When Power required exceeds Power available it can lead to a Helicopter Crash

Paul Salmon, CFII reviews several accidents where power required exceeded power available and it was the cause of the crash

[@MichaelHeliGuy]

Regarding the water landing at 4:56, at the beginning the helicopter seemed fine in the high hover over the water. The left turn didn't seem too excessive. The pilot seemed to make the turn in small steps and there doesn't appear to be any loss of altitude during the turn. The descent seems to start at 5:22 when the pilot pitches forward from a high hover to pick up speed. In my experience, take-offs in a light helicopter near MGW or at higher DA over hard ground can be near the limits of available power. You have to push over very gently until you pick up speed. When the helicopter starts to move forward, it starts to descend. To arrest the descent, the pilot likely added collective and overpitched the helicopter. This is evident between 5:25 and 5:26. By 5:27 it looks like the pilot has pulled up level. The helicopter was happily hovering over the water just a few seconds ago, but at this point the engine has likely sagged due to over pitching so down she goes. Given that ground effect for a helicopter is reduced over water, the hover over water likely required more power than the pilot realized leaving an insufficient power margin for the take-off profile attempted.

[@KWMQ]

No ground effect over water? Don't tell the Ekranoplan designers..

[@ganthrithor]

Right? This is why I tell students not to watch too much KZbin: they think they're going off to learn about flight dynamics, they come back telling you all about how birds aren't real.

[@kachinaaviation1628]

Yes there is ground effect over water. Handbook of aeronautical knowledge.. don way to many bambi bucket dips to not have experienced that.

[@tx2sturgis]

Maybe he means in most helicopter scenarios, no G/E over water. Because, you know, ekranoplane. (giant flying ships that use ground effect over water)

[@MichaelHeliGuy]

Great video. This underscores that, as helicopter pilots, we need to know the limits of our training. If we want to move past the limits of our training into something unfamiliar, we need to get more training from an experienced instructor. Overpitching can be avoided. We just need to be flexible in our thinking. IFR pilots plan for this as a "missed approach". They have a criteria for moving forward or aborting. As part of the pre-landing check, while still flying at speed, what is your power at? What kind of margin do you need to hover? Better to know you're running low on power before you run out of power. My commercial instructor has me do my running landings while keeping the power below 20" (in the R44). While not necessarily useful in the situations shown in the video, it illustrates that you can't hover a normally weighted R44 with such a reduction in available power. I'm curious what other R44 pilots find. I only fly at sea level. For me, I'm usually below 20" in the downwind cruising at 70kts. I think my hovers are usually around 23". I'll double check some of my videos.

[@hansiyoutube534]

Based on the videos, it might also be worth explaining how overpitching (low rotor rpm) affects the power available. It's also important to note the terminology used. The term 'Power' can easily be confused with the actual power used by the pilot in flight (MAP or torque) which can never exceed the power available. Power required is really only correct terminology for level flight. To stop a descent or to climb, a power margin (or surplus power) must be used. If there is no power margin for an IGE hover, then the power is 'limited'. So at normal flying rpm's, the power available from the engine is primarily a function of air density whereas the power required to fly level is a function of both density, weight and airspeed. It is however still very possible to both overpitch a heli and to get into vortex ring state without necessarily being limited in power. Cheers.

[@ganthrithor]

What are you talking about that there's "no ground effect" over water: there's literally an entire class of pseudo aircraft that exploit ground effect to achieve high-speed flight over water. They're called Ekranoplans or Ground-Effect Vehicles. The Russians built one the size of a small town (not really but it's pretty damn large). That Schweitzer dude just ran out of engine power-- he got slow, got into LTE, pushed a bunch of pedal and drooped the rotor RPM until he sank into the lake.

[@stephen5147]

Not to quibble, but "settling with power" (which is what your video examples seemed to demonstrate) is not the same as "Vortex Ring State." (re: Helicopter Flying Training Handbook)

[@rdwelch2]

I have the same hat (A thru E models) and probably some of the same t-shirts! Good video

[@waynejennings7046]

Good Information for any rotary pilot.

[@hughbassoon]

Excellent thanks

[@Daimo83]

Speed is life

[@stevenlee2202]

I don't know anything about this, nor plan on flying a helicopter but this power ratio thing is interesting. I know enough now that I'm not curious anymore.

[@jonnimart1]

Why is ground effect reduced over still water with no waves?

[@thedevilsadvocate5210]

Do you have insurance on a helicopter?

[@capecopters]

Yes, most people that operate helo's have them insured, but it's not required.

[@chippyjohn1]

Any quality helicopter has a turbocharger. Turbines and NA engines are not suitable for a helicopter.