keepemflying130 Posted April 7, 2010 Share Posted April 7, 2010 Fun one. Induction run for Mod aircraft (KC130T) had a problem on #1. Above lights out, with either 2 or 3 selected as Master #1 would flux (increase) about 4000 in lbs. 500 pph, and about 125 degrees. But get this, RPM stable. De-selecting a master, or putting #1 in mechanical would fix the problem. Pitchlocked it a couple of times, but every time I would follow up with a re-index, same thing. Pitchlocks were normal. STABLE rpm was bugging me, but I asked to borrow a sync box for troubleshooting. Outgoing runs. borrowed sync box on hand, but not installed. #1 ran without problems. Could not duplicate the incoming discrepancy. Had some other stuff pop up...down for maint. changed #2 prop..ect... A couple of runs later the same problem popped up on number #3, No fluxing this time, just a steady Increase +- 4000 in lbs, 500 pph, 150 degrees. WTF? Turn sync off, problem goes away in about 10 sec. Put in mech., prob goes away in about 5 secs. RPM still stable this whole time. Put in the borrowed sync box and the problem goes away and stays away. Full runs without issue. Now I would like a Fuel Control for the first and second instances at a glance with the RPM;s being stable. But being able to control it with the sync switch and Normal/Mech switch kind of makes it a no brainer. I know they are touchy boxes, and I have seen problems move around engines, but how can the sync box get this kind of reaction at the engine without any effect on RPM? Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted April 8, 2010 Share Posted April 8, 2010 Had something similar several times in the last few years. In one case #1 would increase rpm to 102% with #3 as master - #3 valve housing change fixed it. The others all got traced back to the synchrophaser rack. Quote Link to comment Share on other sites More sharing options...
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