Official Word From Bell On 412 Operating Rrpm
Greetings All,
This just in from my own Bell Rep this week for your edification:
On the issue operation at 97% NR, In order to standardize operations, Bell Helicopter will be issuing a rev to the flight manual that will limit rotor RPM to 100 % during all operations. Normal governor excursions above or below 100 % will be acceptable but continuous ops shall be at 100%.
At this point in time normal rotor RPM limits (Green arc) can be anywhere from 97 to 100 %. There is no restriction. There is a perceived ride quality 4/rev improvement at 97 % if the aircraft is not equipped with a FRAHM damper (412-SI-47) as well as a slight fuel burn improvement. At 100% rotor blade lift is optimized .At high altitude, high gross weights and airspeeds at or near VNE, control system loads increase dramatically as the rotor approaches retreating blade stall. Because retreating blade stall occurs at a lower airspeed at 97%, operation at 100 % will reduce these loads and will be stipulated as the RPM limit used for continuous ops.
A revision to the flight manual, plus a decal to install on the instrument panel will be release thru ASB shortly advising operators.
Hope this helps those of you who are still flogging about at 97% to start changing your checklists now!
Cheers,
Oracle