PPRuNe Forums - View Single Post - As350 Hydraulic System Failures: too many??
Old 4th Dec 2012, 15:14
  #52 (permalink)  
FH1100 Pilot
 
Join Date: Nov 2006
Location: Pensacola, Florida
Posts: 770
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Well that's not really the point, is it Shawn?

*MY* point is this: Jack Carson wondered how the AS-350 ever got certified with its hydraulic-off control forces so high? He referenced an FAA design document and said the FAA calls for a maximum of only 6-8 pounds of force to be applied to a control (which seemed pretty low to me). He implied that this maximum is/was mandatory. But if you look on the chart that Mr. Carson referenced, look at movement #6 and we see that the recommended force is defined at 71 to 78 pounds. Perhaps Mr. Carson mistakenly referred to this chart and really meant to reference something else.

But even this is all moot because the FAA's Human Factor Design Guide is *not* mandatory, *AND* our U.S. FAR part 27 defines no maximum amount of control pressure. And whether the FAA did the original testing or not, the AS-350 has a U.S. Type Certificate and the certification of the aircraft is based on...wait for it...FAR part 27.

So. Are the hydraulics-off forces in an AS-350 high? Most certainly. Are they unacceptably high? Perhaps for some pilots, yes although no pilot worth his salt will ever admit to it. How did the AS-350 ever get certified with such high control forces? Easy! There are no standards.

For comparison, I had an hydraulic failure once (recently) in a Sikorsky S-55. It made the Astar seem like a piece of cake. Foolishly (and arrogantly) thought I could just fly back to my LZ and land, but abandoned that plan pretty quickly when I realized how much effort it was taking just to fly the bitch. It was horrible. Sometimes you have to admit to yourself that it's not worth it trying to be the hero. So I found a level patch of land and put 'er down. It flew so poorly that I was realistically prepared for it to "not work out so well" (i.e. roll over on landing). It did not...not due to my superior airmanship, but rather sheer dumb luck.

Dang, give me back my JetRanger!
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