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Single Drive Dual Mag - Prop Governor Install - Another FYI

eaglen92ce

Well Known Member
Patron
I just bought a new PCU 5000X governor for intallation on my IO-360-A1B6D engine (single drive dual mag case). I bought it to replace my old Woodward which was starting to surge some. Initially it would not work correctly due to a slight configuration problem. I have an aerobatic counterweighted prop (oil pressure to decrease pitch). Basically the new PCU governor install was not getting oil to the prop. It worked perfectly at the prop shop though, what was the deal... I spent a lot of time troubleshooting and switching back and forth from Woodward (always worked) to the PCU (never worked). Ultimately I sent some pictures of my install to PCU and talked to the President John DeJoris. He say the picture of my governor drive pad (unique apparently to the single drive dual mag case) and immediately knew the problem with the install. He told me "oh, those engines need a .040" adapter plate and an additional gasket between the governor and the drive pad". Without the adapter plate the PCU governor has a path back to the sump due to the addition of a slot on the engine drive pad. He said no one seems to know what the slot was for, but it requires a plate to work with most ''normal" governors. Anyway he was right and the unit works perfectly with the simple adapter plate installed. This is just an FYI if someone else is battling with a governor install on a single drive dual mag case engine (at least the IO-360s often found in Mooneys and later Cardinal RGs). Lycoming Service Instruction 1438 addresses this issue and gives you the proper part numbers for the adapter and gasket. The adapter is easy to homebuild out of .040 alum and the Lycoming SI gives you enough data to figure it out. Worked for me! My Woodward worked without the adapter for some reason which I do not directly know. It was a fairly custom piece originally from a six cylinder twin engine. PCU and John were very helpful by the way. I did not buy the unit directly so no blame on them for not giving me the right info initially! I have the SI as a PDF if anyone is having trouble finding it. I also have a picture of the governor drive pad with shows the mystery slot that seem to cause the problem if anyone is interested.

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Happy Flying
 
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