AD 99-03-09

This amendment adopts a new airworthiness directive (AD) that is applicable to Allison Engine Company, Inc. AE 2100A, AE 2100C, and AE 2100D3 series turboprop engines. This action requires removing from service affected turbine wheels prior to exceeding new, reduced cyclic life limits. This amendment is prompted by the results of a refined life analysis. The actions specified in this AD are intended to prevent an uncontained turbine wheel failure, which could result in damage to the aircraft.

Final rule; request for comments.

99-03-09 Allison Engine Company, Inc.: Amendment 39-11023. Docket 98-ANE-83-AD.
Applicability: Allison Engine Company, Inc. AE 2100A, AE 2100C, and AE 2100D3 series turboprop engines, with turbine wheels, part numbers (P/Ns) 23053358, 23059878, 23062373, 23062376, 23063462, 23064473, 23064474, 23064822, 23065891, 23065892, 23066791, and 23068072 installed. These engines are installed on but not limited to Saab Aircraft AB 2000, Industri Pesawat Terbang Nusantara (IPTN) Model N-250-100, and Lockheed Martin Model 382J (Military C130J) series aircraft.
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 ofcompliance 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 an uncontained turbine wheel failure, which could result in damage to the aircraft, accomplish the following:
(a) Remove from service the following turbine wheels installed in AE 2100A series engines prior to exceeding new, reduced cyclic life limits and replace with serviceable parts as follows:
(1) 4th Stage Turbine Wheels, P/N 23053358, prior to 8,900 cycles since new (CSN).
(2) 1st Stage Turbine Wheels, P/N 23062373, identified by serial numbers (S/N's) in Table 9 of Rolls-Royce Alert Service Bulletin (ASB) No. AE 2100A-A-72-191, dated December 17, 1998, prior to 10,000CSN.
(3) 1st Stage Turbine Wheels, P/N 23062376, prior to 11,600 CSN.
(4) 2nd Stage Turbine Wheels, P/N 23063462, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100A-A-72-191, dated December 17, 1998, prior to 10,000 CSN.
(5) 2nd Stage Turbine Wheels, P/N 23063462, not identified by S/N's in Rolls-Royce ASB No. AE 2100A-A-72-191, dated December 17, 1998, prior to 12,400 CSN.
(6) 2nd Stage Turbine Wheels, P/N 23064822, prior to 12,400 CSN.
(7) 1st Stage Turbine Wheels, P/N 23065891, identified by S/N's in Table 9 of Rolls-Royce ASB No. AE 2100A-A-72-191, dated December 17, 1998, prior to 10,000 CSN.
(8) 2nd Stage Turbine Wheels, P/N 23065892, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100A-A-72-191, dated December 17, 1998, prior to 10,000 CSN.
(9) 2nd Stage Turbine Wheels, P/N 23065892, not identified by S/N's in Rolls-Royce ASB No. AE 2100A-A-72-191, dated December 17, 1998, prior to 12, 400 CSN.
(10) 1st Stage Turbine Wheels, P/N 23066791, prior to 11, 600 CSN.
Note 2: Rolls-Royce ASB No. AE 2100A-A-72-191, dated December 17, 1998, provides information concerning specific S/N wheels and their cyclic life limits.
(b) Remove from service the following turbine wheels installed in AE 2100C series engines prior to exceeding new, reduced cyclic life limits and replace with serviceable parts as follows:
(1) 4th Stage Turbine Wheels, P/N 23053358, prior to 8,900 CSN.
(2) 1st Stage Turbine Wheels, P/N 23062373, identified by S/N's in Table 9 of Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, prior to 10,000 CSN.
(3) 2nd Stage Turbine Wheels, P/N 23063462, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, prior to 10,000 CSN.
(4) 2nd Stage Turbine Wheels, P/N 23063462, not identified by S/N's in Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, prior to 12,400 CSN.
(5) 1st Stage Turbine Wheels, P/N 23065891, identified by S/N's in Table 9 of Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, prior to 10,000 CSN.
(6) 2nd Stage Turbine Wheels, P/N 23065892, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, prior to 10,000 CSN.
(7) 2nd Stage Turbine Wheels, P/N 23065892, not identified by S/N's in Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, prior to 12, 400 CSN.
Note 3: Rolls-Royce ASB No. AE 2100C-A-72-141, dated December 17, 1998, provides information concerning specific S/N wheels and their cyclic life limits.
(c) Remove from service the following turbine wheels installed in AE 2100D3 series engines prior to exceeding new, reduced cyclic life limits and replace with serviceable parts as follows:
(1) 4th Stage Turbine Wheels, P/N 23053358, identified by S/N's in Table 12 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(2) 3rd Stage Turbine Wheels, P/N 23059878, identified by S/N's in Table 11 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(3) 1st Stage Turbine Wheels, P/N 23062373, identified by S/N's in Table 9 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(4) 1st Stage Turbine Wheels, P/N 23062376, prior to 8,400 CSN.
(5) 2nd Stage Turbine Wheels, P/N 23063462, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(6) 2nd Stage Turbine Wheels, P/N 23063462, not identified by S/N's in Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 7,500 CSN.
(7) 2nd Stage Turbine Wheels, P/N 23064473, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(8) 2nd Stage Turbine Wheels, P/N 23064473, not identified by S/N's in Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 6,700 CSN.
(9) 2nd Stage Turbine Wheels, P/N 23064474, prior to 7,500 CSN.
(10) 1st Stage Turbine Wheels, P/N 23065891, identified by S/N's in Table 9 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(11) 2nd Stage Turbine Wheels, P/N 23065892, identified by S/N's in Table 10 of Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 2,160 CSN.
(12) 2nd Stage Turbine Wheels, P/N 23065892, not identified by S/N's in Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, prior to 7,500 CSN.
(13) 2nd Stage Turbine Wheels, P/N 23068072, prior to 7,500 CSN.
Note 4: Rolls-Royce ASB No. AE 2100D3-A-72-130, dated December 17, 1998, provides information concerning specific serial number wheels and their cyclic life limits.
(d) This AD establishes new cyclic life limits for the turbine wheels identified in paragraphs (a), (b), and (c) of this AD. Except in accordance with paragraph (e) of this AD, no alternative life limits may be approved for the turbine wheels identified in paragraphs (a), (b), and (c) of this AD.
(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, Chicago Aircraft Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Chicago Aircraft Certification Office.
Note 5: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Chicago Aircraft Certification Office.
(f) The actions required by this AD shall be done in accordance with the following Rolls-Royce ASB's:

