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Hydraulic "Transparancy"?


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I have been unfortunate enough to have had both a total hydraulic failure in an Astar D with the accumulators full and one without. The first thing I did was turn off that **** horn.

As to the problem with "Cyclic Transparency"

In the twinstar there is a limit light to advise that you have reached the G limit of the AC ( 2 Hyd Systems).

In the Astar you feel feedback but there is no sudden pitch up and the aircraft remains fully controllable at all times.

If you run into the ground in this situation you have already exceeded the G limits of the AC and the problem is not the AC.

I have never flown the later model Astars so don''t know the no Hydraulic performance.

In the old days the 205 only had 1 HYD system so we were expected to be able to land with no HYD - just never go below 35 PSI Q. or you may not be able to get the collective back up.

A very good 205 pilot demonstrated a " No Collective" Landing to me but he also taught me turns over 30 degrees so we would not want to pay attentiomn to him today as that would be dangerous!!@!!old time ( 1978).

I had a student on the 212 who refused to do any turn over 30 Deg. When asked what he would do if a tower or power line appeared in front of him he stated that he would never fly in weather with less than 3 miles Vis so it was a mute point. Any comments?

 

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SharkBait, I have some comments...You wrote....

"In the Astar you feel feedback but there is no sudden pitch up and the aircraft remains fully controllable at all times. If you run into the ground in this situation you have already exceeded the G limits of the AC and the problem is not the AC."

 

?????Fully Controllable?????????????? Is that what you call it? I found controls that were almost impossible to move, if I was in a flight position that required a cyclic movement, it would not have happened, and I would also have run into something in front of me. I was circling a spot fire in a 30 degree bank when my Astar locked up...tell me what G limitation I exceeded that day?? I must have been pulling all of .5 G's.

Give me a break, Don't be afraid to admit that the HYD system can't always handle the flight loads, so fly the aircraft accordingly.

All pilots out there who have NEVER exceeded a manufacturers limitation, be it G's, CG, Lbs, Q, Vne, V anything, N anything, please raise your hand...?

We sometimes do, and we fly away and learn, our Wrench inspects and fixes our mistakes. SharkBait is correct, My friend may have exceeded a "G" limitation crossing that ridge low and fast on Christmas Day, but what a price to pay in doing so? Is it really only the pilots problem or a design problem?

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Sorry if I seemed to be referring to that particular accident.

I have always been very sceptical that Hydraulic Transparency was a contributing factor in that accident. I could be wrong but I just don''t think that was the problem - perhaps another type of Hyd / control problem - I just do not know - did not mean seem to be critcal of the pilot but see how it could sound like I was - Sorry if I offended anyone.

As to your incident _

As you say you were in a 30 deg turn with no G and low power then I wonder if you had some kind momentary Hydraulic failure (Servo Jam ??)causing the symptoms and not a hydraulic transparency caused by high G loads on the head. Did that stupid horn go off? What model were you in at the time? Not trying to second guess you just wondering. Suprising two people can get 2 different results from the same problem.

Astar Hyd systems always seemed a little bit mickey mouse to me what with bearing failures, belt failures, ice on the servos ( talked to a dude who had that problem and he was still pale 6 months later - scary - happened in a confined area on take off.)

Yes I can say that it was always fully controlable with no lock or pitch up - we used to demonstrate it ( very carefully ) on training flights but stopped doing it when never got any reports of people having encountered it in the field.

Thanks for the feedback.

 

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