# AD 99-06-03: Main Rotor Head Frequency Adapter - Type: Airworthiness directive - Status: Current - Products: Airbus Helicopters AS-365N2, SA-365N and SA-365N1 - Effective: April 13, 1999 - Published: March 9, 1999, 64 FR 11375–11376 - Issued as: Final rule - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-11067 - Docket: 97-SW-64-AD - Registered aircraft: 7 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/94/18/9418bf88ff263a4972657f8880c85ed96f39a4bc43ee4a2a8c3446a884d90ac6 (from https://www.govinfo.gov/content/pkg/FR-1999-03-09/pdf/99-5726.pdf) - Federal Register: https://www.federalregister.gov/documents/1999/03/09/99-5726/airworthiness-directives-eurocopter-france-model-as-365n-n1-and-n2-helicopters - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/4781EABC2C5A0BC986256A4D0066D9D0.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/99-06-03 ## Summary This amendment adopts a new airworthiness directive (AD), applicable to Eurocopter France Model AS-365N, N1, and N2 helicopters, that requires inspecting the helicopter to determine if a certain main rotor head frequency adapter (frequency adapter) is installed and, if so, replacing it with an airworthy frequency adapter. This amendment is prompted by a report of disbonding of the metal center section of a frequency adapter from the elastomer on a main rotor head caused by a lack of adherence during the production process. The actions specified by this AD are intended to prevent increased vibrations caused by disbonding of the center section of a frequency adapter from the elastomer and subsequent reduced controllability of the helicopter. ## The airworthiness directive 99-06-03 EUROCOPTER FRANCE: Amendment 39-11067. Docket No. 97-SW-64-AD. Applicability: Model AS-365N, N1, and N2 helicopters, certificated in any category. NOTE 1: This AD applies to each helicopter 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 helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (c) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD. Compliance: Required within the next 100 hours time-in-service or 6 calendar months, whichever occurs first, unless accomplished previously. To prevent vibrations caused by disbonding of the center section of a frequency adapter from the elastomer on the main rotor head and subsequent reduced controllability of the helicopter, accomplish the following: (a) Determine the part number, serial number, and date of manufacture of the main rotor head frequency adapter (frequency adapter). (b) If a frequency adapter part number (P/N) 704A33-640-031 (E1T2624-01A), or delivered in pairs under the P/N 365A31-1858-01, manufactured before April 1, 1991, with a serial number (S/N) equal to or less than 8188, or P/N 704A33-640-046 (E1T3023-01), or delivered in pairs under the P/N 365A31-1858-02, manufactured before April 1, 1991, with a S/N equal to or less than 3122, is installed, remove the frequency adapter and replace it with an airworthy frequency adapter. NOTE 2: Eurocopter France AS 365 Service Bulletin No. 01.00.44, dated May 9, 1996, pertains to the subject of this AD. (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, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Standards Staff. NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Standards Staff. (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 helicopter to a location where the requirements of this AD can be accomplished.NOTE 4: The subject of this AD is addressed in Direction General De L'Aviation Civile (France) AD 96-117-040(B), dated June 19, 1996. (e) This amendment becomes effective on April 13, 1999. ## Rule preamble ### Supplementary information A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that is applicable to Eurocopter France Model AS-365N, N1, and N2 helicopters was published in the Federal Register on June 5, 1998 (63 FR 30662). That action proposed to require inspecting for certain frequency adapters and if they are installed, replacing them with airworthy frequency adapters. Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed. The FAA estimates that 91 helicopters of U.S. registry will be affected by this AD, that it will take approximately 6 work hours per helicopter to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts willcost approximately $5,200 per helicopter. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $505,960. 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 will 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 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 criteriaof 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 FAA, Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 97-SW-64-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, 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 a new airworthiness directive (AD) to read as follows: ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H10EU](https://openairdocs.org/tcds/H10EU): Airbus Helicopters; names 3 of 10 models: AS 365 N2, SA 365 N, SA 365 N1 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 7 (7 by airframe model, 0 by engine model) - Makers: Aerospatiale 3, Eurocopter France 3, Eurocopter 1 Models with the most aircraft: - [Eurocopter France AS-365N2](https://openairdocs.org/model/eurocopter-france-as-365n2): 3 aircraft (airframe model) - [Aerospatiale SA365N1](https://openairdocs.org/model/aerospatiale-sa365n1): 1 aircraft (airframe model) - [Aerospatiale SA365N-1 DAUPHIN](https://openairdocs.org/model/aerospatiale-sa365n-1-dauphin): 1 aircraft (airframe model) - [Aerospatiale AS 365 N2](https://openairdocs.org/model/aerospatiale-as-365-n2): 1 aircraft (airframe model) - [Eurocopter AS365N2](https://openairdocs.org/model/eurocopter-as365n2): 1 aircraft (airframe model) All 5 models: https://openairdocs.org/ad/99-06-03/models.md Every aircraft: https://openairdocs.org/ad/99-06-03/aircraft.md ## Related documents - [Proposed rule 97-SW-64-AD](https://openairdocs.org/proposed/97-SW-64-AD): Notice of proposed rulemaking (NPRM), published Jun 5, 1998 Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.