Relationship between twist grip and throttle levers

The two throttle levers next to the collective are used to change the operating modes of the engines between idle, normal, and emergency (for single engine flight). They are in the normal (center) position upon spawning and should stay there throughout the flight.

The twist grip is used to control the engines in their normal operating mode, the throttle levers override this when they are in the "idle" or "emergency" mode.

Now, I've recently run into some confusing behavior involving the way these two controls interact with each other. There appears to be a mechanical linkage that moves the twist grip when the levers are in emergency mode. The amount it gets moved seems to depend on collective pitch.

I encountered this while working on an aggressive vertical takeoff. I put the levers into emergency and use the extra 5% rotor RPM to pop into the air more quickly. Then, I put the levers back to normal because emergency mode likes to overspeed the rotors under certain conditions. The problem is, when the levers go back to normal, the twist grip is rolled back significantly and must be returned to full before the engines throttle themselves down and rotor RPM drops.

Does anyone know why this "linkage" exists, or if it's implemented correctly?

They all go to the same place, ultimately. The throttle levers are for individual engines, while the throttle on the collective is for both engines simultaneously. They connect under the floor. I'll see if I can find the picture and post it here.

EDIT: Okay the picture is hard to look at, so I won't bother, but the point is that the twist throttle and the separate engine control levers mix together right at the bottom of the pilot's collective assembly.

They all go to the same place, ultimately. The throttle levers are for individual engines, while the throttle on the collective is for both engines simultaneously. They connect under the floor. I'll see if I can find the picture and post it here.

 

EDIT: Okay the picture is hard to look at, so I won't bother, but the point is that the twist throttle and the separate engine control levers mix together right at the bottom of the pilot's collective assembly.

Makes sense, thanks!

Trying to get my head around this:

I only need the ECLs if the Governors fail, right? Even in the case of single engine failure, the governor adjusts N1 RPM as I understand it.

But when do I use the N2 Trim on the collective? And how do I use it?

The only emergency procedure which calls for the use of the ECLs is engine surging, which is not simulated here. Otherwise, the ECLs are only used for maintenance/testing purposes. In other words, there is no reason to use the ECLs at this time, unless you just want to do it for fun. Even if the governors fail, you modulate power with the collective and visually verify that you remain within the engine's operating limits.

The N2 trim switch is used to set the rotor speed to 95% when on the ground with the throttle full right and 3 degrees of collective pitch in the rotor blades.

I just stumpled across this thread, sorry to pop in and ask :book:

Does it mean that I should always turn the twist grip to full power before lifting off ?

I never did so and left that grip untouched, ever since :doh:

I just stumpled across this thread, sorry to pop in and ask :book:

 

Does it mean that I should always turn the twist grip to full power before lifting off ?

 

I never did so and left that grip untouched, ever since :doh:

Yes. When the twist grip is in the full throttle position, the governor has full authority over the engines.

My understanding of a document linked in another thread is that the twist grip determines the maximum throttle setting available to the governor, but I'm not sure.

The only emergency procedure which calls for the use of the ECLs is engine surging, which is not simulated here.

Wait, I thought you were supposed to pull them up in case of engine failure to switch the rotor governor to single engine mode?

Wait, I thought you were supposed to pull them up in case of engine failure to switch the rotor governor to single engine mode?

No that's automatic. Who has time to futz with ECLs during an engine failure? You have better things to do.

Also, the term "governor" is bring thrown around a lot. It should be noted that there are different governors depending on the context. Items 1-4 below are all contained within the Fuel Control Unit mounted on each engine.

1. During engine start, there is an automatic start control unit that regulates fuel flow during engine start. It works up until around 45% N1 then it's wide open.

2. Above 40% N1, the acceleration time control unit takes over and schedules fuel flow into the engine until the engines reach idle speed, around 75% N1.

3. When the throttle grip is twisted to full right, the turbocompressor speed governor (inside the FCU, not the one in the EEG) schedules fuel flow up until the main rotor speed is above 93%. Then it's wide open.

4. The main rotor speed governor schedules the fuel flow at a main rotor rpm above 93%.

All of the items above are integral to each engine's fuel control unit and cannot be changed by the pilot. They are purely mechanical and operate based on rotational speeds (N1/N2) and fuel pressure inside the FCU.

5. Engine Electronic Governor (EEG): Limits N1 (GG/TC) speed and EGT (PTIT), and monitors for N2 (FT/PT) overspeed. Has a control panel on the central console. N1 is limited to 101.15%, unless and engine fails, then it stops limiting N1, but N1 is still limited by the N1 and N2 speed governors within the fuel control, and is typically around 102.5% depending on air temperature and pressure. EGT is limited to 990 degrees, even if an engine fails. The only way around this EGT limit is to turn off the governor. The N2 governor in the EEG shuts down the engine if the N2 reaches 118% plus or minus 2%, so it technically doesn't limit anything, it just shuts off the engine. This would typically only happen in the event of a failure of the input quill from that engine to the main gearbox, or a failure of the free turbine shaft to the main gearbox.

Sorry for the multiple posts, but another clarification on the ECLs.

The collective, the throttle, and the ECLs all affect the engine's throttle position. I.e. raising the collective, increases throttle setting (on both engines simultaneously). Twisting the throttle grip to the right increases throttle setting (on both engines simultaneously). Moving an ECL up increases the throttle setting (only on that individual engine).

Increasing all three of these can result in hitting the throttle stop on the engine fuel control unit. In other words, if you have the throttle twist grip full right, and you raise an ECL to full up, you will NOT be able to raise the collective all the way, you will hit the throttle stop first. You would have to twist the throttle left a bit (not recommended) or reduce the ECL position in order to continue increasing collective pitch.