So let’s discuss helicopter!
This article discusses Collective Pull down during low Rotor RPMs,
“Mark what’s low Rotor RPM?”
Low Rotor RPM is when your RPMs for your rotor is less then normal, in the R22/R44 the Low Rotor RPM horn starts screaming at 97%. We typically want Rotor RPMs between 101 - 104%
There are several reasons why we would get this.
- Flying outside of the aircraft’s envelope so abusing it.
- High D.A Day
- Heavy loads.
With Low Rotor RPM comes along with Retreating blade stall which basically the retreating blade isn’t producing lift. So how do we, as helicopter pilots, recognize Low Rotor RPM?
A noticeable decrease in engine and rotor noise, A slight vibration and cyclic stick shake at higher speeds, The activation of the low rotor RPM warning light and horn system, Also a yaw to left and slight descent of helicopter.
The solution for this is to lower collective and roll on throttle with gentle aft cyclic. You let those rotor RPM’s build up and figure out why that happened.
So now HeliTrak has produced an item that will actually lower the Collective incase of any Low Rotor RPM situations It takes a second for this system to lower the Collective, typically it takes a pilot 2 - 3 seconds.
Since we’re talking about Low Rotor RPM I provided some video of what happens if you don’t recover properly.
Not recovering properly:
This is what that Low Rotor RPM horn sounds like, this guy pulled more collective in trying to get more power, which didn’t work.
This is what the Low Rotor RPM horn sounds like again, this guy lowered his collective and open his throttle, gained speed and carried on.