Fuel paranoia or concern????

[Desertdoc75]

So i've spent some time searching and trying to pinpoint what is either a delusion or a problem with my fuel tanks, now I'm going ask for some feedback..................

 

Bought a Mooney D a couple of weeks back and still in the infant learning stage with her. I notice her performance and flight characteristics are on par and I had a pretty extensive pre-buy done, but I'm concerned about a fuel smell in the cabin and I notice when I top off the tanks, within a week, I'm down a gallon or two. I have not noticed a leak, nor noticed any stains or discoloration. I also haven't noticed a huge overwhelming smell in my T-Hangar, but when I open the door, I can detect a moderate fuel smell. It's not overwhelming, but I'm one of those "stay ahead of the curve" type of guys..............

Thoughts??? 

Leak? Fuel sender gaskets? Bad fuel valve? Gascolator?

[Hank]

My guess would be the gaskets where the fuel line comes out of the wing. Take off the inside side panels for access. Do you see any  kue on your carpets? That's another frequent sign. 

[N201MKTurbo]

Hank is right, but the fuel sender gasket. The change in level is probably due to thermal expansion. It takes a huge leak to cause a level change. 

[par]

So I had a very similar issue with my C. If your fuel sending unit gaskets are not leaking, you need to check the selalant on the outboard side of the tanks. If the smell is only happening with full tanks, it may be a leak at the very top of the outside of the fuel tank. Since the cockpit is not sealed, some of the smell will make its way into the cockpit even without fuel in the cockpit. This was the problem with mine.

[cliffy]

You can check the rear of the tank by looking in the wheel well. I've seen lots of leaks there.

If the leak is in the leading edge it entails removing a couple small access covers to see it. Just don't remove a tank access cover. Same with the outboard end. Fuel smell can travel down the leading edge and into the cockpit. Best guess though is behind the sidewalls at the inboard ends of the tank. One option, don't fill it until you fly it depending on how much it leaks. The Maint manual has the leak rates shown in drawings 

[BDPetersen]

I had the same experience with my C. Disappearing fuel with no evidence, right tank. Opened the tank during annual last month, did bubble test, addressed the specific leak and all is well now.  Oddly, the left tank shows some staining but the fuel level not significantly afffected. Yet.

[Yetti]

There is a access cover just behind the leading edge of the wing on the bottom.  Fuel tank access are flush mounted access covers are not.  If it looks sealed it probably is. Pull the cover and look around and you might see fuel stains.

[mpg]

this whole disscousion is starting to freek me out,,,,   i was a pilot 30 years ago,, and never worried about gas  as much as i am worried about gas now...   we always talk about landing before we have used our planned "reserve",,,  but even with sticking the tank and checking the gauges,,, even the great cies specials you dont know if there is a a leak,, or a blader is getting sucked up to wreck the real readings,,,

in a car you can bring a gallon of gas in the trunk for just in case,, but in the plane,, your extra gallon is in the main tanks with all the other suspect gas,, and you just dont know,,,,....   planes need a special,,, reserve tank,,, one you can count on,,,,, 5 gallons,, under the pilots seat,, with a inside fill cap,, and a sight gauge,,  that cant leak, or missread,, and cant be used up untill you know you want it,,,,  so when all else goes to shit and you want your "reserve"  you can turn the very special valve,,,   and it will be there for your emergancy use...

 

i own a cherokee that i bought in idaho,, and need to fly it 375 mi to my home drome,,,,, i was feeling very confident about a straight through flight home,,,,   now i want to make a fuel check stop half way here just to make sure,,,,   maybe i should make 2 fuel check stops on the way home,,,,   how many stops are really enough???

[Yetti]

Stopping to make operational checks on a new plane is not a bad idea.   After maintenance my return to service flight is up to 6000 feet above the airport.   Last year did the annual, then the RTS flight saw the fuel pressure gauge hiccup. Replaced the fuel pump.

