AD 98-11-32

This amendment adopts a new airworthiness directive (AD) that is applicable to Allison Engine Company AE 3007A and AE 3007C series turbofan engines. This action supersedes priority letter AD 98-02-09, that currently requires certain checks of the center sump magnetic chip collector plug for paste. Engines found with paste are required to be removed from service. This action references revisions of the applicable Alert Service Bulletins (ASB) providing clarifications of check procedures. This amendment is prompted by a change in the part number applicability, a change in the check interval, and the publication of these revised ASBs. The actions specified by this AD are intended to prevent No. 4 bearing failure due to excessive bearing wear, which can result in an inflight engine shutdown. DATES: Effective June 18, 1998
The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of June 18, 1998.
Comments for inclusion in the Rules Docket must be received on or before August 3, 1998.

98-11-32 Allison Engine Company: Amendment 39-10557. Docket No. 97-ANE-60-AD. Supersedes AD 98-02-09.
Applicability: Allison Engine Company AE 3007A and AE 3007C series turbofan engines with No. 4 bearing, Part Number (P/N) 23062504, installed on but not limited to EMBRAER EMB-145 and Cessna 750 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 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 beeneliminated, the request should include specific proposed actions to address it.
Compliance: Required as indicated, unless accomplished previously.
To prevent No. 4 bearing failure due to excessive bearing wear, which can result in an inflight engine shutdown, accomplish the following:
(a) For Allison Engine Company AE 3007A series engines, within 8 flight hours after the effective date of this AD, accomplish the following in accordance with Allison Engine Company Alert Service Bulletin (ASB) No. AE 3007A-A-79-014, Revision 4, dated April 14, 1998.
(1) Remove the center sump magnetic chip collector plug (non-indicating) on each engine and examine it for paste.
Note 2: Paste is a mixture of very fine metallic particles and oil or soft carbon.
(2) If no paste is found, reinstall the center sump magnetic chip collector, perform an oil leak check, and thereafter inspect both engines at intervals not to exceed 8 flight hours.
(3) If paste is found, accomplish the following prior to further flight:
(i) Remove the engine from service if paste was previously found on the same engine during any previous checks performed in accordance with this AD, otherwise continue with the following procedure:
(ii) Collect the paste on a clean white paper. Cover the sample with clear tape and retain it for analysis.
(iii) Examine the O-ring for damage and replace as necessary.
(iv) Clean the center sump magnetic chip collector plug.
(v) Reinstall the center sump magnetic chip collector plug.
(vi) Perform a ground run-up of the engine as follows:
(A) Ground Idle for 5 minutes.
(B) Maximum Takeoff for 2 minutes.
(C) 50% N1 (Fan speed) for 5 minutes.
(D) Ground Idle for 3 minutes.
(E) Stop the engine.
(vii) Re-examine the center sump magnetic chip collector plug for paste. If paste is found, remove the engine from service. If no paste is found, thereafter inspect in accordance with paragraph (a)(2) ofthis AD.
(viii) Send any removed paste to a laboratory or facility capable of analysis with a scanning electron microscope and an energy dispersive x-ray microanalyzer for analysis.
Note 3: Two laboratories capable of performing this analysis are:

Aviation Laboratories, 910 Maria Street, Kenner, LA 70062, (504) 469-6751 or Spectro Oil Analysis, Palace Gate, High Street, Oldham, Hook, Hampshire, RG 291 NP, United Kingdom.

