[Federal Register Volume 59, Number 228 (Tuesday, November 29, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-29304] [[Page Unknown]] [Federal Register: November 29, 1994] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 94-ANE-42] Airworthiness Directives; AlliedSignal Inc. TFE731-3 Series Turbofan Engines AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to AlliedSignal Inc. (formerly Garrett Turbine Engine Company) TFE731-3 series turbofan engines. This proposal would require the removal of suspect low pressure turbine (LPT) disks due to their susceptibility to creep fatigue. This proposal is prompted by reports of LPT disks that have separated through the disk web due to creep fatigue. The actions specified by the proposed AD are intended to prevent an LPT disk web separation, which may result in an uncontained engine failure and damage to the aircraft. DATES: Comments must be received by January 30, 1995. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 94-ANE-42, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from AlliedSignal Inc., Aviation Services Division, Data Distribution, Dept. 64-3/2102-1M, P.O. Box 29003, Phoenix, AZ 85038- 9003; telephone (602) 365-2548. This information may be examined at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA. FOR FURTHER INFORMATION CONTACT: Joseph Costa, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3229 East Spring Street, Long Beach, CA 90806-2425; telephone (310) 988-5246; fax (310) 988-5210. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal 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 94-ANE-42.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 94-ANE-42, 12 New England Executive Park, Burlington, MA 01803-5299. Discussion The Federal Aviation Administration (FAA) has received reports of three low pressure turbine (LPT) disks that have separated through the disk web due to creep fatigue on the AlliedSignal Inc. (formerly Garrett Turbine Engine Company) Models TFE731-3 and -3B turbofan engines. Two of the three disk failures were uncontained. Metallurgical examination of the failed second stage LPT disks revealed that two heat treatment production processes created a microstructure more susceptible to creep fatigue cracking. Both production processes affected AlliedSignal Inc. TFE731-3 series engines' first and second stage LPT disks. The FAA has determined that this microstructure in the AlliedSignal Inc. TFE731-3 series disks contributed to the separations. In addition, other factors contributed to the separations, such as engine misassembly, excessive seal clearance, and mismachining. This microstructural condition, if not corrected, could result in an LPT disk web separation, which may result in an uncontained engine failure and damage to the aircraft. The FAA has reviewed and approved the technical contents of AlliedSignal Inc. Alert Service Bulletin (ASB) No. TFE731-A72-3544, dated October 8, 1993, and ASB No. TFE731-A72-3557, dated May 12, 1994, that describe procedures for removal and replacement of specific serial numbered first and second stage LPT disks. Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design, the proposed AD would require removal of suspect disks due to their susceptibility to creep fatigue cracking and disk separation. The actions would be required to be accomplished in accordance with the service bulletin described previously. There are approximately 350 engines with the affected serial numbered disks in the worldwide fleet. The FAA estimates that 175 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 10 work hours per engine to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Required parts would cost approximately $18,000 per engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $3,256,000. The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this 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) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: AlliedSignal Inc.: Docket No. 94-ANE-42. Applicability: AlliedSignal Inc. (formerly Garret Turbine Engine Company) TFE731-3, -3A, -3AR, -3B, -3BR, and -3R turbofan engine models installed on but not limited to Avions Marcel Dassault Falcon 50, Lockheed 1329-23, -25 series (731 Jetstar, Jetstar II), Israel Aircraft Industries (IAI) Ltd. 1124 (Westwind), Raytheon Corporate Jets Inc. (formerly British Aerospace) (BAe) DH/HS/BH 125 series, Learjet 55 series, Cessna 650 Citation III, VI, Sabreliner NA-265 series (Sabreliner 65). This airworthiness directive (AD) is not applicable to TFE731-3A and TFE731-3AR-200G engines installed on IAI 1125 Westwind Astra aircraft. Compliance: Required as indicated, unless accomplished previously. To prevent a low pressure turbine (LPT) disk web separation, which may result in an uncontained engine failure and damage to the aircraft, accomplish the following: (a) Remove from service first and second stage LPT disks, with Part Numbers (P/N) 3072351-(), 3072542-(), 3073113-(), and 3073114- (), where () denotes any dash number, identified by serial number in the Compliance Sections of AlliedSignal Aerospace Alert Service Bulletin (ASB) No. TFE731-A72-3544, dated October 8, 1993, and AlliedSignal Aerospace ASB No. TFE731-A72-3557, dated May 12, 1994, within 1500 hours time in service (TIS) after the effective date of this airworthiness directive (AD), or at the next removal of the LPT assembly, whichever occurs first, in accordance with the Accomplishment Instructions of AlliedSignal Aerospace ASB No. TFE731-A72-3544, dated October 8, 1993, and AlliedSignal Aerospace ASB No. TFE731-A72-3557, dated May 12, 1994, and replace with serviceable disks. (b) 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, Los Angeles Aircraft Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles Aircraft Certification Office. Note: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Los Angeles Aircraft Certification Office. (c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished. Issued in Burlington, Massachusetts, on November 22, 1994. Jay J. Pardee, Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 94-29304 Filed 11-28-94; 8:45 am] BILLING CODE 4910-13-U