# AD 2021-13-05: Tail Rotor Control System - Type: Airworthiness directive - Status: Current - Products: Airbus Helicopters Deutschland EC135P3, EC135T3, EC135P1, EC135P2, EC135P2+, EC135T1, EC135T2 and EC135T2+/EC635T2+ - Effective: August 11, 2021 - Published: July 7, 2021, 86 FR 35599–35601 - Issued: June 10, 2021 - Issued as: Final rule - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-21610 - Docket: FAA-2019-0293 (https://www.regulations.gov/docket/FAA-2019-0293) - Registered aircraft: 345 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/84/86/848657718203126b62a83edd8a6684ce22228d0b46658148a216d9dc1bf30713 (from https://www.govinfo.gov/content/pkg/FR-2021-07-07/pdf/2021-14343.pdf) - Federal Register: https://www.federalregister.gov/documents/2021/07/07/2021-14343/airworthiness-directives-airbus-helicopters-deutschland-gmbh-helicopters - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/D2E6C764D73943B38625870B005651F7.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/2021-13-05 ## Summary The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Deutschland GmbH (Airbus Helicopters) Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters. This AD requires modifying the tail rotor (T/R) control installation, a functional test, and corrective actions as necessary. This AD was prompted by cases of insufficient clearance between a certain T/R control bearing connection and the helicopter structure, which were detected on the production line. The FAA is issuing this AD to address the unsafe condition on these products. ## The airworthiness directive 1. The authority citation for part 39 continues to read as follows: 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2021-13-05 Airbus Helicopters Deutschland GmbH: Amendment 39-21610; Docket No. FAA-2019-0293; Product Identifier 2017-SW-052-AD. ### (a) Effective Date This airworthiness directive (AD) is effective August 11, 2021. ### (b) Affected ADs None. ### (c) Applicability This AD applies to Airbus Helicopters Deutschland GmbH Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters with serial number (S/N) up to and including 1254 (except S/N 1235), certificated in any category. ### (d) Subject Joint Aircraft Service Component (JASC) Code: 6720, Tail Rotor Control System. ### (e) Unsafe Condition This AD defines the unsafe condition as interference between the tail rotor (T/R) control bearing connection close-tolerance bolt and the helicopter structure, which could lead to blockage of the pedal controlling the T/R thrust. This condition could result in loss of T/R control, prompting a forced landing. ### (f) Compliance Comply with this AD within the compliance times specified, unless already done. ### (g) Required Actions Within 360 hours time-in-service, modify the T/R control by installing a Teflon washer and perform a functional test of the modification in accordance with the Accomplishment Instructions, paragraphs 3.B.2 through 3.B.4.2., of Airbus Helicopters Alert Service Bulletin ASB EC135-67A-031, Revision 0, dated March 30, 2017. If, during the functional test, the clearance between the end of the close‐tolerance bolt, castellated nut, and the lower stringer is less than 1.0 mm, repair in accordance with FAA-approved procedures. ### (h) Alternative Methods of Compliance (AMOCs) (1) The Manager, International Validation Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the International Validation Branch, send it to the attention of the person identified in paragraph (i)(1) of this AD. Information may be emailed to: 9-AVS-AIR-730-AMOC@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. ### (i) Related Information (1) For more information about this AD, contact David Hatfield, Aviation Safety Engineer, Aircraft Systems Section, Technical Innovation Policy Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5110; email david.hatfield@faa.gov. (2) The subject of this AD is addressed in European Aviation Safety Agency (now European Union Aviation Safety Agency) (EASA) AD 2017-0147, dated August 10, 2017. You may view the EASA AD at https://www.regulations.gov in Docket No. FAA-2019-0293. ### (j) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) Airbus Helicopters Alert Service Bulletin ASB EC135-67A-031, Revision 0, dated March 30, 2017. (ii) [Reserved] (3) For Airbus Helicopters service information identified in this AD, contact Airbus Helicopters, 2701 North Forum Drive, Grand Prairie, TX 75052; telephone 972-641-0000 or 800-232-0323; fax 972-641-3775; or at https://www.airbus.com/helicopters/services/technical-support.html. (4) You may view this service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX 76177. For information on the availability of this material at the FAA, call (817) 222-5110. (5) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, email: fedreg.legal@nara.gov, or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html. ## Rule preamble ### Dates This AD is effective August 11, 2021. The Director of the Federal Register approved the incorporation by reference of a certain document listed in this AD as of August 11, 2021. ### Addresses For service information identified in this final rule, contact Airbus Helicopters, 2701 North Forum Drive, Grand Prairie, TX 75052; telephone 972-641-0000 or 800-232-0323; fax 972-641-3775; or at https://www.airbus.com/helicopters/services/technical-support.html. You may view the referenced service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX 76177. Service information that is incorporated by reference is also available at https://www.regulations.gov by searching for and locating Docket No. FAA-2019-0293. ### For further information contact David Hatfield, Aviation Safety Engineer, Aircraft Systems Section, Technical Innovation Policy Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5110; email david.hatfield@faa.gov. ### Background The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to Airbus Helicopters Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters with serial number (S/N) up to and including 1254 (except S/N 1235). The NPRM published in the Federal Register on April 16, 2021 (86 FR 20089). In the NPRM, the FAA proposed to require modifying the T/R control within 360 hours time-in-service (TIS) by installing a Teflon washer and performing a functional test in accordance with specified portions of Airbus Helicopters Alert Service Bulletin ASB EC135-67A-031, Revision 0, dated March 30, 2017 (ASB EC135-67A-031). Based on the results of the functional test, the NPRM proposed to require making repairs in accordance with FAA-approved procedures. The NPRM was prompted by EASA AD 2017-0147, dated August 10, 2017 (EASA AD 2017-0147), issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for Airbus Helicopters Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, EC135T3, EC635P2+, EC635P3, EC635T1, EC635T2+, and EC635T3 helicopters. EASA advises that several cases of insufficient clearance between a certain T/R bearing connection and the helicopter structure were detected during inspections of helicopters on the production line. EASA states that this condition, if not corrected and in the case of an unglued bearing, could lead to blockage of the pedal controlling the T/R thrust and loss of the T/R control. EASA further advises that this could result in a forced landing with damage to the helicopter and injury to the occupants. Accordingly, EASA AD 2017-0147 requires modifying the T/R control installation by adding a Teflon washer, which reduces the degree of freedom in case of a drifting bearing at the affected connection. EASA AD 2017-0147 also requires a functional test for clearance, and depending on the results, either accomplishing additional corrective actions or contacting Airbus Helicopters for instructions. ### Comments The FAA received no comments on the NPRM or on the determination of the costs. ### Conclusion These helicopters have been approved by EASA and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with the European Union, EASA has notified the FAA about the unsafe condition described in its AD. The FAA reviewed the relevant data and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these helicopters. ### Related Service Information Under 1 CFR Part 51 The FAA reviewed ASB EC135-67A-031 for Airbus Helicopters Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, EC135T3, EC635P2+, EC635P3, EC635T1, EC635T2+, and EC635T3 helicopters. For S/Ns up to 1254 inclusive, except S/N 1235, this service information specifies retrofitting a Teflon washer on the T/R controls, performing a functional test of the modified T/R control installation to inspect for clearance, and making any necessary adjustments. This service information advises that S/N 1255 and up will have the Teflon washer installed in production. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section. ### Differences Between This AD and the EASA AD The EASA AD sets compliance times at 12 months, while this AD requires compliance within 360 hours TIS. The EASA AD applies to Airbus Helicopters Model EC635T1, EC635T2+, EC635T3, EC635P2+, and EC635P3 helicopters; this AD does not because these models do not have an FAA type certificate. The EASA AD requires contacting Airbus Helicopters for approved repair procedures; this AD requires a repair using FAA-approved procedures. The EASA AD requires revising the “aircraft maintenance program,” whereas this AD does not because not all U.S. operators are required to have a maintenance program. ### Costs of Compliance The FAA estimates that this AD affects 331 helicopters of U.S. registry. Labor rates are estimated at $85 per work-hour. Based on these numbers, the FAA estimates the following costs to comply with this AD. Modifying the T/R control installation and conducting a functional test takes about 3 work-hours and parts cost about $25 for an estimated cost of $280 per helicopter and $92,680 for the U.S. fleet. If required, adjusting the clearance takes about 1 work-hour for an estimated cost of $85 per helicopter. ### Authority for This Rulemaking Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority. The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on helicopters identified in this rulemaking action. ### Regulatory Findings This AD will not have federalism implications under Executive Order 13132. This AD will 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. For the reasons discussed above, I certify that this AD: (1) Is not a “significant regulatory action” under Executive Order 12866, (2) Will not affect intrastate aviation in Alaska, 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. ### The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H88EU](https://openairdocs.org/tcds/H88EU): Airbus Helicopters Deutschland GmbH (AHD); names 7 of 9 models: EC135P1, EC135T1, EC135P2, EC135T2, EC135P2+, EC135P3, EC135T3 ## 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: 345 (345 by airframe model, 0 by engine model) - Makers: Eurocopter Deutschland 242, Airbus Helicopters Deutschland 74, Airbus Helicopters 29 Models with the most aircraft: - [Eurocopter Deutschland EC 135 P2+](https://openairdocs.org/model/eurocopter-deutschland-ec-135-p2-plus): 166 aircraft (airframe model) - [Airbus Helicopters Deutschland EC135 P3](https://openairdocs.org/model/airbus-helicopters-deutschland-ec135-p3): 34 aircraft (airframe model) - [Eurocopter Deutschland EC 135 P2](https://openairdocs.org/model/eurocopter-deutschland-ec-135-p2): 31 aircraft (airframe model) - [Airbus Helicopters Deutschland EC135T3](https://openairdocs.org/model/airbus-helicopters-deutschland-ec135t3): 27 aircraft (airframe model) - [Eurocopter Deutschland EC135T2](https://openairdocs.org/model/eurocopter-deutschland-ec135t2): 16 aircraft (airframe model) - [Airbus Helicopters EC135 P3](https://openairdocs.org/model/airbus-helicopters-ec135-p3): 16 aircraft (airframe model) - [Eurocopter Deutschland EC135T1](https://openairdocs.org/model/eurocopter-deutschland-ec135t1): 14 aircraft (airframe model) - [Eurocopter Deutschland EC135P1](https://openairdocs.org/model/eurocopter-deutschland-ec135p1): 14 aircraft (airframe model) - [Airbus Helicopters Deutschland EC135 P2+](https://openairdocs.org/model/airbus-helicopters-deutschland-ec135-p2-plus): 13 aircraft (airframe model) - [Airbus Helicopters EC135T3](https://openairdocs.org/model/airbus-helicopters-ec135t3): 13 aircraft (airframe model) - [Eurocopter Deutschland EC135 P3](https://openairdocs.org/model/eurocopter-deutschland-ec135-p3): 1 aircraft (airframe model) All 11 models: https://openairdocs.org/ad/2021-13-05/models.md Every aircraft: https://openairdocs.org/ad/2021-13-05/aircraft.md ## Related documents - [Proposed rule FAA-2019-0293](https://openairdocs.org/proposed/FAA-2019-0293): Notice of proposed rulemaking (NPRM), published Apr 16, 2021 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.