[Federal Register Volume 63, Number 181 (Friday, September 18, 1998)]
[Proposed Rules]
[Pages 49879-49881]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-25008]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-56-AD]
RIN 2120-AA64


Airworthiness Directives; CFM International CFM56-5 Series 
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 CFM International CFM56-5 series 
turbofan engines. This proposal would reduce the low cycle fatigue 
(LCF) retirement lives for certain high pressure turbine rotor (HPTR) 
front air seals, and provide a drawdown schedule for those affected 
parts with reduced LCF retirement lives. This proposal is prompted by 
results of a refined life analysis performed by the manufacturer that 
revealed minimum calculated LCF lives significantly lower than the 
published LCF retirement lives. The actions specified by the proposed 
AD are intended to prevent a LCF failure of the HPTR front air seal, 
which could result in an uncontained engine failure and damage to the 
aircraft.

DATES: Comments must be received by October 19, 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-56-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.
    The service information referenced in the proposed rule may be 
obtained from CFM International, Technical Publications Department, 1 
Neumann Way, Cincinnati, OH 45215; telephone (513) 552-2981, fax (513) 
552-2816. 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: Robert Ganley, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7138; 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-56-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-56-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    During a routine engine shop visit, a crack was detected in a CFM 
International CFM56-5 high pressure turbine rotor (HPTR) front air 
seal. Investigation revealed that the crack initiated from a nick in 
the scallop fillet. Review of the manufacturing records revealed 
documented surface nicks in the scallop area of the cracked seal, as 
well as three other seals. As a precaution, these three additional 
seals were removed from service. As part of this investigation, CFM 
International also performed a study using updated lifing analyses that 
revealed that certain

[[Page 49880]]

HPTR front air seals have minimum calculated low cycle fatigue (LCF) 
lives that are significantly lower than published LCF retirement lives. 
This condition, if not corrected, could result in a LCF failure of the 
HPTR front air seal, which could result in an uncontained engine 
failure and damage to the aircraft.
    The FAA has reviewed and approved the technical contents of CFM 
International CFM56-5 Service Bulletin (SB) No. 72-541, dated July 
27,1998, that describes the drawdown schedule for those affected parts 
with reduced LCF retirement lives.
    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 reduce the LCF retirement lives for certain HPTR 
front air seals, and provide a drawdown schedule for those affected 
parts with reduced LCF retirement lives. The actions would be required 
to be accomplished in accordance with the SB described previously.
    There are approximately 863 engines of the affected design in the 
worldwide fleet. The FAA estimates that 131 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, and 
that it would not take any additional work hours per engine to 
accomplish the proposed actions. Assuming that the parts cost is 
proportional to the reduction of the LCF retirement lives, the required 
parts would cost approximately $14,000 per engine. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $1,834,000.
    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:

CFM International: Docket No. 98-ANE-56-AD.

