Hard Overs

[lineworker]

If you have a hard over in an a-star, fore/aft servo, what is it like?

 

If anyone has an experience I'd like to hear it. I remember the forestry machine in Ontario on a cutblock that has a sad ending. And I once met an instructor who was playing with his pen in his collective hand and accidentally pushed his actuator dump valve. That sounded difficult to deal with. It had a happy ending.

 

 

[Phil Croucher]

There was one at Remote Helicopters during 2003 and another at Canadian a little bit further North. Luckily both were on the ground at the time, but the Remote incident was such that a guy who was fairly strong couldn't pull the cyclic back. Don't know about the Canadian one because it wasn't officially recorded. At least, not initially.

 

There is no proof, as far as I am aware, that the OMNR machine was subject to that, but maybe someone else knows more about it.

 

BTW, in the Remote machine, the cyclic went over to the left.

 

Phil

[pilot5]

If you have a hard over in an a-star, fore/aft servo, what is it like?

 

If anyone has an experience I'd like to hear it. I remember the forestry machine in Ontario on a cutblock that has a sad ending. And I once met an instructor who was playing with his pen in his collective hand and accidentally pushed his actuator dump valve. That sounded difficult to deal with. It had a happy ending.

 

 

Felt it a few times, the best way out of it is not to be there in the first place and overload the hydraulic system. Surprised the french military, when the machine first came out didn't do something about the transparency problem or ask for a design change. The hydraulic system on the 350 is my only complaint. Easy on maneuvering and you will never have the experience. If you do get that "skippy stick", don't move it and it will stop. It can be induced not just during hard overs, but any repetitive maneuvering that loads or unloads G's .

 

 

 

 

[widgeon]

http://www.tsb.gc.ca/ENG/rapports-reports/.../2005/index.asp

 

read report of VIH in Guyana it has links to many other incidents.

 

http://www.tsb.gc.ca/ENG/rapports-reports/...25/a05f0025.pdf

 

Direct link,

 

[407 too]

"hard over" and "transperancy" are 2 different things, as far as my knowledge base is concerned.

 

We should not mix the two up here.

 

I believe the thread is about a "hard over" in which the servo O-rings fail and allows fluid past the piston.

 

I do believe that servo transperancy with respect to the a-star has more to do with an inadequate hydraulic system that cannot move the servos in all aggresive manouvers, and not the malfunctioning of a servo. (which is again different from the belts slipping on the hydraulic pump)

[pilot5]

"hard over" and "transperancy" are 2 different things, as far as my knowledge base is concerned.

 

We should not mix the two up here.

 

I believe the thread is about a "hard over" in which the servo O-rings fail and allows fluid past the piston.

 

I do believe that servo transperancy with respect to the a-star has more to do with an inadequate hydraulic system that cannot move the servos in all aggresive manouvers, and not the malfunctioning of a servo. (which is again different from the belts slipping on the hydraulic pump)

 

 

You are right! The very matter that there is more than one problem points a clear line in the direction of poorly designed system. Bell did a better job. Fail safe on!

 

Really nicely engineered engines in the 350 though, expensive, but nicely engineered, Guess the engineers at EC where hungover or something the day they started drafting up the schematics for the hydraulics .Dunno??

 

 

[widgeon]

Maybe it was another of the systems they 'borrowed' from renault.

 

The AS.350 in fact uses many automobile parts such as a cooling fan from a normal Citroen car and an oil radiator by another automobile manufacturer, .........

 

http://www.aviastar.org/helicopters_eng/snias-350.php

[Winnie]

Not to say that insane Peugeot HORN in the dash, ####, scared the crap outta me a few times, before I remembered to turn the horn OFF before rolling the throttle/s back...

 

nothing to say on hardovers...

 

Cheers

H.

[M&M]

I had a pax dropping a heavy GPS unit on the collective in a B3 once - breaking the switch guard and dumping the hydraulics - we were doing 120kts in a desending RH turn. The helicopter went nose up and right and then rolled to the right pretty hard before I realized what happened ! I remember hearing a little `bong` through my heatset ( audio warning ) - looked down on the collective - saw the switch turned off - and turned it back on again which restored hydraulics and we continued to base - I remember yelling at the guy which got me in trouble afterwards - he complained to my boss - oh well. All this happened within a few seconds and it sure gets your attention. A hydraulics failure in a high speed, heavy aircraft configuration is hard to controll - nothing like a simulated one in training. I guess one could call this `a hard over` - thats what it felt like to me !

 

Cheers

 

M&M