Ulysse

My POH recommends switching boost pump On before changing fuel tank. I did that for the initial flights after I acquired the plane. However, on a downwind leg, I switched the boost pump to select the fullest tank, but before I had time to change, the engine stumbled. I immediately stopped the pump which restored normal operation after a few seconds. Since then, I do not switch ON the boost pump anymore and just change tanks watching closely any variation of FF. What is the correct procedure ?

thank you for calling jlunseth !

Thank you @jlunseth for all the advice. I think, given my low experience, that I will make a fuel stop until such time as I know my plane better and get more accustomed to this specific route

How would the autopilot know?

yes, I have Garmin EIS on all 6 cylinders

When I got my training on the 252, I was told by the instructor to reduce MP to 33" and RPM to 2500 during climb. This works fine, but the POH says to stay full throttle/2600 RPM. I suppose the manufacturer knows better. Which settings do you use? is there anything wrong with 33/2500?

I thought "maestria" was almost universal ! another maestro! I do not have the expertise (maestria !) to confidently fly to the limits. I think I'll learn how to fly LOP in my plane and see if it allows me to extend the range.

So, since the g3x pitch is off by almost 1 deg, I could switch it off and fly with the g5 and see if the autopilot still disconnects ? I am so frustrated that I am currently traveling and will not be able to test anything before many weeks.

Many thanks for all the advice here. I learnt a lot from all the contributions. I must say I am impressed by @David Lloyd's maestria !

Interesting! They actually do not. The g3x is off by more than 1/2 deg pitch (almost 1 deg) compared to the g5. But then, why doesn't it disconnect much earlier in the flight?

Yes, the data was actually stored in my g3x card, not in the g5 Every time the AP disconnects I see the following error in both the "Autopilot State" and "Yaw damper State" columns: Fail/Attitude comparator/00002004 00001000 Any clue in what the source of the error could be?

I am planning to fly frequently a route which will require a bit less than 60gal of fuel. This leaves in theory 15 gal, enough to fly to the alternate + reserve However, if I were to need these 15 gal of fuel, it would probably be in an emergency or stressful situation. I'd rather have most of that fuel in one tank. My question is: when Mooney says "usable fuel" does this mean that once you have used 37 gal from one tank, the engine will stop or does it rather mean that you must switch tank at this point because the engine would be running some more minutes on the "unusable" fuel, approx 1.5 gal/tank? Of course, I do not want to go to that limit, but I am wondering if I can safely use 35gal out of the theoretical 37.5 gal on each tank? Maybe I am wrong in thinking that I should have most of the fuel in one tank. What would you do ? (except a fuel stop enroute ;-)

There is a very detailed breakdown of the costs here: http://www.n97nm.com/2017/?m=1 However, it seems that the costs have increased sharply due to the pandemic. A professional pilot doing this for you would charge probably no less than 15k, maybe 20k, as long as you do that by September/October.

don't they have a fix for it now?

Yes, I have the 220HP engine. So, to achieve 65% LOP, I should start ROP at a higher power setting in order to reach 65% when power starts to drop after peak EGT or should I start 65% ROP and once LOP increase MP and FF ?

I agree, I did not let time to the engine to settle. The reason is that I did not see a significant decrease in egt6 from its peak value while the FF had dropped to 8gph and the engine started to run rough. It means that if I wanted to run LOP, cylinder #6 would be almost at peak EGT. Is this a problem?

here is the link to the flight https://apps.savvyaviation.com/flights/4957870/54c3da88-9453-4b14-8b56-60574e5fec9e I followed the test procedure suggested by savvy. They recommend doing this at 65% power setting. https://resources.savvyaviation.com/resources/other-documents/flight-test-profile/ I do not understand @jlunseth comment regarding MP: My understanding is that at a given pressure altitude and OAT, when ROP, power is determined by a combination of MAP+RPM. at 2500RPM, If I increase the MAP then the power will no longer be 65%. Anyway, attached is another graph with MAP and %power. MAP remains constant throughout the test at about 25.8-26". So does power until I get LOP which is consistent with the fact that when LOP, power is a function of FF. In my test in the LOP region, power goes down from 64% to 56%. Supposing that decrease in percentage remains the same at a different setting, then if I wanted 65% power LOP, I would need to start the test at about 73% ROP which would have been in this case 29" MAP. This would probably lead to the 10.4gph FF mentionned by jlunseth. Is this reasoning correct ?

thank you! I didn't know that. I only run the test at 4500ft. Going from 65% power and about 12gph, all my EGTs peaked at 9.4-9.3 gph except EGT6 which peaked at 9. So the spread is .4 but then I do not understand : How can I be at 10.4 LOP if the peak is at 9.4 , and by leaning FF can only go down? Unless 10.4 gph is for a higher power setting ? (or my power went down in the process of leaning ?)

I did a Gami test and found that my EGT6 is almost flat on the LOP side and the engine starts to run a bit rough when that cylinder is 20deg LOP at 8gph FF. In these conditions can I run LOP and if yes at which settings? 2 pictures are attached: peak EGT6 and 20 LOP

Thank you. I found the post. I hope I will not have to replace the senders.

The stock ones

my fuel gauges were quite accurate before the g3x + eis installation. Now the left tank always shows 38 gal and almost never moves (I once saw the gauge suddenly move when the tank was almost empty). The right one instead shows 28gal when full but moves with fuel consumption. My installer says he calibrated the system during installation. Is this a coincidence or is there an issue with the garmin system ?

It is maybe my poor understanding of English, so pardon me but aren't these 2 statements contradictory? On one hand you seem to point out a fundamental hardware problem and the risk of fixing it with software, and in the other hand you are confident in installing it in your aircraft although there are pending issues which are maybe addressed inadequately? PS: I highly esteem your contributions to this site, so, please do not take this comment in a negative way