A video to go with an earlier blog post.
I’ve written at least twice in this blog about the low rotor RPM warning system on Robinson helicopter:
I thought it might be good to illustrate what it looks and sounds like on video. You can find the video at the bottom of this post.
Before you watch the video, please read this explanation. The video is not narrated; I wanted the helicopter sound to be heard. If you don’t read this, you won’t know what’s going on or why.
- At first the helicopter is at cool-down RPM (around 65%). I’d just come in from a flight and was getting ready to shut down when I decided to use my Flip camera to make the video.
- I wind up the RPM by twisting the throttle. Watch the tachometer in the upper right corner. Needles are matched for engine (E) and rotor (R) RPM.
- When RPM gets to about 80%, the R44’s electronic governor takes over and brings it up to 100-102% engine RPM (the green arc).
- I simulate a low rotor RPM situation to test the system. (The system is required to function for flight so I test before every flight.) This requires me to raise the collective about an inch and then slowly roll off the throttle to reduce RPM. You can hear the engine pitch change and see the needles start to droop.
- At 97% RPM, the warning system engages with an audible horn and a light. A pilot who misses this would have to be blind and deaf (and thus, would not be good as a pilot).
- In the test, I push the collective down to shut the horn off and let the governor roll the throttle back up. If the horn came on in flight, you’d use the low rotor RPM recovery procedure, as discussed in “Reacting to Low Rotor RPM,” to regain RPM before it dropped to the point where it was not recoverable and became catastrophic.
Here’s the video:
The system looks and works slightly differently on different helicopter models. But the basic operation and test is the same.