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Tach Specification

Tony__L

By Tony__L
in Vintage Mooneys (pre-J models)

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Tony__L Enthusiast

Tony__L

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Following on from a post of mine on another thread I wondered if anyone can point me in the direction of where to go to look for the required specification for equipment for our aircraft. Is there an online resource or is there someone at the factory that we can contact to get the info?

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carusoam Grand Master

carusoam

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We get some good factory support here....

Our point person is Mr. Stacey Ellis. Aka Sellis here...

If he doesn't have an answer for you, he can point you to the proper person in the organization.

As far as tachs go...

Have you considered EI, JPI or others...? There are some nice electronic devices worth considering. The manufacturers themselves can tell if their product matches your airframe/engine combo...

Some digital tachs can help with mag drop calculations and other problem solving messages...

Best regards,

-a-

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Aerodon Mentor

Aerodon

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Following on from a post of mine on another thread I wondered if anyone can point me in the direction of where to go to look for the required specification for equipment for our aircraft. Is there an online resource or is there someone at the factory that we can contact to get the info?

Google Mooney Type Certificate 2A3 and read through it.  It will have the RPM limits - be sure to read the notes at the end to see if there is a yellow arc for your prop.  And if you don't have the original prop (or engine), read the STC's that go along with it.

 

Don

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pinerunner Proficient

pinerunner

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I have a prop upgrade on my M20E and was able to get the RPM restriction from Hartzell via e-mail. I gave them all the serial number, model number information via email and they (Hartzell representative) got back to me with RPM restriction info and why (harmonic oscillations at certain RPM's with the more powerful 4-bangers like our IO-360). Hartzell was very helpful. Mine had been upgraded to a prop model that didn't require 100-hour inspections but still had a slightly different prop RPM restriction.

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Tony__L Enthusiast

Tony__L

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We get some good factory support here....

Our point person is Mr. Stacey Ellis. Aka Sellis here...

If he doesn't have an answer for you, he can point you to the proper person in the organization.

As far as tachs go...

Have you considered EI, JPI or others...? There are some nice electronic devices worth considering. The manufacturers themselves can tell if their product matches your airframe/engine combo...

Some digital tachs can help with mag drop calculations and other problem solving messages...

Best regards,

-a-

 

I will message Sellis and see if he can help.

 

I am not looking to replace my tach, unless it is not the correct one for my plane.

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Tony__L Enthusiast

Tony__L

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Google Mooney Type Certificate 2A3 and read through it.  It will have the RPM limits - be sure to read the notes at the end to see if there is a yellow arc for your prop.  And if you don't have the original prop (or engine), read the STC's that go along with it.

 

Don

 

Will google it and see what I can learn from that.  I am however not trying to find RPM limits for the prop, etc.  I am trying to figure out why my tach over reads when compared to actual flight time.

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Tony__L Enthusiast

Tony__L

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I have a prop upgrade on my M20E and was able to get the RPM restriction from Hartzell via e-mail. I gave them all the serial number, model number information via email and they (Hartzell representative) got back to me with RPM restriction info and why (harmonic oscillations at certain RPM's with the more powerful 4-bangers like our IO-360). Hartzell was very helpful. Mine had been upgraded to a prop model that didn't require 100-hour inspections but still had a slightly different prop RPM restriction.

 

Thanks for your response. As per post above, this not quite what I am looking for ;)

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Tony__L Enthusiast

Tony__L

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Based on his previous post I think he may have been asking at what RPM the tach will accumulate 1 hr of tach time in exactly 1 hr.  For my plane it is 2566 rpms, but that changed with model and year.

 

Yip, this is what I am after . . . .  :)

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Tony__L Enthusiast

Tony__L

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M20J is also 2566 RPM per Bill Eldred, chief engineer. PSI labs also confirmed it, they sel SLI tachs. Mitchell shows 2300 RPM which is incorrect.

 

This is all I am trying to confirm, that along with what the tach that is currently installed works to . . .

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Tony__L Enthusiast

Tony__L

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Talking about non-standard props on a plane.  I have 3 blade hartzell on my Mooney as opposed to the standard 2 blade.  Would this make any difference to the accuracy of the tach.  My feeling is no but stranger things have happened . . . .

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carusoam Grand Master

carusoam

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Tony,

I think our collective expectation of the Hobbs/Tach time has evolved since the 60s...

The original tach's hour meter that was in my C is really an engine revolution counter that can only be accurate (relative to time) at one rpm set point.

In the mechanical realm, counting revolutions is a good way to measure wear.

Consider using a stop watch while flying...

Write down the tach time before and after a five minute interval at 2400rpm and again at 2600 rpm.

You should be able to collect some data to calculate how many rpms does it take to equal 1.00 hours.

Wait until after you land to do the math...

How does that sound?

If you are not getting linear data (rpm:time) there is a method to lubricate the tach...See the oil cup on the back of this ancient device.

If you need some logic to impress your finance administrator....

Modern tachs don't use oil cups.

Modern FP gauges don't bring a fuel line into the cabin.

Modern oil P lines don't bring hot oil into the cabin.

Consider JPI, EI, et al....

Best regards,

-a-

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N601RX Grand Master

N601RX

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Talking about non-standard props on a plane.  I have 3 blade hartzell on my Mooney as opposed to the standard 2 blade.  Would this make any difference to the accuracy of the tach.  My feeling is no but stranger things have happened . . . .

Talking about non-standard props on a plane.  I have 3 blade hartzell on my Mooney as opposed to the standard 2 blade.  Would this make any difference to the accuracy of the tach.  My feeling is no but stranger things have happened . . . .

If your concerned about the accuracy of your tach download the Engine RPM app. It has always matched my JPI exactly.

post-7624-0-70011200-1422033435_thumb.jp

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RobertGary1 Grand Master

RobertGary1

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Talking about non-standard props on a plane. I have 3 blade hartzell on my Mooney as opposed to the standard 2 blade. Would this make any difference to the accuracy of the tach. My feeling is no but stranger things have happened . . . .

It will be called out in the stc for your prop installation. The stc modifies your original type certificate.

-Robert

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