Tach replacement

[gsxrpilot]

On a flight Saturday, my tach started behaving very erratically. Sunday my A&P checked the cable and the tach and has diagnosed the tach as the problem. This is obviously not the original tach that came with the plane back in 1964.

 

Now that I'm looking for a replacement, how much flexibility do I have with regards to choosing a tach from a salvage yard or buying a new tach? Doing some searching online, I've not found any that have the exact same markings as this one. Is that required?

 

I'm not ready to go to an electric from JPI or EI, but am interested if anyone here has had to replace a tach and what was involved in finding the correct one for this application.

 

1964 - M20C

http://mooneyspace.com/gallery/image/36584-tach/

 

[MB65E]

I had one fail recently at just over 300hrs in another aircraft. Chief aircraft had the best pricing and lead times. Spruce wanted 3 weeks, and PSI didn't have any. It was around 300 to replace it. I'd try to find one from MS where someone has upgraded to a digital unit.

-Matt

[Marauder]

If I am not mistaken, you will need to have the correct markings on the tach.

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[M20F-1968]

Go to an avionics shop. purchase the Tach from them and have them re-paint the dial to correspond to the correct markings.   I believe Central Texas Avionics can do this for you as well as many other shops.

 

John Breda

[Guest]

On a flight Saturday, my tach started behaving very erratically. Sunday my A&P checked the cable and the tach and has diagnosed the tach as the problem. This is obviously not the original tach that came with the plane back in 1964.

 

Now that I'm looking for a replacement, how much flexibility do I have with regards to choosing a tach from a salvage yard or buying a new tach? Doing some searching online, I've not found any that have the exact same markings as this one. Is that required?

 

I'm not ready to go to an electric from JPI or EI, but am interested if anyone here has had to replace a tach and what was involved in finding the correct one for this application.

 

1964 - M20C

Tachometer range markings must agree with the P o H, the Type certificate or Supplemental Type Certificate as applicable.

Clarence

[Andy95W]

On a flight Saturday, my tach started behaving very erratically. Sunday my A&P checked the cable and the tach and has diagnosed the tach as the problem. This is obviously not the original tach that came with the plane back in 1964.

Now that I'm looking for a replacement, how much flexibility do I have with regards to choosing a tach from a salvage yard or buying a new tach? Doing some searching online, I've not found any that have the exact same markings as this one. Is that required?

I'm not ready to go to an electric from JPI or EI, but am interested if anyone here has had to replace a tach and what was involved in finding the correct one for this application.

1964 - M20C

Paul- check out the UMA tachs, 3 1/8", TSO'ed.

Electronic, but analog display. Very nice, very accurate, and the hour meter can be set at whatever you like, and they can paint the correct green and red arc markings.

Easy installation and my hours now match the A/C total time, and no more big clunky tachometer cable.

[Piloto]

I replaced mine with the original markings from Aircraft Spruce

 

http://www.aircraftspruce.com/catalog/inpages/mech_tachs.php?clickkey=213904

 

Under options check silk screen markings and provide the markings range.

 

Mine has 700hrs with no problems so far. The markings looks the same as the factory original. Check the POH for markings range.

 

José

[N201MKTurbo]

I put in a UMA Tach and have no regrets. It works perfectly. I have the tach cable pickup and the connector kept coming loose so I wrap it with aluminum tape and it hasn't come loose sense. Reading the tach time is a bit of an eye test. The install was real easy, I cut the connector off, fished the wire through the tach cable feed through and re-soldered the connector.

[gsxrpilot]

I looked at several options for new replacement tach's but the lead time on the silk screening the face to match the POH specs, was anywhere from 4 weeks to 10 weeks. I fly this airplane regularly and can't have it down for service that long. Actually, it's just a hobby, but I really do like to fly it.  And I wanted to attend the Mooney Caravan clinic at KERV this weekend.

 

So I bought the used tach from Edward in Canada. He got it out to me overnight fedex (thanks to Edward for skipping work to get it to FedEx on very short notice) and we got it installed this morning. I'll probably get a UMA Tach ordered, but at least I've got an airworthy airplane in the interim. 

[Flying074]

Sorry for jumping into this thread late.  I recently had a problem with my original mechanical Tach in my 1967 M20F - instrument binding and the cable snapped.  I would much rather install a more modern electric Tach than spend the money to find a replacement analog one.  Does anyone who performed this replacement have a copy of the 337?  I have the UMA tach and the installation is a cinch.  However, the local FSDO told my A&P he doesn't support certifying an electric Tach as the primary for my plane.  The A&P recommended I reach out for anyone who may have had this done already to show there is a preceident set.  I appreciate any advice out there. 

[carusoam]

Welcome aboard ...074

While waiting for a response, what model of the UMA tach do you have?

So many (legal) digital tachs have been installed lately. They have to have proper paperwork to be legal replacements of primary engine instruments.

Best regards,

-a-

[Flying074]

Thanks.  I've spent a lot of time reading the forum but my wife and I just bought our M20F this summer and are looking forward to becoming participants. 

 

The Tach is the UMA 3 1/8" Electronic with TSO paperwork for it to be a primary.  I picked it up from Aircraft Spruce and look forward to installing it.  The wire from the sending unit is much easier to route than a new mechanical cable.  I just need to make sure I am doing this legally.  According to my FSDO, I should just get a replacement mechanical tach and cable, which is a step backwards in my opinion.  Eventually I'd like to go with a full engine monitoring suite, but the money isn't there yet. 

