FAA Mandates Propeller Gearbox Fixes for Rotax Engines
Published Date: 3/4/2026
Rule
Summary
If you own or operate aircraft with BRP-Rotax Model 915 iSc2 C24 or 915 iSc3 C24 engines, listen up! The FAA found some engines missing a key collar nut on the propeller gearbox, which could be unsafe. Starting March 19, 2026, you’ll need to check your propeller gearbox and replace it if that nut is missing—better safe than sorry, and no big surprise costs unless a fix is needed.
Analyzed Economic Effects
4 provisions identified: 2 benefits, 2 costs, 0 mixed.
Mandatory pre‑flight gearbox inspection
If you own or operate an aircraft with a BRP‑Rotax Model 915 iSc2 C24 or 915 iSc3 C24 engine, you must visually inspect the propeller gearbox for a M40 x 1.5 collar nut before further flight starting March 19, 2026. If the collar nut is not installed, you must replace the propeller gearbox with a serviceable gearbox and perform the required test run per the Rotax Alert Service Bulletin.
What counts as a serviceable gearbox
A 'serviceable gearbox' for compliance is defined as one of the following: Part Number 686790 that passed the required inspection, a gearbox manufactured after November 18, 2025, a gearbox overhauled after November 18, 2025, or a gearbox with a serial number not listed in the Rotax ASB appendix dated November 27, 2025. Use these rules when choosing a replacement gearbox.
U.S. registry: no compliance costs stated
The FAA states there are no costs of compliance with this AD because there are no engines with this type certificate on the U.S. Registry. The AD is nonetheless effective March 19, 2026.
Approved method required if contamination found
If contamination is found during the inspection, you must, before further flight, accomplish further action using a method approved by the Manager, International Validation Branch, FAA; EASA; or Rotax's EASA Design Organization Approval. If approved by the DOA, the approval must include the DOA‑authorized signature.
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