Send documentation referencing this AD or ASB along with the sample.
(ix) Send the results of the analysis to Allison as follows: Manager, AE Customer Support, Large Commercial Engines, fax (317) 230-4010.
(x) An engine found with paste either after the engine ground run-up or during subsequent checks performed in accordance with this AD may not be operated again without the approval of the Manager, Chicago Aircraft Certification Office.
(b) For Allison AE 3007C series engines, within 8 flight hours after the effective date of this AD, accomplish the following in accordance with Allison Engine ASB No. AE 3007C-A-79-018, Revision 3, dated April 21, 1998:
(1) Remove the center sump magnetic chip collector plug (non-indicating) on each engine and examine it for paste. (See Note 2)
(2) If no paste is found, reinstall the center sump magnetic chip collector, perform an oil leak check, and thereafter inspect both engines at intervals not to exceed 8 flight hours.
(3) If paste is found, accomplish the following prior to further flight:
(i) Remove the engine from service if paste was previously found on the same engine during any previous checks performed in accordance with this AD.
(ii) Collect the paste on a clean white paper. Cover the sample with clear tape and retain it for analysis.
(iii) Examine the O-ring for damage and replace as necessary.
(iv) Clean the center sump magnetic chip collector plug.
(v) Reinstall the center sump magnetic chip collector plug.
(vi) Perform a ground run-up of the engine as follows:
(A) Ground Idle for 5 minutes.
(B) Maximum Takeoff for 2 minutes.
(C) 50% N1 (Fan speed) for 5 minutes.
(D) Ground Idle for 3 minutes.
(E) Stop the engine.
(vii) Re-examine the center sump magnetic chip collector plug for paste. If paste is found, remove the engine from service. If no paste is found, thereafter inspect in accordance with paragraph (b)(2) of this AD.
(viii) Send any removed paste to a laboratory or facility capable of analysis with a scanning electron microscope and an energy dispersive x-ray microanalyzer for analysis. Send documentation referencing this AD or ASB along with the sample. (See Note 3)
(ix) Send the results of the analysis to Allison as follows: Manager, AE Customer Support, Large Commercial Engines, fax (317) 230-4010.
(x) An engine found with paste either after the engine ground run-up or during subsequent checks performed in accordance with this AD may not be operated again without the approval of the Manager, Chicago Aircraft Certification Office.
(c) For Allison Engine Company AE 3007A series and AE 3007C series engines, remove from service No. 4 main engine bearings, P/N 23062504, at the next engine shop visit, and replace with serviceable parts. Installation of an improved No. 4 main engine bearing constitutes terminating action to the repetitive magnetic chip detector checks required by paragraphs (a) and (b) of this AD.
(d) For the purpose of this AD, the following definitions apply:
(1) A serviceable part is defined as any No. 4 main engine bearing P/N other than 23062504.
(2) A shop visit is defined as any maintenance action resulting in the separation of any major engine flange.
(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 4: 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) 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 check requirements of this AD can be accomplished.
(g) The actions required by this AD shall be accomplished in accordance with the following Allison Engine Company ASBs:

Document No.
Page
Revision
Date
AE 3007A-A-79-014
1-7
4
April 14, 1998
Total Pages: 7.

AE 3007C-A-79-018
1-6
3
April 21, 1998
Total Pages: 6.

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, 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.
(h) This amendment supersedes priority letter AD 98-02-09, issued January 16, 1998.
(i) This amendment becomes effective on June 18, 1998.

On January 16, 1998, the Federal Aviation Administration (FAA) issued priority letter airworthiness directive (AD) 98-02-09, applicable to Allison Engine Company AE 3007A and AE 3007C series turbofan engines, which requires each calendar day, for Allison Engine Company AE 3007A series engines, and every three calendar days, or prior to the next flight, whichever occurs later, for Allison Engine Company AE 3007C series engines, alternating between the left hand and right hand engines, checks of the center sump magnetic chip collector plug. After checking the center sump magnetic chip collector plug, that AD requires, if paste is found, collecting paste, examining the O-ring for damage, cleaning the plug once during the first check only and not subsequently, performing an engine ground run-up and again examining the plug for paste. If paste is found on this second examination or subsequent examinations, the engine must be removed from service. There have been five inflight engine shutdowns associated with these bearing failures since December 1, 1997, on Allison Engine Company AE 3007A and AE 3007C series turbofan engines, which occurred with total time in service since new (TSN) ranging from 36 to 1,284 hours. The investigation revealed that the No. 4 bearings deteriorate due to manufacturing anomalies, which lead to excessive bearing wear. Analysis of failed bearings and service history has narrowed the unsafe condition to one particular bearing part number. That condition, if not corrected, could result in No. 4 bearing failure due to excessive bearing wear, which can result in an inflight engine shutdown.
Since the issuance of that priority letter AD, Allison Engine Company has issued Alert Service Bulletin (ASB) No. AE 3007A-A-79-014, Revision 4, dated April 14, 1998, and ASB No. AE 3007C-A-79-018, Revision 3, dated April 21, 1998, which provide clarifications of check procedures. In addition, this final rule has added oil leak checks after each magnetic chip detector inspection, in order to minimize the possibility of maintenance-induced errors. Also, this final rule adds a terminating action which eliminates the requirement for repetitive magnetic chip detector inspections by installing an improved No. 4 main engine bearing.
Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design, this AD supersedes priority letter AD 98-02-09 to reference revisions of the applicable Allison Engine Company ASBs providing clarifications of check procedures, change the part number applicability, and change the check interval. The actions are required to be accomplished in accordance with the ASBs 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 effectivein 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 97-ANE-60-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 nothave 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: