Dumb Engine Question

[RCT44]

Good Evening, I have had my Super D 2005 for about 2 months now. I have give or take 20 super fun hours on it thus far. I flew it on Sunday and came back today to open the hangar and find a small pool of fuel dripping from one of the drains at the bottom of the engine cowling/nose area. Just curious if anyone has any experience with his or her insights. When I checked the fuel tanks/gauges from where I left them on Sunday, the amount of fuel that leak was not even noticeable. I am just trying to get a baseline understanding of what these two lines do and what the longer one, which is currently slowly dripping, is meant to do. I attached a few photos here for reference. When I went into the cockpit and turned the fuel off the dripping stopped immediately.

4 new photos · Wednesday, Dec 22, 2021 📸

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[Bartman]

there are three drains under there. the mechanical and electric fuel pumps each have drains and the gascolator also has a drain at about that location. the gascolator might not be fully closing after being drained before flight. the other two, i'm not 100% sure but I don't think there should be any fuel coming out of them at any time.

 

[Goodyear]

Good Evening, I have had my Super D 2005 for about 2 months now. I have give or take 20 super fun hours on it thus far. I flew it on Sunday and came back today to open the hangar and find a small pool of fuel dripping from one of the drains at the bottom of the engine cowling/nose area. Just curious if anyone has any experience with his or her insights. When I checked the fuel tanks/gauges from where I left them on Sunday, the amount of fuel that leak was not even noticeable. I am just trying to get a baseline understanding of what these two lines do and what the longer one, which is currently slowly dripping, is meant to do. I attached a few photos here for reference. When I went into the cockpit and turned the fuel off the dripping stopped immediately.

4 new photos · Wednesday, Dec 22, 2021 📸

Tap to view!

photos.app.goo.gl

If the leak is coming from your fuel sump valve then I would run about 4 oz or so of fuel through it to see if it cleans out any dirt or deposit keeping the valve open. Make sure you put a bucket under it when you do this in case it sticks open. Replacement is also a prudent option.

 

[Big Ed]

That is a lot of fuel. I have been flying Decathlons for 23 years and have never seen fuel on the ground like that.

A few recommendations:
1. Keep your fuel shutoff closed until you resolve the issue
2. Pull the top and bottom cowl off. Get someone to show you how if you have not done it before.
3. Get a parts manual and familiarize yourself with the firewall forward installation. Take some time to trace the fuel, oil, air, electrical, and engine control systems. If you can't find a manual, let me know and I'll post some scans from an older one. It's 99% the same.
4. Once you can identify the parts, trace the path that fuel takes from your tanks into your engine.
5. Identify where the fuel on the ground is coming from. My guess is your gascolator drain is stuck open a bit. An easy fix.
6. Go find an A&P and ask him to help fix it.

Anyone flying as much as you is going to have to get comfortable pulling off the cowl. Unless you are Thurston Howell the 3rd. Find someone who knows the type to show you how to put it back on.

 

[Bob Turner]

Would a failing fuel pump diaphragm do it? One way to test the diaphragm is to turn the electric pump on and look at the mechanical pump overflow.
2005? Could be the fuel drain. Depending on type, wise to replace these at 15 year intervals.

 

[Bartman]

One way to test the diaphragm is to turn the electric pump on and look at the mechanical pump overflow.

Interesting.

 

[RCT44]

Guys - I am so happy to hear from everyone here and really can't tell you how much I appreciate everyone's responses in such short order. I will work on this problem and be sure to keep everyone posted on what I find. I do know that even a small amount of fuel dripping around cars and planes for a bit of time can look like a lot. As I mentioned the fuel gauges did not show any different than when I left them a few days ago.

Couple of things I am not following exactly:

1. I am curious about the three drains mentioned here as I can only find two, wondering where the other is.
2. The gascolater has a drain that is separate from the gascolater? I see the gascolater which is a bit removed from this drainage tube but perhaps it is there to let air escape as the gascolater drains?

thanks again everyone,

Cheers

RCT

 

[RCT44]

Would a failing fuel pump diaphragm do it? One way to test the diaphragm is to turn the electric pump on and look at the mechanical pump overflow.
2005? Could be the fuel drain. Depending on type, wise to replace these at 15 year intervals.

What is the mechanical pump overflow? How can I monitor that once I turn the fuel off and turn the pump on? Do I need to play with the
mixture during this process?

 

[Bartman]

If you found the gascolator, is there a small diameter aluminum tube coming off the bottom? All it does is extend the drain down a bit.

The mechanical fuel pump is on the back left corner of the engine I think. There should be a rubber hose or other drain line coming off of it. Same thing for the electric fuel pump. Both drains give the fuel somewhere to go that is less flammable if the pumps start to leak internally. Don't know how else to put it, maybe someone can elaborate on it.

If those two lines don't go to the two fuel pumps and/or the gascolator, then just grab a flashlight, maybe remove one or both cowl pieces, and follow them to wherever they go.

Pics would help too but I'm guessing the gascolator is dripping because it's either got a bit of debris right where the seal is or the seal is old and not doing its job. Goodyear said it, run a good bit of fuel out of the gascolator into a cup or something to try to clear any debris that might be in there.

 

[Bartman]

What is the mechanical pump overflow? How can I monitor that once I turn the fuel off and turn the pump on? Do I need to play with the
mixture during this process?

leave the mixture closed, turn on the electric fuel pump and then go see if there is any fuel coming from either of those drains. you're pressurizing the system to try to cause a leak. maybe have a fire extinguisher on hand when you do this.

if you're not 100% sure about what's happening, get an A&P involved.