[mpg]

this is true!!!   maintenance induced failures are a real,, and pervasive problem and the cherokee i bought had a fresh annual,,,!!

by the owner!!!.....  i will break up the flight to do extra checkings!!!

[bonal]

Welcome Desertdoc you did not indicate if you've got bladders or not. Tell us a bit more about your new D is it converted to C specs as ours is. What year is it ours is a 64.

If you have bladders the fuel takes a little time to settle to the lowest chamber so if you top off and close it up your fuel drop may be due to that.

[cliffy]

I have never pushed the fuel /time envelope on a "new to me" airplane and until I knew exactly how much it burned by experience, I was very cautious. In my Mooney I flew my first flights by going 1 hr on one tank several times and then filling to get an exact number. Then I flew the second hour on the other tank (in cruise) going back to the first at the end of the hour. Checking again on the ground when filling. Took many fights to nail it down but I can tell you mine burns 10 gals the first hour, 9 the second and 8 there after. Almost exactly to the number (the way I fly). I don't need no stinkin gas gauge :-) I cruise to get somewhere, if I was going for hamburgers down low it would be different. 

Even in big jets I knew how much I burned per hour so I could ball park the given fuel load for the flight before dispatch gave me the fuel load. 

And, I'm lucky in that the way I fly I go with full tanks 99% of the time. 

10+9+8+8+8= 43 giving me 7 left at the end of 5 hrs. I've done it (not any more, too old to sit that long) and its exact. I don't count miles traveled, I count hrs flying for fuel usage. Fuel usage by time is the key IMO. Get to know your airplane. 

Short story- In my initial training (many many years ago) in a 727, never flew one before, they gave me the standard ILS and failed an engine inside the outer marker. Before the failure I was burning 3000 lbs of fuel per hr per engine to maintain the glide slope (yes 9000 lbs per hr of Jet A). When they failed the engine I went to 4500 lbs per on the other 2 running engines. Never varied on the slope and completed the landing. They asked why I went to 4500 lbs and didn't screw around with RPMs or EPR like everyone else did and I said 9000 lbs per hr seemed to work for three engines so I figured 9000 lbs would work for 2 engines also. It did, they were happy.  

Forget the game playing and button pushing and get to know your airplane. :-) :-)

All those buttons up front won't save your tukus but that computer between your ears will!  In other words- GET OFF THE PHONE AND PAY ATTENTION!

[Desertdoc75]

Thanks everyone! Fortunately she is going in for annual next month so we will be able to see more potential evidence soon.

Bonal, no bladders in her right now,  that may change down the line though dependent on what we find. She is was converted to a C model back in the 60's. 

My biggest priority between now and then is to continue to learn her iniquities and uniquities! I run numbers and fuel calculations on her for every leg to get a feel for what is a realistic burn vs what's an unknown loss through leaks. We have a few things to look closer at in the interim and I appreciate everyone's responses.

 

[gsxrpilot]

3 hours ago, cliffy said:

I have never pushed the fuel /time envelope on a "new to me" airplane and until I knew exactly how much it burned by experience, I was very cautious. In my Mooney I flew my first flights by going 1 hr on one tank several times and then filling to get an exact number. Then I flew the second hour on the other tank (in cruise) going back to the first at the end of the hour. Checking again on the ground when filling. Took many fights to nail it down but I can tell you mine burns 10 gals the first hour, 9 the second and 8 there after. Almost exactly to the number (the way I fly). I don't need no stinkin gas gauge :-) I cruise to get somewhere, if I was going for hamburgers down low it would be different. 

 

I agree with you for the most part. Except that with modern fuel totalizers and fuel flow, I'm much more accurate flying based on gallons of fuel used rather than time. Sometimes I fly fast, sometimes I lean it out for best economy. Sometimes I'm up in the flight levels and sometimes I'm down low in the weeds. So my fuel used per hour varies. But my EDM 900 measuring flow, can tell me at any time, exactly how much fuel has been used, and how much remains. It will also indicate how much is in each tank, but I don't rely on that, rather I keep track of at what point I've switched tanks and therefore how much is in each tank.

