06-9674. 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).

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: [phone].
• 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 [phone]; fax [phone].

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.

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 [phone]) 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.

§ 39.13

[Amended]

2. The FAA amends § 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.

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

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:

(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.

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