Airworthiness Directives; CFM International CFM56-5C Series Turbofan Engines

[Federal Register Volume 62, Number 84 (Thursday, May 1, 1997)]
[Rules and Regulations]
[Pages 23642-23643]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-11298]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-ANE-64; Amendment 39-9998; AD 97-09-02]
RIN 2120-AA64


Airworthiness Directives; CFM International CFM56-5C Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to CFM International CFM56-5C series turbofan engines, that 
requires a reduction of the low cycle fatigue (LCF) retirement lives 
for certain high pressure turbine rotor (HPTR) front shafts, HPTR front 
air seals, HPTR disks, booster spools, and low pressure turbine rotor 
(LPTR) stage 3 disks. This amendment is prompted by results of a 
refined life analysis performed by the manufacturer which revealed 
minimum calculated LCF lives lower than published LCF retirement lives. 
The actions specified by this AD are intended to prevent an LCF failure 
of the HPTR front shaft, HPTR front air seal, HPTR disk, booster spool, 
and LPTR stage 3 disk, which could result in an uncontained engine 
failure and damage to the aircraft.

DATES: Effective June 30, 1997.

FOR FURTHER INFORMATION CONTACT: Glorianne Messemer, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone (617) 238-7132, 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 CFM International (CFMI) CFM56-
5C2/G-5C3/G, and -5C4 series turbofan engines was published in the 
Federal Register on March 26, 1996 (61 FR 13110). That action proposed 
to require a reduction of the low cycle fatigue (LCF) retirement lives 
for certain high pressure turbine rotor (HPTR) front shafts, HPTR front 
air seals, HPTR disks, booster spools, and low pressure turbine rotor 
(LPTR) stage 3 disks.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    Two commenters object to the use of an AD to accomplish life limit 
changes, and suggest instead that operators incorporate the new limits 
into their FAA-approved maintenance programs. One commenter argues that 
the use of the AD process places unnecessary burdens on operators 
through additional record keeping. That commenter suggests 
alternatively that if the FAA does issue the AD, a new paragraph be 
added that states that incorporating the requirements of paragraphs (a) 
through (f) into an operator's maintenance program should be considered 
compliance with the AD and that after making that incorporation the AD 
would no longer apply. The FAA does not concur. Service life limits 
that appear as airworthiness limitations at the time of type 
certification can be changed to more restrictive limits only by way of 
rulemaking through an AD. A change to one operator's maintenance 
program alone will not mandate new, more restrictive, life limits for 
other operators. While these new limits may have appeared in service 
instructions or manuals before an AD is published, the FAA must 
complete the change by publishing the final rule AD. The FAA believes 
that recording the AD and its accomplishment is no more burdensome on 
operators than making changes to their maintenance program to 
specifically incorporate the same changes. Under the commenter's 
proposal, additional record keeping may be necessary to ensure that 
purchasers or other users of that operator's aircraft, who may not have 
FAA-approved maintenance programs, comply with the new, more 
restrictive limits. The FAA also does not concur with the commenter's 
proposed new paragraph which provides that once the changes are 
incorporated into a maintenance program the requirements of the AD 
would no longer apply, including the requirement that the changes may 
not be further adjusted without FAA approval. The FAA believes that 
these changes to life limits must be finalized in the form of an AD, 
and that no changes to the proposed AD are necessary.
    Two commenters note that the booster spool life of 13,800 cycles 
identified in paragraph (d) of the AD is 1,200 cycles since new (CSN) 
less that the Chapter 05 life noted in Revision 3 of the CFM56-5C 
Engine Shop Manual (ESM), dated December 1, 1995. The FAA does not 
concur. An initial booster spool life for the CFM56-5C2/G, -5C3/G, and 
-5C4 series engines of 13,900 CSN was introduced by Temporary Revision 
(TR) TR-05-003, dated October 7, 1994. Temporary Revision TR-05-007, 
dated October 28, 1994, reduced the life to 13,000 CSN. The FAA has 
revised paragraph (d) of this final rule to state a life of 13,000 CSN 
to be consistent with current published life.
    Two commenters note that the LPTR stage 3 disk life of 8,630 cycles 
identified in paragraph (e) of the AD is 930 CSN higher than the 
Chapter 05 life stated in Revision 3 of the CFM56-5C ESM, dated 
December 1, 1995. The FAA does not concur. An initial LPTR stage 3 disk 
life for the CFM56-5C2/G, -5C3/G, and -5C4 series engines of 9,200 CSN 
was introduced by TR-05-004, dated October 7, 1994. Temporary Revision 
TR-05-008, dated October 28, 1994, reduced the life to 7,000 CSN. The 
FAA has revised paragraph (e) of this final rule to state a life of 
7,000 CSN to be consistent with the current published life.
    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 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 10 engines of the affected design in the 
worldwide fleet. The manufacturer has advised the FAA that there are no 
engines installed on U.S. registered aircraft that would be affected by 
this AD. Therefore, there is no associated cost impact on U.S. 
operators as a result of this AD. However, should an affected engine be 
imported on an aircraft and placed on the U.S. registry in the future, 
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 $25,736 per engine. Based on these figures, the 
total cost impact of the AD is estimated to be $25,736 per engine.
    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,

[[Page 23643]]

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, 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:

97-09-02  CFM International: Amendment 39-9998. Docket 95-ANE-64.

    Applicability: CFM International (CFMI) CFM56-5C2/G, -5C3/G, and 
-5C4 series turbofan engines, installed on but not limited to Airbus 
A340 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 (h) 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 (LCF) failure of the high 
pressure turbine rotor (HPTR) front shaft, HPTR front air seal, HPTR 
disk, booster spool, and low pressure turbine rotor (LPTR) stage 3 
disk, which could result in an uncontained engine failure and damage 
to the aircraft, accomplish the following:
    (a) Remove from service HPTR front shafts, Part Numbers (P/N's) 
1498M40P03, 1498M40P05, and 1498M40P06, prior to accumulating 8,400 
cycles since new (CSN), and replace with a serviceable part.
    (b) Remove from service HPTR front air seals, P/N's 1523M34P02 
and 1523M34P03, prior to accumulating 4,000 CSN, and replace with a 
serviceable part.
    (c) Remove from service HPTR disks, P/N 1498M43P04, prior to 
accumulating 6,200 CSN, and replace with a serviceable part.
    (d) Remove from service booster spools, P/N 337-005-210-0, prior 
to accumulating 13,000 CSN, and replace with a serviceable part.
    (e) Remove from service LPTR stage 3 disks, P/N's 337-001-602-0 
and 337-001-605-0, prior to accumulating 7,000 CSN, and replace with 
a serviceable part.
    (f) This action establishes the new LCF retirement lives stated 
in paragraphs (a) through (e) of this AD, which are published in 
Chapter 05 of the CFM56-5C Engine Shop Manual, CFMI-TP.SM.8.
    (g) For the purpose of this AD, a ``serviceable part'' is one 
that has not exceeded its respective new life limit as set out in 
this AD.
    (h) 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.

    (i) 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.
    (j) This amendment becomes effective on June 30, 1997.

    Issued in Burlington, Massachusetts, on April 22, 1997.
Robert E. Guyotte,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 97-11298 Filed 4-30-97; 8:45 am]
BILLING CODE 4910-13-U

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