 

[Big Ed]

leave the mixture closed, turn on the electric fuel pump and then go see if there is any fuel coming from either of those drains. you're pressurizing the system to try to cause a leak. maybe have a fire extinguisher on hand when you do this.

if you're not 100% sure about what's happening, get an A&P involved.

You'll need to turn on the fuel shutoff on (eg allow fuel to flow again) to do this. I don't know for sure, but running pumps dry is generally not a good idea since they often depend on flow for cooling.

I'll post some parts drawings.

 

[RCT44]

Thanks again everyone! I have an update from this morning. I was set to fly the plane from Texas to Florida for the holidays but canned the trip and I’m currently on American Airlines. :-(

When I opened the hangar and i found a larger pool than the last one. Drop was steady after a brief flight yesterday. I taxi’d it over to local AP at my field. We had cowlings off within 30 mins and found the issue to be the fuel pump. Guess he is trying to find the part but the usual suspects are out of this pump replacement. Guess he is going to do some leg work to try and get this fixed over next couple weeks while I am out. Photos below.

 

[Bartman]

Very interesting. Thanks for posting the photos and the follow up. Good luck with it!

 

[Big Ed]

Bummer to have an epic trip cancelled. Been there, done that. But you definitely needed to get this sorted out. Bad things can happen when pools of fuel are laying about.

By fuel pump, I assume you mean your electric boost pump, and not the engine driven pump? The boost pump is the one on the firewall, just above the gascolator. The engine driven pump is on the back of the engine, below the oil filter.

When you get it fixed, ask your A&P to show you how to put the cowl back on. Once you get comfortable doing that, you'll find yourself doing it all the time. You'll get a much greater comfort level with the maintenance status of your aircraft if you give the compartment a good inspection every few months, and you will find little problems before they develop into bigger problems.

Geez, that engine is CLEAN.

 

[Hiperbiper]

Tulsa Aircraft accessories can rebuild your pump in a week or so and probably around $3-4 hunnert deenero.
Just in case your A&P can't find a replacement.
Chris

 

[RCT44]

Tulsa Aircraft accessories can rebuild your pump in a week or so and probably around $3-4 hunnert deenero.
Just in case your A&P can't find a replacement.
Chris

Awesome thank you!

 

[RCT44]

Bummer to have an epic trip cancelled. Been there, done that. But you definitely needed to get this sorted out. Bad things can happen when pools of fuel are laying about.

By fuel pump, I assume you mean your electric boost pump, and not the engine driven pump? The boost pump is the one on the firewall, just above the gascolator. The engine driven pump is on the back of the engine, below the oil filter.

When you get it fixed, ask your A&P to show you how to put the cowl back on. Once you get comfortable doing that, you'll find yourself doing it all the time. You'll get a much greater comfort level with the maintenance status of your aircraft if you give the compartment a good inspection every few months, and you will find little problems before they develop into bigger problems.

Geez, that engine is CLEAN.

yes, that's exactly the one...i didn't know it was called the boost pump. Do you run this any other time than when you are priming the engine before initial start up? I only run it then but see it throughout the checklists sometimes as needing to be set to "on".

I watched them take the cowling off and I will be mimicking this in the future for my own uses. Does anyone here have a good instructional video or directions on how to change my own oil? I think my engine has been on the extreme conservative side as it relates to oil changes (every 20-25 hours) historically and I would like to keep that up.

I got very lucky with how previous owners kept this engine and plane in extremely good condition and it is my goal to continue that!

 

[Big Ed]

You have 2 fuel pumps. An engine driven pump which is your primary source of fuel pressure, and an electric pump which serves as a backup or secondary. Sometimes called a boost pump. I think the manual calls it the emergency fuel pump. You use it 3 times: to prime for cold start, on takeoff/landing, and if your engine quits. Usage for takeoff/landing is a precautionary measure in case the engine driven pump were to suddenly fail at low altitude. Some pilots feel that checklist item is unnecessary.

Best way to learn how to change oil is to do it once with your A&P. It is not difficult, but you will need a few tools, most notably safety wire pliers.

20-25 hours is excessive with a fuel filter, especially if you are flying it regularly. Filters are expensive. The factory spec of 50 hours should be plenty. If you want to do more, you could do the oil at 25 and the filter at 50.

Hardest part of putting the cowl on is getting the air induction tube in place. Make sure your guy shows you how. My trick is to remove the air filter bracket.

 

[RCT44]

You have 2 fuel pumps. An engine driven pump which is your primary source of fuel pressure, and an electric pump which serves as a backup or secondary. Sometimes called a boost pump. I think the manual calls it the emergency fuel pump. You use it 3 times: to prime for cold start, on takeoff/landing, and if your engine quits. Usage for takeoff/landing is a precautionary measure in case the engine driven pump were to suddenly fail at low altitude. Some pilots feel that checklist item is unnecessary.

Best way to learn how to change oil is to do it once with your A&P. It is not difficult, but you will need a few tools, most notably safety wire pliers.

20-25 hours is excessive with a fuel filter, especially if you are flying it regularly. Filters are expensive. The factory spec of 50 hours should be plenty. If you want to do more, you could do the oil at 25 and the filter at 50.

Hardest part of putting the cowl on is getting the air induction tube in place. Make sure your guy shows you how. My trick is to remove the air filter bracket.

This makes perfect sense, thank you BIG ED!

 

[RCT44]

Just heard from my AP - they found the pump to replace mine and will be changing oil plus a few other minor items they found and get it all done for me by Thursday next week.

Thanks again, everyone. Merry Christmas.