AD 99-17-09

This amendment adopts a new airworthiness directive (AD) that is applicable to Allison Engine Company, Inc AE 2100A and AE 2100C series turboprop engines. This action requires initial and repetitive visual inspections of the propeller gearbox (PGB) and power section (P/S) strut fittings for notches and cracks, and, if necessary, replacement with serviceable parts. In addition, this action requires removing and replacing strut fittings as well as reworking them to the latest configuration identified by a new part number (P/N). This amendment is prompted by reports of P/S strut fitting notches and cracks. The actions specified in this AD are intended to prevent PGB and P/S strut fitting cracks, which could result in PGB misalignment, in-flight engine shutdown, and possible loss of the propeller.

Final rule; request for comments.

99-17-09 ALLISON ENGINE COMPANY, INC: Amendment 39-11257. Docket 99-NE-14-AD. Issued August 11, 1999.
Applicability: Allison Engine Company, Inc AE 2100A and AE 2100C series turboprop engines, installed on but not limited to SAAB 2000 series and Industri Pesawat Terbang Nusantara (IPTN) N-250 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 (c) 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 propeller gearbox (PGB) and power section (P/S) strut fitting cracks, which could result in PGB misalignment, in-flight engine shutdown, and possible loss of the propeller, accomplish the following:
(a) Perform initial and repetitive visual inspections of the PGB and P/S strut fittings for notches and cracks, and, if necessary, replace with serviceable parts, in accordance with Rolls-Royce Alert Service Bulletin (ASB) AE 2100A-A-72-193, also designated AE 2100C-A-72-143, Revision 1, dated October 20, 1998, as follows:
(1) Perform the initial inspection within 100 hours time-in-service (TIS) after the effective date of this AD. Record findings in Table 1 at the end of the ASB to determine the inspection interval.
(2) If parts are found cracked, prior to further flight, remove from service cracked propeller gearboxesor power section strut fittings and replace with serviceable parts.
(3) If both strut fittings are found notched, thereafter inspect at intervals not to exceed 100 hours time-in- service (TIS) since last inspection.
(4) If one strut fitting is found notched, thereafter inspect at intervals not to exceed 400 hours TIS since last inspection.
(5) If no parts are found cracked and neither strut fitting is found notched, no repetitive inspections are required, and rework the strut fittings in accordance with paragraph (b of this AD.
(b) Perform one of the following in accordance with Rolls-Royce ASB AE 2100A-A-72-197, also designated AE 2100C-A-72-149, dated May 19, 1999:
(1) Remove the old PGB and P/S strut fittings and install the new serviceable strut fittings in accordance with the strut fittings part number charts in paragraph (4) of the ASB.
(2) Rework the existing parts within the schedule determined by the inspection results of paragraph (a) of this AD in accordance with the Rolls-Royce ASB AE 2100A-A-72-193, or AE 2100C-A-72-143, Revision 1, dated October 20, 1998, page 12, Table 1, entries in the "Answer" column, as follows:
(i) If two "Yes" entries are contained in the "Answer Column, rework within the next 100 hour TIS after the inspection performed in accordance with paragraph (a) of this AD.
(ii) If one "Yes" entry is contained in the "Answer Column", or there are no "Yes" entries in the "Answer Column" refer to Section 2 in Rolls-Royce ASB AE 2100A-A-72-197, also designated AE 2100C-A-72-149, dated May 19, 1999, for the affected PGB and P/S strut fittings rework or replace instructions.
(iii) Following completion of the rework, mark affected parts in accordance with the following configuration chart:

NEW P/N
NAME
OLD P/N
QTY/ENG
23071762
Fitting, Strut (RH), Propeller Gearbox
23055218
1
23071763
Fitting, Strut (LH), Propeller Gearbox
23055217
1
23071764
Fitting, Strut (RH), Power Section
23055228, 23057098
1
23071765
Fitting, Strut (LH), Power Section
23055229 23057099
1

(c) 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 2: 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.
(d) 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 inspection requirements of this AD can be accomplished.
(e) The actions required by this AD shall be done in accordance with the following Rolls-Royce ASBs:

Document No.
Pages
Revision
Date
AE 2100A-A-72-193
/AE 2100C-A-72-143
1-12
1
October 20, 1998
Total pages: 12.

ASB AE2100A-A-72-197 /AE 2100C-A-72-149
1-25
Original
May 19, 1999
Total pages: 25

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 Rolls-Royce Allison, P.O. Box 420, Speed Code R-01B, Indianapolis, IN 46202-0420; telephone (317) 230-2720, fax (317) 230-3381. 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.
(f) This amendment becomes effective on September 7, 1999.

The Federal Aviation Administration (FAA) has received reports of propeller gearbox (PGB) and power section (P/S) strut fitting failures on Allison Engine Company AE 2100A and AE 2100C series turboprop engine. The investigation revealed small radius notched strut fittings on 90% of the engines inspected. Four of the P/S strut fittings were cracked, and one of the PGB strut fittings was cracked. The notched fittings cause a concentrated stress region that can lead to cracks in the notched strut fitting areas. This condition, if not corrected, could result in PGB and P/S strut fitting cracks, which could result in propeller gearbox misalignment, in-flight engine shutdown, and possible loss of the propeller.
The FAA has reviewed and approved the technical contents of Rolls-Royce Alert Service Bulletin (ASB) AE 2100A-A-72-193, also designated AE 2100C-A-72-143, Revision 1, dated October 20, 1998, that describes procedures for visual inspections of PGB andP/S strut fittings for notches and cracks; and ASB AE 2100A-A-72-197, also designated AE 2100C-A-72-149, dated May 19, 1999, describes the procedures to remove and replace strut fittings as well as rework them to the latest configuration identified by a new part number (P/N). Rolls-Royce has acquired the Allison Engine Company and now publishes the service documents (including manuals and bulletins) for Allison engines.
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 PGB and P/S strut fitting failures. This AD requires visual inspections of PGB and P/S strut fittings for notches and cracks. If the affected parts are found cracked, this AD requires, prior to further flight, replacement with serviceable parts. If notched fittings are found on both struts, this AD requires repetitive inspections at intervals not to exceed 100 hours time-in-service (TIS). If notched fittings are found on only one strut, the repetitive inspection intervals is 400 hours TIS. In addition, this AD requires removing and replacing strut fittings as well as reworking them to the latest configuration identified by a new P/N. 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 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 commenters' 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 99-NE-14-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 Policiesand 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: