For 212/412 Pilots, weird fact.

[BlenderPilot]

I just realized than in the 212/412, the two triangle shaped switches (one for each engine) that are clearly labeled GOV (governor) AUTO or MANUAL, do not control the Governor! They control the FCU.

Everytime I do my runup checks I say "GOV 1/2 to MANUAL" and check for the engine response thinking I was putting the governor in manual mode.

It's imposible to put the, ENG 1 GOV to MANUAL, and leave ENG 2 AUTO since the aircraft has only ONE governor!

Therefore I have concluded that the switches in question have been clearly mislabeled during the 31 years the 212 has exsisted!

Anybody know why?

[SASless]

Each engine has an N1 and N2 Governor within the Fuel Control Unit (FCU) consisting of an Automatic Fuel Control Unit (AFCU) and a Manual Fuel Control Unit (MFCU). The Governor switch, when moved to the Manual Mode position, causes fuel to be redirected thus holding the Transfer Valve in such a position that fuel is not allowed into the AFCU. The N1 governor is mounted on the N1 Accessory section of the engine and the N2 governor is located on the N2 Accessory section . The N1 governor is throttle based and the N2 governor is collective and N2 Beep trim based.

[Arm out the window]

I could be talking crap, but from my understanding of Bell governor systems from my Huey days, the N1 and N2 governors had inputs to the FCU, combining to reach equilibrium and to produce a resultant position for the main fuel control valve, also modified by temperature and air pressure.
Going to the 'Manual' governor switch position simply bypassed all the automatic stuff and made your throttle into a direct fuel tap, so the labelling seems OK to me.
Perhaps this is a bit too simplistic though.
On another tack, how smart would those people have been who designed the 'steam-driven' FCUs from those days?
I remember racking my brain trying to understand how the old
'3-D cam' and all that stuff kept all the rotating bits going at the right speed - hats off to those designers!

[sprocket]

It's imposible to put the, ENG 1 GOV to MANUAL, and leave ENG 2 AUTO since the aircraft has only ONE governor!


BlenderPilot, were you meaning the helicopter has only one twin beep actuator? The one you see under the #1 eng.

Both N2 governors (at the rear of the engines) input come from the twin beep actuator in earlier models and later or modified models (412HP and on) have a second beep (ITT trim) actuator on the #2 eng N2 gov. But they have nothing to do with the manual control.

As SASless has said, When you select ‘manual’ for #1 eng the #1 AFCU, which also has input from the #1 eng N2 governor, is bypassed and you become the governor controlling the Ng[N1] for the #1 engine.
The #2 eng will still be controlled/governed by its own AFCU and N2 gov.