• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

How I almost Wrecked My Super Cub Today

Steve Pierce

BENEFACTOR
Graham, TX
I bet that got your attention. The event sure did get mine and figured I better tell the tale so someone else isn't as fortunate. So normally I fly around with 6-12 gallons of gas in my Super Cub. My playground is 7 miles from my airport and I like being light when playing. On several occasions when running the stock fuel system and stock valve I would forget to switch tanks when needed and run a tank dry. That is an un-nerving feeling and I am very quick to switch to the tank with the fuel but my fear was to have this brain fart and the engine quitting at the most inopportune time like climbing out of a short strip with no where to go. A few years ago I decided to install the Dakota Cub fuel valve which has a Both position but does not require you to replumb the entire fuel system like their STC'd headerless fuel system and the one from Cub Crafters. There are limitations since you are feeding out of one line on the right tank it does tend to burn out of the left tank faster and therefore on cross country flights I use left and right tank selection periodically to balance the fuel load. Thread on installing my Dakota Cub fuel valve. https://www.supercub.org/forum/showthread.php?52341-Installing-a-Dakota-Cub-Fuel-Valve

Yesterday morning SJ flew down to Wichita Falls to do an insurance check out with Tony in Mac's amphib Super Cub so I put on 20 some odd gallons of fuel to fly the 60 miles up to see him and explore the Brazos River that had crested the night before at almost 27 feet, (flood stage is 21 feet) which means the playground is gonna be new. I took off and switched over to the right tank with the intent to switch back over to both before I landed. Needless to say I didn't and after hanging out through lunch and flying the river back to Graham I put the airplane back in the hangar and didn't think about the fuel valve. This morning I took off and flew the river to the end of our normal route, pulled up out of the river in a left hand banking turn and the engine quits. Oh, forgot to switch back to Both position on the fuel valve so I reach down to turn the valve, it won't turn. CRAP. Put a lot of force on it and it still won't turn. WTF. Fly the airplane. There is a row of trees and a spotty field full of mesquite just beyond them. I am thinking, glide past the trees if I can, pull flaps and find a line between the mesquite. Problem is I don't see a line that doesn't include any trees. I'm gonna have to rebuild my airplane. CRAP. I don't want to tear up my plane, no options. I grab the handle and crank on it and it goes to Both, engine restarts and I feel my heart racing. Holy smokes. I get some altitude and rotate the valve a little, it is smooth but then hits a tight spot. To heck with that, back to Both and I will jack with it on the ground. Having had these valves apart all I can think is that an o'ring has come loose and bound up in there.

I get back to the airport and taxi down to my work hangar and start draining fuel. I pull the fuel valve placard and remove the snap ring holding the spool in the valve. I installed the handle, slip a ziplock bag over the assembly to catch the detent springs and balls and pulled on it, it won't come out. Oh yea, there is a limit screw on the back that engages the rotation stop machined in the back of the valve body to meet the part 23 regulation about only being able to turn the fuel valve off in one direction. Crap, I gotta pull the valve out of the airplane.

Ignore the dog hair, my dogs usually fly with me on my adventures.
PXL_20210606_141708651.jpg
View attachment 56087
I get the valve out and I notice that the limit screw is bent and later realize it has backed out as well. How did that happen. Only thing I can think is I got a little rodeo with it turning it all the way to the Left tank or to Off but can't recall doing that.
View attachment 56088
PXL_20210606_152138050.jpg

PXL_20210606_153058929.jpg
View attachment 56089
I get the bent screw out and the spool out of the valve body, no smoking gun. Put some EZ Turn on the spool, install it in the valve body and it all works great. What the heck. I call Mark Erickson at Dakota Cub to see if he has ever heard of this, he has not. While talking to him and relaying my story I realized what happened. The screw backed out of the spool while in the Right position. It backed out so much that the head hit the rotation stop when I tried to go back to Both the Limit screw head wouldn't allow the spool to rotate. When I got real forceful with it the screw bent allowing the spool to rotate to the Both position. Not sure if the Loctite let go allowing the limit screw to vibrate out or what. I ended up leaving the limit screw out since I didn't have an MS35265-48 screw which has a lower profile head than normal. I don't have to meet part 23 and if I do I can install stops like Cub Crafters does with bushings and AN3 bolts on the cover plate of the fuel valve. Refueled, tested and flew some more with everything working normally. So that was my excitement for Sunday morning. Hopefully it is educational to someone else and this was a freak incident.

