Low rotor RPM blade stall

[lelebebbel]

Lelebebbel- since you're such an expert on blade grip failure could you please provide me with some data to support your claim? I've never seen nor heard of grip or blade failure from running rpms below the redline in a low hover.

 

Where did I say anything about grip failure? That was someone else.

I do agree though that low RPM hovers very obviously put high and unnecessary stress on the head and the blade roots.

Have you ever seen or heard of a piston heli that was proven to have failed from using more than the specified MAP limit? Does that mean we should be doing it?

 

Parts don't need to immediately fail while you are exceeding a limitation. It's bad enough if you have to retire a part before it reaches its time limit because it was worn out by improper use. And Robinson blades aren't exactly famous for being very sturdy. (link)

 

Also, if your hover autos are hard on the aircraft I would contest you're not doing them right. There are machines out there that have had thousands and thousands of hoverautos performed on them. Are they unsafe aircraft?

 

I'm not doing them at all, my students are, or used to while I was instructing. And no, of course they are not (always) doing them right, that's why they are called students. So yes, hover autos are hard on the helicopter. If you would always do them perfectly, there wouldn't be any reason to do them at all, would there?

 

 

The point of my post is just because you dont do something doesnt mean it is wrong or dangerous.

 

Certainly not, but if that "something" is exceeding a limitation set by the manufacturer of the helicopter, then at least I am not alone with my opinion that it is wrong and possibly dangerous.

Edited October 5, 2009 by lelebebbel

[RockyMountainPilot]

That failure, IIRC, was in South America where two obese guys flew overloaded, and at max MP quite frequently. That failure is actually testament to how well Robinsons are built.

[lelebebbel]

That failure, IIRC, was in South America where two obese guys flew overloaded, and at max MP quite frequently. That failure is actually testament to how well Robinsons are built.

 

The picture is from NZ I think. It is an example of what can happen if you ignore limitations.

Edited October 5, 2009 by lelebebbel

[choppedair]

It makes me wonder what the MP is while holding a hover at 70% RPM anyway.

[RockyMountainPilot]

The picture is from NZ I think. It is an example of what can happen if you ignore limitations.

 

How many hours on it? At least a few years ago, there had only been one blade failure accident and that was the one I mentioned in South America.

[Helo-Pilot]

Something I said in my last post is something I heard my previous boss say a lot. I ask myself these questions frequently when I am flying, and asked to do something questionable by a passenger.

"Do I need to be here, do I need to be doing this, and/or how am I going to explain this if something goes wrong?"

 

Very good questions. Be carefull when customers ask you to do something questionable. RUN when an operator asks.

 

 

The picture is from NZ I think. It is an example of what can happen if you ignore limitations.

 

It really doesnt matter where this happened. The fact is that unneccesary stresses cause failures like this to happen. We have proof that it happens. And we have the ability to prevent them from happening.

[hooked4life]

"Do I need to be here, do I need to be doing this, and/or how am I going to explain this if something goes wrong?"

 

This reminds me of couple things from my time in the Navy. One is that they always stressed the importance of ORM(Operational Risk Management), where you basically weigh the risks versus the benefits. Another is something one of my commanding officers used to say when talking about safety: Basically, if you're ever going to do something non-standard you should really think about how the mishap report will read.

Edited October 7, 2009 by hooked4life