Changing Operating Arcs on Tach

SoCal 182 Driver

SoCal 182 Driver

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SoCal 182 Driver
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As part of the installation of my XP470, I need to have the operating arcs on my tach changed. I would have thought this would be a simple task, but apparently not. Does anyone know of a shop (preferably on the left coast) that can open my tach and change the operating arcs (either by just replacing decals or re-screening)? If necessary, I'm not opposed to have the tach overhauled in the process.

Thanks!
 
Keystone Instruments in Lock Haven PA does a nice job if you can’t find anyone where you are to do it.
 
Any instrument shop worth their stuff can do this. Capital did mine a long time ago but I wouldn't recommend those scoundrels even if they were still in business.
 
flyingron said:
Any instrument shop worth their stuff can do this.
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That's what I would have thought, but the shops I called acted like I was asking them to grow wings and fly. My sense is that they just wanted to sell me a new tach.
 
SoCal 182 Driver said:
Does anyone know of a shop (preferably on the left coast) that can open my tach and change the operating arcs (either by just replacing decals or re-screening)?
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Can't help with a shop, but it can be hit or miss with getting in-service mechanical indicators worked on at least in my experience. Curious, does the 470 STC call for a shop doing to work? Maybe Northpoint can offer a direction for the work?
 
I can’t help with a shop recommendation but you can order a new Mitchell mechanical tachometer with custom arcs incorporated into them for a fairly reasonable price. That may be a backup option if you don’t find a willing overhaul shop.
 
mondtster said:
I can’t help with a shop recommendation but you can order a new Mitchell mechanical tachometer with custom arcs incorporated into them for a fairly reasonable price. That may be a backup option if you don’t find a willing overhaul shop.
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^^^This^^^. Just order a new one. Tachs get less accurate as they wear out, so if yours has some hours on it then it probably is ready to be replaced anyways. Mitchell does a great job. You can order drop shipped from Spruce. You can have the hours preset too.

If you really want to keep your old tach, you can just order a decal kit from Spruce and do it yourself.

Here's a picture of my new Mitchell tach a few years ago. They do the PMA factory tach for my aircraft, so they already had a custom marked face on the shelf.

PXL_20210309_205201325.jpg
 
Ed Haywood said:
^^^This^^^. Just order a new one. Tachs get less accurate as they wear out, so if yours has some hours on it then it probably is ready to be replaced anyways.
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It's interesting that you mention that. I finally found a shop that could screen the face. When I asked if they could also overhaul the tach, they told me to just throw it away and get a new one.
 
SoCal 182 Driver said:
It's interesting that you mention that. I finally found a shop that could screen the face. When I asked if they could also overhaul the tach, they told me to just throw it away and get a new one.
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www.aircraftspruce.com

Mitchell Clockwise Mechanical Tachometers | Aircraft Spruce

Mitchell Clockwise Mechanical Tachometers In 1985, AC discontinued production of the popular RT series of mechanical tachometers. We now offer Mitchell tachometers to fill this void.
www.aircraftspruce.com www.aircraftspruce.com
 
My local instrument shop did mine. Merrill Field Instruments in Anchorage. Easy peasy. Any shop worthy of doing it should ask for a copy of the STC to reference the change.
 
mondtster said:
I can’t help with a shop recommendation but you can order a new Mitchell mechanical tachometer with custom arcs incorporated into them for a fairly reasonable price. That may be a backup option if you don’t find a willing overhaul shop.
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Good luck. They screwed up our order and failed to set the hours or paint it at all. We had already waited 3 weeks at that point so we said F it and painted the face ourselves.
 
23103a said:
Good luck. They screwed up our order and failed to set the hours or paint it at all. We had already waited 3 weeks at that point so we said F it and painted the face ourselves.
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I've ordered numerous tachs from them with no issue.
 
Ditto. Ordered through Spruce, received in less than a week. 3x.
 
SoCal 182 Driver said:
Did the one week turnaround include putting arcs on it, and resetting the hours meter?
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In my limited experience, that depended on whether they have faces pre-screened for your arcs.

When you order through Spruce, Mitchell will contact you to verify order instructions. Part of that data will include aircraft type. If they commonly produce tachs for that aircraft and your arcs match the factory specs, they'll probably have a face on the shelf ready to go. If your arcs are different and must be custom screened, then it will probably take longer. Spruce says 3 weeks, but in my experience Mitchell was more responsive than that.
 
SoCal 182 Driver said:
and resetting the hours meter?
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Resetting to 0 or the time on old tach? If use tach for tracking mx may want to consider the latter, if possible. If not, best to make separate entry to show tach time change and update any recurring AD due times.
 
Bell206 said:
Resetting to 0 or the time on old tach? If use tach for tracking mx may want to consider the latter, if possible. If not, best to make separate entry to show tach time change and update any recurring AD due times.
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Resetting (or setting) the new tach to the hours on the old tach.
 
Ed Haywood said:
In my limited experience, that depended on whether they have faces pre-screened for your arcs.

When you order through Spruce, Mitchell will contact you to verify order instructions. Part of that data will include aircraft type. If they commonly produce tachs for that aircraft and your arcs match the factory specs, they'll probably have a face on the shelf ready to go. If your arcs are different and must be custom screened, then it will probably take longer. Spruce says 3 weeks, but in my experience Mitchell was more responsive than that.
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The new tach is definitely not standard. It's for an XP470 (P-Ponk) going into a 182K.
 
Bell206 said:
Resetting to 0 or the time on old tach? If use tach for tracking mx may want to consider the latter, if possible. If not, best to make separate entry to show tach time change and update any recurring AD due times.
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They come set to zero, but you can request pre-set to match old tach. That's what I did.

When I installed my engine, I installed a new hobbs set to zero. So now tach shows TTAF and hobbs shows SMOH. Seems like that might be backwards for mx tracking purposes, since tach is more accurate gauge of engine strain, but AFAIK regs are agnostic on which metric is used.
 
SoCal 182 Driver said:
The new tach is definitely not standard. It's for an XP470 (P-Ponk) going into a 182K.
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They still might have faces on the shelf, if it is a common conversion. Give 'em a call. They have been quite friendly and responsive when I have called.

mitchellproducts.com

Mitchell Aircraft Products

Inspired By Service & Quality We Value Quality All Mitchell instruments are manufactured under a FAA approved Quality System. Mitchell has continuously served the general aviation industry for over 30 years and has
mitchellproducts.com mitchellproducts.com
 
SoCal 182 Driver said:
Did the one week turnaround include putting arcs on it, and resetting the hours meter?
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I think all the ones I have gotten came within a week. They’ve all included the arcs and resetting the tach time to match the one being replaced. They have all been for fairly common applications however, so it is possible that Mitchell had a stack of pre-printed tach faces that already had the correct arcs on them.

Perhaps a call directly to the manufacturer would provide the best insight on lead time.
 
mondtster said:
I think all the ones I have gotten came within a week. They’ve all included the arcs and resetting the tach time to match the one being replaced. They have all been for fairly common applications however, so it is possible that Mitchell had a stack of pre-printed tach faces that already had the correct arcs on them.

Perhaps a call directly to the manufacturer would provide the best insight on lead time.
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I just got off the phone with Mitchell. They're running about a week back-log. The rep said that I'd probably see the new tach within two weeks (including shipping transit) from the day of my order, and that would include the new arcs and setting the hours meter to the current tach's reading.
 
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