Airworthiness Directive · Amendment 39-23261 · Turbine engine reduction gear
BRP-Rotax GmbH & Co KG (Formerly BRP-POWERTRAIN GMBH & CO KG and Bombardier-Rotax GmbH) Engines
This AD applies to all BRP-Rotax GmbH & Co KG (formerly BRP-POWERTRAIN GMBH & CO KG and Bombardier-Rotax GmbH) (Rotax) Model 915 iSc2 C24 and 915 iSc3 C24 engines.
The FAA is adopting a new airworthiness directive (AD) for all BRP-Rotax GmbH & Co KG (Rotax) Model 915 iSc2 C24 and 915 iSc3 C24 engines. This AD was prompted by a report of a certain collar nut that was not installed on the propeller gearbox. This AD requires a visual inspection of the propeller gearbox to determine if a collar nut is installed on the propeller shaft and, if not installed, replacement of the propeller gearbox with a serviceable propeller gearbox. The FAA is issuing this AD to address the unsafe condition on these products.
For the purpose of this AD:
(1) A “serviceable gearbox” is a propeller gearbox that meets one of the conditions in paragraphs (g)(1)(i) through (iv) of this AD.
(i) A propeller gearbox having Part Number 686790 that has passed the inspection required by paragraph (h)(1) of this AD.
(ii) A propeller gearbox manufactured after November 18, 2025.
(iii) A propeller gearbox that was overhauled after November 18, 2025.
(iv) A propeller gearbox having a serial number that is not listed in paragraph 4) Appendix, of Rotax Alert Service Bulletin ASB-915 i-021R1/ASB-916 i-009R1, Revision 1, dated November 27, 2025 (published as a single document) (Rotax ASB-915 i-021R1/ASB-916 i-009R1).
(2) An “affected propeller gearbox” is a propeller gearbox that is listed in paragraph 4) Appendix, of Rotax ASB-915 i-021R1/ASB-916 i-009R1.
(1) Before further flight after the effective date of this AD and thereafter before further flight after installation of an affected propeller gearbox, do a visual inspection of the propeller gearbox for a collar nut installed on the propeller shaft in accordance with the Accomplishment/Instructions, paragraph 3.5.1) of Rotax ASB-915 i-021R1/ASB-916 i-009R1.
(2) If, during the inspection required by paragraph (h)(1) of this AD, any propeller gearbox is found without the collar nut installed on the propeller shaft, replace the propeller gearbox with a serviceable propeller gearbox and perform a test run in accordance with paragraphs (3.5.2) and (3.6) of Rotax ASB-915 i-021R1/ASB-916 i-009R1.
Where Rotax ASB-915 i-021R1/ASB-916 i-009R1 specifies “If contamination is found, contact your local ROTAX Authorized Distributors or their independent Service Centers,” this AD requires, before further flight, accomplishing further action in accordance with a method approved by the Manager, International Validation Branch, FAA; European Union Aviation Safety Agency (EASA); or Rotax' EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
