Airworthiness Directive · Amendment 39-21024 · Bell Helicopter Textron Inc. Helicopters
Bell Helicopter Textron Inc. Helicopters
This AD applies to Model 412 and 412EP helicopters with serial number (S/N) 33001 through 33213, 34001 through 34036, 36001 through 36648, 36650 through 36657, 36660 through 36672, 36674 through 36680, 36685, 36687, 36689, 36691, 36693, 36695, and 37002 through 37012, certificated in any category, with a static inverter (inverter) part number (P/N) 412-375-079-101 or 412-375-079-103 with S/N 29145 or higher, installed.
The FAA is superseding Airworthiness Directive (AD) 2015-04-04 for Bell Helicopter Textron Inc. (Bell) Model 412 and 412EP helicopters. AD 2015-04-04 required revising the Rotorcraft Flight Manual (RFM) for your helicopter and installing a placard to limit flights to visual flight rules (VFR) and prohibit night operations because of failing inverters. This AD requires replacing the affected inverter with a new inverter. This AD was prompted by numerous failures of inverters. The FAA is issuing this AD to address the unsafe condition on these products.
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.
(1) Within 25 hours time-in-service:
(i) For helicopters with S/N 33001 through 33213, 34001 through 34036, and 36001 through 36086, replace the inverter with inverter P/N 412-375-079-105.
(ii) For helicopters with a S/N 36087 through 36648, 36650 through 36657, 36660 through 36672, 36674 through 36680, 36685, 36687, 36689, 36691, 36693, 36695, and 37002 through 37012, install retrofit kit P/N 412-704-058-103 and replace the inverter with inverter P/N 412-375-079-105.
(2) After accomplishing the actions required by paragraph (f)(1) of this AD, you may remove the placard and Rotorcraft Flight Manual limitations, required by AD 2015-04-04, prohibiting night operations and restricting flights to visual flight rules.
(3) After the effective date of this AD, do not install an inverter P/N 412-375-079-101 or 412-375-079-103 on any helicopter.
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.