This works well for me, but a good fuel flow meter is required.

[bradp]

I had previously traced a fuel smell in the cabin to an outboard access panel. Anything forward is contiguous with the leading edge. The leading edge is contiguous with the cabin so you can "smell" almost all the way to the wingtip up front.

 

 

Sent from my iPhone using Tapatalk

 

[carusoam]

Lost the finished post, but this is most of what I was summarizing...

fear and concern are both helpful to keep you from doing something hazardous...paranoia, may be to much...

1) fuel aroma in the cabin is not normal. Neither are oil drips.  Some people may say these are normal... they are not helping you.

2) in my M20C the seep showed up under the carpet n the floor of the back seat. Check for blue stains there.

3) small rubber hose connectors for the fuel lines, near the tanks, got replaced at about 40years on the maintenance Calendar.

4) fuel level sensor seals got exchanged. Out with the cork, in with the rubber, seals...

5) Fuel Flow (FF)gauges are the basis of modern fuel useage knowledge. 20 year old technology that has been full vetted.

6) FF systems require some interaction by the pilot.  This can cause a forgetful pilot to be missing some important data along the way...

7) Cies has recently supplied the market with digital Fuel Level (FL) sensors for Mooneys with a new level of performance over the analog version.

8) Having both, fully calibrated, digital FF and digital FL you are not ever going to run out of fuel without having a really fair warning along the way. (Right?)

9) keep in mind a fuel leak prior to the engine can occur.  Having really good FL information would know the difference between the accumulated FF data and the FL data. 

10) the pilot still needs to oversee the details, and make proper decisions.

11) Low Level LL of fuel warnings can be set properly by your mechanic. Some don't give enough warning to get to an airport if you are relying on that... know when your specific system will give a warning. Test it.

12) Some Mooney LL of fuel warnings need to be activated each flight.  Mine requires a test of the message center like annunciator panel.

 

there are a few things to be aware of...

A) running out of fuel.  We have seen a few Mooney's do this.  Some MS members and some not. Some without injury.

B ) running out of VMC. Don't intentionally fly into clouds unless you have the rating.  Prepare for flying into clouds in the event this does happen to you...  the ability to do a 180° turn to get out of clouds is an important skill to have in your tool chest.

C) running into thunderstorms... Have a way to avoid them.  Know that 180° turn mentioned above.

D) Know your take off performance calcs, including effects of density altitude.

This is ordinary PP thoughts. Not a mechanic or CFI.

Best regards,

-a-

 

 

Edited May 1, 2017 by carusoam

[Desertdoc75]

18 hours ago, carusoam said:

Lost the finished post, but this is most of what I was summarizing...

fear and concern are both helpful to keep you from doing something hazardous...paranoia, may be to much...

1) fuel aroma in the cabin is not normal. Neither are oil drips.  Some people may say these are normal... they are not helping you.

2) in my M20C the seep showed up under the carpet n the floor of the back seat. Check for blue stains there.

3) small rubber hose connectors for the fuel lines, near the tanks, got replaced at about 40years on the maintenance Calendar.

4) fuel level sensor seals got exchanged. Out with the cork, in with the rubber, seals...

5) Fuel Flow (FF)gauges are the basis of modern fuel useage knowledge. 20 year old technology that has been full vetted.

6) FF systems require some interaction by the pilot.  This can cause a forgetful pilot to be missing some important data along the way...

7) Cies has recently supplied the market with digital Fuel Level (FL) sensors for Mooneys with a new level of performance over the analog version.

8) Having both, fully calibrated, digital FF and digital FL you are not ever going to run out of fuel without having a really fair warning along the way. (Right?)

9) keep in mind a fuel leak prior to the engine can occur.  Having really good FL information would know the difference between the accumulated FF data and the FL data. 

10) the pilot still needs to oversee the details, and make proper decisions.

