pjvr99 Posted April 13, 2012 Share Posted April 13, 2012 During TD system check, moving the TD switch from AUTO to LOCKED, the fuel flow and TIT are supposed to remain unchanged. However after three to five seconds, the TIT drops about 20°C and fuel flow 50 - 100pph. Three TD amps, 4 TD valves, 3 relay boxes, and a J3 lead have resulted in no discernable improvement. Coordinator has been checked, and electrical system has been checked all the way back to the TD switch. The engine is on the test cell. Any thoughts on where I can look for a solution? Thanx PJ Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted April 13, 2012 Share Posted April 13, 2012 What is your torque doing? Seems like a large fuel flow drop for only 20 degrees... Quote Link to comment Share on other sites More sharing options...
tenten Posted April 14, 2012 Share Posted April 14, 2012 Not familiar with test cell, but; ... check the system correction at x-over during "Auto" selection, if the value is as the drop you mentioned, then it seems to me that the TD system is shifting to “nullâ€; then while in “Locked†you may perform the following two checks: 1- Temperature controlling check at 910 ̊C. (the existence or the lack of cut back). 2- Over temperature check at max TIT. (the cut back and the illumination of the correction light). The results of the two check will limit your defective wiring target. Quote Link to comment Share on other sites More sharing options...
topboltsto400 Posted April 14, 2012 Share Posted April 14, 2012 I worked test cell for 4 yrs.... when we would get some funky stuff going on....usually wound up being the test cell itself.....celltech 21D/A Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted April 14, 2012 Author Share Posted April 14, 2012 Natops, the torque drops off also. When the system is operating as advertized, the change in TIT seldom exceeds 10°C, and fuel flow 50pph. Tenten, this is the part that kills me - this is the ONLY check that fails. Everything else is right on the money. The checks in the cell are the same as for the aircraft. TB400, I checked the wiring, continuity and voltage, all the way back to the engine control panel. We have an AM37-T21D Quote Link to comment Share on other sites More sharing options...
herky400M Posted April 27, 2012 Share Posted April 27, 2012 PJ, maybe to late, but maybe your engine anti icing system is operative..... Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted April 28, 2012 Author Share Posted April 28, 2012 PJ, maybe to late, but maybe your engine anti icing system is operative..... I wish it was. Still trying to isolate the problem, but seems to be in the cell somehow, not in the engine Quote Link to comment Share on other sites More sharing options...
tenten Posted April 28, 2012 Share Posted April 28, 2012 Can’t be the anti-icing if the system having “dignity”. If not TEST SELL issue; I advise to track and check the wires involved in locking the TD for not having any power leakage disturbing the “Brake Release Solenoid” especially through plug connections/TBs. Quote Link to comment Share on other sites More sharing options...
herky400M Posted May 1, 2012 Share Posted May 1, 2012 PJ already looked at the spider wiring? we had a simular problem long time ago, and it was the wiring, corrosive wirings!! TEST SELL? test cell should be better.....:rolleyes: Quote Link to comment Share on other sites More sharing options...
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