[Federal Register Volume 64, Number 92 (Thursday, May 13, 1999)]
[Rules and Regulations]
[Pages 25802-25804]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-11635]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-ANE-02; Amendment 39-11164; AD 99-10-11]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT8D-200 Series
Turbofan Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to Pratt & Whitney JT8D-200 series turbofan engines,
that currently requires periodic inspection of fan blades for locked
rotors and foreign object damage (FOD), unlocking of shrouds if
necessary, lubrication of fan blade shrouds, and dimensional
restoration of the fan blade leading edge. In addition, that AD
requires installation of improved design fan blades as terminating
action for the inspections. This AD will reduce the lubrication
interval, and require removal of rotors that experience repeat lockups
within 225 cycles in service. This supersedure is prompted by reports
of twenty-five fan blade failures to date. The actions specified by the
AD are intended to prevent fan blade failure, which can result in
damage to the aircraft.
DATES: Effective June 14, 1999. The incorporation by reference of
certain publications listed in the regulations is approved by the
Director of the Federal Register as of June 14, 1999.
ADDRESSES: The service information referenced in this AD may be
obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108;
telephone (860) 565-6600, fax (860) 565-4503. This information may be
examined at the Federal Aviation Administration (FAA), New England
Region, Office of the Regional Counsel, 12 New England Executive Park,
Burlington, MA 01803-5299; or at the Office of the Federal Register,
800 North Capitol Street, NW, suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Peter White, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7128, fax (617) 238-7199.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) by superseding airworthiness
directive (AD) 96-23-15, Amendment 39-9821 (61 FR 63706, December 2,
1996), applicable to certain Pratt & Whitney (PW) JT8D-200 series
turbofan engines, was published in the Federal Register on December 2,
1998 (63 FR 66500). That action proposed to require periodic inspection
of fan blades for locked rotors and foreign object damage (FOD),
unlocking of shrouds if necessary, lubrication of fan blade shrouds,
removal from service of fan rotors which experience repeat lockup
events within 225 cycles in service, and dimensional restoration of the
fan blade leading edge. In addition, that AD requires installation of
improved design fan blades as terminating action for the inspections.
Since the issuance of that AD, the FAA has received reports of 7
additional fan blade failures on engines that had been inspected in
accordance with the current AD, bringing the total of reported failures
to 25. The fan blades are failing as a result of high cycle fatigue.
Contributing factors are foreign object damage (FOD), leading edge
erosion, manufacturing discrepancies, and locked fan shrouds. These fan
blade failures indicate that the currently mandated fleet management
plan is insufficient.
The FAA has reviewed and approved the technical contents of PW
Alert Service Bulletin (ASB) No. A6241, Revision 2, dated June 29,
1998, that reduces the lubrication interval, and requires removal of
rotors that experience repeat lockups within 225 cycles in service
(CIS).
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Three commenters concur with the rule as proposed. Two of these are
already in compliance with the rule as proposed.
One commenter suggests that alternate method of compliance (AMOC)
approvals for ADs 95-12-19 and 96-23-15 should be applicable to this
AD, without requiring additional approval. The proposal only references
AMOC approvals to 95-12-19. The FAA does not agree. This AD represents
the third AD in a line of ADs addressing the fan blade shroud locking
problem on PW JT8D-200 engines. Normally when an AD supersedes a
previously issued AD, all AMOC approvals to the superseded AD cease on
the effective date of the superseding AD, and operators must either
comply with the requirements of the new AD or reapply for a new AMOC
approval. On further review of the issue
[[Page 25803]]
of whether previous AMOC approvals should be allowed to continue in
force, the FAA has determined that AMOC approvals for neither of the
previous ADs should be allowed to continue in force after the effective
date of this AD. The inspection requirements for ASB 6241, Rev. 2,
dated June 29, 1998, incorporated in this AD, differ significantly from
those of the current AD in that blades that experience repeat lockups
within 225 cycles must be removed. Therefore, the FAA has determined to
remove proposed paragraph (e) from the final rule. All AMOC approvals
issued for either AD 95-12-19 or AD 96-23-15 will cease on the
effective date of this AD.
