Project near completion Need Imput

[Snert]

Last Feb. I bought a real nice L4 C-90-8F in Florida. I flew it for an hour with an instructor for an insurance sign off. It ran great and I was very pleased with my new purchase. Not often do you go to look at an airplane and it better than represented. Then next day I topped off the tanks and headed for home in Raleigh. Two and a half hours into the flight the engine quit cold and I was forced to land in the middle of a huge marsh 20 miles south of Savanna. The tires of course dug into the knee deep muck and flipped. I guess the engine picked a decent spot to quit because my cell phone worked and it was only 20miles to a Coast Guard Station. An hour and eight minutes I was in their helicopter. I have waited longer for a towtruck on the side of the road.

The feds were pretty decent and called it an incident. This has not alway been the case but on this flight all the "T"'s were crossed and "I"'s dotted on my paperwork and the aircraft. A 709 ride was threatened but never materialized. Since nobody was hurt and no property was damaged the feds didn't spend much time troubleshooting cause of the engine failure.
The official cause was undetermined. They tried to say I ran out of gas but the Coast Guard video showed a fuel ring around the airplane and they reported that I stunk of avgas.

I really didn't want another project but I bought the salvage from the insurance company and am near completion on a total restoration/repair right down to bare metal.
Hanger space is rented for Apr 1st and I will move the cub there for assembly.

Here is the problem: The engine started and ran fine in the salvage yard for the feds. I actually started on the second blade. It starts and runs fine for me now, at least at idle. Before I strap my butt to the seat and fly I want to know why it quit. Plans are to put it on floats in June and fly it to our cottage in Cable WI for the summer.

I am thinking a fuel delivery problem or venting problem.

Fuel system is two twelve gallon wing tanks with exit ports front and rear
for a headerless system . Tanks are plumbed together for venting and outflow to a commom shutoff. The shutoff was not accidentally bumped in flight..

The tanks are clean, as are the tank screens, gasolator screen and finger screen at the carb.

There was a fuel imbalance at the time the engine quit. Approx 5 gallons one side an 3 on the other.

Fuel caps were the standard dome shaped venting caps.

The carb is a Marvel-Schebler MA-33SPA 85 Hrs since overhaul by SE Fuel Systems.

No Auto Fuel has been used since the fuel system and OH carb were installed.

There was no indication of carb ice. No gradual loss of power No running rough. It just quit cold

Tanks were topped off and properly sumped.

Bracket air filter was intact

The aircraft is lics. exp as it was built from parts started with a zero time fuselage, new spars ,Dakota Cub wings Paper work is meticulous. All parts or mods have STC's for J-3/ L4 The only thing I can find that would put it in the exp. cat is the coilspring shocks as opposed to bungees. This was and is a very nice airplane.

This is what I have done to the fuel system on the rebuild:

Atlee Dodge Fuel Caps ( stainless) on wing tanks.
Installed a 12 gal center tank giving 36 gal fuel.. This will be used as a ferry tank when I make the treck to Wisc in June.
Installed an Andover fuel selector Wing Tanks/Center Tank/ Off
All new fuel lines with a more direct routing and above the carb inlet.
Raised the gasolator two inches on the firewall and installed a heat shield
New teflon hose/fire sleeve firewall forward.

Other things I have done not relevant to the fuel system:
Atlee Dodge weld on float fittings
Welded extra tabs with nutplates so the seats and floorboards can be easily removed. Fabricated a new boot cowl in five pcs with stainless firewall for easy access
Installed shoulder harness

I guess I am looking for some input or thoughts on why the engine quit or what I have overlooked.

Thank You in advance
Dave Johnson

 

[Steve Pierce]

CraigH on this forum had a similar incident in a Tri-Pacer. Ironically he landed in a marsh also but being a Texas marsh it was dry and his 8.5 tires and pilot skills allowed him to roll out with no damage to the airplane. His engine quit like you switched it off. I never found anything wrong with it. It has flown now several years with no problems. We checked the weather conditions for that day and area on the internet and it came out to be ideal conditions for carb ice. That is the only thing we came up with. Still don't really think that was it. I guess it was PFM.

 

[Longwinglover]

Snert,

You stated that the original fuel caps were "standard dome shape vented caps". There is a great deal of discussion about wing tank caps in J3's and the need for a vent tube sticking up from the cap and which way that tube should face. Honestly I can't speak to the PA 18 system/venting/fuel caps, but have experience with the J3. Is the PA 18 system vented differently?

I'd think that on the ground where there is no force other than gravity acting on the flow of fuel from the tank(s) to the engine, even the smallest quantity of fuel would flow freely and the engine would start and run with no problem. In flight with the system as you described it has TWO vents. By chance, the Cub wing fuel caps are situated close to the area of lowest pressure on the top of the wing. The vent(s) in the cap(s), can cause negative pressure on the tanks in flight. Gravity and the weight of the fuel in full tanks would overcome this negative pressure for some period of time and fuel would flow to the engine.

