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Part# 10-01021


An inaccurate tachometer can waste performance, fuel and engine life. Mechanical tachometers are notoriously inaccurate and should be checked at each annual and 100 hour inspection or any time aircraft performance is in question. The TruTach II Optical Digital Tachometer measures the true speed of your propeller from inside or outside the aircraft. Just point it at the propeller or rotor blades and TruTach II will directly display the rotational speed with a resolution of 1 RPM. No connection to aircraft systems is required and measurements may be made at any speed setting from 240 to 70000 RPM.

Direct display is available for 2, 3, 4, and 5 blade propellers. Digital Signall Processing assures rock-solid display in single and multi-engine aircraft as well as helicopters. The compact 4-inch instrument weighs just 4 ounces and may be used with fast turning ultra-lights and kit plane propellers. Just turn it on, select the number of propeller blades and point. Automatic shut-off turns the unit off if you forget. The Tru Tach II includes a standard 9 volt battery providing 150 hours of operation.


Works perfect.! Also it is easy to check calibration. Just point it at a fluorescent light bulb 3600 rpms!

Johnny W
September 17, 2020

Installed with velcro in less than 5 minutes. Works well.

Eugene S
May 26, 2020

Could not be easier. Literally, set it on the glareshield and it begins its readout almost immediately. Confirmed our two different RPM readouts in the aircraft and now we know which one is more accurate. If you want a simple, effective means of validating prop RPM this is it.

Chris R
April 20, 2020

Very accurate readings. Good value!

April 9, 2020

This product works exactly as advertised. Very pleased. I tried a $30 optical tachometer from the internet. Total failure. Got this, checked calibration with a fluorescent bulb as instructed by mfg. It varied +/- 2 rpm (precision better than 0.001%). Got in the airplane and pointed it at the propeller. In 1-2 seconds, I got the propeller RPM. Also, very simple to change to correct number of prop blades.

Fred G
March 22, 2020

Product worked perfect.

February 23, 2020

Fast delivery service from Aircraft Spruce and device works as specified. Simple to setup and use on my Arrow with easily read display.

December 6, 2019

Awesome little unit. Easy to use, easy to read. Confirmed my suspicions that my tach was reading high, which is unusual. Had my prop balanced after purchasing the unit and while balancing the prop, the mechanics unit showed I was turning at 2180 when my tach showed 2300. This little unit read the same as the mechanics prop balancer.

Jeff A
August 19, 2019

I didnt know what I was missing until buying this electronic tach. I have been flying our A36 Bonanza at 2320 RPM when the Beechcraft guage said 2400 RPM! This is a great addition to any propeller driven aircraft. Its accuracy is easily verified by simply pointing it to any florescent light!

George H
August 15, 2019

Excellent product. I keep it on the glare shield as a backup. Of course I still have the factory tach and use it primarily, and the analog tach is easier for run up tests etc. but this is a great way to always know your rpm exactly. You can see the governor operate and whether it’s wandering. It does get hot In the sun though. Battery lasts a looong time. Even though I have it on for every flight. Don’t forget it’s optical. At dusk it gets funny until it quits altogether. Also can give some interesting readings sitting behind another plane waiting for the runway.

Will H
August 12, 2019


Q: What are the panel dimensions for the TruTach II?

The dimensions are 2-1/4" W x 1-7/16 H x 3-3/4" D. This product in not meant to be installed in a panel.

Q: Does the Trutach II Optical Digital Tachometer come with a protective casing or box?

The Trutach II Optical Digital Tachometer is packaged inside of a box.

Q: Do you have to set the Trutach II Optical Digital Tachometer for 2, 3 or4 blades every time you turn it on in a two blade C-172?

No, the Trutach II will store the desired number of blades and start with this input every time.

Q: Does the Trutach II digital instrument remain on for the duration of flight, or is one constantly cycling it prior to altering engine parameters?

The Trutach II is able to monitor changes in RPM and display them in real time. There is no need to turn the instrument off during flight.

Q: Does the TRUTACH II OPTICAL DIGITAL TACHOMETER Part # 10-01021 come calibrated or have the capibilities of being calibrated?

Per Trutach: The only calibration available is to switch from 2-5 prop blades.

Q: Will it work if I put it on the glare shield inside the aircraft?

Yes, the Trutach II is intended to be put on the glare shield for prop reading.

Q: Is this Trutach II Optical Digital indicator an FAA/EASA approved item and ifit cannot be installed in the panel, can it be used as primary engine instrument?

This unit is not FAA / EASA approved since it is not intended to be installed in a panel. You will still need to keep an approved panel mount tachometer.

Q: Does this unit come with a Certificate of Conformity stating that it complies with some form of National Calibration Standard or aa certificate of calibration?

No certifications are available for part # 10-01021.

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