[Federal Register Volume 64, Number 184 (Thursday, September 23, 1999)]
[Proposed Rules]
[Pages 51484-51486]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-24787]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-69-AD]
RIN 2120-AA64


Airworthiness Directives; CFE Company Model CFE738-1-1B 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 CFE Company model CFE738-1-1B turbofan 
engines, that would have required a one-time dimensional inspection of 
the curvic coupling tooth profile of certain high pressure compressor 
(HPC) rotor

[[Page 51485]]

components to check for machining mismatches in the curvic coupling in 
specific engines and, if necessary, replacement with serviceable parts. 
That proposal was prompted by reports of machining mismatches in 
certain HPC rotor components that may decrease the service life of 
these HPC parts. This action, based on subsequent material stress 
testing and analysis by CFE Company, revises the proposed rule by 
eliminating the dimensional inspection requirement and imposing new, 
reduced life limits for certain HPC rotor components in all engines. 
The actions specified by this proposed AD are intended to prevent 
failure of certain HPC rotor components, which could result in an 
uncontained engine failure and damage to the airplane.

DATES: Comments must be received by November 22, 1999.

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-69-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``9-ane-
[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.
    The service information referenced in the proposed rule may be 
obtained from CFE Company, Data Distribution, M/S 64-03/2101-201, PO 
Box 52170, Phoenix, AZ 85072-2170; telephone (602) 365-2493, fax (602) 
365-5577. This information may be examined at the FAA, New England 
Region, Office of the Regional Counsel, 12 New England Executive Park, 
Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Keith Mead, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7744, fax (781) 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 98-ANE-69-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-69-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to CFE 
Company model CFE738-1-1B turbofan engines, was published as a notice 
of proposed rulemaking (NPRM) in the Federal Register on December 14, 
1998 (63 FR 68707). That NPRM would have required a one-time 
dimensional inspection of the curvic coupling tooth profile of certain 
high pressure compressor (HPC) rotor components installed on specific 
engines to check for machining mismatches in the curvic coupling, and, 
if necessary, replacement with serviceable parts. That NPRM was 
prompted by the determination that certain stage 4 and 5 blisks, 
impeller aft shafts, and impellers in specified engines may have 
machining mismatches in the curvic coupling tooth profiles. That 
condition, if not corrected, could result in failure of certain HPC 
rotor components, which could result in an uncontained engine failure 
and damage to the airplane.

Events Since Issuance of the NPRM

    Since the issuance of that NPRM, additional material stress testing 
indicates that the machining mismatch does not reduce cyclic life, as 
previously predicted by analysis. Therefore, the requirement for 
dimensional inspection of the curvic coupling tooth profile of the 
stage 4 and 5 blisk, impeller, and impeller aft shaft to check for 
machining mismatch can be removed. However, the additional testing 
indicates that for certain 4th and 5th stage blisks and impeller aft 
shafts the cyclic lives, for reasons not yet fully understood, are 
below previously predicted cyclic lives, independent of the presence of 
curvic coupling machining mismatches. Therefore, this proposal would 
reduce the cyclic life limits on certain stage 4 and 5 blisks and the 
impeller aft shafts.

Proposed Actions

    This AD would require removal from service of certain stage 4 and 5 
blisks and impeller aft shafts prior to exceeding new, reduced cyclic 
life limits, and replacement with serviceable parts. No parts in 
service at this time are near the reduced cyclic life limits. The 
manufacturer anticipates that the reduced limits may be increased based 
upon further testing and analysis.
    Since this change expands 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.

Economic Analysis

    There are approximately 245 engines of the affected design in the 
worldwide fleet. The FAA estimates that 156 engines would be affected 
by this proposed AD, that it would take approximately 10 work hours per 
engine if performed at a scheduled inspection, and 450 work hours if 
not performed at a scheduled inspection (applicable for 2 engines 
only). The average labor rate is $60 per work hour. Required parts, on 
a pro-rated basis, would cost approximately $13,613 per engine. Based 
on these figures, the total cost impact of the proposed AD on US 
operators is estimated to be $2,159,665.

Regulatory Impact

    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.

[[Page 51486]]

    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:

CFE Company: Docket No. 98-ANE-69-AD.

    Applicability: CFE Company Model CFE738-1-1B turbofan engines, 
installed on but not limited to the Dassault Aviation Falcon 2000 
series airplanes.

    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 failure of certain high pressure compressor (HPC) 
rotor components, which could result in an uncontained engine 
failure and damage to the airplane, accomplish the following:
    (a) Remove from service certain stage 4 and 5 blisks and 
impeller aft shafts prior to exceeding the new reduced cyclic life 
limits as follows, and replace with serviceable parts:

------------------------------------------------------------------------
                                                                 Cyclic
                                                                  Life
                                                                 Limit
            Nomenclature                  Part No. (P/N)        (cycles
                                                                 since
                                                                  new)
------------------------------------------------------------------------
Stage 4 and 5 Blisk................  6079T74P07                    2,370
                                     6079T74P08                    3,450
                                     6079T74P09                    3,790
Impeller Aft Shaft.................  6079T80P04                    5,100
                                     6079T80P05                    2,160
                                     6079T80P06                    7,100
                                     6079T80P07                    7,100
------------------------------------------------------------------------

    (b) Except for the provisions of paragraph (c) of this AD, no 
parts, identified by P/N in paragraph (a) of this AD, may be 
installed that exceed the new life limits.
    (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 (ECO). 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

    Issued in Burlington, Massachusetts, on September 16, 1999.
Donald E. Plouffe,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-24787 Filed 9-22-99; 8:45 am]
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