Prop synchrophaser issues

[ELENator]

This bird has had this problem come back a few times - not repeat/recur though.

Basically, the props wont sync with No. 3 selected as master. Replaced valve housing, no fix. Repalced synchrophaser, no fix. Shot wires on sync rack - all are good. Shot all pins on all plugs on valve housing, tach gen, and pulse gen, and all are good. The last time this happened we found wires in the wrong spots on the terminal board on the electrical rack (TB1C, I believe). After we fixed that, it op checked good. This was a month or two ago. Now the problem has returned. Engine shop replaced the syncrophaser and now they're telling us the problem has gotten worse - it won't sync at all with either prop selected. Obviously the first thing to do is check and see if it's a bad part out of supply. But in every case we've had this issue, the system tests OK with the sync tester set.

Anyone got any ideas?

[Lkuest]

How do they know it won't "sync"? Are the slaves just not following the master?

As for problems with both masters, there was a TCTO to install a Constant Voltage Transformer. I don't know anything about it, but I do have a bread crumb. The TCTO is supposedly 1C-130-1309. It might be able to tell you more about it.

With synchrophaser problems, you have to look at everything the synchrophaser does. Throttle anticipation? Pitchlocking? Sync and Droop? RPM correction (if mechanical isn't set at exactly 100%, is there difference between mech gov/normal gov)? If all of this is dead, there is definately a power issue or something frying new synchrophasers.

If only one of these things is bad, you should have a wiring issue, but how to hunt that down, I'm sure you'd know better than I would.

[keepemflying130]

The sync itself is one stuck up bitch, and the sync test set is like the rest of us, half in the bag, trying to figure her out. Quote me..."Im giving her all the right signals..but she just wont respond...im getting the feedback..but i dont know what to do..." not making fun of you. Although I do find it funny. Latent faults in the sync is your problem. Shit in the valvle housing, and all of the other elen..type stuff is gonogo. The sync is the only ESD sensitive piece on the eng. cntrl loop. I have been quoted before that LATENT or SOFT esd related issues would become more frequent. There are standards in place. They are not production friendly. They have not been followed.. Latent, non reproducible, intermittent faults have been introduced into black boxes like the sync. I know how old the sys is . But this issue is going to keep coming up. make sure all the gaps are OK an pulse gen pickups...but r2 another sync box. fixed..

[pjvr99]

When doing the droop check, do any of the slaves INCREASE rpm?