jcasey21 Posted February 26, 2011 Share Posted February 26, 2011 running the Aux Pump with ground test valve tied we get a presure of 2600-2800 psi. The second we take the elevator off the stops it jumps up to 3100 psi. We have already changed the Aux pump. Were could our problem be located at Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted February 26, 2011 Share Posted February 26, 2011 You have NO problem. The elevator has a built in bypass when resting on the stop. There is verbage in the books addressing your limitations and the elevator being "Off the stop". Our book says "It is possible that the full system pressure may not be reached if the control column is full forward because of normal internal bypass of fluid in the elevator boost package. Pulling the column off the stop will eliminate this bypass." If you run an engine you may see the same issue. Quote Link to comment Share on other sites More sharing options...
Lkuest Posted February 26, 2011 Share Posted February 26, 2011 running the Aux Pump with ground test valve tied we get a presure of 2600-2800 psi. The second we take the elevator off the stops it jumps up to 3100 psi. We have already changed the Aux pump. Were could our problem be located at I'm no hydro troop, but I also want to say that's normal. Quote Link to comment Share on other sites More sharing options...
jcasey21 Posted February 26, 2011 Author Share Posted February 26, 2011 We have figured out that the elevator is bypassing, but is there any tech data that supports the pressure drop so if flight crew complains about it again. Quote Link to comment Share on other sites More sharing options...
jcasey21 Posted February 26, 2011 Author Share Posted February 26, 2011 Also we did not see any difference when engines were running we only see it with the ground test valve tied Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted February 27, 2011 Share Posted February 27, 2011 -1 (Change 9) pg 2-56 NOTE A positive hydraulic pressure indication must be noted by the time the engine is on speed. Normal operating pressure should be indicated within 30 seconds after on speed. This pressure may not be reached if the control column is full forward due to the normal internal fluid bypass in the elevator boost package. Pulling the column off the stop 2 to 3 inches will eliminate this bypass. Quote Link to comment Share on other sites More sharing options...
larry myers Posted February 27, 2011 Share Posted February 27, 2011 It always made my day when I was able to sign off an inflight squawk iaw the dash 0ne. Quote Link to comment Share on other sites More sharing options...
jcasey21 Posted February 27, 2011 Author Share Posted February 27, 2011 Thank you everyone for your help Quote Link to comment Share on other sites More sharing options...
victorp1 Posted February 28, 2011 Share Posted February 28, 2011 In Lockheed Service Information Letter No. 18 dated 1 NOV 77 it has acceptable pressure reading for the auxiliary system as 2,700 to 3,200 PSI with the ground test valve tied and flight control boost shutoff switches open. If the elevator control column is at the forward stop the elevator boost package can bypass approximately 3.5 GPM causing the lower pressure reading on the auxiliary system gage. Quote Link to comment Share on other sites More sharing options...
Dan Wilson Posted March 2, 2011 Share Posted March 2, 2011 OUCH, do you need a cup of coffee this morning? Quote Link to comment Share on other sites More sharing options...
brooksma Posted May 13, 2011 Share Posted May 13, 2011 That is normal operation the elevator pack has a run around in it there is a reference i will look and see if I can find it. Quote Link to comment Share on other sites More sharing options...
trectenwald Posted July 3, 2011 Share Posted July 3, 2011 Can't get much easier than that. You pretty much answered your question with your question. I hope you're not a hydro troop. Quote Link to comment Share on other sites More sharing options...
tenten Posted July 3, 2011 Share Posted July 3, 2011 Having the same issue three weeks ago, and since our books doesn’t have a direct approval of the case, the Aux pump had been changed, the new pump(zero hours) worked fine with us and was maintaining the 3000 where ever the elevator resting. Therefore convince ALL of them to accept the drop or…… find another good pump to make “Switch Operators†happy. TIP: Adjusting the pump pressure (caped adjustment) failed to recover the drop during ground connection to utility; it only increases the pressure to 3300 once the pump is servicing its own system. Quote Link to comment Share on other sites More sharing options...
Ben Legere Posted July 5, 2011 Share Posted July 5, 2011 I don't have a -1 with me at the moment but there is a blurp in it about not having full system pressure until the engines are up-sped. This is one of those common sense things that you won't find an actual reference for kind of like when the flap lines "shake" when you run the flaps through or the #3 tail pipe "vibration". Quote Link to comment Share on other sites More sharing options...
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