11) Low Level LL of fuel warnings can be set properly by your mechanic. Some don't give enough warning to get to an airport if you are relying on that... know when your specific system will give a warning. Test it.

12) Some Mooney LL of fuel warnings need to be activated each flight.  Mine requires a test of the message center like annunciator panel.

 

there are a few things to be aware of...

A) running out of fuel.  We have seen a few Mooney's do this.  Some MS members and some not. Some without injury.

B ) running out of VMC. Don't intentionally fly into clouds unless you have the rating.  Prepare for flying into clouds in the event this does happen to you...  the ability to do a 180° turn to get out of clouds is an important skill to have in your tool chest.

C) running into thunderstorms... Have a way to avoid them.  Know that 180° turn mentioned above.

D) Know your take off performance calcs, including effects of density altitude.

This is ordinary PP thoughts. Not a mechanic or CFI.

Best regards,

-a-

 

 

Some great info and advise here, and as I discovered today, you are spot on with #2. Fuel is coming in under the carpet from the posterior right wing (pic below).

 

She was going in for an annual in a couple weeks, she now is going on Thursday! lol

While I'm financially prepared for the "first" annual, I'm hoping this issue doesn't run me into a ton of $$$. We shall see.............

[Raptor05121]

tl;dr most of the thread:

My fuel selector is leaking the tiniest bit of fuel, I think I need new O-rings. Stuff a shop towel on the selector at the bottom of the opening and see if it absorbs any 100LL overnight. This is how I pinpointed my leak

[carusoam]

DesertDoc,

During your annual, have them take the fabric sidewalls off to see what is hiding behind them...

1) fuel level sensor seals, expect to replace them since you are in there...

2) fuel line rubber connectors, one on each side... two pieces of rubber fuel hose that connect steel tube.

3) insulation that may be some old fiber junk that is known to hold water against the steal tubes.  Replace if not modernized.

4) expect a lot of fuel dried blue goo hiding in there.

5) use caution, that stuff is pretty flammable.

6) an over abundance of caution would be good. Put a fire extinguisher nearby, this way you won't need it.

PP thoughts only, I have no mechanical experience.

Best regards,

-a-

Edited May 2, 2017 by carusoam

[Yetti]

Bring your paint stirrer and a sharpie on the way home fill up the tank at each stop and create the measure stick.  The nice thing about creating the stick is that you can look in the tank and pretty much know how many gallons are in there

[gsxrpilot]

I'd be interested in how this is best done with a K.  It takes so long to actually fill it to the top. And sometimes after I'm sure it's full, and I've gone to the other tank, I come back and it's down an inch. There are also flappers in the filler necks that make it difficult to "stick" the tank. It was MUCH easier with the C.

[Desertdoc75]

23 minutes ago, Yetti said:

Bring your paint stirrer and a sharpie on the way home fill up the tank at each stop and create the measure stick.  The nice thing about creating the stick is that you can look in the tank and pretty much know how many gallons are in there

I've got a custom stick from the previous owner, has helped immensely!

[Desertdoc75]

So as mentioned in my other thread, I finally got Moonship out of annual. Corrosion issues addressed, JPI 700 installed, and the fuel leak addressed.

It turned out to be the fuel sender unit. Had both sent off for overhaul, got them back looking like new! All is good................well maybe not.................

Topped the tanks to test out the repair and to play with the JPI, right tank immediately started leaking again (which sucks as I just had the spar splice plate treated with Corrosion X)! Same issue, anything over 2 gallons causes a leak. We checked the tank, scraped out some old Pro-Seal, and resealed. Finally got a decent pic and I think I have the answer. It's still the sender unit I believe, leaking from the screws.  

Gonna have the unit to pulled again and inspected, may be going back to the overhaul shop. More to come........

[carusoam]

Are the blue stains The after picture?

Short study of fuel sealants or the procedure may be in order?

Best regards,

-a-

[Guest]

You might want to install some Parker 600-001-10 Stat O Seals under the screws.

Clarence