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sirlandsalot

212 Hydraulic check.

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Having a discussion here, with lots of opinions,    So here I go with my first post in years onto the vertical forums!!!

 Why is it the hydraulic control check is done at 100% vs doing it at the preliminary hydraulic check at ground idle?      Other than because the flight manual says so.....?

 

is it because of blade sailing or potential contact of blade and tail?

 

aaaaaaand go!

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There is a hyd check at idle and at full rpm on the 212.  First check is at idle to ensure that if something was wrong with the system (eg:motoring servo) you should be able to overcome the forces.  Also at idle, to be overcome forces if the hyds were not enough to override unusually stiff flight controls (possibly mechanical issues with the flight controls eg: minimum frictions set too high or swashplate issues)  You wouldn't want to find out you have these issues at full rpm as you may not be able to overcome the flight forces.  Next check is at full rpm to ensure that everything functions normally at full rpm and flight forces.   You already know at this point that there shouldn't be any major issues as you already determined this with the idle check. 

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18 hours ago, Heliian said:

Because you need to have full Hydraulic pressure and flow?  

It’s a constant flow pump that maintains  PSI no matter the rpm.

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13 hours ago, Torque Split said:

There is a hyd check at idle and at full rpm on the 212.  First check is at idle to ensure that if something was wrong with the system (eg:motoring servo) you should be able to overcome the forces.  Also at idle, to be overcome forces if the hyds were not enough to override unusually stiff flight controls (possibly mechanical issues with the flight controls eg: minimum frictions set too high or swashplate issues)  You wouldn't want to find out you have these issues at full rpm as you may not be able to overcome the flight forces.  Next check is at full rpm to ensure that everything functions normally at full rpm and flight forces.   You already know at this point that there shouldn't be any major issues as you already determined this with the idle check. 

Thanks for a good reply,  a few of my coworkers don’t do the check, and/or do it at ground idle as they want to rule out any chance of hitting the gov switch by accident.  I personally feel this is wrong, but to each and their own I guess.  

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I was going to say that the hydraulic warning light usually comes on when the rotor is almost stopped. As mentioned if any of the controls move uncommanded doing the idle check you have a servo problem. Hench the don't shut them off at full rpm.

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As per the Flight Manual please see the following:

Flight Manual Paragraph 2-6-B.

PRELIMINARY

CHECK

HYDRAULIC

Throttles -Set to idle. 

NOTE:

Uncommanded control movement or motoring with either hydraulic system off may Indicate hydraulic system malfunction.

 

HYDR NO. 1 switch- OFF, then ON.

 

HYDR SYS NO. 2 switch -OFF, then ON.

 

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18 hours ago, Crusty said:

Check is not done at idle to prevent excessive MR flapping and and MR hub damage.

THIS is what I thought!  Thanks.

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13 hours ago, Torque Split said:

As per the Flight Manual please see the following:

Flight Manual Paragraph 2-6-B.

PRELIMINARY

CHECK

HYDRAULIC

Throttles -Set to idle. 

NOTE:

Uncommanded control movement or motoring with either hydraulic system off may Indicate hydraulic system malfunction.

 

HYDR NO. 1 switch- OFF, then ON.

 

HYDR SYS NO. 2 switch -OFF, then ON.

 

I am aware of the flight manual and the checks.  What I asked is WHY do we do it at 100% ?        

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