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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2020-1037; Project Identifier 2019-SW-077-AD; Amendment 39-21407; AD 2021-03-04]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Final rule.

# SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Airbus Helicopters Deutschland GmbH Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters. This AD requires removing certain Titanium (Ti) bolts from service and prohibits installing these Ti-bolts in a critical area. This AD was prompted by a report of a broken Ti-bolt. The actions of this AD are intended to address an unsafe condition on these products.

# DATES:

This AD is effective March 29, 2021.

# ADDRESSES:

                        For service information identified in this final rule, contact Airbus Helicopters, 2701 N 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.                    

## Examining the AD Docket

                    You may examine the AD docket on the internet at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2020-1037; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the European Union Aviation Safety Agency (EASA) AD, any comments received, and other information. The street address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.                

# FOR FURTHER INFORMATION CONTACT:

                        Katherine Venegas, Aviation Safety Engineer, Los Angeles ACO, FAA, 3960 Paramount Blvd., Lakewood, CA 90712; telephone 562-627-5353; email                         *katherine.venegas@faa.gov.*

# SUPPLEMENTARY INFORMATION:

## Discussion

                    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 Deutschland GmbH Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters with a Ti-bolt part number (P/N) L535M2001203 marked with manufacturer monogram “D” or with an illegible manufacturer monogram installed on the forward tail rotor (T/R) drive shaft. The NPRM published in the                     **Federal Register**                     on November 30, 2020 (85 FR 76490). The NPRM proposed to require removing any affected Ti-bolt installed on the forward T/R drive shaft from service and prohibit installing an affected Ti-bolt on the forward T/R drive shaft of any helicopter. The proposed requirements were intended to prevent failure of an affected Ti-bolt installed in a critical location, possibly resulting in reduced control of the helicopter.                

                    The NPRM was prompted by EASA AD No. 2019-0199, dated August 16, 2019, issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for Airbus Helicopters Deutschland GmbH (AHD), formerly Eurocopter Deutschland GmbH, Eurocopter España S.A., Model EC135 P1, EC135 P2, EC135 P2+, EC135 P3, EC135 T1, EC135 T2, EC135 T2+, EC135 T3, EC635 P2+, EC635 P3, EC635 T1, EC635 T2+, and EC635 T3 helicopters. EASA advises of a report of a broken Ti-bolt. Subsequent investigation revealed that an improper heat treatment process was accomplished on a batch of Ti-bolts, which can lead to hydrogen embrittlement. The investigation also identified the critical location where these Ti-bolts are installed on helicopters. According to EASA, this condition, if not detected and corrected, could lead to failure of an affected Ti-bolt installed in a critical location, possibly resulting in reduced control of the helicopter. Accordingly, the EASA AD requires a one-time inspection of Ti-bolt P/N L535M2001203 marked with                           ( print page 10450)                        manufacturer monogram “D” or with an illegible manufacturer monogram installed on the forward T/R drive shaft and, depending on the inspection results, replacing the Ti-bolt. The EASA AD also prohibits the (re)installation of these Ti-bolts.                

## Comments

The FAA gave the public the opportunity to participate in developing this final rule, but the FAA did not receive any comments on the NPRM or on the determination of the cost to the public.

## FAA's Determination

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 of the unsafe condition described in its AD. The FAA is issuing this AD after evaluating all of the information provided by EASA and determining the unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs and that air safety and the public interest require adopting the AD requirements as proposed.

## Differences Between This AD and the EASA AD

The EASA AD applies to Model EC135 P1, EC135 P2, EC135 P2+, EC135 P3, EC135 T1, EC135 T2, EC135 T2+, EC135 T3, EC635 P2+, EC635 P3, EC635 T1, EC635 T2+, and EC635 T3 helicopters and requires inspecting Ti-bolt P/N L535M2001203 marked with manufacturer monogram “D” or with an illegible manufacturer monogram installed on the forward T/R drive shaft. This AD applies to Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters with a Ti-bolt P/N L535M2001203 marked with manufacturer monogram “D” or with an illegible manufacturer monogram installed on the forward T/R drive shaft instead. This AD does not apply to Model EC635 P2+, EC635 P3, EC635 T1, EC635 T2+, or EC635 T3 helicopters because these models are not FAA type-certificated. The EASA AD requires discarding the affected Ti-bolts, whereas this AD requires removing the affected Ti-bolts from service instead.