Witness marks from the Limit Screw on the Rotation Stop on the back of the Fuel Valve Body.
PXL_20210606_153851102.jpg

PXL_20210603_125405553.jpg
 

Attachments

  • PXL_20210606_153851102.jpg
    PXL_20210606_153851102.jpg
    92.2 KB · Views: 6,027
  • dc11383 fuel selector valve ica.pdf
    1.9 MB · Views: 271
  • PXL_20210603_125405553.jpg
    PXL_20210603_125405553.jpg
    105.9 KB · Views: 5,800
  • PXL_20210606_141708651.jpg
    PXL_20210606_141708651.jpg
    129.3 KB · Views: 6,234
  • PXL_20210606_152138050.jpg
    PXL_20210606_152138050.jpg
    107.3 KB · Views: 6,159
  • PXL_20210606_153058929.jpg
    PXL_20210606_153058929.jpg
    238.7 KB · Views: 5,860
SP
Looks like you survived to fight another day! Good on ya. Thanks for the heads up.
Lou
 
Maybe use a headless stud with a jam nut? Glad you didn't damage anything besides the seat cushion.

Web
 
On my very first flight lesson, a leaky stuck fuel valve made me super nervous (the smell mostly). Since then I am paranoid about them. Sure glad this worked out like it did!

Great to see you on your birthday!

sj
 
I know all the advantages of having a fuel selector valve, but on my experimentals I always set them up for BOTH tanks, ALL the time. I never feel a heavy wing though it IS heavy as one side always drains out before the other, it's a non issue. Parking on slopes off airport, I use the slip indicator to get level side to side, that's what it's for I'm told.

I wouldn't reach out to pet that little dog on a dare, quite a crew you fly with!
 
Thanks for sharing this info, Steve. I just installed the Dakota valve a few months ago and appreciate knowing about this potential issue.

Glad it all worked out for you.

Jeff


Sent from my iPad using SuperCub.Org
 
I might be wrong but I think you could safety wire that screw. You might even be able to do it without pulling the whole valve out. Just not sure of the clearances. I run the stock piper valve and am unfamiliar with the new stuff.
 
Glad it worked out for you Steve!

Now, the flight instructor in me would like to add: USE THE CHECKLIST! Spin the valve on the ground sometimes. Create a simple cheklist for take-offs that you will do... I use Fuel, Flaps, Flippers on the Beaver... that simple!

While you might be able to take a bent up coke can and two years later it has become a beautiful Cub, your body will not come back to life like that... so stay safe.

Having fun with planes is cool, but you can not defy physics... so use a checklist!
 
I usually burn my right tank dry then go to the left. I have never noticed a heavy wing with a empty right and full left in the cub.
DENNY
 
I’ve been partial to using the left or right position and not using both. Several advantages. When measuring fuel burn you can isolate the time on one tank. You can turn on one tank after takeoff and time it accurately and then go back to the other tank.

In addition if your running very low on fuel I find it best to run one tank dry and have all my fuel in one tank when I land. At least when you rock your wings you will see fuel in one of your gauges.

having had an engine failure due to contaminated fuel I prefer to take off on the left tank, primary for a cub, then switch to the right in flight at a place where having an engine failure wouldn't be too inconvenient. At that point I know the left is good and I can go back to it. I used to do a lot of fueling out of drums and cans. I tried when possible to fuel the right tank with cans. I used a chamois and later a mr funnel but I guard my left tank. In the event of a slug of bad fuel if your on one tank you can select the other tank and perhaps purge the bas fuel in the system. If your on both tanks, there is no pace to turn to.

one word of caution, on one tank, when taking off on a slant such as a steep beach, fuel many not feed from the low wing. if the fuel in that tank is low, it will flow toward the outboard side of the tank and might port the fuel line
 
Glad you weren’t running a catto. In my experience, when you run dry (like no fuel) it stops. If you have no starter it doesn’t give you a warm fuzzy feeling.
 
I wouldn't reach out to pet that little dog on a dare, quite a crew you fly with!
Smart man, he has little man syndrome and a serious attitude. He is really harmless except the tip of your boot but have seen the FedEx guy jump out of his skin and the water guy walk around with using a 5 gallon water bottle as a shield. He is protective of his person and territory.
 
I might be wrong but I think you could safety wire that screw. You might even be able to do it without pulling the whole valve out. Just not sure of the clearances. I run the stock piper valve and am unfamiliar with the new stuff.
Yes, I think a loop of safety wire through the screw and around the spool would do the trick. The Instructions for Continued Airworthiness from Dakota Cub call out Loctite but I see no evidence on mine. From my conversation with Mark at DC yesterday I bet they all will now.
 
