Airworthiness Directives; AlliedSignal Inc. TFE731 Turbofan Engines

[Federal Register Volume 64, Number 144 (Wednesday, July 28, 1999)] [Proposed Rules] [Pages 40789-40790] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 99-19322]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-10-AD] RIN 2120-AA64

Airworthiness Directives; AlliedSignal Inc. TFE731 Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain AlliedSignal Inc. high pressure compressor (HPC) impellers installed on TFE731 series turbofan engines. This proposal would require replacing the HPC impeller with a serviceable impeller that has been eddy-current inspected. This proposal is prompted by an incident of an uncontained impeller failure due to cracking in the seal relief area of the HPC impeller. The actions specified by the proposed AD are intended to prevent fatigue cracking of the HPC impeller, which could result in an uncontained failure of the impeller, an in-flight engine shutdown, and damage to the airplane.

DATES: Comments must be received by September 27, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No.99-NE-10-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: ``9-ane- [email protected].'' Comments sent via the Internet must contain the docket number in the subject line. 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 Aerospace Services Attn: Data Distribution, M/S 64-3/2101-201, P.O. Box 29003, Phoenix, AZ 85038-9003; telephone (602) 365-2493, fax (602) 365-5577. This information may be examined at the FAA, New England Region, Office of the Regional 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, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone (562) 627-5246, fax (562) 627-5210.

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 action 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 99-NE-10-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRM's

Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-10-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

The Federal Aviation Administration (FAA) has determined that on May 10, 1998, a high pressure compressor (HPC) impeller, part number (P/N) 3073394-1, separated and exited from an AlliedSignal Inc. TFE731- 3R-1D turbofan engine. This impeller had accumulated 9,080 engine cycles since new (CSN) and 5,829 engine cycles since rework of the seal relief area in November, 1982, performed in accordance with AlliedSignal Service Bulletin (SB) TFE731-72-3239 RWK. Fracture analysis revealed a subsurface primary origin in the area of the seal relief and that the crack propagated through the bore for about 1.0 inch. No melt or forging related discrepancies were found at the fatigue origin; however, localized alpha grain colonies with an unfavorable fracture plane orientation were present. Recent low- temperature fatigue testing with a sustained peak hold time (dwell) at higher than engine-operating stresses indicate that normal cyclic fatigue lives may be influenced by dwell times and an unfavorable titanium macrostructure. The FAA has determined that low-cycle fatigue (LCF) cracking in high stressed areas of the HPC impeller may lead to an uncontained impeller separation. This condition, if not corrected, could result in fatigue cracking of the HPC impeller, which could result in an uncontained failure of the impeller, an in-flight engine shutdown, and damage to the airplane. The FAA has reviewed and approved the technical contents of AlliedSignal Inc. Alert Service Bulletin (ASB) TFE731-A72-3641, dated November 24, 1998, that describes procedures for replacing the HPC impellers, P/Ns 3073393-1, 3073394-1, 3073433-1, and 3073434-1 with impellers that have been inspected using a specialized eddy

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current inspection. At present, only AlliedSignal is properly trained and equipped to perform this inspection that requires specialized training and tooling. Within the near future, the FAA expects to approve a revision to ASB TFE731-A72-3641 which will include a reference to the eddy-current procedure document and additional facilities that are properly trained and equipped to perform this specialized inspection. The Final Rule will incorporate the revised ASB. Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design, this AD is being issued to prevent fatigue cracking of the HPC impeller, which could result in an uncontained failure of the impeller, an in-flight engine shutdown, and damage to the airplane. This AD requires replacing the HPC impeller with a serviceable impeller, which has been eddy- current inspected, at the next core zone inspection (CZI) or at the next access to the HPC module, and repetitive inspections at each subsequent CZI or each subsequent access to the HPC impeller for cause if the impeller has more than 1,000 cycles since the last eddy current inspection. These replacements must be done in accordance with the SB described previously. There are approximately 2,105 engines of the affected design in the worldwide fleet. The FAA estimates that 1,537 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 3 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. The FAA also estimates that some of the impellers will be replaced, and that the impeller will cost about $45,000. Based on these figures, the FAA estimates the total cost impact of the proposed AD on U.S. operators to be $996,660. 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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

AlliedSignal Inc.: Docket No. 99-NE-10-AD.

Applicability: AlliedSignal Inc. TFE731 series turbofan engines with high pressure compressor (HPC) impeller part numbers (P/Ns) 3073393-1, 3073394-1, 3073433-1, and 3073434-1 installed on, but not limited to Avions Marcel Dassault--Breguet Aviation (AMD/BA) Falcon 10, Dassault-Aviation Mystere-Falcon 50, and 900 series airplanes; Dassault Aviation Mystere-Falcon 20 series airplanes, Learjet Inc. Models 31, 35, 36, and 55 series airplanes; Lockheed-Georgia Corporation 1329-23 and -25 series airplanes; Israel Aircraft Industries Ltd. 1124 series and 1125 Westwind series airplanes; Cessna Aircraft Co. Model 650 Citation III, VI, and VII series airplanes; Raytheon Aircraft Co. HS-125 series airplanes; and Sabreliner Corporation NA-265-65 airplanes.

Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously. To prevent fatigue cracking of the HPC impeller, which could result in an uncontained failure of the impeller, an in-flight engine shutdown, and damage to the airplane, accomplish the following: (a) Replace the HPC impeller, P/N's 3073393-1, 3073394-1, 3073433-1, and 3073434-1, in accordance with Section 2.A. of the Accomplishment Instructions of AlliedSignal Alert Service Bulletin (ASB) TFE731-A72-3641, dated November 24, 1998, at the earlier of the following: (1) At the next core zone inspection (CZI) after the effective date of this AD, or (2) At the next access to the HPC module after the effective date of this AD. (b) Thereafter, replace the HPC impeller, P/N's 3073393-1, 3073394-1, 3073433-1, and 3073434-1, in accordance with Section 2.A. of the Accomplishment Instructions of AlliedSignal SB TFE731-A72-3641, dated November 24, 1998, whenever either of the following conditions are met: (1) At every CZI, or (2) When accessing the HPC module and the impeller has accumulated more than 1,000 cycles since the last ECI. (c) This AD defines access to the HPC module as whenever the low pressure compressor case is removed from the compressor interstage diffuser. (d) Installation of HPC impellers having P/N's 3073398-X, 3073435-X, and 3075171-X, where ``X'' represents any dash number, constitutes terminating action for the inspection requirements of this AD.

Note 2: Installation of HPC impellers having P/N's 3070274-1 and 3072639-1, which are subject to AD 82-23-03 R1, are not considered eligible parts for terminating action. (e) 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. Operators shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles Aircraft Certification Office.

Note 3: 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.

(f) Special flight permits may be issued in accordance with Secs. 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 July 22, 1999. David A. Downey, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 99-19322 Filed 7-27-99; 8:45 am] BILLING CODE 4910-13-P