[Federal Register Volume 72, Number 77 (Monday, April 23, 2007)]
[Proposed Rules]
[Pages 20075-20078]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-7504]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27229; Directorate Identifier 2007-NE-03-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for CFM International, S.A. CFM56-7B Series Turbofan Engines. This 
proposed AD would require revising the Airworthiness Limitations 
Section (ALS) in the Engine Shop Manual (ESM) and the air carrier's 
approved continuous airworthiness maintenance program (CAMP) to add 
mandatory inspections of certain low pressure turbine rear frames 
(TRFs) to the ALS or CAMP. This proposed AD results from a refined 
lifing analysis by the engine manufacturer that shows the need to 
identify an initial threshold for inspecting certain TRFs. We are 
proposing this AD to prevent failure of the TRF from low-cycle fatigue 
cracks. Failure of the TRF could result in engine separation from the 
airplane, which could lead to loss of control of the airplane.

DATES: We must receive any comments on this proposed AD by June 22, 
2007.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    You may examine the comments on this proposed AD in the AD docket 
on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Colleen M. D'Alessandro, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803; 
telephone (781) 238-7133; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send us any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2007-27229; 
Directorate Identifier 2007-NE-03-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of the 
DOT Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78) or you 
may visit http://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the proposal, any comments 
received and, any final disposition in person at the DOT Docket Offices 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Office (telephone (800) 647-5227) is located on 
the plaza level of the Department of Transportation Nassif Building at 
the street address stated in ADDRESSES. Comments will be available in 
the AD docket shortly after the Docket Management Facility receives 
them.

Discussion

    This AD is required because TRFs, part numbers 340-166-205-0, 340-
166-206-0, 340-166-207-0, 340-166-208-0, 340-166-209-0, 340-166-210-0, 
now require an initial inspection threshold of 25,000 cycles-in-service 
(CIS) on the commercial (air carrier) models engines and 19,000 CIS on 
the business jet models. This proposed AD would not affect any other 
CFM56-7B part number TRFs. We have been monitoring CFM's revised life 
analysis progress since February 2005. CFM International provided to us 
the November 15, 2006 revision to the ESM to introduce mandatory 
inspections of the TRF. CFM International has been using a damage 
tolerant lifing approach, based on an FAA approved methodology for 
structural lifed components, to prepare life extensions for all CFM56 
TRFs using on-condition life management. This improved life management 
process defines a first inspection threshold and reinspection intervals 
accounting for crack initiation and propagation. The previous life 
management process was based on crack initiation only. This condition, 
if not corrected, could result in failure of the TRF from low-cycle 
fatigue cracks. Failure of the TRF could result in engine separation 
from the airplane, which could lead to loss of control of the airplane.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other products 
of this same type design. We are proposing this AD, which would require 
revising the Airworthiness Limitations Section in the ESM and the air 
carrier's approved continuing airworthiness maintenance program to 
incorporate life reductions for certain TRFs.

Costs of Compliance

    We estimate that this proposed AD would affect 1,228 engines 
installed on airplanes of U.S. registry. Since life extensions are 
possible on condition, the cost of the proposed AD will be limited to 
performing TRF inspections. We also estimate that it would take about 
3.0 work-hours per engine to perform the proposed actions, including

[[Page 20076]]

the TRF inspections, and that the average labor rate is $80 per work-
hour. There are no required parts. Based on these figures, we estimate 
the total cost of the proposed AD to U.S. operators to be $294,720.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect 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.
    For the reasons discussed above, I certify that the 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. Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD. See the ADDRESSES section for a location 
to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Under the authority delegated to me by the Administrator, the 
Federal Aviation Administration proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive:

CFM International: Docket No. FAA-2007-27229; Directorate Identifier 
2007-NE-03-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by June 22, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to CFM International CFM56-7B18, -7B20, -
7B22, -7B24, -7B26, -7B27, -7B22/B1, -7B24/B1, -7B26/B1, -7B27/B1, -
7B22/B2, -7B26/B2, -7B27/B3 turbofan engines with Turbine Rear Frame 
(TRF), part numbers 340-166-205-0, 340-166-206-0, 340-166-207-0, 
340-166-208-0, 340-166-209-0, 340-166-210-0, installed. These 
engines are installed on, but not limited to, Boeing 737 series 
airplanes.

