Airworthiness Directives; Eurocopter France Model AS332C, L, and L1 Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking (SNPRM); reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD) for the specified Eurocopter France (Eurocopter) model helicopters that would have required, for bevel gears with more than 6,600 hours time-in-service (TIS), inspecting the bevel gear for a crack using a borescope within 50 hours TIS, and thereafter at intervals not to exceed 150 hours TIS. That proposal was prompted by a crack that was detected on a bevel gear during a main gearbox teardown inspection. This action revises the proposed rule by requiring the borescope inspection at intervals not to exceed 150 hours TIS or 1,000 torque variation cycles (cycles) for helicopter operations involving frequent torque variations, whichever occurs first. This action is prompted by an analysis of the crack growth rate, which indicates that the growth rate is higher in helicopters with operations involving a torque variation frequency of 4 or more cycles per hour. The actions specified by this proposed AD are intended to detect a bevel gear crack and prevent failure of the bevel gear, loss of torque to the main rotor system, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before November 17, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2002-SW-45-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: 9-asw-adcomments@faa.gov. Comments may be inspected at the Office of the Regional Counsel between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Uday Garadi, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Safety Management Group, Fort Worth, Texas 76193-0110, telephone (817) 222-5123, fax (817) 222-5961.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this document may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their mailed comments submitted in response to this proposal must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2002-SW-45-AD.” The postcard will be date stamped and returned to the commenter.

Discussion

A proposal to amend 14 CFR part 39 to add an AD for the specified Eurocopter model helicopters was published in the Federal Register on December 31, 2002 (67 FR 79893). That NPRM would have required for bevel gears with more than 6,600 hours TIS, inspecting the bevel gear for cracks using a borescope within 50 hours TIS, and thereafter at intervals not to exceed 150 hours TIS. If a crack were found in the bevel gear, replacing the bevel gear would be required. That NPRM was prompted by a crack that was detected on a bevel gear during a main gearbox teardown inspection. That condition, if not corrected, could result in failure of the bevel gear, loss of torque to the main rotor system, and subsequent loss of control of the helicopter.

Since issuing that NPRM, the FAA discovered that certain part numbered bevel gears were omitted from the applicability and one was incorrectly stated in that NPRM. Also, the manufacturer has revised the service information to introduce the new inspection interval of 1,000 cycles for helicopter operations involving a torque application frequency of more than 4 cycles per hour for helicopters that conduct external load operations involving more frequent torque applications. Additionally, we inadvertently included Model AS332C1 helicopters in the “Applicability” section of the NPRM—those model helicopters are not on the U.S. Registry. Finally, the DGAC has issued a revised AD for helicopters operated in France.

This SNPRM revises the NPRM to:

• Correct the basic bevel gear part number (P/N) stated in the “Applicability” of the NPRM to state “332A32-2181-00”;
• Add bevel gear P/Ns 332A32-2181-01 and -08 to the “Applicability”;
• Delete the Model AS332C1 helicopters from the “Applicability”;
• Incorporate the latest Eurocopter Alert Telex and references the latest DGAC AD;
• Require the repetitive inspection at intervals not to exceed 150 hours TIS or 1,000 torque cycles, whichever occurs first; and
• Exclude from the “Applicability” any main gearbox (regardless of the P/N of the main reduction gear module or bevel gear) overhauled after December 31, 2002, and any part number inspected in accordance with AS332 letter to Repair Stations No. 183 or repaired in accordance with Repair Sheet (F.R.) 332A32-2181-ZA or 331A32-3110-ZA.

Since this change expands the scope of the originally proposed rule, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

The Direction Generale De L'Aviation Civile (DGAC), the airworthiness authority for France, notified the FAA that an unsafe condition may exist on Eurocopter Model AS332C, C1, L, and L1 helicopters, equipped with main gearbox main reduction gear modules, part numbers (P/N) 332A32-2027-00 or 332A32-2026-00, containing bevel gears, P/N 332A32-2181-00, -01, -02, -03, or -04, or 331A32-3110-07, -09, or -19. The DGAC advises that borescope inspections of the bevel gear are necessary to detect cracks.

Eurocopter has issued Alert Telex No. 05.00.58 R2, dated February 3, 2003, which indicates that as a result of metal particles found on the chip detector of the main gearbox sump on a helicopter, further investigation has revealed a longitudinal crack that grows lengthwise in the shaft, up to the combiner gear, in the bevel gear where the ring retains the pinion toe bearing. The alert telex specifies inspecting the bevel gear for cracks using a borescope, pending the result of the investigation into the cause of the fatigue crack initiation currently being conducted in France. The DGAC classified this alert telex as mandatory and issued AD 2002-424-081(A) R2, dated March 19, 2003, to ensure the continued airworthiness of these helicopters in France.

On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. Because we have now included this material in part 39, we no longer need to include it in each individual AD. Therefore, Note 1 of the original NPRM has been removed and paragraph (c) has been modified in this SNPRM.

The FAA estimates that 4 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 4 work hours per helicopter to accomplish the inspections and 16 work hours per helicopter to replace the bevel gear. The average labor rate is $65 per work hour. Required parts would cost approximately $31,372. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $130,688, assuming that upon the first inspection a crack is detected and the bevel gear will be replaced.

The regulations proposed herein would not have a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.