 

Thanks

[Marauder]

Thanks. I've spent a lot of time reading the forum but my wife and I just bought our M20F this summer and are looking forward to becoming participants.

The Tach is the UMA 3 1/8" Electronic with TSO paperwork for it to be a primary. I picked it up from Aircraft Spruce and look forward to installing it. The wire from the sending unit is much easier to route than a new mechanical cable. I just need to make sure I am doing this legally. According to my FSDO, I should just get a replacement mechanical tach and cable, which is a step backwards in my opinion. Eventually I'd like to go with a full engine monitoring suite, but the money isn't there yet.

Thanks

If you replace the tach cable at the same time, make sure it is absolutely the correct length. My tach was destroyed by a shop installing a cable that was too long and took out the innards.

Another option if you elect not to go full engine analyzer is to look at the EI gauge. It is considered primary. I went this route initially with my F. I now have it as a backup to the JPI 900.

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[KSMooniac]

You need to remind the FSDO of the regulations and certification standards.  They're absolutely in the wrong here.  And that is not unusual.  It is always easier for them to just say NO to anything as they won't get in trouble for that.

[RobertGary1]

You need to remind the FSDO of the regulations and certification standards.  They're absolutely in the wrong here.  And that is not unusual.  It is always easier for them to just say NO to anything as they won't get in trouble for that.

 

I think there may be confusion on the thread. The FSDO is saying they don't want to issue an approval for an electric tach. That's understandable since it would require a lot of documentation, etc. However, that is not the same as saying you cannot use an electric tach that has already received approval for your aircraft.

 

-Robert

[KSMooniac]

It is a TSO'd part, not an STC or field approval.  The mechanic can install it with a logbook entry and not involve the FSDO at all.

 

"Owners of Lycoming and Continental powered airplanes now have an electronic, analog alternative to the old cable driven tachometer. The new UMA tach is certified to FAA TSO C49b standards for fixed wing aircraft. The system uses a tach sender mounted on the engine in place of the mechanical cable and is connected to the indicator with a single, 3-conductor cable. "

 

EDIT:  I went back to re-read the TSO regulations and it does sound like a 337 needs to be submitted for a TSO part installation not already covered by an approval of some sort.  It still should be an easy approval.  You might try working through another FSDO somewhere else if you cannot find an example 337.  Years ago I installed a non-TSO HID landing light via 337 and it went through the Wichita FSDO without issue.

[gsxrpilot]

As this thread has been revived, here's an update. The second-hand mechanical tach I installed as the replacement worked fine for three months before the internals disintegrated. I'm now in the process of replacing it with an electronic tach. I'm installing the EI R-1 tach. We'll see how it goes.

[RobertGary1]

May also consider seeing if there is anyone in your area that is authorized to repair it. Ordering one from AircraftSpruce will have almost a 2 month lead time to customize the required markings.

 

-Robert

[gsxrpilot]

May also consider seeing if there is anyone in your area that is authorized to repair it. Ordering one from AircraftSpruce will have almost a 2 month lead time to customize the required markings.

 

-Robert

 

I ordered mine from AircraftSpruce and it only took two weeks.

[RobertGary1]

I ordered mine from AircraftSpruce and it only took two weeks.

 

That's actually a good point. I've found on a number of occasions that AircraftSpruce is actually much faster than they claim. In fact I have an order arriving today that I was told at checkout wouldn't arrive until next week. This is what Spruce says in this regard though. At noted the range markings are part of your aircraft type certificate amended by any STC's so its required.

 

http://www.aircraftspruce.com/catalog/inpages/mech_tachs.php?clickkey=213904

"$35.50 for custom range marks (specify ranges, 45 day lead time). "

 

-Robert

[Andy95W]

It's a minor alteration because the UMA tach is TSO'ed. Doesn't matter if it is electric or not. Mitchell makes a TSO'ed mechanical replacement tach. It is also allowed to be installed as a minor alteration by the same rationale.

Seatbelts are another good example. You can swap out your seatbelts for a different color when you change your interior as long as they are TSO'ed and are the proper length for the airplane. Is there anyone out there who would seriously consider submitting a 337 for seatbelts?

The local FSDO person who "told my A&P he doesn't support certifying an electric Tach as the primary for my plane" doesn't realize he isn't certifying the tach for your airplane. The tach is already certified because it meets all the requirement of the TSO, and your A&P certifies that the installation in your airplane is airworthy and was completed using approved practices. Logbook entry by the A&P, doesn't even require an IA.

The tach does need the proper markings on it for the airplane from the Type Certificate Data Sheet, such as red and green arcs.

[Flying074]

Thanks Andy, and everyone who jumped in.  I'll call around and see what I can do about finding an A&P comfortable with installing and signing off on the work.  Maybe someone more familiar with working on Mooney's will have less of an issue. 

[Yetti]

For range marking on the tach..... http://www.aircraftspruce.com/catalog/cspages/rangemarkdecal.php

[RobertGary1]

Thanks Andy, and everyone who jumped in.  I'll call around and see what I can do about finding an A&P comfortable with installing and signing off on the work.  Maybe someone more familiar with working on Mooney's will have less of an issue. 

 

Honestly I have to guess its a misunderstanding. If the replacement is TSO'd for your aircraft I can't see why the A&P would get the FSDO involved. I think he may think that you've found a tach intended for experimentals that requires a field approval.

 

-Robert

[Flying074]

Yetti, Thanks for the link!  I was looking at a replacement Tach card but that will involve quite a bit more work than adding the limits with a sticker.  The panel is already placarded with the limits but this is good stuff.