[Federal Register Volume 63, Number 174 (Wednesday, September 9, 1998)]
[Proposed Rules]
[Pages 48140-48141]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-24185]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-ANE-36-AD]
RIN 2120-AA64
Airworthiness Directives; Williams International FJ44-1A Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to Williams International FJ44-1A
turbofan engines. This proposal would require removing the high
pressure turbine (HPT) disk from service prior to accumulating a
reduced cyclic life limit of 1,900 cycles since new (CSN) and replacing
with a serviceable disk. As an option, the HPT nozzle can be modified
thereby increasing the HPT disk cyclic life limit from the new reduced
cyclic life limit. This proposal is prompted by a revised life analysis
conducted by the manufacturer after the failure of a similarly designed
HPT disk. The actions specified by the proposed AD are intended to
prevent HPT disk rim failure, which could result in an uncontained
engine failure and damage to the aircraft.
DATES: Comments must be received by November 9, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 98-ANE-36-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``9-ad-
[email protected]''. Comments sent via the Internet must contain
the docket number in the subject line. Comments may be inspected at
this location between 8:00 a.m. and 4:30 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Patricia Bonnen, Aerospace Engineer,
Chicago Aircraft Certification Office, FAA, Small Airplane Directorate,
2300 East Devon Avenue, Des Plaines, IL 60018; telephone (847) 294-
7134, fax (847) 294-7834.
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 98-ANE-36-AD.'' 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 Regional Counsel,
Attention: Rules Docket No. 98-ANE-36-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
Williams International, manufacturer of FJ44-1A turbofan engines,
recently conducted a revised life limit analysis of high pressure
turbine (HPT) disks, part number (P/N) 55291. This revised analysis was
prompted by the failure of a similarly designed HPT disk. The revised
analysis revealed that the calculated low cycle fatigue lives are
significantly lower than the current published maximum approved service
lives. To this date no failures of HPT disk, P/N 55291, have been
reported. This condition, if not corrected, could result in HPT disk
rim failure, which could result in an uncontained engine failure and
damage to the aircraft.
Williams International has also published service information which
authorizes certain modifications to the
[[Page 48141]]
HPT nozzle assembly and subsequent reidentification of the HPT disk and
assembly. Incorporation of these modifications increases the approved
service life limit from the new reduced service life.
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would require removing the HPT disk from service prior to
accumulating a reduced cyclic life limit of 1,900 cycles since new
(CSN) and replacing with a serviceable disk.
There are approximately 223 engines of the affected design in the
worldwide fleet. The FAA estimates that 165 engines installed on
aircraft of U.S. registry would be affected by this proposed AD. The
cost of removing a disk earlier than the original life-limit rather
than reworking the disk is $12,546 per engine. The costs of reworking
the HPT nozzle assembly to obtain increased HPT life are substantially
less than the costs of replacement of the HPT disk. Based on these
figures, the total cost impact of the proposed AD on U.S. operators is
estimated to be $2,070,090 assuming all disks are replaced. The actual
total cost to U.S. operators, however, will be less depending on how
many operators exercise the rework option. In addition, the
manufacturer may reimburse operators for the costs of removing disks
earlier than the original life limit reducing even further the total
cost impact for U.S. operators.
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 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Williams International: Docket No. 98-ANE-36-AD.
Applicability: Williams International FJ44-1A turbofan engines,
installed on but not limited to Cessna 525 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 (c) 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 high pressure turbine (HPT) disk rim failure, which
could result in an uncontained engine failure and damage to the
aircraft, accomplish the following:
(a) Prior to accumulating 1,900 cycles since new (CSN), remove
from service HPT disk, part number (P/N) 55291, and replace with a
serviceable part.
(b) As an option to paragraph (a), modify the HPT nozzle
assembly and remark the HPT disk and assembly with new part numbers
in accordance with Williams International Service Bulletin FJ44-72-
36, dated October 21, 1997.
Note 2: The low cycle fatigue retirement lives for the HPT disks
remarked with new part numbers in accordance with paragraph (b) of
this AD may be found in Williams SB FJ44-A-72-38, dated October 21,
1997.
(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, Chicago Aircraft Certification
Office. Operators shall submit their request through an appropriate
FAA Principal Maintenance Inspector, who may add comments and then
send it to the Manager, Chicago Aircraft Certification Office.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Chicago Aircraft Certification
Office.
(d) Thereafter, except as provided in paragraph (c) of this AD,
no alternative replacement times or life limits may be approved for
HPT disk, P/N 55291.
(e) 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 September 2, 1998.
Donald E. Plouffe,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 98-24185 Filed 9-8-98; 8:45 am]
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