l) For those diffuser cases that have been inspected in
accordance with PW SB No. 5591, Revision 4, dated March 6, 1986, and
contain rear rails with ``C'' cracks at any boss location other than
Boss 6 at last ECI, with or without weld repairs in the rear rail
along the shell wall at Boss 6, remove from service and replace with
a serviceable part as follows:
(1) For shell wall cracks of greater than or equal to 2 inches,
remove from service and replace with a serviceable part prior to
further flight.
(2) For shell wall cracks of less than 2 inches, remove from
service and replace with a serviceable part within 5 CIS after the
effective date of this AD.
(m) Thereafter, perform repetitive ECI of the diffuser case rear
rail for cracks in accordance with the new criteria, improved
technique, intervals, requirements, and removal from service
criteria defined in the Accomplishment Instructions of PW SB No.
5591, Revision 7, dated August 25, 1992.
(n) For those diffuser cases that have been weld repaired at any
boss location, at the next K flange separation of the diffuser case
after the effective date of this AD, perform a one-time x-ray
inspection of the diffuser case rear rail and sides of all bosses
for weld quality in accordance with PW SB No. 6088, dated August 5,
1992, prior to installation of the diffuser case. Remove any weld
defects within the inspection zone in accordance with PW SB No.
6088, dated August 5, 1992, prior to installation of the diffuser
case.
(o) For those diffuser cases with rear rails that have been weld
repaired at any boss location, incorporate the modifications
described in PW SB No. 5805, Revision 6, dated September 15, 1993,
at the next removal of the diffuser case for repair after the
effective date of this AD.
(p) Installation of an improved diffuser case in accordance with
PW SB No. 6105, Revision 2, dated May 14, 1993, constitutes
terminating action to the inspections and modifications required by
this AD.
(q) 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.
(r) Except for diffuser cases that have cracks that require
removal prior to further flight, 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
airplane to a location where the requirements of this AD can be
accomplished. For diffuser cases that have cracks that require
removal prior to further flight, on aircraft that are eligible for
an engine-inoperative ferry, 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 airplane to a
location where the requirements of this AD can be accomplished with
one engine inoperative.
(s) The inspections and modifications shall be done in
accordance with the following PW service bulletins:
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Document No. Pages Revision Date
----------------------------------------------------------------------------------------------------------------
SB No. 5591.......................................... 1-3 7................. Aug. 25, 1992.
4-9 6................. Aug. 14, 1992.
10 7................. Aug. 25, 1992.
11-12 6................. Aug. 14, 1992.
13 7................. Aug. 25, 1992.
14-15 6................. Aug. 14, 1992.
16 7................. Aug. 25, 1992.
17-19 6................. Aug. 14, 1992.
Total pages: 19
SB No. 5805.......................................... 1-4 6................. Sept. 15, 1993.
5 Original.......... Apr. 20, 1988.
6-72 6................. Sept. 15, 1993.
Total pages: 72
ASB No. 6076......................................... 1-5 1................. Aug. 20, 1992.
6-19 Original.......... July 31, 1992.
Total pages: 19
SB No. 6088.......................................... 1-11 Original.......... Aug. 5, 1992.
Total pages: 11
SB No. 6105.......................................... 1 2................. May 14, 1993.
2-7 Original.......... Jan. 15, 1993.
8 1................. Apr. 14, 1993.
9 2................. May 14, 1993.
10-15 Original.......... Jan. 15, 1993.
16 2................. May 14, 1993.
17-18 Original.......... Jan. 15, 1993.
19 2................. May 14, 1993.
20-46 Original.......... Jan. 15, 1993.
47 1................. Apr. 14, 1993.
48 2................. May 14, 1993.
49-56 Original.......... Jan. 15, 1993.
Total pages: 56
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This incorporation by reference was approved previously by the Director
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR
part 51 as of October 18, 1993 (58 FR 51212, October 1, 1993). 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.
(t) This amendment becomes effective on October 17, 1994.
Issued in Burlington, Massachusetts, on September 22, 1994.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 94-24070 Filed 9-29-94; 8:45 am]
BILLING CODE 4910-3-P
