UMA tach sending unit

[robN72QT]

Hello, I’m trying to connect a UMA digital tach sender to the tach port on a Lycoming O320-A2B and am running into an issue with the sender unit not mounting flush to the tach port/accessory case side. Anyone ever run into this issue? Checked with UMA engineer and the sending unit measurements and key are to spec… appears (engine side) tach shaft assembly impacts the sending unit key housing and results in the gap seen in photo. Original mechanical cable housing sits flush, for what that’s worth…

Any insight, hints or comments (including pointing out the obvious and saying “You are and idiot”) are welcome!

Best regards,

Rob

 

[Farmboy]

I can’t answer your question other than the typical “make sure it’s keyed and inserting properly”.

But, what display are you driving with this sender? Since I didn’t know UMA even made such a thing - is there a reason to not use a magnetic sensor/pickup on a mag? I think it’s a T1A9.

 

[robN72QT]

I can’t answer your question other than the typical “make sure it’s keyed and inserting properly”.

But, what display are you driving with this sender? Since I didn’t know UMA even made such a thing - is there a reason to not use a magnetic sensor/pickup on a mag? I think it’s a T1A9.

Thanks,
It’s driving the UMA Electronic tach (T19-801-112) - pretty nice unit…
Yep, keyed and inserting properly - the tach shaft seems to be the issue. Went with the digital sending unit (T1A3-4) as it seemed a ”no brainer” … maybe the mag pick up is the way to go…

 

[Farmboy]

Only downfall to the mag pickup is sometimes the mag is clocked so you have to pull it to install the pickup. Well, that and when a new guy installs it in the vent hole instead.
Otherwise they have been flawless for us.

 

[robN72QT]

Only downfall to the mag pickup is sometimes the mag is clocked so you have to pull it to install the pickup. Well, that and when a new guy installs it in the vent hole instead.
Otherwise they have been flawless for us.

Good to know! Hah, I can, without a doubt, give the new guy a run for his money when it comes to wrenching on mags

 

[skywagon8a]

Stick a drill bit into the drive shaft hole and twist it with your fingers to see if there is something in there which is blocking the insertion. By turning with your fingers you will be able to determine the density of the obstruction and may be able to pull out the blockage, if there is some.

 

[robN72QT]

Stick a drill bit into the drive shaft hole and twist it with your fingers to see if there is something in there which is blocking the insertion. By turning with your fingers you will be able to determine the density of the obstruction and may be able to pull out the blockage, if there is some.

Thanks - I’ll take a look at that!