arete

My Feedback: (1)

Have you had a problem with a fuel tank stopper popping out?

Recently I was flying my plane and upon take off, the plane lost power and I was unable to recover adequately before it nosed into the turf. When I examined the plane the stopper on the fuel tank was completely out and I could insert and pull it out with little or no resistance. My thought was that the pressure on the fuel tank pushed it out after the bolt had vibrated loose. Stopper has two metal disks - one on each side of the rubber gasket material and the bolt that threads into the disk inside the fuel tank applies the pressure when tightened. I am very careful with the fuel tank assembly knowing that they are often in difficult positions for routine inspection and the tank may not be seen again until the plane is crashed, modified, or examined thoroughly. I had a couple of hours on the plane when this happened.

After the incident, I talked with a pilot at another field and he told me the same thing happened to him just one week earlier with the same model plane. Although his tank stopper did not come completely out, it was partially out causing his plane to lose power and fortunately he was able to land it without any damage to his plane.

I contacted the manufacturer of the kit and they were very responsive, but indicated in their testing and personal experience, no such thing had ever happened. They suggested that perhaps I did not install the stopper correctly. I believe the tank provided in the kit is a quality product, but the coincidence I thought warrented a general inquiry here.

My improper installation is, I believe not correct. I tug on the stopper routinely and I am the sort of person that does it 5 times not being sure I did it enough. The fuel is conventional glow plug fuel and I am sure it did not destroy the integrity of the gasket material.

Have any of you had a similar problem with any of your plane fuel tanks?

Have you had a crash where the stopper was out of the tank and you assumed the stopper popped out upon impact and not before impact while in flight?

Any comments?

rajul

My Feedback: (58)

Try applying some silicone or tamiya threadlock around the screw head to prevent it from loosening. This problem is common with stoppers with metal discs.

DBCherry

My Feedback: (4)

I've never had it happen with the metal disk type stoppers. I've had the plastic ones strip when installing.
Dennis-

Deadeye

I'm curious, arete. What manufacturer was this? I had something similar happen with a Sig ARF and a world models fuel tank. Only, the glow fuel ate my stopper, spilling fuel into the fuselage and ruining the plane on the ground. Thankfully, Sig acknowledged a stopper problem and gave me a new Four Star ARF. Sig rocks!

arete

My Feedback: (1)

Deadeye. The manufacturer of my ARF was also SIG, same manufacturer as your ARF kit, however, the manufacturer rep stated: "In all the time that this kit has been on the market, yours is the first such story we've heard regarding the problem." Problem being the popping of the fuel tank stopper.

Thanks for your posting and I was pleased to hear that SIG refectified your problem.

Bob

green river rc

My Feedback: (2)

I've blown a couple plugs running the pressurized YS motors. Now I just wrap a piece of 1/2" nylon strapping tape around the tank and between the brass tubes, and I havent soaked a plane since.

rajul

My Feedback: (58)

Hi greenriverrc, you said between the brass tubes ? Did you wrap the tape around the tank, going in between the brass tubings ?

arete

My Feedback: (1)

Rajul,

I took Green River RC to mean that he wrapped the tank and wrapped the tank running between the brass tubes too. On one of my models I did the same with string (on continuous piece) and left a loop of string on the "back end" of the tank for tank pulling purposes. I never that it would be necessary to secure the stopper with a back up mechanism, but I never thought the bolt holding the two metal places would back out. On the Somethin Extra model, pulling the tank was easy enough without my application of string. I did not thought or expected that the stopper required a backup securing device. I relied on the torquing of the bolt to secure the stopper.

The SIG representative (in his response to me) stated that the compression of the stopper (rubber?) material would expand to close the hole around the bolt and thereby secure the bolt in place. I do not believe the expansion of the rubber will be sufficient to hold the bolt under vibration circumstances. The expansion of the rubber should be sufficient to hold the stopper in place by securing the stopper against the tank collar. The bolt thread configuration (in conjunction with the metal plate) should be designed to resist loosening with vibration of only two hours of flight.

Thanks for the posting.

AirBearMA

My Feedback: (1)

I've been lucky as I've never had a stopper pop out or any problem that would cause a fuel leak. I would rate dumping a tank of fuel in a plane as a major sucking event.

Wabbit

Its not good that your stopper popped out, duh, but that happened to one of my flying buddies and the heat from the engine set the glow fuel on fire and it was cool because we found out the glow fuel burns clear! He was flying his sportster and saw a vapor trail and the engine cut out. When he landed in the dirt, amazingly, the plane was not on fire anymore and the only damage was a few quarter sized holes in the monokote!

elmerfud

I had this happen! i was at the field... plane starting running abnormal...i landed it... was fuel every where.
i removed wing and canopy.... to find fuse. full of fuel(oh geez. i was thrilled) so i removed tank. found stopper out...was like ***!..... its a relitivly new tank.// so i cleaned it out (was no fun) re assembled . ( i figured i left screw loose to hold stopper in or rubber may have shrunk some on stopper)
i put it back together... and made sure it was tight. (pulled Yanked ect on it) it was tight..re assembled blah blah blah. made 2 flights......noticed poor running once again......landed.... low and behold....... same shizit!..

i dumped out fuse......( was soaked again// threw that plane in truck . got out another one......i am sure same thing happened...i guess i will be changing tank.... i suppose plastic is soft....(now ......not sure why). and plunger hates life under heavy g-moves.

sucks . its a nice plane.... older. but nice. i hate to have it soaked in fuel

elmerfud

update...
.

after further checking.... the second time i had fuel issue`s...(leaking in fuse) was not the stopper.. the tank blew up....still not sure why...ill enclose a photo or two..

so end result is the same.. new tank

CCRC1

My Feedback: (13)

Arete, The stopper that was included with the ARF Sig kits actually shrinks after a period of time. My Somethin Extra ARF and three other identical ARF Somethin Extra's in my club had the same thing happen. There is nothing wrong with the tank, just replace the stopper with a better quality one.
I also dont think its the first time they heard about the problem because I called them myself, and sent them the shrunk stopper to make them aware of the problem.

rajul

My Feedback: (58)

Elmer, looks like the crack could have initiated from the stopper opening in the tank. I suspect that you overtightened the screw. When you install the stopper, turn the screw until you feel the first slight resistance (that's when the front and back plates start to press againt the rubber stopper), then a further 3/4 - 1 turn. No further ! I also do a air leak test after I complete the installation. Recently I replaced a couple of tanks in my arfs that came with metal plates with Ernst Super Stoppers. They are working well so far......