AD 94-09-08

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Allied-Signal Inc., Garrett Engine Division, TPE331 series turboprop and Model TSE331-3U turboshaft engines. This action requires inspection of certain third stage turbine stator assemblies, and replacement, if necessary, with serviceable assemblies. This amendment is prompted by reports of six third stage turbine stator assemblies assembled with inner seal supports made of incorrect material that results in a significantly reduced cyclic life. The actions specified by this AD are intended to prevent an uncontained failure of the third stage turbine wheel.

94-09-08 ALLIED-SIGNAL INC., GARRETT ENGINE DIVISION: Amendment 39-8897. Docket 93-ANE-80.
Applicability: Allied-Signal Inc., Garrett Engine Division, Model TPE331-1, -2, -2UA, -3U, -3UW, -5, - 5A, -6, and -6A turboprop and Model TSE331-3U turboshaft engines incorporating third stage stator turbine assemblies, Part Number (P/N) 868379-3, repaired at the Garrett General Aviation Service Division (GGASD) facility in Phoenix, Arizona, between November 1988 and May 1991, and identified by serial numbers listed in AlliedSignal Aerospace Alert Service Bulletin (ASB) No. TPE331-A72-0906, dated October 15, 1993. These engines are installed on but not limited to Mitsubishi MU-2B series (MU-2 series); Construcciones Aeronauticas, S.A. (CASA) C-212 series; Fairchild SA226 series (Swearingen Merlin and Metro series); Prop-Jets, Inc. Model 400; Twin Commander 680 and 690 (Jetprop Commander), Rockwell Commander S-2R, Shorts Brothers and Harland, Ltd. SC7 (Skyvan), Dornier 228 series, Beech18 and 45 series and Models JRB-6, 3N, 3NM, 3TM, and B100, Pilatus PC-6 series (Fairchild Porter, Peacemaker), De Havilland Model DH 104 series 7AXC (Dove), and Ayres S-2R series airplanes; and Sikorsky S-55 series helicopters.
Compliance: Required as indicated, unless accomplished previously.
To prevent an uncontained failure of the third stage turbine wheel, accomplish the following:
(a) Inspect suspect third stage turbine stator assemblies, P/N 868379-3, and replace, if necessary, with serviceable assemblies, in accordance with the Accomplishment Instructions of AlliedSignal Aerospace ASB No. TPE331-A72-0906, dated October 15, 1993, and the following schedule:

Third Stage Turbine Stator
Cycles in Service
Since Repair by GGASD
Inspection Schedule
900 or more cycles
Within 50 cycles in service after the effective date of this AD
450 to 899 cycles
Within 150 cycles in service after the effective date of this AD, but not to exceed 950 cycles in service since repair by GGASD
Less than 450 cycles
Prior to accumulating 600 cycles in service since repair by
GGASD

NOTE: The FAA has determined that cracking of third stage turbine stator assemblies is related to operating cycles, rather than operating hours.
(b) If cycles cannot be determined, calculate cycles by multiplying third stage turbine stator assembly hours time in service by 1.5.
(c) An alternative method of compliance or adjustment of the initial 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.
(d) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the aircraft to a location where the requirements of this AD can be accomplished.
(e) The inspection, and replacement, if necessary, of the third stage turbine stator assembly, shall be accomplished in accordance with the following ASB, which also identifies third stage turbine stator assemblies, P/N 868379-3, repaired at GGASD between November 1988 and May 1991, by serial number:

Document No.
Pages
Date
AlliedSignal Aerospace
ASB No. TPE331-A72-0906
Total pages: 10.
1-10
October 15, 1993

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from AlliedSignal, Inc., Aviation Services Division, Data Distribution Dept. 64-3/2102-IM, P.O. Box 29003, Phoenix, AZ 85038-9003. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(f) This amendment becomes effective on May 20, 1994.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of May 20, 1994.

Comments for inclusion in the Rules Docket must be received on or before July 5, 1994.

The Federal Aviation Administration (FAA) has received reports of six third stage turbine stator assemblies assembled with inner seal supports made of incorrect material that significantly reduces the cyclic life of the assembly. The manufacturer has identified part serial numbers of 150 third stage turbine stator assemblies that may contain the inner seal supports made of Hastelloy S material. These assemblies were repaired at the Garrett General Aviation Service Division (GGASD) facility in Phoenix, Arizona between November 1988 and May 1991. Fatigue failure of the inner seal support has resulted in the seal support moving aft and contacting the third stage turbine wheel. This condition, if not corrected,can result in an uncontained failure of the third stage turbine wheel.

The FAA has reviewed and approved the technical contents of AlliedSignal Aerospace Alert Service Bulletin (ASB) No. TPE331-A72-0906, dated October 15, 1993, that describes procedures for inspecting the third stage turbine stator assemblies, and replacing, if necessary, with serviceable assemblies.

Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design, this AD is being issued to prevent an uncontained failure of the third stage turbine wheel. This AD requires inspection of third stage turbine stator assemblies to determine the acceptability of the inner seal supports, and replacement, if necessary, with serviceable assemblies. The actions are required to be accomplished in accordance with the service bulletin described previously.

Since a situation exists that requires the immediate adoption of this regulation, it is found that noticeand opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD 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 93-ANE-80." The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will 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 amongthe various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulations 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.

39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive: