AD 94-25-08

This amendment supersedes an existing airworthiness directive (AD), applicable to Turbomeca Arriel 1 series turboshaft engines, that currently requires a gearbox chip detector inspection prior to further flight, subsequent inspection at designated intervals, and if necessary, removal of the gearbox, and also requires modification of the gearbox if not accomplished previously. This amendment requires modification to the intermediate gear that would constitute terminating action to the repetitive chip detector inspections. On certain engines this amendment requires immediate modification of the intermediate gear prior to further flight. This amendment is prompted by the availability of design improvements to the intermediate gear. The actions specified by this AD are intended to prevent damage to the aircraft resulting from engine debris following an uncontained engine failure.

Final rule.

94-25-08 Turbomeca: Amendment 39-9092. Docket 93-ANE-78. Supersedes AD 92-24-08, Amendment 39-8413.
Applicability: Turbomeca Arriel Model 1B, 1D, 1D1, 1A with TU13, and 1A1 with TU13, turboshaft engines installed on but not limited to Aerospatiale AS-350B helicopters.
Compliance: Required as indicated, unless accomplished previously.
To prevent damage to the aircraft resulting from engine debris following an uncontained engine failure, accomplish the following:
(a) For the following Turbomeca Arriel engine models: 1D not modified to TU232, 1D1 not modified to TU232, 1B modified to TU39 but not modified to TU232, 1A with TU13 modified to TU39 but not modified to TU232, and 1A1 with TU13 modified to TU39 but not modified to TU232, accomplish the following:
(1) Except for those engines that have been inspected in accordance with AD 92-24-08 within 8 hours time in service (TIS) prior to the effective date of this AD, prior to further flight remove and inspect the reduction gearbox chip detector for evidence of metal chips.
(2) Remove from service reduction gearbox modules that do not meet the return to service criteria described in Turbomeca SB No. 292 72 0157, Update No. 2, dated July 30, 1993, and replace with a serviceable part.
(3) Thereafter, at intervals not to exceed 8 hours TIS since the last inspection, accomplish the following:
(i) Remove and inspect the reduction gearbox chip detector in accordance with paragraph (a)(1) of this AD.
(ii) Remove from service, if necessary, the reduction gearbox module in accordance with paragraph (a)(2) of this AD, and replace with a serviceable part.
(4) At the next overhaul or repair of the reduction gearbox module after the effective date of this AD, incorporate modification TU232 in accordance with Turbomeca SB No. 292 72 0169, dated July 12, 1993. Incorporation of modification TU232 constitutes terminating action to the inspections, and replacement, if necessary, required in paragraphs (a)(1), (a)(2), and (a)(3) of this AD.
(b) For the following Turbomeca Arriel engine models: 1B not modified to TU39, 1A with TU13 not modified to TU39, and 1A1 with TU13 not modified to TU39, prior to further flight replace reduction gearbox module No. 5 with a reduction gearbox module No. 5 modified to standard TU39.
(c) For the following Turbomeca Arriel engine models: 1B, 1A with TU13, and 1A1 with TU13; with reduction gearbox modules identified by serial numbers specified in paragraph C.(c) of Turbomeca SB No. 292 72 0157, Update No. 2, dated July 30, 1993, that were overhauled prior to June 1, 1992, but not overhauled between that date and the effective date of this AD, and with less than 200 hours TIS since overhaul, remove from service and return for overhaul within 30 days after the effective date of this AD, in accordance with Turbomeca Service Bulletin (SB) No. 292 72 0157, Update No. 2, dated July 30, 1993.
(d) The checks required by paragraphs (a)(1) and (a)(3)(i) of this AD may be performed by the pilot holding at least a private pilot certificate as an exception to the requirements of part 43 of the Federal Aviation Regulations (14 CFR part 43). The checks must be recorded in accordance with Sections 43.9 and 91.417(a)(2)(v) of the Federal Aviation Regulations (14 CFR 43.9 and 14 CFR 91.417(a)(2)(v)), and the records must be maintained as required by the applicable Federal Aviation Regulation.
(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, Engine 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, Engine Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Engine 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 requirements of this AD can be accomplished.
(g) The actions required by this AD shall be done in accordance with the following service bulletins:

Document No.
Pages
Update
Date
Turbomeca SB No. 292 72 0157
1-5
2
July 30, 1993
Total pages: 5.

Turbomeca SB No. 292 72 0169
1-5
Original
July 12, 1993
Total pages: 5.

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 Turbomeca Engine Corporation, 2709 Forum Drive, Grand Prairie, TX 75051. 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.
(h) This amendment becomes effective on January 17, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding airworthiness directive (AD) 92-24-08, Amendment 39-8413 (57 FR 54293, November 18, 1992), which is applicable to Turbomeca Arriel 1B, 1D, 1D1, 1A with TU13, and 1A1 with TU13, turboshaft engines, was published in the Federal Register on March 15, 1994 (59 FR 11944). That action proposed to require removing gearboxes that were overhauled prior to June 1, 1992, within 30 days after the effective date of that AD. Those gearboxes have intermediate gears that are prone to gear teeth wear due to mixing of used gear train components with new components. That proposed AD would also require immediate modification of certain engines to the TU39 which introduces a thicker web intermediate gear that is more resistant to high cycle fatigue (HCF) failure. Finally, that proposed AD would also continue to require repetitive inspections of the chip detector for evidence ofmetal chips until installation of modification TU232 to the intermediate gear at the next overhaul or repair of the reduction gearbox. Installation of modification TU232 would constitute terminating action to the inspection requirements of that AD. The actions would be required to be accomplished in accordance with Turbomeca Service Bulletin (SB) No. 292 72 0157, Update No. 2, dated July 30, 1993, and Turbomeca SB No. 292 72 0169, dated July 12, 1993.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
One commenter (the manufacturer) states that the economic analysis in the proposed rule is incorrect, and provides revised economic information. The FAA concurs and has revised the economic analysis of this final rule accordingly.
One commenter states that the provision to allow the pilot to perform the chip detector inspection that was specified in AD 92-24-08 shouldbe included in this AD. The FAA concurs and the compliance section has been revised to include this provision.
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
The FAA estimates that 270 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately 4 work hours per engine to accomplish the required actions, and that the average labor rate is $55 per work hour. Required parts will cost approximately $4,222 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,199,340.
The regulations adopted herein will not have substantial direct effects on the States, on the relationship betweenthe 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.
For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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. 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 removing amendment 39-8413 (57 FR 54293, November 18, 1992) and by adding a new airworthiness directive, Amendment 39-9092, to read as follows: