E7-17384. Airworthiness Directives; Honeywell International Inc. TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, -5R, -20R, -20AR, -20BR, -40, -40AR, -40R, and -60 Series 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 Honeywell International Inc. (Honeywell) TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, -5R, -20R, -20AR, -20BR, -40, -40AR, -40R, and -60 series turbofan engines. This proposed AD would require removal from service of certain high pressure (HP) turbine rotor assemblies with part numbers (P/Ns) 3075772-1 and 3060841-1 using a drawdown schedule, and returning them to Honeywell for curvic root radius inspection. This proposed AD results from the manufacturer's report that some HP turbine rotor discs received improperly machined radii in the root of the forward and aft curvic teeth during manufacture. We are proposing this AD to prevent uncontained failure of the HP turbine rotor assembly and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by November 5, 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: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
• Fax: [phone].
• You can get the service information identified in this proposed AD from Honeywell Technical Publications and Distribution, M/S 2101-201, P.O. Box 52170, Phoenix, AZ 85072-2170; telephone: [phone] (General Aviation), [phone] (Commercial Aviation), fax: [phone] (General Aviation and Commercial Aviation).
• Also, for technical support regarding the curvic root dimensional inspection criteria, contact the Technical Operations Center: telephone: [phone] (U.S.) or [phone] (International) and press option #9; e-mail: [e-mail]; or fax: [phone].

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:

Joseph Costa, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; e-mail: [e-mail]; 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-2007-27891; Directorate Identifier 2007-NE-14-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 AD docket on the Internet at http://dms.dot.gov;​; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone [phone]) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

In June of 2006, we became aware of a manufacturing audit that found that some HP turbine rotor discs, part numbers (P/Ns) 3075772-1 and 3060841-1, received improperly machined radii in the root of the forward and aft curvic teeth. We have determined that the improperly machined radii will cause a higher stress in the curvic area of the HP turbine rotor disc than originally calculated. Although no reports of cracked HP turbine rotor discs due to improperly machined radii have been received, this higher stress reduces the calculated low-cycle-fatigue life limit, to below the current published life limit. This condition, if not corrected, could result in uncontained failure of the HP turbine rotor assembly and damage to the airplane. Honeywell established a serial number list of suspect HP turbine rotor discs possibly having the improperly machined radii. This proposed AD would require operators to send suspect HP turbine rotor discs to Honeywell for curvic root inspection before the discs are eligible for reinstallation in an engine. Since the dimensional inspection requires proprietary tooling and methods, Honeywell is specified as the sole provider of the curvic root inspections. Other repair or maintenance facilities that believe they are capable of conducting the inspection may apply for an alternative method of compliance (AMOC) in accordance with the AMOC paragraph in the proposed AD.

Relevant Service Information

We have reviewed and approved the technical contents of Honeywell Alert Service Bulletin No. TFE731-A72-5185, dated July 5, 2006, and Service Bulletin No. TFE731-72-3720, dated July 5, 2006. These service bulletins contain the serial numbers of suspect HP turbine rotor discs, and describe procedures for removing the suspect HP turbine rotor assemblies from service.

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 removal of certain HP turbine rotor assemblies from service using a drawdown schedule and returning them to Honeywell Engines, Systems, and Services for curvic root radius inspection. The proposed AD would require you to use the service information described previously to identify suspect HP turbine rotor discs by serial number.

Costs of Compliance

We estimate that this proposed AD would affect 400 HP turbine rotor discs installed in TFE731-20R, -20AR, -20BR, -40, -40AR, -40R, and -60 series turbofan engines, and 170 HP turbine rotor discs installed in TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, and -5R series turbofan engines, installed in airplanes of U.S. registry. We also estimate that it would take about 42 work-hours per engine to perform the proposed actions at an unscheduled removal, and about 2 work-hours at a scheduled removal. The average labor rate is $80 per work-hour. Required parts would cost about $46,535 per engine. We estimate that 50 percent of the HP turbine rotor discs will fail the curvic root radius inspection. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $13,490,000.

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 AD:

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. You may get a copy of this summary at the address listed under ADDRESSES.

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:

Honeywell International Inc. (formerly AlliedSignal Inc. and Garrett Turbine Engine Co.): Docket No. FAA-2007-27891; Directorate Identifier 2007-NE-14-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by November 5, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Honeywell International Inc. (Honeywell) TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, -5R, -20R, -20AR, -20BR, -40, -40AR, -40R, and -60 series turbofan engines with certain high pressure (HP) turbine rotor discs part numbers and serial numbers. These engines are installed on, but not limited to, the following airplanes:

Avions Marcel Dassault Mystere-Falcon 10 and 50 Series

Cessna Model 650; Citations III, VI, and VII

Dassault-Aviation 20, 50, 50EX, 900, MF900, and 900EX (900DX) Series

Gulfstream Aerospace LP (formerly IAI) 1125 Westwind Astra, Astra SPX, Gulfstream 100 Series

Israel Aircraft Industries (IAI) 1124 Series (Westwind 1124)

Learjet 31, 35, 36, 45 (or Learjet 40), and 55 Series

Lockheed-Georgia 3329-25 Series (731 Jetstar, Jetstar II)

Raytheon Corporate Jets (formerly British Aerospace) Hawker 800 and 850 Series

Sabreliner NA-265-65 (Sabreliner 65)

Unsafe Condition

(d) This AD results from a report that some HP turbine rotor discs received improperly machined radii in the root of the forward and aft curvic teeth during manufacture. We are issuing this AD to prevent uncontained failure of the HP turbine rotor assembly and damage to 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.

TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, and -5R Series Turbofan Engines

(f) For TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, and -5R series turbofan engines, remove HP turbine rotor assemblies from service containing HP turbine rotor discs, part number (P/N) 3075772-1, having any serial number (SN) in Table 1 of Honeywell Service Bulletin (SB) No. TFE731-72-3720, dated July 5, 2006. Use the following drawdown schedule:

(1) For HP turbine discs with 4,200 cycles-since-new (CSN) or more on the effective date of this AD, remove HP turbine rotor assemblies within 100 cycles-in-service (CIS) after the effective date of this AD.

(2) For HP turbine discs with fewer than 4,200 CSN on the effective date of this AD, remove HP turbine rotor assemblies at the next access to the HP turbine rotor discs, but not to exceed 4,300 CSN.

TFE731-20R, -20AR, -20BR, -40, -40AR, -40R, and -60 Series Turbofan Engines

(g) For TFE731-20R, -20AR, -20BR, -40, -40AR, -40R, and -60 series turbofan engines, remove HP turbine rotor assemblies from service containing HP turbine rotor discs, P/N 3060841-1, having any SN in Table 1 of Honeywell Alert SB No. TFE731-A72-5185, dated July 5, 2006. Use the following drawdown schedule:

(1) For HP turbine discs with 3,200 CSN or more on the effective date of this AD, remove HP turbine rotor assemblies within 100 CIS after the effective date of this AD.

(2) For HP turbine discs with fewer than 3,200 CSN on the effective date of this AD, remove HP turbine rotor assemblies at the next access to the turbine rotor discs, but not to exceed 3,300 CSN.

For All Engines

(h) HP turbine rotor discs removed per paragraphs (f) and (g) of this AD must pass a curvic root radius inspection performed by Honeywell Engines, Systems and Services, Phoenix, Arizona, Certificate Repair Station No. ZN3R030M, before the discs are eligible for reinstallation in an engine.

(i) For the purposes of this AD, access to the HP turbine rotor discs is defined as the removal of the HP turbine rotor assembly from the engine.

Alternative Methods of Compliance

(j) The Manager, Los Angeles Aircraft 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.

Related Information

(k) Contact Joseph Costa, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; e-mail: [e-mail]; telephone: [phone]; fax: [phone], for more information about this AD.

(l) For more information regarding the engine manufacturer's accomplishment instructions or material information, refer to Honeywell Alert SB No. TFE731-A72-5185, dated July 5, 2006, and SB No. TFE731-72-3720, dated July 5, 2006.

Issued in Burlington, Massachusetts, on August 28, 2007.

Peter A. White,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.