Garyo 1 Posted October 23, 2017 Share Posted October 23, 2017 With all HYD pumps in the off position, I am still able to do a control check and run the flaps. I don't there should be any movement on the FLT CONT synoptic page. GaryO Please login to display this image. Link to comment Share on other sites More sharing options...
Developer Hans Hartmann 3694 Posted October 23, 2017 Developer Share Posted October 23, 2017 The CRJ is true fly-by-wire (= cables with hydraulic support) so you can move the controls without hydraulics, it just requires a bit more strengh. The flaps and slats have electrical motors and are not connected to the hydraulic system at all. Link to comment Share on other sites More sharing options...
Ak47e6 42 Posted October 23, 2017 Share Posted October 23, 2017 Respectfully that is not correct only the flaps and stab trim run off electric motors. The alierons rudder and elevators are moved by hydraulic power control units which receive inputs from the cables but with no hydraulic power moving the cables will cause no move to control surfaces. The multi function spoilers and ground lift dump are electro hydraulic. The SSCU receives input from various systems and sends electrical signals the the power control units to use hydraulic pressure to extend the surface however hydraulic power is still needed to move the controls. Link to comment Share on other sites More sharing options...
Garyo 1 Posted October 24, 2017 Author Share Posted October 24, 2017 You are so correct on the Slats/Flaps. They are electrically powered. I don't think I should get any control surface movement without HYD power. Link to comment Share on other sites More sharing options...
Garyo 1 Posted October 25, 2017 Author Share Posted October 25, 2017 Can a CRJ pilot confirm that with NO HYD power,you will get NO HYD powered contro surface movememnt. I.E., on the ground doing a control check. Should you,or should you not get any control movement and what type of indication would you see on the FLT. CTRL synoptic page? Thanks, GaryO Link to comment Share on other sites More sharing options...
Ak47e6 42 Posted October 25, 2017 Share Posted October 25, 2017 Yes. I can and I will. With the engines off and no ACMP operating you will not be able to move any alierons, rudder, elevator or any of the multi function spoilers or ground spoilers. The rudder alierons and elevators are moved by moving the control wheel which through cables moves a valve body to direct hydraulic pressure to the actuator to move the surface. With no hydraulic pressure you can move the controls all day long which will move the valve body but if there is no pressure then nothing will happen as there is no fluid for the valve to port to the actuator. On the spoiler side same kind of deal except the valve moves in response to electrical signals from the SSCU and not cables Link to comment Share on other sites More sharing options...
Developer Hans Hartmann 3694 Posted October 26, 2017 Developer Share Posted October 26, 2017 Please login to display this image. This is what the FCOM says. I took the underlined part as "the control wheels mechanically control the control surfaces". I never asked a pilot or tech about it since it seemed very clear. But apparently the FCOM is in Canadian, not English, and the sentence means "we put wires all through the aircraft and don't connect them to the actual surfaces but to hydraulic actuators right next to them"... I'll change it. Link to comment Share on other sites More sharing options...
Ak47e6 42 Posted October 26, 2017 Share Posted October 26, 2017 You got it sir. No mech connection to the actual control surface just to the pcu. With no hyd pressure the pcu can't do any work. Those Canadians aye. Link to comment Share on other sites More sharing options...
Garyo 1 Posted October 26, 2017 Author Share Posted October 26, 2017 So,,, if the yoke is moved with no HYD power on, there will be NO movement of the aileron, rudder, stab and MFS indications on the HYD synoptic page. Is that correct? GaryO Link to comment Share on other sites More sharing options...
Ak47e6 42 Posted October 26, 2017 Share Posted October 26, 2017 The stab and flaps are electric and work with no hydraulics. No other surfaces can move without hydraulics. Link to comment Share on other sites More sharing options...
Meese 18 Posted October 30, 2017 Share Posted October 30, 2017 ... Cables throughout the fuselage to trigger PCUs? Wow. Link to comment Share on other sites More sharing options...
mcdonaldgt5 7 Posted November 19, 2017 Share Posted November 19, 2017 Common older technology still in use. Link to comment Share on other sites More sharing options...
terks43 1 Posted December 25, 2017 Share Posted December 25, 2017 On 10/26/2017 at 9:07 AM, Hans Hartmann said: Please login to display this image. This is what the FCOM says. I took the underlined part as "the control wheels mechanically control the control surfaces". I never asked a pilot or tech about it since it seemed very clear. But apparently the FCOM is in Canadian, not English, and the sentence means "we put wires all through the aircraft and don't connect them to the actual surfaces but to hydraulic actuators right next to them"... I'll change it. Just went through systems class on the CRJ 700/900. I can confirm that is correct wires to a pcu then HYD to move the surfaces. Link to comment Share on other sites More sharing options...
bryank1988 7 Posted February 17, 2018 Share Posted February 17, 2018 We should have a repaint showing paint peeling around the PCU panels since in real life they constantly leak skydrol! Link to comment Share on other sites More sharing options...
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