[Federal Register Volume 62, Number 22 (Monday, February 3, 1997)]
[Rules and Regulations]
[Pages 4900-4902]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1700]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-ANE-49; Amendment 39-9898; AD 97-02-13]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JFTD12A Series and T73
Series Turboshaft Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to Pratt & Whitney JFTD12A series and T73 series turboshaft
engines, that requires initial and repetitive fluorescent penetrant
inspections (FPI) of compressor hubs, disks, spacers, and bolted on
(rotating) airseals for cracks, and replacement, if necessary, with
serviceable parts. This amendment is prompted by reports of extensive
compressor rotor part cracking. The actions specified by this AD are
intended to prevent disk rupture, an uncontained engine failure, and
possible damage to the aircraft.
DATES: Effective April 4, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of April 4, 1997.
ADDRESSES: The service information referenced in this AD may be
obtained from Pratt & Whitney, Publications Department, Supervisor
Technical Publications Distribution, M/S 132-30, 400 Main St., East
Hartford, CT 06108; telephone (860) 565-7700, fax (860) 565-4503. This
information may be examined at the Federal Aviation Administration
(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: 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: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to Pratt & Whitney (PW) JFTD12A
series and T73 series turboshaft engines was published in the Federal
Register on October 20, 1995 (60 FR 54203). That action proposed to
require initial and repetitive fluorescent penetrant inspections (FPI)
of compressor hubs, disks, spacers, and bolted on (rotating) airseals
for cracks, and replacement, if necessary, with serviceable parts, in
accordance with PW Alert Service Bulletin (ASB) No. 5856, Revision 1,
dated December 13, 1991.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
[[Page 4901]]
One commenter states specific part numbers (P/N's) for all parts
affected by the AD should be added to the compliance section, in order
to eliminate the need to revise the AD if future part modifications
occur that negate the necessity for inspection. The FAA does not
concur. As written, the AD applies to all JFTD12A-4A, -5A, T73-P-1, and
-P-700 engines regardless of the hardware installed. The note following
the applicability paragraph clarifies that if a future part
modification occurs, the operator must request an alternative method of
compliance in order to comply with the AD. The operator cannot make the
determination to not comply with the AD independently. There may not be
a need to revise or supersede the AD since an alternative method of
compliance may be available.
The commenter also states that a specific inspection of the third
stage disk tiebolt holes utilizing eddy current techniques in
accordance with a Pratt & Whitney approved procedure must be
accomplished in addition to FPI. Cracks have only occurred in the third
stage disk tiebolt holes and the second stage disk blade pin holes. The
commenter takes specific exception to the use of FPI to detect these
cracks as they have significant experience that the utilization of the
highest sensitivity penetrant required by Pratt & Whitney does not
consistently identify cracked disks. The FAA does not concur. The risk
analysis used to determine the AD compliance interval takes into
account the reliability of the FPI, including the probability that an
FPI inspection will not identify all cracks. The FAA has determined
that FPI is adequate for detecting cracks in the third stage disk
tiebolt holes and second stage disk blade pin holes.
The commenter also states that the AD should only address second
and third stage disks and allow all the other parts to remain at the
overhaul inspection interval of 3,000 hours time in service (TIS).
Cracks have been found only in the third stage disk tiebolt holes and
the second stage disk blade pin holes. There has never been a crack
found in first stage or fourth through ninth stage disks. Therefore,
continued inspection of all other parts at 1,500 hour TIS intervals is
unnecessary and an economic burden, especially due to the complexity of
deblading all nine stages of compressor disks. The FAA concurs in part.
The FAA agrees that the inspection of the first stage disk and fourth
through ninth stage disks may be accomplished at a 3,000 hour TIS
overhaul interval; this final rule has been revised accordingly.
However, inspection of all other parts, including second and third
stage disks, hubs, spacers and bolted on (rotating) airseals, must
still be accomplished at 1,500 hour TIS intervals. The FAA has revised
the AD accordingly.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest the adoption 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.
There are approximately 120 engines of the affected design in the
worldwide fleet. The FAA estimates that 47 engines installed on
aircraft of U.S. registry will be affected by this AD, that it will
take approximately 140 work hours per engine to accomplish the required
actions, and that the average labor rate is $60 per work hour. Required
parts will cost approximately $40,670 per engine. Based on these
figures, the total cost impact of the AD on U.S. operators is estimated
to be $2,306,290.
