Electronic Tachs

[Marauder]

I've been thinking about converting to an electronic tach ever since my last issue with the tach cable. I searched the forum and couldn't find any threads dedicated to the topic. What are you guys using? How much work is involved in installing one and does it have any limitations or concerns I need to be worried about?

[TTaylor]

I've been thinking about converting to an electronic tach ever since my last issue with the tach cable. I searched the forum and couldn't find any threads dedicated to the topic. What are you guys using? How much work is involved in installing one and does it have any limitations or concerns I need to be worried about?

E.I.; no cable, all electric. Ties into the mag if I remember correctly. Very easy to read and I like the flight time function. Nice to check total flight time.

[Oscar Avalle]

I agree is an excellent choice. Good combination of a nice precise read out and lights.

[tyrefoote]

I hve the EI R1 tach and have had intermitten problems on the right mag RPM only (during run-up)

After a year of troubleshooting, I have isolated the problem to the new Slick Mag installed a year ago

 

EI is a great company with great Products and fantastic tech support

 

The EI tach gets its reading from voltage spikes taken on the P lead and pads them with resistors

 

Champion Rep. told me they don't recomend this type hook up for safety reasons, due to an instrument failure causing a ground in the system and killing the engine. They recomended useing a magnetic pickup in the back of the mag @ vent plug

 

Champion Insists that the Mags are fine because the engine is running great and they don't control the voltage being supplied to the P lead.

 

Ei does not make a magnetic pickup that will work for this tach. and gave me some more resistors to wire in but they didn't fix the intermitten problem

 

I love the EI tach, size and looks, and don,t want to change it out to another brand.  My A&P wants to change out the condenser in the right Mag ( 4 HR LABOR)   I don't really want to spend any more money on this intermitten problem.  They are only 500 HR Mags and I now have 150 hours on them.

 

I don't really like the fact that a resistor,  they call it an isolator, Is suppposed to keep the engine running in the event of a failure.

 

Good luck with your decision.  Ty 

 

[Seth]

I replaced my mechanical Tach with an electronic Tach when my Tach stopped keeping the engine time (but for flight purposes still displayed the RPM setting). 

 

I looked at both the E.I and Horizon units.  Both are great units and originally I was set on the EI unit but the moved to the Horizon.  There is a third option, a digital tach with an analog readout that looks like it's a mechanical Tach.  That way the panel would still have the same look.  Though it would keep the panel looking the same, I figured the digital readout was worth a change.  Also, in my mind, this is the right time to upgrade.  When you can spend money to replace/fix a unit, use that money to upgrade. 

 

Both units are fine, I went with Horizon.  I think the Horizon unit is what the pre G-1000 Mooneys came with from the factory.  Also, the EI unit is smaller, where the Horizon fills the hole in the panel that the other Tach removed will vacate.  I forget which is which - the EI and Horizon start counting for engine time at different RPM settings, which can lead to issues with your engine life for value purposes when it comes time to sell, espeically if you spend a lot of time taxing on the ground or with low RPM settings.  The LED placement in an arc I thought would be a big deal but very quickly it became a non issue when flying to not have an arc.  Also, I forget which one stops at 10, vs one showing 1, for instance:  2730 RPM vs 2734 RPM - the one that shows 2734 will always be fluctuating which can be annoying from the pilot perspective.

 

Take care,

 

-Seth

[Piloto]

Mechanical tachometers are pretty reliable specially when you loose electrical power. I replaced mine at overhaul time because the hour meter failed at 1997 hours.

An analog type indicator may look old fashion when compared to a digital read out. But have you noticed that there are no pilot watches with digital read out but needles. And that all cars use analog indicators for mph, rpm, oil pressure, temp and voltage. True that digital readouts offer a greater resolution in a smaller space but all of them require electricity to work. You can get and old fashion analog thermometer to read -30F outside. Try that with an LCD display and all you get is a frozen display. Try that with your LCD tachometer.

José

[rob]

My Breitling B-1 pilot watch has both digital and analog displays. And for what it's worth, most of the corporate pilots I know wear a timex anyway.

"Pilot watches" are analog because they date back to a time when digital and/or quartz watches didnt exist. Being analog doesn't make them any more functional.

Also, many new cars are going to digital displays. I believe the new Viper has a completely digital OLED display.

