[Federal Register Volume 71, Number 239 (Wednesday, December 13, 2006)]
[Proposed Rules]
[Pages 74873-74878]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-9674]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23871; Directorate Identifier 2006-NE-01-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company (GE) CF6-80C2 
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 GE CF6-80C2 series turbofan engines. This proposed AD would require 
replacing certain installed part number (P/N) and serial number (SN) 
cast titanium weld-repaired forward engine mount platforms and cast 
titanium forward mount yokes, with a forged titanium or a non-welded 
cast titanium part. This proposed AD results from the discovery of 
cracks, in a weld-repaired area on a forward engine mount platform and 
a forward engine mount yoke, found during a fluorescent penetrant 
inspection (FPI). These parts were weld-repaired during manufacture. We 
are proposing this AD to prevent cracks in the forward engine mount 
platform and forward engine mount yoke that could result in possible 
separation of the engine from the airplane.

DATES: We must receive any comments on this proposed AD by January 12, 
2007.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
     Fax: (202) 493-2251.
     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: James Lawrence, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; telephone (781) 238-
7176; 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-2006-23871; 
Directorate Identifier 2006-NE-01-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.

[[Page 74874]]

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 Office 
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

    During an FPI inspection of the forward engine mount platform and 
forward engine mount yoke, an air carrier found crack indications in 
the forward engine mount platform and yoke, and reported the findings 
to GE. An audit of GE's manufacturing records revealed 25 cast titanium 
forward engine mount platforms, including the one found cracked, and 59 
cast titanium forward engine mount yokes, had been weld-repaired at 
manufacture in either the pylon thrust pin hole or in the pylon attach 
bolt-hole region. Therefore, 25 cast titanium forward engine mount 
platforms and 59 cast titanium forward engine mount yokes would be 
affected by this proposed AD. Although the weld repairs were an 
approved GE practice at the time, it has since been determined that the 
welding results in cracking in critical areas of the forward engine 
mount platforms and yokes. This condition, if not corrected, could 
result in possible separation of the engine from 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 
replacing certain installed P/N and SN cast titanium weld-repaired 
forward engine mount platforms and cast titanium forward mount yokes 
with a forged titanium or a non-welded cast titanium part.

Costs of Compliance

    There are 25 engines in service that contain the substandard 
forward engine mount platforms and 59 engines in service that contain 
the substandard forward engine mount yokes. We estimate that this 
proposed AD would affect 84 CF6-80C2 engines installed on airplanes of 
U.S. registry. We estimate that it would take 34 work-hours per engine 
to replace the weld-repaired cast titanium forward engine mount 
platforms and the weld-repaired cast titanium forward engine mount 
yokes. The average labor rate is $80 per work-hour. Required forward 
engine mount parts would cost about $12,168 per engine. Required 
forward engine mount yoke parts would cost about $39,560 per engine. 
Based on these figures, we estimate the total cost of the proposed AD 
to U.S. operators to be $2,866,720.

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:

General Electric Company: Docket No. FAA-2006-23871; Directorate 
Identifier 2006-NE-01-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by January 12, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the following General Electric Company 
(GE) turbofan engines with cast titanium assembly engine mount 
platforms part numbers (P/Ns) 1292M13G06, 1301M28G08, 1459M70G07, 
and 1846M24G04 and cast titanium assembly engine mount yokes P/Ns 
9383M43G14 and 9383M43G16 installed.

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CF6-80C2A1...........................  CF6-80C2A8.............  CF6-80C2B4.............  CF6-80C2B4F
CF6-80C2A2...........................  CF6-80C2A5F............  CF6-80C2B6.............  CF6-80C2B5F
CF6-80C2A3...........................  CF6-80C2B1.............  CF6-80C2B1F............  CF6-80C2B6F
CF6-80C2A5...........................  CF6-80C2B2.............  CF6-80C2B2F............  CF6-80C2B6FA
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[[Page 74875]]

    These engines are installed on, but not limited to, Boeing 747, 
Boeing 767, and Airbus A300-600 airplanes.

Unsafe Condition

    (d) This AD results from the discovery of cracks in a forward 
engine mount platform and a forward engine mount yoke found during 
fluorescent penetrant inspection (FPI). We are issuing this AD to 
prevent cracks in the forward engine mount platform and forward 
engine mount yoke that could result in possible separation of the 
engine from the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.

P/N and SN Weld-Repaired Forward Engine Mount Platforms and Forward 
Engine Mount Yokes Requiring Replacement

    (f) Table 1 of this AD lists the P/Ns and serial numbers (SNs) 
of the weld-repaired forward engine mount platforms that have a weld 
repair in a non-redundant area of the mount and must be replaced.

    Table 1.--Weld-Repaired Forward Engine Mount Platforms Requiring
   Replacement That Have a Weld Repair in a Non-Redundant Area of the
                                 Mount.
------------------------------------------------------------------------
                            P/Ns                                 SNs
------------------------------------------------------------------------
1292M13G06 or 1846M24G04...................................     WACHH228
                                                                WACHH254
                                                                WACHH285
                                                                WACHH290
                                                                WACHH292
                                                                WACHH295
                                                                WACHH299
                                                                WACHH384
                                                                WACHH427
                                                                WACHH440
                                                                WACHH604
1301M28G08.................................................     WACAR292
                                                                WACAR354
------------------------------------------------------------------------

    (g) Table 2 of this AD lists the P/Ns and SNs of the weld-
repaired forward engine mount platforms that have a weld repair in a 
redundant area of the mount. Because it is impossible to detect 
whether the mount is operating on the redundant feature, each of 
these mounts must be replaced. The compliance time for mounts in 
this category can be longer than for the mounts listed in Table 1 of 
this AD.

    Table 2.--Weld-Repaired Forward Engine Mount Platforms Requiring
  Replacement That Have a Weld Repair in a Redundant Area of the Mount
------------------------------------------------------------------------
                            P/Ns                                 SNs
------------------------------------------------------------------------
1292M13G06 or 1846M24G04...................................     WACHH173
                                                                WACHH189
                                                                WACHH274
                                                                WACHH278
                                                                WACHH314
                                                                WACHH325
                                                                WACHH486
1301M28G08.................................................     WACAR294
                                                                WACAR304
                                                                WACAR353
                                                                WACAR372
1459M70G07.................................................     MTXT1282
------------------------------------------------------------------------

    (h) Table 3 of this AD lists the P/Ns and SNs of the weld-
repaired forward engine mount yokes that have a weld repair in a 
redundant area of the yoke. Because it is impossible to detect 
whether the mount yoke is operating on the redundant feature, each 
of these mount yokes must be replaced. The compliance time for 
mounts in this category can be longer than for the mounts listed in 
Table 1 of this AD.

Table 3.--Weld-Repaired Forward Engine Mount Yokes Requiring Replacement
       That Have a Weld Repair in a Non-Redundant Area of the Yoke
------------------------------------------------------------------------
                            P/Ns                                 SNs
------------------------------------------------------------------------
9383M43G14.................................................     WACV0388
                                                                WACV0394
                                                                WACV0405
                                                                WACV0406
                                                                WACV0477
                                                                WACV0498
                                                                WACV0529
                                                                WACV0556
                                                                WACV0579
                                                                WACV0581
                                                                WACV0582
                                                                WACV0600
                                                                WACV0605
                                                                WACV0617
                                                                WACV0625
                                                                WACV0627
                                                                WACV0633
                                                                WACV0645
                                                                WACV0683
                                                                WACV0703
                                                                WACV0733
                                                                WACV0737
                                                                WACV0759
                                                                WACV0775
                                                                WACV0791
                                                                WACV0799
                                                                WACV0875
                                                                WACV0883
                                                                WACV0885
                                                                WACV0909
                                                                WACV1097
                                                                WACV1615
                                                                WACV1713
                                                                WACV1753
                                                                WACV1797
                                                                WACV1867
                                                                WACV1987
                                                                WACV2131
                                                                WACV2159
                                                                WACV2185
                                                                WACV2343
                                                                WACV2511
                                                                WACV2695
                                                                WACV2707
                                                                WACV2881
                                                                WACV2899
9383M43G16.................................................     WACV0511
                                                                WACV0515
                                                                WACV0518
                                                                WACV0540
                                                                WACV0542
                                                                WACV0571
                                                                WACV0689
                                                                WACV0721
                                                                WACV0727
                                                                WACV0730
                                                                WACV0786
                                                                WACV0816
                                                                WACV0954
------------------------------------------------------------------------

    (i) GE advises that forward engine mount platform, P/Ns 
1292M13G06 and 1846M24G04, are the same, except that P/N 1846M24G04 
incorporates a previously approved field rework. This rework allows 
the thrust pin hole in the forward engine mount platform to be bored 
out to accept installation of an oversized thrust pin. GE cannot 
identify which SN goes with which P/N, but all SNs are affected.

Welded Cast Titanium Forward Engine Mount Platform and Forward Engine 
Mount Yoke Removal

    (j) If the P/N and SN of the forward engine mount platform 
listed in Table 1 and Table 2 and the forward engine mount yoke 
listed in Table 3 of this AD are not installed on the engine, no 
further action is necessary.
    (k) If the P/N and SN of the forward engine mount platform 
listed in Table 1 of this AD is installed on the engine:
    (1) Remove the forward engine mount platform from the engine 
within 500 cycles or 6 months, after the effective date of this AD, 
whichever occurs first.
    (2) Information for removal of the forward engine mount platform 
from the engine can be found in the CF6-80C2 Engine Manual, 72-00-
01, Disassembly.
    (l) If the P/N and SN of the forward engine mount platform 
listed in Table 2 of this AD is installed on the engine:
    (1) Remove the forward engine mount platform at the next shop 
visit, or within 4,800 cycles after the effective date of this AD, 
whichever occurs first.
    (2) Information for removal of the forward engine mount yoke can 
be found in the CF6-80C2 Engine Manual, 72-00-01, Disassembly.
    (m) If the P/N and SN of the forward engine mount yoke listed in 
Table 3 of this AD is installed on the engine:

[[Page 74876]]

    (1) Remove the forward engine mount yoke at the next shop visit, 
or within 4,800 cycles after the effective date of this AD, 
whichever occurs first.
    (2) Information for removal of the forward engine mount yoke can 
be found in the CF6-80C2 Engine Manual, 72-00-01, Disassembly.
    (n) Replace the affected forward engine mount platform and or 
the affected forward engine mount yoke with a non-weld-repaired cast 
titanium forward engine mount platform and or the forward engine 
mount yoke or a forged titanium forward engine mount platform or a 
forged titanium forward engine mount yoke.
    (o) Information for installing the forward engine mount platform 
and forward engine mount yoke can be found in the CF6-80C2 Engine 
Manual, 72-00-01, Assembly.
    (p) Location of the forward engine mount platform and forward 
engine mount yoke and SN are illustrated in the following Figure 1.
BILLING CODE 4910-13-P

[[Page 74877]]

[GRAPHIC] [TIFF OMITTED] TP13DE06.002

BILLING CODE 4910-13-C
    (q) After the effective date of this AD, do not install a weld-
repaired, cast forward engine mount platform or a weld-repaired,

[[Page 74878]]

cast forward engine mount yoke in any engine.

Alternative Methods of Compliance

    (r) 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.

    Issued in Burlington, Massachusetts, on December 7, 2006.
Robert Ganley,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 06-9674 Filed 12-12-06; 8:45 am]
BILLING CODE 4910-13-P