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.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it 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. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
97-02-13 Pratt & Whitney: Amendment 39-9898. Docket 94-ANE-49.
Applicability: Pratt & Whitney Models JFTD12A-4A and -5A, and
T73-P-1 and -P-700 turboshaft engines, installed on but not limited
to Sikorsky S-64 series and CH-54 series aircraft.
Note 1: 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 request
approval for an alternative method of compliance in accordance with
paragraph (e) of this AD. The request should include an assessment
of the effect of the modification, alteration, or repair on the
unsafe condition addressed by this AD; and, if the unsafe condition
has not been eliminated, the request should include specific
proposed actions to address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent disk rupture, an uncontained engine failure, and
possible damage to the aircraft, accomplish the following:
(a) Perform a fluorescent penetrant inspection (FPI) of
compressor hubs, second stage and third stage disks, spacers, and
bolted on (rotating) airseals for cracks in accordance with PW Alert
Service Bulletin (ASB) No. 5856, Revision 1, dated December 13,
1991, as follows:
(1) Prior to further flight, for engines that equal or exceed
2,200 hours time in service (TIS) since last FPI of affected parts
on the effective date of this airworthiness directive (AD).
(2) At or before 2,200 hours TIS since last FPI of affected
parts on the effective date of this AD, for engines that equal or
exceed 1,500 hours TIS but have less than 2,200 hours TIS since last
FPI of affected parts on the effective date of this AD.
(3) At or before 1,500 hours TIS since last FPI of affected
parts on the effective date of this AD, for engines that have less
than 1,500 hours TIS since last FPI of affected parts on the
effective date of this AD.
(4) Prior to further flight, remove cracked compressor hubs,
second and third stage disks, spacers, and bolted on (rotating)
airseals, and replace with serviceable parts.
(b) Thereafter, except for engines described in paragraphs (c)
and (d) of this AD, perform repetitive FPI of affected parts for
cracks at
[[Page 4902]]
intervals not to exceed 1,500 hours TIS since last FPI in accordance
with PW ASB No. 5856, Revision 1, dated December 13, 1991.
(c) Perform FPI of compressor first stage and fourth through
ninth stage disks for cracks, in accordance with PW ASB No. 5856,
Revision 1, dated December 13, 1991, as follows:
(1) At or before 3,000 hours TIS since last FPI of affected
parts on the effective date of this AD.
(2) Thereafter, perform repetitive FPI of affected parts for
cracks at intervals not to exceed 3,000 hours TIS since last FPI, in
accordance with PW ASB No. 5856, Revision 1, dated December 13,
1991.
(3) Prior to further flight, remove cracked compressor first
stage and fourth through ninth stage disks, and replace with
serviceable parts.
(d) For all engines inspected in accordance with paragraphs (a)
or (b) of this AD that have zero time second and third stage
compressor disks installed after the effective date of this AD,
perform the next FPI of affected parts at or before 3,000 hours TIS
since the last FPI performed in accordance with paragraph (a) or (b)
of this AD, and thereafter perform repetitive FPI of affected parts
for cracks at intervals not to exceed 1,500 hours TIS since the last
FPI, in accordance with PW ASB No. 5856, Revision 1, dated December
13, 1991. Prior to further flight, remove cracked compressor disks,
and replace with serviceable parts.
(e) 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 2: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Engine Certification Office.
(f) 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.
(g) The actions required by this AD shall be done in accordance
with the following PW ASB:
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Document No. Pages Revision Date
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No. 5856....................... 1-3 1.......... December 13, 1991.
4 Original... June 16, 1989.
5-7 1.......... December 13, 1991.
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Total pages: 7.
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, Publications
Department, Supervisor Technical Publications Distribution, M/S 132-
30, 400 Main St., East Hartford, CT 06108; telephone (860) 565-7700.
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.
(h) This amendment becomes effective on April 4, 1997.
Issued in Burlington, Massachusetts, on January 13, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 97-1700 Filed 1-31- 97; 8:45 am]
BILLING CODE 4910-13-P
