Learning the Mooney

[csfahey]

As a new owner I am still trying to learn everything I can about owning and maintaining my 77 Mooney M20C.  One thing that is missing from the manual is fuel burn rate for climbing and descending required for flight planning.  Does anyone have any suggestions on how to determine these values?  This is bothering me as I am using more fuel that I anticipate. 

 

Also what about fuel dipsticks.  What are people using to dip the tanks?  The plane came with this PVC pipe with lines marked on it but it doesn't seem to be all that accurate since the tank is sloped and when a little fuel is visible, the dipstick will show zero.

 

Lastly, coming from the Cesna world and training, I learned to lean at cruise above 5000.  When do Mooney owners generally lean, always?  The manual indicates to lean below 75%. 

 

Any other little things I might like to know that are not in the manual that experience has taught them?

[mjc]

Quote: csfahey

As a new owner I am still trying to learn everything I can about owning and maintaining my 77 Mooney M20C.  One thing that is missing from the manual is fuel burn rate for climbing and descending required for flight planning.  Does anyone have any suggestions on how to determine these values?  This is bothering me as I am using more fuel that I anticipate. 

Lastly, coming from the Cesna world and training, I learned to lean at cruise above 5000.  When do Mooney owners generally lean, always?  The manual indicates to lean below 75%. 

Any other little things I might like to know that are not in the manual that experience has taught them?

[Lood]

Congratulations - Wish you many happy hours in your Mooney.

The long way around the fuel burn issue is to top up your tanks and do all taxiing, etc on the one. Change over to the other just before take off and do the take off and climb on that tank while timing. Once you level out, stop the time and change over to the other tank. When back on the ground, you fill the timed tank and you'll get the answer to your airplanes fuel burn in the climb. Next time around, you can time the other tank in the cruise to determine that fuel burn as well and you can do the same for descend. Regarding the dipstick, I emptied my tanks completely and then started filling them with 5 gal at a time while calibrating my dipstick. It's true that the dipstick cannot measure 5 gals or less due to the angle, but who wants to fly with that little amount of fuel anyway. The nice thing is that your fuel flow computer cannot measure leaks or evaporation when the airplane has been sitting for a while, but the dipstick can and sometimes, you will find it more accurate than the computer.

Regarding the leaning, I lean according to what my CHT's and EGT's are telling me. I mainly operate from 4000 feet but even when I fly from the coast, I'll take off fully rich and then I'll keep the hottest EGT around 1250 - 1300 deg and I never let the hottest CHT go higher than 380 deg. If I have trouble with the CHT wanting to go up to 400 deg, like on a hot day, I immediately trade ROC for some additional airspeed.

[Kwixdraw]

If you are bothered by the PVC dipstick you have, you might want to look in the Aircraft Spruce catalog. They have a clear acrylic tube with graduations marked on it that you can see better because you dip it and cap the tube with your thumb then remove it to read the level in the tube. I made up a chart to go in my POH and can usually plan my fuel burn to within a half gallon.

[piperpainter]

I used a stick from the home depot. Just like mentioned above I had the tank drained (for MX reasons) and when I went to fill it I just put 5 gallons in for a start then did different increments from there markingthe ones that are important to me. I think I did every 2 gallons.

[csfahey]

Great tips.  Thanks guys.  I am looking forward to knowing exactly how much fuel I have and am using and not fly with anxiety anymore. 

[Hank]

Welcome to the club!

     I have a '70C, and it's a dream machine. I read somewhere to allow 2-3 gallons for runup and taxi [sounds good unless you're at a large commercial field], and plan one gallon per cylinder per hour extra for full-rich climb. I don't trust the second one as much. The POH shows my max fuel burn to be 18 gph at sea level and full throttle. I usually cruise 7500-9500', so my longest climbs are less than a half hour at 100 mph - ALT in thousands [higher speed, slower climb when it's hot], so that would put me no more than 4.5 gallons above cruise burn.

     The key is to manage your descent and make up some of the climb fuel. I normally pull 2-3" out of the throttle and trim for 500 fpm, keeping airspeed at or slightly above cruise if it's not rough. Fuel burn goes down and speed drops off slowly; just keep inching the throttle back and the mixture forward as you come down, whenever manifold pressure climbs more than an inch works well. Richen the mixture to keep no more than your cruise EGT.

     Flying this way I am able to average 9 gph and close to 140 knots groundspeed.

     I strongly suggest making time to attend one of the MAPA Pilot Proficiency Programs, which will give you lots of Mooney-specific instruction in your own plane, with plenty of reading material to review afterwards. It will give you knowledge of how your Mooney is put together and functions, and confidence to use it as it was designed.

               --Hank