[Federal Register Volume 59, Number 18 (Thursday, January 27, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-1762]
[[Page Unknown]]
[Federal Register: January 27, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-ANE-81]
Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes to supersede telegraphic airworthiness
directive (AD) T89-05-52 by adopting a new AD, applicable to Pratt &
Whitney (PW) JT8D series turbofan engines. Telegraphic AD T89-05-52
currently requires repetitive ultrasonic inspections of a combustion
chamber outer case (CCOC) weld, but also allows visual inspection or
fluorescent magnetic penetrant inspection (FMPI) of certain CCOC's
under specified conditions. This proposal would allow ultrasonic
inspections only. This proposal is prompted by the greater availability
of ultrasonic inspection equipment, which provides a more definitive
means of discovering cracks than either visual inspections or FMPI. The
actions specified by the proposed AD are intended to prevent rupture of
the CCOC, which could result in fire, engine cowl release, or aircraft
damage.
DATES: Comments must be received by March 28, 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. 93-ANE-81, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at
this location between 8 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: 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 93-ANE-81.'' 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. 93-ANE-81, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
On March 1, 1989, the Federal Aviation Administration (FAA) issued
telegraphic airworthiness directive (AD) T89-05-52, applicable to Pratt
& Whitney (PW) JT8D series turbofan engines, which requires repetitive
ultrasonic inspections for cracks in the combustion chamber outer case
(CCOC). In addition, that telegraphic AD allowed operators who did not
have ultrasonic inspection capability to perform visual inspections and
fluorescent magnetic penetrant inspections (FMPI) of CCOC's. That
action was prompted by reports of two CCOC's, both part number (P/N)
796761, which were found in service with severe cracking and distress
at the weld which joins the forward case detail to the rear flange
detail. These cracks initiated from an area of incomplete weld created
during the manufacturing process and were not detected during the final
inspection process. Another CCOC, P/N 806675, is manufactured using a
similar process and has the same potential for incomplete welds, but to
date have not been found cracked. That condition, if not corrected,
could result in rupture of the CCOC, which could result in fire, engine
cowl release, or aircraft damage.
Since the issuance of that telegraphic AD, the FAA has received
reports that most operators now have the capability to perform
ultrasonic inspections, which provides a more definitive means of
discovering cracks than either visual inspections or FMPI. In
telegraphic AD T89-05-52, reinspection of all CCOC's is required,
including reinspection of those CCOC's that exhibited minimal
ultrasonic indications during initial inspection. The FAA has
determined analytically that CCOC's that exhibit maximum signal
amplitudes of less than 40 percent are not life limited at the defined
weld area. Therefore, CCOC's that meet this signal criteria for two
consecutive ultrasonic inspections may be marked with a new P/N,
provided the second ultrasonic inspection is accomplished at least
2,500 cycles in service (CIS) after the first inspection and the second
inspection is performed in accordance with Appendix C of PW Alert
Service Bulletin (ASB) No. 5842, Revision 3, dated October 10, 1990.
Finally, the FAA has determined that certain CCOC's, P/N 806675,
were ultrasonically inspected by PW during the manufacturing process,
and therefore do not need to be inspected again until they are
accessible in the shop.
The FAA has reviewed and approved the technical contents of PW ASB
No. 5842, Revision 3, dated October 10, 1990, that describes procedures
for repetitive ultrasonic inspections of CCOC's for cracks.
Since an unsafe condition has been identified that is likely to
exist or develop on other engines of this same type design, the
proposed AD would supersede telegraphic AD T89-05-52 to require
repetitive ultrasonic inspections of CCOC's for cracks. The proposed AD
would also allow CCOC's that meet certain signal criteria for two
consecutive ultrasonic inspections to be marked with a new P/N. Once
remarked, those CCOC's would not need to meet the repetitive ultrasonic
inspection requirements of this AD. Finally, the proposed AD would
require ultrasonic inspections on certain CCOC's, P/N 806675,
identified by serial number, that were ultrasonically inspected by PW
during the manufacturing process, when they are accessible in the shop.
The actions are required to be accomplished in accordance with the
service bulletin described previously.
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 2 work hours per engine to accomplish the proposed
actions, and that the average labor rate is $55 per work hour. Based on
these figures, the total cost impact of the proposed AD on U.S.
operators is estimated to be $110,000.
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 14
CFR part 39 of the Federal Aviation Regulations 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. 93-ANE-81.