Glad it worked out for you Steve!

Now, the flight instructor in me would like to add: USE THE CHECKLIST! Spin the valve on the ground sometimes. Create a simple cheklist for take-offs that you will do... I use Fuel, Flaps, Flippers on the Beaver... that simple!

While you might be able to take a bent up coke can and two years later it has become a beautiful Cub, your body will not come back to life like that... so stay safe.

Having fun with planes is cool, but you can not defy physics... so use a checklist!
Yep, got complacent since I haven't been moving the valve.
 
I usually burn my right tank dry then go to the left. I have never noticed a heavy wing with a empty right and full left in the cub.
DENNY
I have noticed it when on long cross countries from here to Utah, Idaho and Wisconsin.
 
I’ve been partial to using the left or right position and not using both. Several advantages. When measuring fuel burn you can isolate the time on one tank. You can turn on one tank after takeoff and time it accurately and then go back to the other tank.

In addition if your running very low on fuel I find it best to run one tank dry and have all my fuel in one tank when I land. At least when you rock your wings you will see fuel in one of your gauges.

having had an engine failure due to contaminated fuel I prefer to take off on the left tank, primary for a cub, then switch to the right in flight at a place where having an engine failure wouldn't be too inconvenient. At that point I know the left is good and I can go back to it. I used to do a lot of fueling out of drums and cans. I tried when possible to fuel the right tank with cans. I used a chamois and later a mr funnel but I guard my left tank. In the event of a slug of bad fuel if your on one tank you can select the other tank and perhaps purge the bas fuel in the system. If your on both tanks, there is no pace to turn to.

one word of caution, on one tank, when taking off on a slant such as a steep beach, fuel many not feed from the low wing. if the fuel in that tank is low, it will flow toward the outboard side of the tank and might port the fuel line
I have operated the same way with the Left, Right and Both valve. In a very strong, un-forecasted headwind in a strange airplane where I didn't know the site gauges well I switched from Both to Right and started the stop watch on my watch. When the engine quit and I switched tanks I knew approximately how much further I could go. Opted for a nice field by a farm house and got some gas off the farmer. His little kids probably still talk about that airplane that landed in their field.
 
Glad you weren’t running a catto. In my experience, when you run dry (like no fuel) it stops. If you have no starter it doesn’t give you a warm fuzzy feeling.
Was flying with a ground adjustable Sensenich recently and pulled up a ridge and pulled the nose up and the flaps out. When the P-STOL flaps pull real light you know you are slow. Only time I have ever had a prop stop. Was glad I had the button connecting that heavy battery to that heavy starter for sure. ;)
 
Congratulations, and Happy Birthday, Steve! You received a couple of VERY valuable gifts on your Day! Salvation, and a better understanding of your airplane’s systems.

Of course, having to launder your underwear later may have taken some of the shine off.

It’s always fascinating to learn about such seemingly tiny pieces of an airplane which can bring about a religious moment.

Good job Aviating!

MTV
 
Glad you weren’t running a catto. In my experience, when you run dry (like no fuel) it stops. If you have no starter it doesn’t give you a warm fuzzy feeling.

I chickened out and hit the starter one time with I shut it down. Couldn’t get it started in the air


Sent from my iPhone using Tapatalk
 
I chickened out and hit the starter one time with I shut it down. Couldn’t get it started in the air


Sent from my iPhone using Tapatalk

There is another thread here about having a stopped prop. There is almost zero chance of an "air start" if it is dead sticked. You have to use the starter.

sj
 
There is another thread here about having a stopped prop. There is almost zero chance of an "air start" if it is dead sticked. You have to use the starter.

sj
I have done it, 82/42 and 7.0 compression ratio O-320. But it did take "considerable" airspeed. Haven't tried it with the 8.5 pistons.
 
Surely depends on the prop and engine combo but my Catto keeps spinning fine above 60 mph. Slow to 50 mph and it will stop eventually. That wasn't just a click bait headline. Thats the real deal. Glad you made it Steve!

Sent from my SM-G965U1 using SuperCub.Org mobile app
 
Happy birthday Steve, not having a both I always managing my fuel.
I have always been in the habit of shutting off the fuel valve every time
I exit the airplane, I guess my fuel valve will wear out prematurely.
 
Hmmm, I have had one of these valves ordered for some time now. Maybe the issue is being addressed............. They sure make nice parts.
 
Back
Top