Time for a new tach.

EdFred

EdFred

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I don't know if any of you saw my question at either Piper Chat or the AOPA board about a lack of airspeed and high RPMs in my 180. Anyhow, long story made short my tach reads about 200 high when at max RPM. Indicated 2900 = 2700 actual which is red line.

I want to put in a digital tach and was looking at this one:
http://www.aircraftspruce.com/catalog/inpages/ei-digitalgraphic.php
First one on the page. Any reason I should not get that one, or is there a better one out there? I was also looking at putting in the US-8A:
http://www.aircraftspruce.com/catalog/inpages/ei-engineanalyzer.php

Thoughts on these? Anything similar/better for a similar price?
 
Ed,

I know someone who had good success with the EI tach.
 
Ed Fred...there are some that are certified to replace the original instrument. AFAIK the EI is not one of them, but I don't know which ones are. It is NICER to not have to have a bogus hole with a bad tach in it....sigh.
 
I have one of these in my 182 and had one in the 172. I like it better than the EI instrument, but it has the following two downsides.

1. It starts counting tach hours real time as soon as the tach goes over 800 rpm's.

2. It has a ones digit that will drive you bonkers if you let it. Especially in a plane with fixed pitch prop. Just ignore the ones (and only glance at the tens once in a while and you will be OK.

http://www.chiefaircraft.com/cgi-bi...aft/EngineInstruments/HorizonInstruments.html

Very accurate and easy to use. Love mine.

Mark

BTW, I also know folks with the EI instrument and swear by them as well.
 
Better ask Tom Downey if the STC allows replacment of the original instrument or whether it must be used in addition (certification requirements).
 
bbchien said:
Better ask Tom Downey if the STC allows replacment of the original instrument or whether it must be used in addition (certification requirements).
Click to expand...

The documentation should tell you whether the instrument is certified as "primary replacement" for certain planes.
 
bbchien said:
Better ask Tom Downey if the STC allows replacment of the original instrument or whether it must be used in addition (certification requirements).
Click to expand...

Only the FAAwould say you need to have both tachs. I better check the STC for my prop and see if it's a replacement STC, or an in addition to. ;)
 
bbchien said:
Ed Fred...there are some that are certified to replace the original instrument. AFAIK the EI is not one of them, but I don't know which ones are. It is NICER to not have to have a bogus hole with a bad tach in it....sigh.
Click to expand...

Bruce, the EI R-1 is certified primary for a lot of planes. Check with EI for specifics.
 
This is the one that several owners I know have installed. All are happy with it. I think is has some useful features that the EI lacks.

http://www.aircraftspruce.com/catalog/inpages/p1000.php

And if you are going to the trouble of installing an all cylinder egt/cht get one with a graphic display. My all time favorite is JPI's EDM-700.
 
wsuffa said:
The documentation should tell you whether the instrument is certified as "primary replacement" for certain planes.
Click to expand...

If it is STCed, it should be easy to install on a 337 for OKC history records.

IF not it can be done on pre-approval requested by filling out a 337 as to how you plane to install it. After approval the 337 becomes the approved data to install.

BUT this method the aircraft can not be used as a 135 operatrion.

Its pretty easy, just paper work.
 
Look at the Horizon digital tach. I put them in my twin Comanche a couple of years ago and am very happy with them. It is STC'd for replacement of the original equipment tach in all common aircraft. Charlie Melot Zephyr Aircraft Engines
 
So, since this thread is so old I think I'm gonna hijack it to avoid starting a new one.

While flying to OKC from Austin, I was at 10,500 and the tach was still showing 3k rpm if I opened it up all the way. The engine didn't sound like it was over revving based on the sounds from the other Cherokee 180s I've flown. I would still pull it back to 2700 but is the engine really capable of doing that at 10,500? When I would pull it back I would get about 115kts gs with a slight tailwind and with it at "3000" I would end up in the neighborhood of 122-125kts gs with the same tailwind. I really think the tach is showing a lot faster than really is going on, I know what a wound up too tight engine sounds like and this didn't even sound close. Even with a climb prop I don't feel like it would be able to do that level at 10,500.
 
Most likely the tach is off. Either that, or someone snuck in your hangar and put a turbo on your Lyc O-360.

You might want to bring a laptop in the plane running a program that derives RPM from audio. Here's a link.
http://www.tunelab-world.com/rpmsound.html

I have used this program and found it to work pretty well.


bigred177 said:
While flying to OKC from Austin, I was at 10,500 and the tach was still showing 3k rpm if I opened it up all the way. The engine didn't sound like it was over revving based on the sounds from the other Cherokee 180s
Click to expand...
 
nyoung said:
Most likely the tach is off. Either that, or someone snuck in your hangar and put a turbo on your Lyc O-360.

You might want to bring a laptop in the plane running a program that derives RPM from audio. Here's a link.
http://www.tunelab-world.com/rpmsound.html

I have used this program and found it to work pretty well.
Click to expand...

There's also a trick of looking 'through' a rotating prop to see a gas-filled light bulb at night. Due to the 60hz flicker of the lightbulb, you will be able to see the prop at a specific RPM (1200 or 2400 for a 2-blade prop IIRC). It should at least give you a gut check on your tach.
 
Bringing this back one more time. If I do find that the tach is off, can I have the old unit calibrated? Or do I have to buy a less worn out one?
 
bigred177 said:
Bringing this back one more time. If I do find that the tach is off, can I have the old unit calibrated? Or do I have to buy a less worn out one?
Click to expand...

You can get a model airplane tach on ebay for about $25 or probably at a local hobby store. The one I got on ebay is switchable for 2, 3 and 4 blade props. Works great - my overhauled tach was right on. 200 rpm off before.

I used Century Instrument but you might want to call before you send it anywhere to make sure they will work on it.
 
bigred177 said:
Bringing this back one more time. If I do find that the tach is off, can I have the old unit calibrated? Or do I have to buy a less worn out one?
Click to expand...

A tach can be recalibrated or rebuilt. Sometimes it is successful and other times it is not. I ended up with an electronic tach after two rebuilds of the original tach from two different shops. The killer line was "I can't feature what would be wrong with it" from the second shop when I told them the needle still drifted.

As always, YMWV.
 
If you buy a new mechanical tach you should have an instrument shop set your current tach time on the meter. I reset the hour meters myself. I hate digging through old logbooks trying to chase the changes and mistakes when looking at total times. I've installed many of the Horizon electric tachs and have one in the Malibu, it's a great product.

Kevin
 
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