Airworthiness Directive · Amendment 39-18106 · Ac inverter
Bell Helicopter Textron Inc. Helicopters
Superseded. A later AD replaced this one: AD 2020-02-11. Comply with the one in force.
This AD applies to Model 412 and 412EP helicopters with a static inverter (inverter) part number (P/N) 412-375-079-101 or 412-375-079-103 with a serial number 29145 or larger installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Bell Helicopter Textron Inc. (Bell) Model 412 and 412EP helicopters with certain static inverters (inverters) installed. This AD requires revising the Rotorcraft Flight Manual (RFM) and installing a placard in full view of the pilot to limit flight to visual flight rules (VFR) only and prohibit night operations. This AD is prompted by failures of certain inverters, most of which resulted in smoke in the cockpit. The actions specified by this AD are intended to restrict flight to VFR only and prohibit night operations to allow safe operation in the event of failure of an affected inverter. This failure would increase pilot workload during instrument flight rules (IFR) and could result in loss of certain pilot information displays and subsequent loss of control of the helicopter.
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.
Within 5 hours time-in-service:
(1) Add the statement “Flight is restricted to VFR, and night operations are prohibited” to the Limitations section of the Rotorcraft Flight Manual by making pen and ink changes or by inserting a copy of this AD.
(2) Install a placard stating “LIMITED TO VFR ONLY; NIGHT OPERATIONS PROHIBITED” on the instrument panel in full view of the pilots.
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.
