Airworthiness Directives; CFM International, S.A. CFM56-7B Series Turbofan Engines

[Federal Register Volume 63, Number 200 (Friday, October 16, 1998)]
[Rules and Regulations]
[Pages 55504-55506]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-27464]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-65-AD; Amendment 39-10831, AD 98-21-23]
RIN 2120-AA64


Airworthiness Directives; CFM International, S.A. CFM56-7B Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to CFM International, S.A. (CFMI) CFM56-7B series 
turbofan engines. This action supersedes telegraphic AD T98-18-51 that 
currently requires an inspection of electronic engine control (EEC) 
fault messages on both engines for the presence of any of the 
hydromechanical unit (HMU) fuel metering valve (FMV) signal faults 
identified in the All Operators Wire every 20 flight cycles or 3 
calendar days, whichever occurs first, and, if necessary, removing the 
HMU and replacing it with a serviceable HMU. This action also requires 
installation of improved EEC software that constitutes terminating 
action to the repetitive fault message inspections. This amendment is 
prompted by development of improved EEC software that obviates the need 
for the repetitive fault message inspections. The actions specified by 
this AD are intended to prevent an uncommanded engine acceleration 
event, or inflight engine shutdown.

DATES: Effective November 2, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 2, 1998.
    Comments for inclusion in the Rules Docket must be received on or 
before December 15, 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-65-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.
    The service information referenced in this AD may be obtained from 
CFM International, S.A., 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; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.

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: On August 28, 1998, the Federal Aviation 
Administration (FAA) issued telegraphic airworthiness directive (AD) 
T98-18-51, applicable to CFM International, S.A. (CFMI) CFM56-7B series 
turbofan engines, which requires an inspection of electronic engine 
control (EEC) fault messages on both engines for the presence of any of 
the hydromechanical unit (HMU) fuel metering valve (FMV) signal faults 
identified in the all operators wire every 20 flight cycles or 3 
calendar days, whichever occurs first. If any of the HMU FMV signal 
faults identified in CFMI All Operators Wire 98/CFM/312R1, dated August 
28, 1998, are detected on only one of the engines, that AD requires, 
prior to further flight, removal from service of the HMU and 
replacement with a serviceable HMU. If any of the HMU FMV signal faults 
identified in the All Operators Wire are detected on both engines, that 
AD requires removing the HMU and replacing it with a serviceable HMU, 
prior to further flight, on the engine that

[[Page 55505]]

has logged the faults for the most flight cycles; and after 
accumulating at least three flight cycles, but not to exceed ten flight 
cycles, removing the HMU and replacing it with a serviceable HMU on the 
other engine.
    That action was prompted by reports of 3 uncommanded engine 
acceleration events, one of which resulted in an inflight engine 
shutdown. The cause of the uncommanded acceleration events has been 
attributed to faults in channel B of the HMU FMV resolver. The 
investigation has not yet identified the root cause for these faults on 
all three events. Under current time-limited dispatch (TLD) guidelines, 
these faults are classified as short or long time dispatch faults, and 
therefore, they are not annunciated in the cockpit. A review of the EEC 
non-volatile memory following these events has indicated that the 
faults had been present for previous flight cycles. These faults were 
not detected under the current TLD guidelines. Therefore, the FAA has 
determined that these faults need to be reclassified as no dispatch 
faults, and that the inspection frequency must be increased. That 
condition, if not corrected, could result in an uncommanded engine 
acceleration event, or inflight engine shutdown.
    Since the issuance of that telegraphic AD, the manufacturer has 
developed improved EEC software that changes the dispatch level for the 
HMU FMV signal faults identified in the All Operators Wire to engine 
control light level/no dispatch.
    The FAA has reviewed and approved the technical contents of CFMI 
CFM56-7B All Operators Wire 98/CFM/312R1, dated August 28, 1998, that 
describes procedures for inspection for the presence of engine EEC 
fault messages; and CFM56-7B Alert Service Bulletin (ASB) No. 73-A024, 
dated September 2, 1998, that describes procedures for installation of 
the improved software.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other engines of this same type design, this AD 
supersedes telegraphic AD T98-18-51 to require installation of improved 
EEC software, within 75 cycles in service (CIS) after the effective 
date of this AD, or by November 9, 1998, whichever occurs first. The 
calendar end-date was determined based upon risk analysis. Installation 
of this improved software constitutes terminating action to the 
repetitive fault message inspections required by this AD. The actions 
are required to be accomplished in accordance with the ASB described 
previously.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD 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-65-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, 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 adding the following new 
airworthiness directive:

98-21-23  CFM International, S.A.: Amendment 39-10831. Docket No. 
98-ANE-65-AD. Supersedes telegraphic AD T98-18-51.