Document No.
Pages
Date
AE 2100A-A-72-191
1-8
December 17, 1998
AE 2100C-A-72-141
1-8
December 17, 1998
AE 2100D3-A-72-130
1-8
December 17, 1998
Totalpages: 8.

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 Allison Engine Company, Inc., P.O. Box 420, Speed Code U-15, Indianapolis, IN 46206-0420, telephone (317) 230-6674. Copies may be inspected at the FAA, New England Region, Office of the Regional 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.
(g) This amendment becomes effective on February 19, 1999.

Allison Engine Company, Inc., the manufacturer of AE 2100A, AE 2100C, and AE 2100D3 series turboprop engines, suspects that certain serial number turbine wheels may have Tungsten contamination. Additionally, the manufacturer reevaluated the effect on the service life of a wheel surface treatment, which is part of the current manufacturing process. A refined life analysis, which took both the possibility of Tungsten contamination and the surface treatment into account, revealed new maximum service lives significantly lower than those previously published. This condition, if not corrected, could result in an uncontained turbine wheel failure, which could result in damage to the aircraft.
The FAA has reviewed and approved the technical contents of Rolls-Royce Alert Service Bulletin (ASB) AE 2100A-A-72-191, AE 2100C-A-72-141, and AE 2100D3-A-72-130, all dated December 17, 1998, that list new, reduced cyclic life limits for affected turbine wheels.
Sincean 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 uncontained turbine wheel failure. This AD requires removing from service affected turbine wheels prior to exceeding new, reduced cyclic life limits. The actions shall be accomplished in accordance with the ASB's described previously.
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and 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 98-ANE-83-AD." 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 among the 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 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. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: