[Federal Register Volume 61, Number 108 (Tuesday, June 4, 1996)]
[Proposed Rules]
[Pages 28114-28116]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-13889]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-ANE-79]
RIN 2120-AA64
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 (PW) JT8D series turbofan
engines, that would have superseded a current AD by reducing the rear
flange inspection interval for combustion chamber outer cases (CCOC's)
when only the aft face of the rear flange has been inspected, and
introducing an improved ultrasonic probe assembly. That proposal was
prompted by reports of crack origins in the forward face of the rear
flange that could not be detected by the inspection methods for
installed CCOC's that were mandated in the current AD. This action
retains the elements of the original proposal, but simplifies the
compliance instructions, and incorporates a new PW Alert Service
Bulletin (ASB). This action also revises the proposed rule by
introducing new non-destructive inspection procedures (NDIP's), and
introducing a rotating eddy current probe for shop inspections in which
the case is removed from the engine. In addition, this action
eliminates fluorescent penetrant inspection (FPI), fluorescent magnetic
particle inspection (FMPI), and visual inspections from hot section
disassembly level inspection procedures. This action also revises the
proposed rule by consolidating the inspection requirements of an
additional current AD, 95-08-15, into this proposed AD. The actions
specified by this proposed AD are intended to prevent CCOC flange
cracks that could result in uncontained engine failure, inflight engine
shutdown, engine cowl release, and airframe damage.
DATES: Comments must be received by August 5, 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. 93-ANE-79, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be
submitted to the Rules Docket by using the following Internet address:
ts@mail.hq.faa.gov''. 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 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.
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
[[Page 28115]]
must submit a self-addressed, stamped postcard on which the following
statement is made: ``Comments to Docket Number 93-ANE-79.'' 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-79, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
On October 3, 1989, the Federal Aviation Administration (FAA)
issued airworthiness directive (AD) 87-11-07 R1, Amendment 39-6360 (54
FR 46045, November 1, 1989), applicable to Pratt & Whitney (PW) JT8D
series turbofan engines, to require repetitive eddy current,
fluorescent penetrant, fluorescent magnetic penetrant, or visual
inspections for cracks in the rear flange, and ultrasonic, fluorescent
penetrant, or fluorescent magnetic penetrant inspections for cracks in
the PS4 boss, and drain bosses of the combustion chamber outer case
(CCOC). That action was prompted by reports of uncontained rupture of
the CCOC. That condition, if not corrected, could result in CCOC flange
cracks that if undetected could result in uncontained engine failure,
inflight engine shutdown, engine cowl release, and airframe damage.
Since the issuance of that AD, the FAA has received reports of
crack origins in the forward face of the rear flange that cannot be
detected by the inspection methods for installed CCOC's that were
mandated in that AD. While no failures have been attributed to these
undetected cracks, analysis indicates that a reduced inspection
interval is necessary to prevent crack propagation to critical lengths
as the CCOC's age. The FAA has determined that to reduce the fleet-wide
risk to an acceptable level, the inspection interval should be reduced
if only the aft face of the rear flange is inspected.
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to add an AD, applicable to PW JT8D series turbofan
engines, was published as a notice of proposed rulemaking (NPRM) in the
Federal Register on March 15, 1994 (59 FR 11942). That NPRM would have
reduced the inspection interval for CCOC's that have had only the aft
face of the rear flange inspected and introduced an improved ultrasonic
probe assembly. That NPRM was prompted by reports of rupture of CCOC's
that had only the aft face of the rear flange inspected in accordance
with the current AD.
Since the issuance of that NPRM, the manufacturer has introduced
improved non-destructive inspection procedures (NDIP's) that are
applicable to the existing CCOC inspection requirements of AD 87-11-07
R1. The FAA has determined that the improved NDIP's should be
incorporated into the CCOC inspection requirements, that the FPI, FMPI,
and visual inspections should be eliminated from the hot section
inspection level of disassembly inspection requirements, that a new
rotating eddy current probe should be introduced for shop level
inspections in which the case is removed from the engine, and that the
compliance section should be simplified.
In addition, since issuance of the NPRM the FAA has issued AD 95-
08-15, Amendment 39-9204 (60 FR 20019, April 24, 1995), which requires
an additional inspection of the CCOC rear flange for intergranular
cracking. In addition, PW has issued Revision 1 to the Alert Service
Bulletin (ASB) incorporated in that AD, No. A6202, dated January 4,
1996, which removes the in-shop ultrasonic inspection requirement and
clarifies the borescope inspection requirements. The FAA has determined
that AD 95-08-15 should be superseded and the compliance requirements
of that AD and that PW ASB No. A6202, Revision 1, dated January 4,
1996, should be consolidated into the existing CCOC inspection
requirements of AD 87-11-07 R1.
In addition, PW has issued ASB No. A6228, dated November 7, 1995,
which introduces the improved NDIP's, eliminates the FPI and FMPI from
the hot section disassembly level inspection requirements, and
consolidates inspection procedures for the CCOC. This ASB is
incorporated in this proposed rule. Pratt & Whitney ASB No. A6228,
dated November 7, 1995, also includes an inspection of PS4 and drain
bosses for a thin walled condition in Paragraph 2.C, Part III of that
ASB. The FAA has determined, however, that this condition does not pose
a significant risk to continued safe flight and therefore is not
included in this proposed AD.