Is the negative vent pressure from two caps enough to reduce the flow of fuel to the point that the engine quits? You state that you have two new caps for the tanks. Do either of them have the vent tube?

As the airplane is experimental (and you have greatly modified your fuel system), you may have to experiment over an airport. Fill only the two wing tanks and drone around for 3 hours over the airport and see what happens. I'd bet you have no problems for the first 2.5 hours. The question is what happens after that.

The new caps may have fixed your problem (if that is what it was). You may find that you need cap(s) with the vent tube to induce positive[/i] pressure to the tank(s).

My 2 cents.

By the way, while I understand your need to ferry to WI, I'd not want to sit in the J3 for the 5+ hrs. endurance you have!! Which seat do you choose front for CG or aft for "comfort"? Either way, my back hurts thinking about it!

Come down to York, SC (SW of CLT approx 15 miles) some weekend while your testing your plane. We have an OSH winning Clipped wing and two other J3's here.

John Scott

PS If is "a penny for your thoughts", why do I think mine are worth 2 cents?

 

[Steve Pierce]

When my Dad installed the right wing tank in his Clipper he wanted to see how low he could run that tank. There is a problem in the Pacer/Tri-Pacer due to fuel line routing that requires a placard for level flight onl if the rt. tank is selected when less than a 1/3rd full. He rerouted the lines and flew unusual attitudes until it quit, switched to the left tank and landed. When he drained the right tank there was a quart of fuel left. You might try something similar. I have also seen vent problems where the tank would actually collapse some. Positive pressure caps work well. I saw one yesterday where they modified an Atlee Dodge cap with a positive forward facing tube.

 

[CraigH]

Yep, it's kinda spooky when you can't put your finger on the problem. FAA was going to do some investigating on mine as well, but later declined since there was no damage or injuries.

Your incident sounds a WHOLE lot like mine. None of the usual signs of carb ice like stumbling or a gradual reduction in RPM. The engine went from 2350 rpm to windmilling at 1200 rpm instantly. I also had a carb temp gauge that showed internal temps to be out of the caution zone. Luckily everything turned out OK other than I've about scared myself out of flying single engine at night. We had plenty of fuel on board (7 gallons in one tank, 11 in the other) and the plane is still flying with no further problems to date.

A buddy posted an MPG of the news report online for me a while back: http://www.dfwpilots.org/movies/N5951Dinthenews.mpg It takes a few minutes to load.

 

[teeweed]

I would think, if it were fuel starvation you would have a small indication from loss of power, even for a few seconds. Having said that I have never had a cub run out of fuel and maybe it is a sudden event. If your cubs fuel burn is, lets say around 8 g.p.h. Fuel flow travels through your lines at about 1 gallon for 7.5 minutes you fly. You fly for 1 minute and the gas that is demanded to travel to the carb. is around 1/8 of a gallon. So in my thinking thats about like taking a piss. Good that your OK. Mark

 

[teeweed]

Just a thought here. After cleaning bugs off my windshield and seeing how tough some of them are to get off, anyway, started me thinking about those tiny-tiny holes on the side of my fuel caps. True they are at a 90 degree to the wind stream...but what if a bugs hit the rim of the cap...juices from the critters run around the cap and then are sucked into the tiny hole and harded. Then you fly for some time and you either get a sunken tank, fuel starvation, or the bug juice clears. Mark

 

[flynlow]

Just a thought, I had a lyc quit cold from application of carb heat. I know you didn't apply carb heat but if you unknowingly accumulated a load of ice in the carb and then flew into a less ice inducing area and the ice 'let go'....
This happened to me (twice) but the engine sounded like a snow cone machine before it got quiet. Both times I got a restart after losing 3000' in a glide.

 

[Snert]

The Atlee Dodge caps are stainless with the little finger vent pointing forward.
I had the same thought about the low pressure on the top of the wing creating a vacuum on the dome shaped cap.

This was the farthest this airplane had ever flown. In the past it was only flown locally for an hour or so.

As far as carb ice: I know that it can form even when conditions are not prime. The Wx was clear and 20 plus miles on the vis temp 60

With a windmilling engine, there is no heat available for the carb heat

Thanks for all the input

Dave Johnson

 

[fobjob]

Any potential of rain entering the forward-facing vents and inducing an engine failure?

 

[JP]

I recently noticed an old AD on the original fuel filler caps on the -11 for drilling out a hole to aid in venting. Apparently there was a problem at some point. I went out and picked up my old cap and sure enough it had the hole drilled in it.