Point being: just because something has been one way for a long time doesn't necessarily mean that way is the best way. In many cases it means that the newer technology wasnt available, affordable, or reliable. But when that newer technology does meet those conditions it's often an improvement.

[Marauder]

Mechanical tachometers are pretty reliable specially when you loose electrical power. I replaced mine at overhaul time because the hour meter failed at 1997 hours.An analog type indicator may look old fashion when compared to a digital read out. But have you noticed that there are no pilot watches with digital read out but needles. And that all cars use analog indicators for mph, rpm, oil pressure, temp and voltage. True that digital readouts offer a greater resolution in a smaller space but all of them require electricity to work. You can get and old fashion analog thermometer to read -30F outside. Try that with an LCD display and all you get is a frozen display. Try that with your LCD tachometer.José

You bring up the reliability question, which is fair. For those of you who have switched to electronic, are you running into issues with them. The mechanical tach in my plane has been there the whole 36 years. It owes me nothing (other the recent replacement cable that I am having problems with). Do the STCs for these units say anything about mechanical backups or restrictions? Since it sounds like the electronic gets its information from the mags, can you have both installed?

[Seth]

Here's the thread from when I looked for PIREPS - it was from Early 2011

 

http://mooneyspace.com/topic/2272-new-tachometer-pireps-requested/?hl=horizon

 

-Seth

[Parker_Woodruff]

I liked the EI Digital tach I had installed on my M20J.  You can pre-program your existing airframe time, too.

[jetdriven]

All those digital tachs add up airframe time at the clock rate, IE no discount for ground running time or flying at low RPM. This means you are adding up airframe and engine time ad a 15-20% higher rate than reality. 

 

In our case, it adds 20 hours in 100, or 80 hours in 400, which is 1600$ in additional engine and airframe devaluation in that period.

[Chimpanzee]

Quite a few digitals mimic analog instruments, and I think the reason is that the anlog instruments needle points to the value same like a watch. So if you glance in the direction of the tach, the position of the needle will tell you roughly which region you are in. Often that is all that is needed. If you have a purely digital instrument than you have to read the numbers. I do not know if anybody has done a study of it, but I would suspect that humans (me included) are more prone to overlook a readout in a digital instrument than in an analog one.
So, I would not buy a purely digital tach, where the presentation is only numbers, but one which has some analog feature with it such as LED which show the region of rpm.

cheers
Norbert

[Marauder]

Here's the thread from when I looked for PIREPS - it was from Early 2011 http://mooneyspace.com/topic/2272-new-tachometer-pireps-requested/?hl=horizon'>http://mooneyspace.com/topic/2272-new-tachometer-pireps-requested/?hl=horizon -Seth

Thanks Seth! You are a better man (ok a better thread searcher) than me. What was the final reason you switched at the last minute to the Horizon unit?

[Seth]

All those digital tachs add up airframe time at the clock rate, IE no discount for ground running time or flying at low RPM. This means you are adding up airframe and engine time ad a 15-20% higher rate than reality. 

 

In our case, it adds 20 hours in 100, or 80 hours in 400, which is 1600$ in additional engine and airframe devaluation in that period.

 

Actually some models start "counting" right away, others at something like 800 RPM, others at a higher RPM so it coincides with the runup prior to takeoff.  I forget exactly what the specifics were from the different manufacturers, but I looked it up back in 2011.

[Marauder]

All those digital tachs add up airframe time at the clock rate, IE no discount for ground running time or flying at low RPM. This means you are adding up airframe and engine time ad a 15-20% higher rate than reality. In our case, it adds 20 hours in 100, or 80 hours in 400, which is 1600$ in additional engine and airframe devaluation in that period.

I can see your point. How does the mechanical tach work with respect to this topic? Since the mechanical one I have is what is measuring my engine time, how does it count time? I guess a bigger question is what is the correct way to measure it? I can understand the concern for devaluing the plane because of time recorded that doesn't apply towards the true usage time. But if TBO is set on actual run time regardless of rpm, is it not better to report the actual usage of the engine rather than report less time? In your example above, this means if I run my engine to 2000 hours, I could also be really running it to 2400 hours (80 in 400 equates to 400 in 2000).

