Tach options?

[jetdriven]

Not quite true, the correct answer is it depends.

It depends on which mechanical tach you have and how you fly. Mechanical tachs come in many flavors, some are 2300, 2500, or 2566. All record as long as the engine is running.

If you want to save on hours you need one with the highest ratio and fly at the lowest rpm. As has been noted already if you have a 2300 rpm model and fly at a higher rpm you are logging extra hours.

The electric generally don't record until a specific rpm is held continuously. As stated the E.I. is 1300 rpm. This means most of the time on the ground is not recorded. I fly now at 2400 rpm and I would guess the non-recorded ground time is just about equal to any time saved by a lower rpm on a mechanical tach.

From Bill Eldred I got the M20J tachometer recording speed is 2566 RPM. This was also confirmed by SLI. Someone put a 2300 RPM recording tach in our machine in 1982, so I installed a 2566 RPM SLI tachometer and made a log entry subtracting 450 hours. Now it records ~80% of Hobbs hours. On a longer flight it's a little higher. But better than flying. 4.0 on the Hobbs and showing 4.5 on the tach.

[carusoam]

What is the engine TBO based on? Hours in real time, Hobbs time, tach time?

Flight experience is based on actual time, tach time, Hobbs time?

What's your preference?

Best regards,

-a-

[N201MKTurbo]

Engine and airframe time is based on the slowest recorder and flight experience is based on the fastest recorder.

[jetdriven]

Actual time in service was defined by the FAA in an advisory circular. They defined it as time from takeoff to landing. They even specifically noted that recording tachometers only approximate this. I think they approximate it better than a digital tach which records the ten minute taxi and runup plus the 4 minutes of taxi time to the hangar. And what about those 30 minute ground holds waiting for a clearance? The EI unit with its 1300 RPM trigger would be a good compromise so long as you kept ground operations to less than 1300 RPM.

Flight time for logging purposes is the time the aircraft moves under it's own power with intention of flight until it comes to rest as the end of the flight. The Hobbs meter triggered from an oil pressure switch does a pretty good job of this.

[carusoam]

The O's electric Hobbs meter is attached to the air speed switch...

The flight timer is a function on the ADF and starts at power up after engine start. It can be reset as well...

Best regards,

-a-

[SkyPilot]

Keep in mind those digital tachometers count hours faster than actual flight time, so it devalues your airplane and engine faster as well.

 

That's awesome! My tach reads 355 hrs. I've got 1038 actual hours on the engine according to the journey and tech logs.

 

In Canada, the log book rules.

[AndyFromCB]

I've been really happy with my combination tach/mp gauge from AeroSpace Logic. Bravo has two 2 1/4 gauges, one for tach, another for MP. I wanted my CHT/EGT/TIT gauge (G1) to be on the pilots side where I could see it, hence I installed the the combo and moved the G1 into the hole vacated by the MP gauge.