I replaced my filler cap a while back with one with a vent tube facing forward as a bit of insurance. Seems to work just fine. I have the Atlee Doge STC PA-18 system with a tank on the left and a tank on the right. The right tank is an old Stoddard tank (there's an STC for that, too) which I had repaired and leaked checked before re-installation.

We obviously damaged it putting it back in as it leaks if you fill it over 5 gallons! If I had to do it again I would have put in one of those nice Wag Aero STCd tanks, but noooooooo, I was trying to save a couple of bucks..... :roll:

 

[Fortysix12]

"The carb is a Marvel-Schebler MA-33SPA 85 Hrs since overhaul by SE Fuel Systems."

I wouldn't go flying until I went through this animal. I think everybody agrees it had to be a fuel problem. Make sure the finger screen is in, and there are no issues with the float assemble. I would real hard the carb and the float needle valve and screen.

 

[Hyrdflyr]

NEED INPUT

I think you might have had carb ice......I had a Cherokee six for years that NEVER had carb ice...... until the time it did.

I was on a long night cross country in winter, over the middle of Nevada, clear skies, about a hundred miles to my destination.....over mountains. Checking weather, my destination went down in fog so I elected to land in a small town near my route. Reduced power gradually so as to not shock cool the engine and set up to make a big circling pattern to land. ( Big black mountains all around) Iwas about a mile out, power still in the green, when it quit cold. Switched tanks, lots of fuel left, pulled on carb heat, hit the fuel boost, checked mags, had fuel pressure...not a pop. To far from the airport...set up for a straight in to the main street, the only lighted street in town.

The Cherokee 6 coming down like a bowling ball, about 1200 ft a minute at best glide..... coming right down to the tops of the buildings, pulled on full flaps to land and it started! Full Power, drug main low level, then straight to the airport and landed. Got to meet the local sheriff! (another story) Spent the night in the only place in town that had a bed to rent (I'll never tell- they had a bar too..).

Next day, found nothing wrong. (after I quit shaking)

I had flown for more than four hours at altitude at a constant throttle setting. I had burned off the tip tanks and was on a main with about an hour and a half left in it.

I believe that ice had accumulated on the throttle plate to the point where it finally came loose and plugged the venturi. Flew it for 4 or 5 more years and never had a problem again.

If I had to go through it again I would shut off the mags then on, and tried to back fire the engine. That might have worked.

I now pull on carb heat every 15 minutes or so routinely, leave it on for a few minutes then push it off.

I fly a C-150 with an O-200 on cross countries a fair amount now and its the worst icer I've ever been around in 30 years. I can't even cross a big lake at 3000 agl without pulling on carb heat and leaning for power. It's only redeeming feature is that it warns you.
(and burns car gas and gets great mileage). Simple fuel system: both on and off.

The O-540 in the Six did not give any warning. Just quit cold.

Looking back, it made me a lot safer pilot..

 

[Jim Guldi]

About 5 years ago I too was flying along in an exp nice wonderful day. The engin quit just like you said it seemed as though the ignition was turned off. Tried everything no start landed. That didn't go well. The engin was recovered and put on a test stand and it started right up. I 100% believe it was ICE. I have since read many articles about carb ice. This is happing much more than is reported. Steve and Hyrdflyr are right on. So happy that you are ok don't underrate the good outcome...it is always in question until you are OUT of the airplane. One last thing, always get out as soon as possible after the plane stops. The plane can go on fire after you have stopped and are sitting there. It happened to me.

 

[JMBreitinger]

"The carb is a Marvel-Schebler MA-33SPA 85 Hrs since overhaul by SE Fuel Systems."

I wouldn't go flying until I went through this animal. I think everybody agrees it had to be a fuel problem. Make sure the finger screen is in, and there are no issues with the float assemble. I would real hard the carb and the float needle valve and screen.

I second this. When mine quit, I wasn't so luck with respect to landing options. I was in a dense urban area, just departing, too low to turn around and too high to land on the remaining runway.

Mine also ran the next day. when my engine was torn down, the needle valve was found to be way out of tolerance. The tensioning spring that keeps the assembly all in line was pretty boogered up so the needle valve was not properly aligned. When pushed up tight, it would stick closed. We put a couple hundred pounds of air pressure on it both wet and dry and could not get it to open.

We will never know for sure but seemed the most likely culprit in my case.

 

[Snert]

Thanks all for your input
I have many skills. Carbs are not one of them. I have alway said that carburetor is a french word for don't fool with it. I will send it out to a good shop. A few hundred dollars in the scope of life is nothing.

Anybody know a good shop? I have been out of general aviation for a few years and don't know who is who anymore. I the past I have used Schneck in Rockford

Thanks Dave Johnson

 

[tempdoug]

aircraft systems, rockford, illinois 815-399-0225