    Applicability: CFM International CFM56-5 series turbofan engines 
installed on, but not limited to, Airbus A319 and A320 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 (g) 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 a low cycle fatigue failure of the high pressure 
turbine rotor (HPTR) front air seal, which could result in an 
uncontained engine failure and damage to the aircraft, accomplish 
the following:
    (a) Remove from service CFM International CFM56-5-A1 and -5-A1/F 
HPTR front air seals, Part Number (P/N) 1319M11P06, 1319M11P07, 
1319M11P08, and 1319M11P09, and CFM56-5-A1 HPTR front air seals, P/N 
1319M11P05, and replace with a serviceable part, in accordance with 
CFM56-5 Service Bulletin (SB) No. 72-541, dated July 27, 1998, as 
follows:
    (1) For seals that have accumulated less than 4,000 cycles since 
new (CSN) on the effective date of this AD, remove the seal from 
service prior to accumulating 11,000 CSN.
    (2) For seals that have accumulated 4,000 CSN or more, but less 
than 11,000 CSN on the effective date of this AD, accomplish the 
following:
    (i) For engines that have an engine shop visit (ESV) prior to 
the seal accumulating 11,000 CSN, remove the seal from service prior 
to the seal accumulating 11,000 CSN.
    (ii) For engines that do not have an ESV prior to the seal 
accumulating 11,000 CSN, remove the seal from service prior to the 
seal accumulating 7,000 cycles in service (CIS) after the effective 
date of this AD, or prior to the seal accumulating 15,300 CSN, 
whichever occurs first.
    (3) For seals that have accumulated 11,000 CSN or more on the 
effective date of this AD, remove the seal from service at the next 
ESV, or prior to the seal accumulating 15,300 CSN, whichever occurs 
first.
    (b) Remove from service CFM International CFM56-5A3 HPTR front 
air seals, P/N 1319M11P06, 1319M11P07, 1319M11P08, and 1319M11P09, 
and replace with a serviceable part, in accordance with CFM56-5 SB 
No. 72-541, dated July 27, 1998, as follows:
    (1) For seals that have accumulated less than 3,000 CSN on the 
effective date of this AD, remove the seal from service prior to 
accumulating 7,700 CSN.
    (2) For seals that have accumulated 3,000 CSN or more, but less 
than 7,700 CSN on the effective date of this AD, accomplish the 
following:
    (i) For engines that have an ESV prior to the seal accumulating 
7,700 CSN, remove the seal from service prior to the seal 
accumulating 7,700 CSN.
    (ii) For engines that do not have an ESV prior to the seal 
accumulating 7,700 CSN after the effective date of the AD, remove 
the seal from service prior to the seal accumulating 4,700 CIS after 
the effective date of this AD, or prior to the seal accumulating 
13,000 CSN, whichever occurs first.
    (3) For seals that have accumulated 7,700 CSN or more on the 
effective date of this AD, remove the seal from service at the next 
ESV, or prior to the seal accumulating 13,000 CSN, whichever occurs 
first.
    (c) For CFM56-5A4, -5A4/F, -5A5, and -5A5/F HPTR front air 
seals, P/N 1319M11P05, 1319M11P06, 1319M11P07, 1319M11P08, and 
1319M11P09, that have previously operated in CFM56-5-A1, -5-A1/F, or 
-5A3 engine models, recalculate the HPTR front air seal total cycles 
remaining using 11,000 cycles for the CFM56-5-A1 and CFM56-5-A1/F 
engine models, and 7,700 cycles for the CFM56-5A3 engine model, in 
accordance with CFM56-5 SB No. 72-541, dated July 27, 1998, within 
750 CIS after the effective date of this AD.

    Note 2: The current HPTR front air seal life for the CFM56-5A4, 
-5A4/F, -5A5, and -5A5/F engine models is 9,100 cycles, and is not 
affected by this AD.
    Note 3: For additional information on recalculating the HPTR 
front air seal total cycles remaining see Chapter 05, Section 05-11-
00, of the CFM56-5 series Engine Shop Manual, CFMI-TP.SM.7.

    (d) This AD establishes new LCF retirement lives of 11,000 
cycles for CFM56-

[[Page 49881]]

5-A1 and -5-A1/F HPTR front air seals, and 7,700 cycles for CFM56-
5A3 HPTR front air seals, which is published in Chapter 05, Section 
05-11-03, of the CFM56-5 series Engine Shop Manual, CFMI-TP.SM.7. 
The following conditions also apply:
    (1) Except as provided in paragraph (g) of this AD, no 
alternative retirement lives may be approved for the CFM56-5-A1, -5-
A1/F, and -5A3 HPTR front air seals.
    (2) After the effective date of this AD, no CFM56-5-A1 and -5-
A1/F HPTR front air seals may be installed or reinstalled on an 
engine if the seals have accumulated more than 11,000 CSN.
    (3) After the effective date of this AD, no CFM56-5A3 HPTR front 
air seals may be installed or reinstalled on an engine if the seals 
have accumulated more than 7,700 CSN.
    (e) For the purpose of this AD, an ``engine shop visit'' is 
defined as the induction of an engine into the shop for maintenance 
involving the separation of any major mating engine flanges, or the 
removal of a disk or spool, except that the separation of engine 
flanges solely for the purposes of transportation without subsequent 
engine maintenance does not constitute an engine shop visit.
    (f) For the purpose of this AD, a ``serviceable part'' is 
defined as one that has not exceeded its respective new life limit 
as set out in this AD.
    (g) 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. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (h) 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 11, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 98-25008 Filed 9-17-98; 8:45 am]
BILLING CODE 4910-13-P