Ovation Fuel Sight Gauges

[Niko182]

Just now, Cruiser said:

Why do you care ? With that much fuel I am pretty sure I can go someplace. 

I did drain my tanks and add 5 gallons of fuel at a time to verify the sight gauges were accurate. I found they were good all the way to 30 but that is on the ground. They consistently read 5 gallons low in flight. 

Besides the needles jump around so much it is nearly impossible to get a valid reading even is smooth air. 

Its odd since the POH states theyre accurate in level flight, but I always figured they were more accurate on the ground and about 3 to 5 gallons low in flight. Glad to know for sure now.

[GeeBee]

Easiest way to check accuracy of the wing gauges. Fill the tank to the full mark, run fuel out of it if you have say the 44.5 tanks, run 14.5 gallons on the flow meter out. Then look at he gauge. It should read 30. Run another 10 out of it, it should read 20. The accuracy is thus easily verified of both the gauge and the flow.

 

 

 

[carusoam]

5 hours ago, Niko182 said:

Its odd since the POH states theyre accurate in level flight, but I always figured they were more accurate on the ground and about 3 to 5 gallons low in flight. Glad to know for sure now.

See if you can pull that reference...

The sight gauges are intended to know how much fuel you have while on the ground... important for filling the tanks...

The intention... is to accurately know how much fuel you have for partial tank filling...

 

Somebody in Mooney engineering must have decided that 35 gallons was the limit for partially filling the tanks...

Which is smart for WnB and performance, for clearing obstacles...

 

We have discussed using Ceis to do the same...  the Ceis people said a switch of some form would be needed for using the calibration curve for being on the ground...

It would go nicely with a Cies app... where BT could communicate your actual fuel level to an idevice...

 

Sounds kind of expensive, and still would be inaccurate for anything that isn’t level ground...

Send the idea to Mooney.com...

It could be an easy off the shelf fix... where we could buy some new hardware bits when it’s time to replace the broken needles...

PP thoughts only, not a mechanic...

Best regards,

-a-

[TheStig]

On 3/10/2021 at 4:45 PM, Cruiser said:

Why do you care ? With that much fuel I am pretty sure I can go someplace. 

I did drain my tanks and add 5 gallons of fuel at a time to verify the sight gauges were accurate. I found they were good all the way to 30 but that is on the ground. They consistently read 5 gallons low in flight. 

Besides the needles jump around so much it is nearly impossible to get a valid reading even is smooth air. 

Mine are the same. Up to 30 they seem to be good, then after that not so much. And yes, I use them as a means to know what I have starting out. A couple of flights lately, I have needed greater accuracy so I don't land too heavy i.e., fill as much as possible )for next flight) but with 4 people and bags, don't want to land over 3200#. A good fuel stick would give me accuracy to know I had let's say 55 gallons... 

I think mine are around 3 gallons low in flight. The attitude of the plane is a little more forward than when on the ground and I suspect that makes up for the difference. The good thing is they show less... if you have lost track of fuel and need them as a safety at least you won't over estimate. 

I will make my own from a paint stick or re-score a universal fuel-hawk. I'll do the drain one tank into the other or some method like that and probably 5 gal at a time.

Another question, how do you know you are full? 44.5 gal? I can continue to put more fuel in the tanks if a rock the wings and wait, rock and wait, rinse repeat. From a ferry pilot on here, it has been said that our 89 gal tanks will actually hold 104 gals if we are patient. The tanks are the same size as the 104 gal tanks, but vent at the collar. If that is true (I have not tried to fill 104 gals), then how do you know that you have 44.5 gals in the tanks if you didn't start with an entirely empty tank?

[TheStig]

On 3/10/2021 at 4:47 PM, Niko182 said:

Its odd since the POH states theyre accurate in level flight, but I always figured they were more accurate on the ground and about 3 to 5 gallons low in flight. Glad to know for sure now.

My POH says they are accurate on the ground and not to use in flight. I use it as a check only: needles are moving, something is sloshing around in there...

[TheStig]

Btw, I am only some 30 hours flying the M20R so still learning much about this plane.

 

[TheStig]

...but dang! I am loving every minute of it. What a plane. 

[ilovecornfields]

49 minutes ago, TheStig said:

Btw, I am only some 30 hours flying the M20R so still learning much about this plane.

 

It took me about 100 hours to get comfortable in mine...which took about 4 months. The Ovation is a pretty amazing plane and is well behaved as long as you pay attention to what you’re doing. 

[TheStig]

14 minutes ago, ilovecornfields said:

It took me about 100 hours to get comfortable in mine...which took about 4 months. The Ovation is a pretty amazing plane and is well behaved as long as you pay attention to what you’re doing. 

I believe you on that. Figure about the same

for me to get really comfortable but it seems like a pretty well behaved airplane so far. But that may just be I have not taken myself to my limits yet  ;-).

[Scottknoll]

I’m told fashioning a pipe to go under and around the standpipe to let the air escape speeds up the process. I have not tried this, YMMV. There is also a drawing & AFM supplement available from Mooney to put an official hole in the top of the standpipe, also to allow air to escape, legally. IIRC, it’s 51 gallons per side. AFM Supplement is available on the Mooney website for more info.

[Cruiser]

10 hours ago, TheStig said:

Another question, how do you know you are full? 44.5 gal? I can continue to put more fuel in the tanks if a rock the wings and wait, rock and wait, rinse repeat. From a ferry pilot on here, it has been said that our 89 gal tanks will actually hold 104 gals if we are patient. The tanks are the same size as the 104 gal tanks, but vent at the collar. If that is true (I have not tried to fill 104 gals), then how do you know that you have 44.5 gals in the tanks if you didn't start with an entirely empty tank?

there are three different versions of the fill tube. You are full to your POH quantity when at the bottom of the fill tube. The M20S has the longest (about six inches) and full is 75 gallons, the M20R collar is about 4 inches and is full at 89 gallons, the new Mooneys are full at the top of the tank in the fill cap. (106 gallons)

I might have the lengths wrong, I have them somewhere and will take the time to look later, but you get the idea.

Edited March 15, 2021 by Cruiser

[Cruiser]

REFUELING
Integrally sealed tanks, in forward, inboard sections of wing (LH & RH), carry the standard fuel
quantity. With aircraft positioned on level ground, service each fuel tank after flight with 100 octane
or 100LL aviation grade gasoline. The fuel tank contains 44.5 gal (168.45 li) fuel when
level is at bottom of filler standpipe (M20R). An additional 5.5 gallons (21.0 li.) of fuel may be added
up to the 0.37” hole located top of the neck in the standpipe for a total of 50.0 gallons
(189 li.) in each tank.

[carusoam]

Nice reference TomK!

It even mentions the calibrated hole location...

Some fuel necks got long slits in them...

No two Mooneys share the same fuel necks... so it would seem...

Modifying fuel necks in place is a bit of pain... too many hot metal chips trying to escape...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Cruiser]

here are the different fill tubes in Mooneys. (source unknown)

 

4” neck, 75 gallons usable, 81 gallons total

2” neck, 89 gallons usable, 95 gallons total

No neck, 102 gallons usable, 108 gallons total.