What to do with ship's legacy tach timer

[Derek]

When I upgraded my M20J panel to a Garmin G500TXi with EIS system earlier this year, the shop replaced the existing tach timer's oil pressure sensor switch with the Garmin sensor and were not able to hook the ship's legacy tach timer back up.

As a result the legacy tach timer (over in the passenger footwell) no longer increments, and only the Garmin system/EIS shows the tach time increasing.  I haven't thought much of this, but it raised a question from my shop who normally does my oil changes.  Figure I'll have to answer this question more times in the future... Which I'd like to avoid.

I just pinged my avionics shop about this and they suggested removing the original gauge and putting a blanking plate over it. 

2 questions...

Is it possible (or advisable, if possible) to have both tach gauges running (and in sync)?

Also, is removing the legacy tach and installing a blanking plate in its place what most people do after doing a panel upgrade, or maybe placard it inop?

Thanks!

Edited September 26, 2022 by Derek

[KSMooniac]

Is it a Hobbs meter?  An electrically-signaled mechanical counter?

Years ago at engine overhaul, I added a Hobbs meter to my plane (never had one from the factory) and have it triggered with an airspeed switch to record flight time.  You could do something like that if you wish.  Otherwise, remove and add a close-out/blank plate to fill the hole just like most shops do.

[Pinecone]

The meter looks like a Hobbs.

But at least on my 252, it is driven from the tach at a varying rate based on RPM (tach time).

Yes, Garmin EIS can be primary, so you don't need tach, MP, fuel flow, etc. 

The Garmin EIS should have a setting for the base RPM for the tach time.   

[Derek]

@KSMooniac, the new G500+EIS does have Tach and Hobbs integrated.  I didn't have a hobbs previously, just the tach. Thanks

[PT20J]

My ‘94 J had a B&D electric tach which drove that meter. It looked like a standard Hobbs meter, but it had a third wire that connected to the tach and it read 1:1 at around 2500 rpm.

When I had the G3X installed, the original tach was removed rendering the meter located on the right side of the console inop, and the shop labelled it INOP in accorance with FAR 91.213.

The plastic panel it is mounted in is just a flat piece of black ABS held in by Avex pop rivets. I drilled out the rivets and used the original plastic as a template for a new piece and replaced the panel. This looks better than a patch.

When setting up my G3X, I set it to record flight time. This matches the FAR Part 1 definition of Time in Service which is more advantageous for maintenance records than “tach” or “hobbs” time.

Skip

[carusoam]

Got a panel pic…

MS and OPM are perfect for this challenge…. 

Sure a blanking plate would work….

But there are a few other things that can occupy that precious space…

Got a spare AI?

How about some expensive USB charging ports?

Need a decent clock upgrade?

PP thoughts only…

Best regards,

-a-

[toto]

2 minutes ago, carusoam said:

Got a panel pic…

MS and OPM are perfect for this challenge…. 

Sure a blanking plate would work….

But there are a few other things that can occupy that precious space…

Got a spare AI?

How about some expensive USB charging ports?

Need a decent clock upgrade?

PP thoughts only…

Best regards,

-a-

I'm not sure where the OP's meter is/was, but my now-disconnected Mooney "hour meter" is in the copilot kick panel next to their left knee.  It's pretty much exactly where you would put such a thing if you never wanted anyone to find it -- it's totally impossible for any normal human to read, and outside any normal scan.

[carusoam]

1 minute ago, toto said:

I'm not sure where the OP's meter is/was, but my now-disconnected Mooney "hour meter" is in the copilot kick panel next to their left knee.  It's pretty much exactly where you would put such a thing if you never wanted anyone to find it -- it's totally impossible for any normal human to read, and outside any normal scan.

Compare to the O’s hour meter….  On the back wall of the baggage area….  

Best regards,

-a-

[toto]

1 minute ago, carusoam said:

Compare to the O’s hour meter….  On the back wall of the baggage area….  

Best regards,

-a-

Seriously, the hour meter in my plane is bizarre - it's almost like they needed to move the CG by a micrometer, so they just figured out where to put a few extra grams and stuck it there.

[Pinecone]

8 hours ago, toto said:

It's pretty much exactly where you would put such a thing if you never wanted anyone to find it -- it's totally impossible for any normal human to read, and outside any normal scan.

Yeap.

 

I use my phone to take a picture after every flight.  That is easier than trying to read the dang thing.

[larryb]

I had mine removed. It would be impossible to keep both in sync leading to confused logbooks depending on which hour gauge was used for logging.

[PT20J]

20 minutes ago, larryb said:

I had mine removed. It would be impossible to keep both in sync leading to confused logbooks depending on which hour gauge was used for logging.

There’s an old saying: A man with a watch knows what time it is. A man with two watches is never sure.