Hydralulic Check (How do you do it?)
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Hydralulic Check (How do you do it?)
I was flying with my friend the today (Agusta 109E) and as we readied for takeoff and did the hydraulic systems check, well you switch either system off and move the controls around, cyclic counter clockwise, move the pedals a bit and the pull on the collective, you know . . .
Anyway, when I do this I usually move the collective up and down around 2-3 Inches, cyclic in circles in a 4 inch aproximate diameter, and then the pedals about 2 inches,
But then my friend said that his opinion was that you should not move the controls that much, maybe cyclic and collective about an inch, same with pedals,
I thought that would be too little and that that you can't be too shy about checking the controls, as you want to check normal control throughout the average control motion range.
The manual doesn't specify how much you should move the controls.
What you you think?
Anyway, when I do this I usually move the collective up and down around 2-3 Inches, cyclic in circles in a 4 inch aproximate diameter, and then the pedals about 2 inches,
But then my friend said that his opinion was that you should not move the controls that much, maybe cyclic and collective about an inch, same with pedals,
I thought that would be too little and that that you can't be too shy about checking the controls, as you want to check normal control throughout the average control motion range.
The manual doesn't specify how much you should move the controls.
What you you think?
Last edited by BlenderPilot; 29th Nov 2007 at 00:35.
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I think the best way is to carry out the check as per the advice in the flight manual.
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What power setting?
I'm not endorsed on A109, but in the B206 FM it states to do a preliminary Hyd check at 70%N1 and then a full check at 100%Nr.
Cyclic control in "X" pattern (or figure 8) of about 1" and centre.
THEN collective 1 - 2 inches, 2 to 3 times.
Be gentle and smooth.
Beware of how far you lift the collective. You are at "full noise'. Don't get too light on the skids.
Remember you have a fully articulated rotor head and oleos/tyres underneath. (Ground res.)
Stick to the POH/FM for each type.
Cyclic control in "X" pattern (or figure 8) of about 1" and centre.
THEN collective 1 - 2 inches, 2 to 3 times.
Be gentle and smooth.
Beware of how far you lift the collective. You are at "full noise'. Don't get too light on the skids.
Remember you have a fully articulated rotor head and oleos/tyres underneath. (Ground res.)
Stick to the POH/FM for each type.
The hydraulic control checks are not intended to be checking for response across the full range of normal control inputs. You are simply checking for a correct response, that is, the disc tilts in the right direction to inputs, and no unusual feedback forces or binding in controls. A jammed servo/pilot valve or other hydraulic problems should be self evident with only minimal control inputs. Don't risk exacerbating any problems by making your control check movements outside the range specified in the RFM!!
I'm waiting for Nick Lappos to jump in here, I recall he's posted several very informative responses on this topic several times previously.
I'm waiting for Nick Lappos to jump in here, I recall he's posted several very informative responses on this topic several times previously.
I always liked to move the cyclic so as to move one actuator at a time....generally done by using an X-Pattern vice a scrub out the cockpit method. That isolates any binding, sticky points, or feedback to a single actuator.
Along with the Pilot's manual....reading the maintenance manual can suggest other methods that might prove useful.
The Chinook procedures used to require one to hit all four corners with the cyclic and full up-down on the Thrust Lever (Collective to Skid Kids). That check was done for each flight control system prior to engine start.
If you had a short legged guy in the other seat....it could get a bit painful for him if he had run his seat forward....and you wore out the aft corners for a bit.
Along with the Pilot's manual....reading the maintenance manual can suggest other methods that might prove useful.
The Chinook procedures used to require one to hit all four corners with the cyclic and full up-down on the Thrust Lever (Collective to Skid Kids). That check was done for each flight control system prior to engine start.
If you had a short legged guy in the other seat....it could get a bit painful for him if he had run his seat forward....and you wore out the aft corners for a bit.
According to the FlightManual is the best advice.
I remember an accident in the 80ies with a Seaking. They did the check while in FLIGHTDRIVE at 100% NR and not in ACCDRIVE as correct procedure. Due to some ice somewhere in the PRIM system ( the aircraft was parked outside in temps below zero ), all the controls went at their end ( COLL full up etc. ) when the AUX system was switched off, resulting in some expensive noises, but no one was hurt and the good old lady was able to fly again after a long rebuilding session.....
skadi
I remember an accident in the 80ies with a Seaking. They did the check while in FLIGHTDRIVE at 100% NR and not in ACCDRIVE as correct procedure. Due to some ice somewhere in the PRIM system ( the aircraft was parked outside in temps below zero ), all the controls went at their end ( COLL full up etc. ) when the AUX system was switched off, resulting in some expensive noises, but no one was hurt and the good old lady was able to fly again after a long rebuilding session.....
skadi
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From the Manual
“Make small clockwise cyclic movements, Collective and pedal movements.
Pressure drops must be equal for both systems and should not exceed 70psi.”
The reason for the clockwise movement according to Agusta is that anti-clockwise might introduce unwanted oscillation on the ground. (That’s what I was told in the factory)
“Make small clockwise cyclic movements, Collective and pedal movements.
Pressure drops must be equal for both systems and should not exceed 70psi.”
The reason for the clockwise movement according to Agusta is that anti-clockwise might introduce unwanted oscillation on the ground. (That’s what I was told in the factory)