Unsafe Condition

    (d) This proposed AD results from a refined lifing analysis by 
the engine manufacturer that shows the need to identify an initial 
threshold for inspecting certain TRFs. We are proposing this AD to 
prevent failure of the TRF from low-cycle fatigue cracks. Failure of 
the TRF could result in engine separation from the airplane, which 
could lead to loss of control of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within 30 days after the effective date of this AD, 
unless the actions have already been done.

Mandatory Inspections

    (f) Within the next 30 days after the effective date of this AD, 
revise the applicable inspection program for the Business Jet and 
Air Carrier engine models by adding the Mandatory Inspection 
Intervals as specified in this AD, and revise the Airworthiness 
Limitations Section (chapter 05-21-03) of the CFM56-7B Engine Shop 
Manual, CFMI-TP-SM.10 by adding the following:

``TURBINE REAR FRAME WITH TANGENTIAL STRUTS--MANDATORY 
INSPECTIONS--LIFE LIMITS

TASK 05-21-03-200-001

    1. General
    A. This procedure gives the FAA and EASA mandatory Eddy Current 
inspection intervals for the turbine rear frame with tangential 
struts. The inspection uses:

--A threshold limit,
--Inspection intervals,
    B. The threshold limit is the timing of the first required 
inspection. First inspection must be done before that part has 
reached the threshold number of flight cycles.
    C. The inspection intervals specify the timing of inspections to 
be done after the threshold inspection has been reached. Inspections 
are repetitive without any limit.
    2. Mandatory Inspection Intervals for the Critical Areas of the 
Turbine Rear Frame with Tangential Struts (4 Mount Struts, No. 1, 2, 
15, and 16).
    C. Turbine Rear Frame Part Numbers 340-166-205-0, 340-166-206-0, 
340-166-207-0, 340-166-208-0, 340-166-209-0, 340-166-210-0, for all 
CFM56-7B SAC engine models (except -7B27A engine models). Refer to 
figure 805.

----------------------------------------------------------------------------------------------------------------
                                              Inspection threshold   Inspection intervals
  Figure index No.     Inspection location     (cycles since new)          (cycles)        Inspection  reference
----------------------------------------------------------------------------------------------------------------
805................  Strut/outer ring        25,000* for -7B SAC    Refer to Figure 806*   Refer to SB 72-0579*.
                      fillet radius on        (except business       for -7B SAC
                      trailing edge (A).      jet) engine models.    commercial
                                                                     applications.
                     Strut/outer ring        19,000* for -7B SAC    Refer to Figure 807*
                      fillet radius on        business jet engine    for -7B SAC business
                      leading edge (B).       models.                jet applications.
                     Strut/outer ring
                      fillet radius on
                      trailing edge (C1
                      below outer ring).
                     Strut/outer ring
                      fillet radius on
                      trailing edge (C2
                      above outer ring) .
----------------------------------------------------------------------------------------------------------------
Note: * Applicable to all inspection locations. If inspection is not performed, part must be removed.


[[Page 20077]]

[GRAPHIC] [TIFF OMITTED] TP23AP07.004

Turbine Rear Frame with Tangential struts P/N 340-166-205-0, 340-166-
206-0, 340-166-207-0, 340-166-208-0, 340-166-209-0, 340-166-210-0-Areas 
to Be Inspected

Figure 805,

MANDATORY INSPECTION INTERVAL FOR TURBINE REAR FRAME P/N 340-166-205/
206/207/208/209/210-0

    IF NO CRACK IS FOUND ON ANY OF THE FOUR MOUNT STRUTS, THE 
TURBINE REAR FRAME IS SERVICEABLE AND MUST BE RE-INSPECTED AT 4,700 
CYCLE REPETITIVE INTERVALS. IF CRACKS ARE FOUND ON THE MOUNT STRUTS, 
THE TRF MUST BE RE-INSPECTED ACCORDING TO THE FOLLOWING REPETITIVE 
INTERVALS