One commenter believes that it is unnecessary to track repeat
lockups and remove from service rotors that experience repeat lockups
within 225 cycles, because the foreign object damage (FOD) checks and
lubrication of the shrouds address the root cause of the problem. The
FAA does not concur. Analysis of fan blade fracture events revealed a
strong correlation between repeat lockup histories and subsequent
fractures. The requirement to track lockup events and remove rotors
which experience repeat lockups within 225 cycles is a key part of the
fleet management proposal, and is required to provide the full safety
benefit of this proposal. A statement clarifying the requirement to
remove rotors from service per Part 3 of ASB6241 rev. 2 was added to
paragraph (a) of this AD. Previously this was stated directly only in
the Summary and Supplementary Information sections of the AD. Since
comments indicate that operators implied that to be the case, this
addition to paragraph (a) does not expand the scope of the AD or add
any additional burden to operators.
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 adoption of the rule as proposed.
There are approximately 2,650 engines of the affected design in the
worldwide fleet. The FAA estimates that 960 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, that
it would take no additional work hours to perform these inspections
except at a shorter lubrication interval. Rework costs for the fan
blades are $275 per blade, of which approximately $140 per blade is
attributable to this AD action. With the manufacturer's rebate of $50
per blade, the total cost to industry of reworking these blades is
$2,750 per engine.
The manufacturer estimates that it will take 19 work hours per
engine to remove and reinstall the blades. Using labor costs of $60 per
work hour, the labor costs to remove and reinstall the blades are
$1,140 per engine. Hence, the increased costs generated by this
proposed AD on U.S. operators is estimated to be $3,890 per engine, or
$3,734,400 to retrofit the remaining 960 engines.
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 removing Amendment 39-9821 (61 FR
63706, December 2, 1996) and by adding a new airworthiness directive,
Amendment 39-11164, to read as follows:
99-10-11
Pratt & Whitney: Amendment 39-11164. Docket 96-ANE-02. Supersedes AD
96-23-15, Amendment 39-9821.
Applicability: Pratt & Whitney (PW) Models JT8D-209, -217, -
217A, -217C, and -219 turbofan engines that have not incorporated PW
Service Bulletin (SB) No. 6193, dated October 31, 1994, or with fan
blades, Part Numbers (P/N's) 798821, 798821-001, 808121, 808121-001,
809221, 811821, 851121, 851121-001, 5000021-02, 5000021-022, and
5000021-032 installed. These engines are installed on but not
limited to McDonnell Douglas MD-80 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 (f) 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 fan blade failure, which can result in damage to the
aircraft, accomplish the following:
(a) Inspect fan blades and shrouds, unlock fan blade shrouds,
lubricate fan blade shrouds, restore leading edge dimensions, remove
from service those fan rotors which experience repeat lockup events
within 225 cycles, and modify or install improved design fan blades
in accordance with the schedule and procedures described in Parts 1,
2, and 3 of the Accomplishment Instructions of PW Alert Service
Bulletin (ASB) No. A6241, Revision 2, dated June 29, 1998.
(b) Modification of fan blades to the improved design
configuration or installation of improved design fan blades in
accordance with Part 3 of the Accomplishment Instructions of PW ASB
No. A6241, Revision 2, dated June 29, 1998, constitutes terminating
action to the inspections and maintenance actions described in
paragraph (a) of this AD.
(c) For the purpose of this AD, the accomplishment effective
date to be used for determination of compliance intervals, as
required by Section 2 of PW ASB No. A6241, Revision 2, dated June
29, 1998, is defined as the effective date of this AD.
(d) For the purpose of this AD, ``repair'' as specified in Part
3, Paragraph A. (1)(b) of the Accomplishment Instructions of PW ASB
No. A6241, Revision 2, dated June 29, 1998 is defined as the
modification of fan blades to incorporate the revised shroud angle,
cutback the leading edge, and restore leading edge dimensions in
accordance with Part 3, Paragraph C of the Accomplishment
[[Page 25804]]
Instructions of PW ASB No. A6241, Revision 2, dated June 29, 1998.
(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 method of compliance with this AD, 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 accomplished in
accordance with the following Pratt & Whitney ASB:
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Document No. Pages Revision Date
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A6241.............................. 1-14 Rev. 2........................... June 29, 1998.
Total pages: 14.
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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, Publication
Department, Supervisor Technical Publications Distribution, M/S 132-
30, 400 Main St., East Hartford, CT 06108; telephone (860) 565-7700,
fax (860) 565-4503. Copies may be inspected at the FAA, New England
Region, Office of the Regional 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 June 14, 1999.
Issued in Burlington, Massachusetts, on May 4, 1999.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate,
Aircraft Certification Service.
[FR Doc. 99-11635 Filed 5-12-99; 8:45 am]
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