Hi All,
I am 5 months into the ownership of TB-20. Not so long, but I thought I share some experience.
I think the maintenance costs are not so relevant yet, due to the short period.
I’ve just made an analysis of the specific consumption.
Column 1: Specific consumption vs. Flight time
Column 2: Specific consumption vs. Total time
USG/h USG/h
13,35 11,95
13,36 11,16
15,33 11,15
15,53 11,58
13,13 11,45
The conclusion so far is that for local or short flights I should use 15.5 USG/h, for longer cross-country flight 13,5 USG/h is OK.
I had a landing gear failure once, so the data includes an hour of flight with landing gear extended back to base.
I must admit that I am very conservative with leaning and I end up being above the book figures.
There are two things that are now on the top of my priority list: totalizer and an engine monitor.
Are you injected and do you have individual EGT and CHT ?
Pig wrote:
Are you injected and do you have individual EGT and CHT ?
IO540C4D5D, injected. Only one cylinder measured.
Do you run LOP? Have you got Gami injectors ?
I run an io550 75 LOP and fast cruise at 12gph So it seems to me like you are perhaps running heavy but I know nothing about the TB20.
Yes, probably I could lean more – I just keep the EGT vertical. At the usual altitudes I am around best power figures of the POH.
robirdus wrote:
There are two things that are now on the top of my priority list: totalizer and an engine monitor.
These will pay for themselves in fuel savings. I agree with Mr. Pig – your FF would be ok for about 180 HP, which I doubt you need to cruise at altitude.
Yes, definitely install a multi cylinder engine monitor, and a fuel totaliser.
Those fuel flows seem too high. I fly the TB20, low level, say a few k feet, at 23" 2400rpm, and 11.7 USG/hr which is slightly LOP.
Once you get the above, I would strongly recommend doing the GAMI test (once you have EGT measurement with data logging, although it can be done with a passenger making a note of the values) and perhaps buy some or all GAMI injectors, and then you get smoother running at peak/LOP.
Here is a writeup I did a while ago.
Gami. Individual EGT and CHT. Then learn about the big pull and proper leaning and I bet you can cut that down by 15%.
Peter wrote:
Here is a writeup I did a while ago.
Thanks, Peter. I will study this.
Very true: "In traditional PPL training, the subject of “mixture” is largely avoided and most flight is done with the red mixture lever all the way forward, with various “if you touch this you will cook the engine” dark warnings from instructors" 