------------------------------------------------------------------------
  Total cumulated crack length at each
                location                        Re-inspect within
------------------------------------------------------------------------
L < 0.20 (5)...........................  4,700.
0.20 (5) <= L < 0.28 (7)...............  3,300.
0.28 (7) <= L < 0.39 (10)..............  1,300.
0.39 (10) <= L < 0.59 (15).............  700.
0.59 (15) <= L < 0.79 (20).............  120.
L >= 0.79 (20).........................  IMMEDIATELY REMOVE THE TURBINE
                                          FRAME.
------------------------------------------------------------------------


[[Page 20078]]

    DURING EACH INSPECTION, ALL THE LOCATIONS MUST BE INSPECTED. IF 
CRACKS ARE FOUND AT DIFFERENT LOCATIONS, THE REPETITIVE INSPECTION 
INTERVAL IS THE MINIMUM INTERVAL CORRESPONDING TO THE MAX. CUMULATED 
CRACK LENGTHS.

    NOTE: DIMENSIONS ARE IN INCHES WITH MILLIMETERS IN PARENTHESES.

Inspection Intervals for -7B SAC (Except Business Jet) Engine Models

Figure 806

MANDATORY INSPECTION INTERVAL FOR TURBINE REAR FRAME P/N 340-166-205/
206/207/208/209/210-0

    IF NO CRACK IS FOUND ON ANY OF THE FOUR MOUNT STRUTS, THE 
TURBINE REAR FRAME IS SERVICEABLE AND MUST BE RE-INSPECTED AT 3,300 
CYCLE REPETITIVE INTERVALS. IF CRACKS ARE FOUND ON THE MOUNT STRUTS, 
THE TRF MUST BE RE-INSPECTED ACCORDING TO THE FOLLOWING REPETITIVE 
INTERVALS

------------------------------------------------------------------------
  Total cumulated crack length at each
                location                        Re-inspect within
------------------------------------------------------------------------
L < 0.20 (5)...........................  3,300.
0.20 (5) <= L < 0.28 (7)...............  2,400.
0.28 (7) <= L < 0.39 (10)..............  900.
0.39 (10) <= L < 0.59 (15).............  500.
0.59 (15) <= L < 0.79 (20).............  80.
L >= 0.79 (20).........................  IMMEDIATELY REMOVE THE TURBINE
                                          FRAME.
------------------------------------------------------------------------

    DURING EACH INSPECTION, ALL THE LOCATIONS MUST BE INSPECTED. IF 
CRACKS ARE FOUND AT DIFFERENT LOCATIONS, THE REPETITIVE INSPECTION 
INTERVAL IS THE MINIMUM INTERVAL CORRESPONDING TO THE MAX. CUMULATED 
CRACK LENGTHS.

    NOTE: DIMENSIONS ARE IN INCHES WITH MILLIMETERS IN PARENTHESES.

Inspection Intervals for -7B SAC Business Jet Engine Models

Figure 807

    (g) After the effective date of this AD, we will not approve any 
alternative inspection intervals for these parts except as provided 
for in paragraph (j) of this AD.

TRFs With Unknown Cycles

    (h) If you can not establish the number of cycles accumulated 
since new, remove or inspect the TRF within 300 cycles-in-service 
after the effective date of this AD. The CFM56-7B ESM or CAMP 
contains information for inspecting the TRF.
    (i) You may install a TRF removed in paragraph (h) of this AD 
after the TRF passes an initial inspection for cracks. The CFM56-7B 
ESM or continuous airworthiness program contains information on 
inspecting the TRF.

Alternative Methods of Compliance

    (j) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Maintaining Records of the Mandatory Inspections

    (k) You have met the requirements of this AD by making the 
changes to the Engine Shop Manual as specified in paragraph (f) of 
this AD, and, for air carriers operating under part 121 of the 
Federal Aviation Regulations (14 CFR part 121), by modifying your 
continuous airworthiness maintenance plan to reflect those changes. 
You must maintain records of the mandatory inspections that result 
from those changes to the ALS according to the regulations governing 
your operation. You do not need to record each inspection as 
compliance to this AD. For air carriers operating under part 121, 
you may use the system established to comply with section 121.369.

Related Information

    (l) CFM International Service Bulletin CFM56-7B S/B 72-0579, 
Revision 1, Dated October 27, 2006, contains information about Eddy 
Current inspection.

    Issued in Burlington, Massachusetts, on April 13, 2007.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. E7-7504 Filed 4-20-07; 8:45 am]
BILLING CODE 4910-13-P