##  Related Service Information

The FAA reviewed Airbus Helicopters Alert Service Bulletin (ASB) No. EC135-00A-001, Revision 1, dated September 2, 2019, for Airbus Helicopters Deutschland GmbH Model EC135 T1, T2, T2+, T3, P1, P2, P2+, P3, 635 T1, 635 T2+, 635 T3, 635 P2+, and 635 P3 helicopters, and Airbus Helicopters ASB No. EC135H-00A-001, Revision 1, dated September 2, 2019, for Airbus Helicopters Deutschland GmbH Model EC135, T3H, P3H, 635 T3H, and 635 P3H helicopters. This service information specifies inspecting the forward T/R drive shaft, distance plate of the 5B-0.50-2.50P-XN-1 antenna, main rotor controls, FWD connection of ball bearing control, and AFT connection of ball bearing control and yaw actuator for the installation of Ti-bolt P/N L535M2001203, EN3308-040020F, L221M1040201, EN3740-060020F, and EN3308-060020F, marked with manufacturer monogram “D” or an illegible manufacturer monogram. If a specified Ti-bolt is installed, the service information specifies replacing the Ti-bolt and discarding the removed Ti-bolt.

## Costs of Compliance

The FAA estimates that this AD affects 326 helicopters of U.S. Registry. Labor rates are estimated at $85 per work-hour. Based on these numbers, the FAA estimates that operators may incur the following costs in order to comply with this AD.

Replacing a Ti-bolt takes about four work-hours and parts cost about $82 for an estimated cost of $422 per Ti-bolt.

## 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.

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Incorporation by reference
      - Safety

## Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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

2. The FAA amends § 39.13 by adding the following new airworthiness directive: 

**2021-03-04 Airbus Helicopters Deutschland GmbH:**                             Amendment 39-21407; Docket No. FAA-2020-1037; Project Identifier 2019-SW-077-AD.                        

## (a) Applicability

This airworthiness directive (AD) applies to Airbus Helicopters Deutschland GmbH Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, and EC135T3 helicopters, certificated in any category, with a Titanium (Ti) bolt part number L535M2001203 marked with manufacturer monogram “D” or with an illegible manufacturer monogram installed on the forward tail rotor drive shaft.

**Note 1 to paragraph (a):**                             Helicopters with an EC135P3H designation are Model EC135P3 helicopters. Helicopters with an EC135T3H designation are Model EC135T3 helicopters.                        

## (b) Unsafe Condition

This AD defines the unsafe condition as failure of an affected Ti-bolt installed in a critical location, possibly resulting in reduced control of the helicopter.

## (c) Effective Date

This AD becomes effective March 29, 2021.

## (d) Compliance

                            You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.                                  ( print page 10451)    

## (e) Required Actions

(1) Within 50 hours time-in-service or 3 months, whichever occurs first, remove any Ti-bolt identified in paragraph (a) of this AD, located on the forward tail rotor drive shaft, from service.

(2) As of the effective date of this AD, do not install a Ti-bolt identified in paragraph (a) of this AD on the forward tail rotor drive shaft of any helicopter.

## (f) Alternative Methods of Compliance (AMOCs)

                            (1) The Manager, Strategic Policy Rotorcraft Section, FAA, may approve AMOCs for this AD. Send your proposal to: Manager, Strategic Policy Rotorcraft Section, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5110; email                             *9-ASW-FTW-AMOC-Requests@faa.gov.*

(2) For operations conducted under a 14 CFR part 119 operating certificate or under 14 CFR part 91, subpart K, the FAA suggests that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office, before operating any aircraft complying with this AD through an AMOC.

## (g) Additional Information

                            (1) Airbus Helicopters Alert Service Bulletin (ASB) No. EC135-00A-001 and ASB No. EC135H-00A-001, each Revision 1 and dated September 2, 2019, which are not incorporated by reference, contain additional information about the subject of this AD. For service information identified in this AD, contact Airbus Helicopters, 2701 N. 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 a copy of the service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy, Room 6N-321, Fort Worth, TX 76177.                        

                            (2) The subject of this AD is addressed in European Union Aviation Safety Agency (EASA) AD No. 2019-0199, dated August 16, 2019. You may view the EASA AD on the internet at                             *https://www.regulations.gov*                             in Docket No. FAA-2020-1037.                        

## (h) Subject

Joint Aircraft Service Component (JASC) Code: 1430, Fasteners; and 6510, Tail Rotor Drive Shaft.

Issued on January 22, 2021.

Lance T. Gant,

Director, Compliance & Airworthiness Division,  Aircraft Certification Service.

[FR Doc. 2021-01848 Filed 2-19-21; 8:45 am]

BILLING CODE 4910-13-P