[Marauder]

Quite a few digitals mimic analog instruments, and I think the reason is that the anlog instruments needle points to the value same like a watch. So if you glance in the direction of the tach, the position of the needle will tell you roughly which region you are in. Often that is all that is needed. If you have a purely digital instrument than you have to read the numbers. I do not know if anybody has done a study of it, but I would suspect that humans (me included) are more prone to overlook a readout in a digital instrument than in an analog one. So, I would not buy a purely digital tach, where the presentation is only numbers, but one which has some analog feature with it such as LED which show the region of rpm. cheers Norbert

I see where you are coming from Norbert. After I had my Aspen installed I found myself always looking at the mechanical ASI rather than the digital presentation of that data. I had to force myself to begin using it as a primary indicator. In my case, it was possible to teach an old Chimp a new trick (sorry, couldn't resist).

[Seth]

Thanks Seth! You are a better man (ok a better thread searcher) than me. What was the final reason you switched at the last minute to the Horizon unit?

 

Honestly, probably better salesmanship by the person talking about the two units.  I originally was going to go with the EI but switched to the Horizon.  I'll PM you the exact wording, but it did the job for me.

 

Other reasons which were lesser so facts and not real decision makers were:

 

-3 inch vs 2 inch instrument.  It just wouldn't look as clean on my already pre-six pack M20F cockpit.  You could get a ring for the outer inch to fill the hole in the panel, but the Horizon was the uniform size of the hole.

-MAC has last installed the Horizon Unit prior to the Garmin G1000 unit aircraft and was the stanadard equipment for non G1000 equipped aircraft (though I'm not sure if any were built without the G1000 once that was an option).

-50/50 split on what differet opinions were of others, but my personal MSC had never had an issue with the Horizon units, and honestly, only a few if any with the EI units.  

-Having an arc of LEDs for eye placemnet I figured would be a plus, and it probably was, but I didn't notice it to be an issue after a few flights.

-Price was a non factor, less than $100 difference at the time if I recall.

 

Both units are fine to use.  I would go digital vs analog at this point if your unit needs replacing, as that's when it makes sense to do upgrades.  When you'd be putting money into the airplane anyway, and for a little more, you end up with upgraded technology.

 

-Seth

[TTaylor]

All those digital tachs add up airframe time at the clock rate, IE no discount for ground running time or flying at low RPM. This means you are adding up airframe and engine time ad a 15-20% higher rate than reality. 

 

In our case, it adds 20 hours in 100, or 80 hours in 400, which is 1600$ in additional engine and airframe devaluation in that period.

 

 

 

I agree that each has advantages and disadvantageous.  I don't think it is 20% difference for most of us.  I don't fly very much at under 2500 rpm.  The E.I. doesn't count under 1300 rpm so most of the preflight is not counted.  If you fly at lower rpm then it would be a disadvantage.    For me I don't think there is any difference.  I will have to compare the the flight time and tack times to see if there is any additional time on the tach time that I am missing from the flight time.

 

When do you fly at lower rpm?  I usually just set rpm at 2500 and lean after that.

[jetdriven]

I can see your point. How does the mechanical tach work with respect to this topic? Since the mechanical one I have is what is measuring my engine time, how does it count time? I guess a bigger question is what is the correct way to measure it? I can understand the concern for devaluing the plane because of time recorded that doesn't apply towards the true usage time. But if TBO is set on actual run time regardless of rpm, is it not better to report the actual usage of the engine rather than report less time? In your example above, this means if I run my engine to 2000 hours, I could also be really running it to 2400 hours (80 in 400 equates to 400 in 2000).

The mechanical recording tachometer is similar to an automobile odometer.  In the case of the M20J, hours=recording hours at 2566 RPM.  That's fine, as hours in service are defined as from takeoff to landing.  Even the recording tachometer doesnt accurately count this, but it is a closer approximation of hours of service than a Hobbs meter that runs with oil pressure, or worse yet, a Hobbs meter wired to the master switch. 

 

During ground ops at, say, 1000 RPM it counts a little less than half. 2300 RPM cruise saves you 11%.  We often cruise in the local area at 40% power and 2200 RPM.  Lower stress, lower wear, lower hours.

 

Pretty much every recording tachometer works this way, and every airplane you see with one counts hours like that too.  No sense adding up hours 10-20% more than what is the industry standard, and thats what you are doing with a digital tach.  In our case, our plane had the wrong tach installed in 1982 and added up 440 hours too many. It took a new tachometer and a  log entry to set it right.

[1964-M20E]

I have the EI suite in my plane TACH, MP, Volt/amp, oil pressure/temp, EGT (single point only) and CHT (single point only). I like the digital guages and they all have LEDS to simulate a needle but for the MP and TACH I think I still prefer the old analog dials for a quick look but for accuracy of read out the digitals are the way to go. If you are having issues look at the cost differences betwen the two.