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 case (CCOC), Part
Number (P/N) 796761 or 806675. These engines are installed on but
not limited to Boeing 727 and 737 series, and McDonnell Douglas DC-9
series aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent rupture of the CCOC, which could result in fire,
engine cowl release, or aircraft damage, accomplish the following:
(a) Except for CCOC's cited in paragraph (c) of this
airworthiness directive (AD), ultrasonically inspect CCOC's
installed in engines for cracks within 10 days or 75 cycles in
service (CIS) after the effective date of this AD, whichever occurs
later, in accordance with paragraph 2.A.(3) and Appendix B of PW
Alert Service Bulletin (ASB) No. 5842, Revision 3, dated October 10,
1990.
(b) For CCOC's not installed in engines and not cited in
paragraph (c) of this AD, ultrasonically inspect CCOC's for cracks
prior to returning the CCOC's to service in accordance with
paragraph 2.A.(5) and Appendix C of PW ASB No. 5842, Revision 3,
dated October 10, 1990.
(c) For CCOC's, P/N 806675, listed by serial number in Table 1
and paragraph 2.A.(10) of PW ASB No. 5842, Revision 3, dated October
10, 1990, accomplish the following:
(1) At the next removal of the CCOC from the engine after the
effective date of this AD, ultrasonically inspect CCOC's for cracks
in accordance with paragraph 2.A.(5) and Appendix C of PW ASB No.
5842, Revision 3, dated October 10, 1990.
(2) Remove from service or reinspect CCOC's in accordance with
paragraphs (d) and (e), respectively, of this AD.
(3) Mark CCOC's with new part numbers in accordance with
paragraphs 2.A.(5)(c) and 2.A.(11) of PW ASB No. 5842, Revision 3,
dated October 10, 1990, that:
(i) Have accumulated at least 2,500 CIS since new; and
(ii) Exhibit a maximum ultrasonic signal amplitude of less than
40% during the inspection conducted subsequent to 2,500 CIS since
new.
(d) Remove from service and replace with a serviceable part
CCOC's with maximum ultrasonic signal amplitude determined as
follows:
(1) CCOC's with greater than or equal to 360%, prior to further
flight, with no ferry flight permitted in accordance with paragraph
(i) of this AD below.
(2) CCOC's with less than 360%, but greater than or equal to
240%, prior to further flight, with ferry flight permitted, in
accordance with paragraph (i) of this AD below.
(e) Thereafter, ultrasonically inspect CCOC's, P/N's 796761 and
806675, for cracks at intervals determined by maximum ultrasonic
signal amplitude, in accordance with paragraph 2.A. and Appendix B
of PW ASB No. 5842, Revision 3, dated October 10, 1990, for
installed CCOC's; or paragraph 2.A.(5) and Appendix C of PW ASB No.
5842, Revision 3, dated October 10, 1990, for uninstalled CCOC's; as
applicable, as follows:
(1) For those CCOC's that meet the criteria described in
paragraph (d) of this AD, remove from service and replace with a
serviceable part.
(2) For those CCOC's with less than 240%, but greater than or
equal to 100%, at intervals of 1,000 CIS since last inspection.
(3) For those CCOC's with less than 100%, but greater than or
equal to 40%, at intervals of 2,500 CIS since last inspection.
(4) For those CCOC's with less than 40%, inspect at the next
removal of the CCOC from the engine since last inspection.
(f) Mark CCOC's with new P/N's, in accordance with paragraphs
2.A.(5)(c) and 2.A.(11) of PW ASB No. 5842, Revision 3, dated
October 10, 1990, that meet the following criteria:
(1) At least two consecutive ultrasonic inspections have been
performed on the CCOC; and
(2) the second inspection was performed in accordance with
paragraph (b) of this AD; and
(3) have accumulated at least 2,500 CIS since the first
ultrasonic inspection; and
(4) that exhibit a maximum ultrasonic signal amplitude of less
than 40% in both inspections.
(g) Remarking of CCOC's with a new P/N in accordance with
paragraph (f) of this AD constitutes terminating action to the
inspection requirements of this AD.
(h) 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.
(i) Except for aircraft with engines having CCOC's that must be
removed from service in accordance with paragraph (d)(1) of this AD,
special flight permits may be issued in accordance with FAR 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 January 20, 1994.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 94-1762 Filed 1-26-94; 8:45 am]
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