Interested persons have been afforded an opportunity to participate
in the making of this proposal. Due consideration has been given to the
comments received.
Two commenters state that the new, reduced, rear flange inspection
interval should only apply to future inspections, and not be
retroactive, such that some engines would require inspection
immediately upon AD effectivity. The FAA agrees. This proposed AD
allows the inspection interval previously established under AD 87-11-07
R1 to be completed prior to imposing the new, reduced intervals.
One commenter states that inspection records may not specifically
state whether or not both faces of the rear flange were inspected, or
if only the aft face was inspected, thus precluding determination of
the appropriate reinspection interval in accordance with PW ASB No.
A6228, dated November 7, 1995. The FAA agrees. As stated above, the
previously established inspection interval, determined in accordance
with AD 87-11-07 R1, may be used for the initial inspection without the
need for a more comprehensive records search.
One commenter states that an inspection should not be required at
shop visits that occur within a short time period of a previous shop
visit in which the CCOC was inspected. The FAA agrees. Shop visits that
occur within 1,000 cycles of a previous shop visit that included a CCOC
inspection do not need to be reinspected.
Three commenters state that the shop visit definition conflicted
with the definition contained in the PW ASB, and in some instances CCOC
inspections and associated extensive engine disassembly could be
required during limited scope maintenance activities. The FAA agrees.
This proposed AD requires use of the shop visit definition in the ASB,
and this definition has been refined in response to operators'
concerns.
One commenter states that an incorrect Table reference was
specified in paragraph (d) of the NPRM. The FAA agrees. This proposed
AD contains a simplified compliance section that limits references to
only the applicable major paragraphs of the ASB compliance section.
Three commenters state that the AD applicability section should
specify the applicable CCOC part numbers as well as the applicable
engine models. The FAA agrees. The applicability section in this
proposed AD includes these part number references.
One commenter states that the ASB is complex and could lead to non-
compliance with the AD. The FAA agrees. Both the ASB and the proposed
AD have been simplified.
One commenter states that the equipment and procedures used for the
inspection of the PS4 and drain bosses produce unreliable results. The
FAA agrees in part. The FAA acknowledges that the inspections are
complex and require skilled and trained inspectors,
[[Page 28116]]
and refinements have been made to these inspection procedures and tools
based on past in-service experience and reports from operators of the
PW JT8D series engines.
One commenter concurs with the proposed AD as written.
Since these changes expand the scope of the originally proposed
rule, the FAA has determined that it is necessary to reopen the comment
period to provide additional opportunity for public comment.
The FAA estimates that 6,815 engines installed on aircraft of U.S.
registry would be affected by this proposed AD and that it would take
approximately 4.5 work hours per engine to accomplish the proposed
actions. Since publication of the NPRM, the FAA has revised its average
labor rate estimate from $55 per work hour to $60 per work hour to
better reflect current costs. Based on these figures, the total cost
impact of the proposed AD on U.S. operators is estimated to be
$1,840,050.
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), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-6360 (54 FR
46045, November 1, 1989) and amendment 39-9204 (60 FR 20019, April 24,
1995) and by adding a new airworthiness directive to read as follows:
Pratt & Whitney: Docket No. 93-ANE-79. Supersedes AD 87-11-07 R1,
Amendment 39-6360, AD 87-11-07, Amendment 39-5619, and AD 95-08-15,
Amendment 39-9204.
Applicability: Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7,
-7A, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan
engines, with combustion chamber outer case (CCOC) part numbers (P/
Ns) 490547, 542155, 616315, 728829, 728829-001, 730413, 730413-001,
730414, 730414-001, 767197, 767279, 767279-001 installed. These
engines are installed on but not limited to Boeing 737 and 727
series, and McDonnell Douglas DC-9 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 (c) 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 CCOC flange cracks that could result in uncontained
engine failure, inflight engine shutdown, engine cowl release, and
airframe damage, accomplish the following:
(a) Inspect, disposition, and report CCOC distress, in
accordance with the intervals and procedures described in Paragraphs
2.A and 2.C of PW Alert Service Bulletin (ASB) No. A6202, Revision
1, dated January 4, 1996. Reporting requirements have been approved
by the Office of Management and Budget and assigned OMB control
number 2120-0056.
(1) For the purposes of this AD, the accomplishment effective
date to be used for determination of inspection intervals, as
required by Section 2.A of PW ASB A6202, Revision 1, dated January
4, 1996, is defined as the effective date of this AD.
(b) Inspect, disposition, and report CCOC distress in accordance
with the intervals and procedures described in Paragraphs 2.A. (Part
I), 2.B. (Part II), and 2.D of PW ASB No. A6228, dated November 7,
1995. Reporting requirements have been approved by the Office of
Management and Budget and assigned OMB control number 2120-0056.
(c) 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.
(d) 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 May 22, 1996.
Robert E. Guyotte,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 96-13889 Filed 6-3-96; 8:45 am]
BILLING CODE 4910-13-U