    Applicability: CFM International, S.A. (CFMI) CFM56-7B series 
turbofan engines, with electronic engine control (EEC) software, 
part numbers (P/Ns) 1853M78P07, 1853M78P08, 1853M78P10, or 
1853M78P11 installed. These engines are installed on, but not 
limited to Boeing 737-600, 737-700, and 737-800 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 (d) 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.

[[Page 55506]]

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an uncommanded engine acceleration event, or inflight 
engine shutdown, accomplish the following:
    (a) Inspect for the presence of engine EEC fault messages for 
both engines installed on the aircraft within 20 flight cycles after 
the effective date of this AD, or within three calendar days, 
whichever occurs first, in accordance with CFM56-7B All Operators 
Wire 98/CFM/312R1, dated August 28, 1998.
    (1) If any of the faults identified in the All Operators Wire 
are detected on only one of the engines, remove and replace the 
hydromechanical unit (HMU) with a serviceable HMU, and ensure the 
faults are cleared prior to further flight.
    (2) If any of the faults identified in the All Operators Wire 
are detected on both engines, remove and replace the HMU on the 
engine that has logged the fault for more flight cycles, replace 
with a serviceable HMU, and ensure that the faults are cleared prior 
to further flight. Remove and replace the HMU on the other engine 
with a serviceable HMU, after accumulating at least three flight 
cycles, but not to exceed ten flight cycles, and ensure the faults 
are cleared.
    (3) Thereafter, inspect for the presence of engine EEC fault 
messages on both engines of the aircraft at intervals not to exceed 
20 flight cycles since last inspection, or within three calendar 
days since last inspection, whichever occurs first. If any of the 
faults identified in the All Operators Wire are detected, remove and 
replace the HMU in accordance with paragraph (a)(1) or (a)(2) of 
this AD, as applicable.

    Note 2: Installation of a serviceable HMU in accordance with 
paragraphs (a)(1) or (a)(2) of this AD does not constitute 
terminating action to the repetitive inspections required by 
paragraph (a)(3) of this AD.

    (b) For the purpose of this AD, a serviceable HMU is defined as 
an HMU with P/N 1853M56P06 or AlliedSignal P/N 442098.
    (c) Within 75 cycles in service after the effective date of this 
AD, or by November 9, 1998, whichever occurs first, install EEC 
software, P/N 1853M78P12, in accordance with CFMI CFM56-7B Alert 
Service Bulletin (ASB) No. 73-A024, dated September 2, 1998. 
Installation of this improved software constitutes terminating 
action to the inspections required by paragraph (a) of this AD.
    (d) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (e) The actions required by this AD shall be accomplished in 
accordance with the following CFMI service documents:

------------------------------------------------------------------------
           Document No.                  Page                Date
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All Operators Wire 98/CFM/312R1..  1-2.............  August 28, 1998.
    Total Pages                    2...............  ...................
CFM56-7B ASB No. 73-A024.........  1-23............  September 2, 1998.
    Total Pages                    23
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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 CFM International, S.A., Technical 
Publications Department, 1 Neumann Way, Cincinnati, OH 45215; 
telephone (513) 552-2981, fax (513) 552-2816. 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.
    (f) This amendment supersedes telegraphic AD T98-18-51, issued 
August 28, 1998.
    (g) This amendment becomes effective on November 2, 1998.

    Issued in Burlington, Massachusetts, on October 6, 1998.
Ronald L. Vavruska,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 98-27464 Filed 10-15-98; 8:45 am]
BILLING CODE 4910-13-U

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