Airworthiness Directive · Amendment 39-23163 · Tail rotor system
Airbus Helicopters
This AD applies to Airbus Helicopters Model EC120B helicopters, certificated in any category.
The FAA is superseding Airworthiness Directive (AD) 2021-26- 07, which applies to all Airbus Helicopters Model EC120B helicopters. AD 2021-26-07 requires performing repetitive inspections of the tail rotor (TR) hub body and, depending on the inspection results, replacing certain parts, and accomplishing further inspections. AD 2021-26-07 also requires for certain helicopters removing from service any bolt, washer, and nut installed on the TR hub body at certain life limits and replacing them with airworthy parts and accomplishing further inspections. Additionally, AD 2021-26-07 prohibits the installation of a certain part-numbered TR hub body unless certain requirements are met. Since the FAA issued AD 2021-26-07, it was determined that modifying the link of the TR hub body and splined flange by adding red paint marks is necessary to enable the detection of any loss of tightening torque. This AD retains the same repetitive inspections and corrective actions as AD 2021-26-07 and requires modification of the link of the TR hub body, which is a terminating action for the repetitive inspections. This AD also requires repetitive inspections of the red paint line added during the modification of the link of the TR hub body for alignment. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Within 15 hours time-in-service (TIS) or 7 days, whichever occurs first after the effective date of this AD, and thereafter at intervals not to exceed 15 hours TIS, using a light source and mirror, visually inspect TR hub body part number (P/N) C642A0100103 for a crack in the entire inspection area depicted in Figure 1 of Airbus Helicopters Emergency Alert Service Bulletin 05A020 Revision 3, dated September 19, 2024. If any crack is found, before further flight, perform the actions in paragraphs (g)(1)(i) and (ii) of this AD.
(i) Remove the TR hub body and each bolt, washer, and nut installed on the TR hub body from service and replace with airworthy parts.
(ii) Inspect the TR splined flange for corrosion, impacts, fretting, wear, and a crack in the areas identified in Figure 2 to paragraph (g)(1)(ii) of this AD. If the condition of the part (including corrosion, impacts, fretting, wear, or cracks) exceeds the criteria as specified in Figure 1 to paragraph (g)(1)(ii) of this AD, before further flight, remove the splined flange from service and replace with an airworthy part.
Note 1 to paragraph (g)(1)(ii): You may refer to “Detailed Check-Splined Flange,” Task 64-21-00, 6-5, Airbus Aircraft Maintenance Manual (AMM), dated October 15, 2020, which pertains to the TR splined flange inspection.
(2) For helicopters with 9,000 or more total hours TIS or with unknown total hours TIS, within 15 hours TIS or 7 days, whichever occurs first after the effective date of this AD, and thereafter at intervals not to exceed 1,000 hours TIS, remove each bolt washer, and nut installed on the TR hub body from service and replace with airworthy parts and perform the actions in paragraph (g)(1)(ii) of this AD.
(3) For helicopters with less than 9,000 total hours TIS, within 1,000 hours TIS or before accumulating 9,000 total hours TIS, whichever occurs first after the effective date of this AD, and thereafter at intervals not to exceed 1,000 hours TIS, remove each bolt, washer, and nut installed on the TR hub body from service and replace with airworthy parts and perform the actions in paragraph (g)(1)(ii) of this AD.
(4) Within 24 months after the effective date of this AD, inspect the torque on the nut of the TR hub body in accordance with paragraph 4.1.2 of Airbus Helicopters Alert Service Bulletin ASB EC120-64-21-0001, Issue 001, dated September 19, 2024.
(i) If the torque is not within allowable limits, before further flight, remove the nut on the TR hub body from service and replace it with an airworthy nut; and accomplish the actions in paragraph (g)(4)(ii) of this AD.
(ii) If the torque is within allowable limits, before further flight, using polyurethane paint, apply a red paint line to the bolt and washer on the TR hub body; and apply a red paint line to the nut and washer on the splined flange. These actions terminate the repetitive inspections and replacements required by paragraphs (g)(1) through (3) of this AD.
(5) Within 100 hours TIS or 12 months, whichever occurs first after the action required in paragraph (g)(4)(ii) of this AD, and thereafter at intervals not to exceed 100 hours TIS or 12 months, whichever occurs first, inspect the red paint line for alignment. If the red paint line is misaligned, before further flight, perform the actions as specified in paragraphs (g)(4)(i) of this AD.
As of the effective date of this AD, do not install on any helicopter a TR hub body P/N C642A0100103 or a splined flange unless the part is new (zero hours TIS) or has passed the inspection requirements required by paragraph (g)(1) of this AD.