[Parker_Woodruff]

All those digital tachs add up airframe time at the clock rate, IE no discount for ground running time or flying at low RPM. This means you are adding up airframe and engine time ad a 15-20% higher rate than reality. 

 

In our case, it adds 20 hours in 100, or 80 hours in 400, which is 1600$ in additional engine and airframe devaluation in that period.

 

Byron,

 

The EI tach doesn't do that unless you go over a certain RPM for more than 20 seconds or so.  I want to say it's 2000 RPM.

[Piloto]

My Breitling B-1 pilot watch has both digital and analog displays. And for what it's worth, most of the corporate pilots I know wear a timex anyway.

"Pilot watches" are analog because they date back to a time when digital and/or quartz watches didnt exist. Being analog doesn't make them any more functional.

Also, many new cars are going to digital displays. I believe the new Viper has a completely digital OLED display.

Point being: just because something has been one way for a long time doesn't necessarily mean that way is the best way. In many cases it means that the newer technology wasnt available, affordable, or reliable. But when that newer technology does meet those conditions it's often an improvement.

Try one of those LCD watches over your parka sleeve and let me know what they read. Anything that uses LCD display freezes at temps lower than 20F or they get dark. Russians know better check http://www.google.com/search?q=arctic+watches&hl=en&tbo=u&rlz=1C2SKPL_enUS434US479&tbm=isch&source=univ&sa=X&ei=kEEIUaWME6322AWU-IEY&sqi=2&ved=0CFgQsAQ&biw=1122&bih=604

José

[danb35]

The EI tach doesn't do that unless you go over a certain RPM for more than 20 seconds or so.  I want to say it's 2000 RPM.

The EI tach counts any time above 1300 RPM 1:1.  It's the flight timer that starts when you go over 2000 RPM for 10 seconds (I think, may be 20), and that one resets.

 

It may be that, in Byron's use case, a digital tach would end up reading 20% higher than a mechanical recording tach on the hours (I'm skeptical of this, but he knows his flying better than I do).  For me, though, the EI digital is almost exactly equal to flight time--I'm very rarely over 1300 RPM on the ground, so ground time doesn't get counted at all.  The Horizon starts counting at 800 RPM, which was one of the reasons I went with the EI (another being that EI doesn't give you heartburn about transferring the STC, while Horizon won't let you).

[Bennett]

I have the E.I. 2" unit at the right side of my panel, but it is only there because my JPI 830 is not certified as Primary.  I virtually never look at the E.I.unit because the digital read-out of the JPI 830 is so clear and steady.  Both units are driven off the same mag fitting, but they differ slightly in their readout - the JPI 830 reads 20 RPM lower than the E.I. digital window.  I suspect it has something to do with the respective smoothing or averaging algorhythms of the mag's pulses. I just average the two by adjusting the prop so that the JPI reads about 10 RPM greater than I want for some particular, RPM, mixture and fuel flow. The throttle is always open fully in cruise (with the LoPresti Ram Air open at 5000' or above). Thanks to Knute, I'm running LOP nowadays, which has taken this old old pilot quite some time to adopt to.  I do like the low fuel flow, and low CHTs, even though my old habit inclination is to run at a richer mixture. 

[M016576]

<blockquote class='ipsBlockquote'data-author="Chimpanzee" data-cid="88428" data-time="1359477839"><p>

Quite a few digitals mimic analog instruments, and I think the reason is that the anlog instruments needle points to the value same like a watch. So if you glance in the direction of the tach, the position of the needle will tell you roughly which region you are in. Often that is all that is needed. If you have a purely digital instrument than you have to read the numbers. I do not know if anybody has done a study of it, but I would suspect that humans (me included) are more prone to overlook a readout in a digital instrument than in an analog one.<br />

So, I would not buy a purely digital tach, where the presentation is only numbers, but one which has some analog feature with it such as LED which show the region of rpm.<br />

<br />

cheers<br />

Norbert</p></blockquote>

There have been multiple studies on subjects like this, if you have access to the Embry-Riddle library stacks, you can look them up through voyager. Having both is nice for the precision of digital, and the rate information gleaned from an anolog needle. Really, though, you can program a digital display to show you whatever you want, assuming cost is no issue...