Power Loss on Climb Out

[FlyingMonkey]

2 minutes ago, procharger said:

I had an issue one time on a really hot day. Shut down for about 5 minutes took off and lost a 

some RPM on climb pulled back throttle and it caught back up within a few seconds no issues

after that. Thought I was going to put it down in the water. Once in only 7 years of flying CT.

That sounds like what I experienced.  I wonder if I just got some bad mogas or an old winter blend.  It came from the station I always use, but it could have been sitting in the tank a while.

 

[Anticept]

1 hour ago, FlyingMonkey said:

The one at ACS is marked 477060E so it should be correct.

I guess I'll do more troubleshooting using avgas and determine if it's actually a vapor issue then go from there.  Being a test pilot is fun! 

Honestly adding a pump, wiring, and valves to the fuel system is more re-engineering than I'd like, but it is what it is.  It would be nice to have fuel pressure and flow instrumentation in my airplane for issues like this.

Don't go too crazy at first. Just get it "good enough" for testing purposes. The only thing I foresee being a pain in the butt for a test install is the manually operated bypass valve.

Also you do have to jump the pump frame to ground, it's a single wire pump.

It's only 1.6 amps, 26AWG is the minimum size, but I'd just use what's on hand for testing unless it's speaker wire.

You could probably also take it a step further as well, and just do ground testing with the tail tied down, nose in climb attitude, and hook up a fitting somewhere to push air into the system to see how the fuel system firewall forward behaves with and without the pump on. Again, this is on my list of things to do but insurance renewal isn't until the 10th next month and my current provider won't insure E-LSA.

[FlyingMonkey]

1 minute ago, Anticept said:

It's only 1.6 amps, so use

Cliffhangar!  

[Anticept]

It's been edited.

[FlyingMonkey]

4 minutes ago, Anticept said:

Again, this is on my list of things to do but insurance renewal isn't until the 10th next month and my current provider won't insure E-LSA.

That's interesting.  FWIW, I have been with AIG (using Aviation Insurance Resources as a broker) since the beginning, and when I converted to E-LSA they didn't even change my premium.

[Tom Baker]

The Sport Cruiser I have in the shop has a bypass and check valve for the pump. The older Sport Cruiser I work on does not have a bypass.

[FlyingMonkey]

5 minutes ago, Tom Baker said:

The Sport Cruiser I have in the shop has a bypass and check valve for the pump. The older Sport Cruiser I work on does not have a bypass.

Do you have a picture of what that looks like?

[FlyingMonkey]

BTW guys, I really appreciate all the help trying to sort this out.

[Roger Lee]

18 minutes ago, FlyingMonkey said:

BTW guys, I really appreciate all the help trying to sort this out.

Rotax has them in their diagrams. They prefer to have them.

I'm not saying don't use Avgas in certain circumstances, I'm just saying I've never had a problem and I live in hot country. Plus all the other Rotax owners in the world. Yes some have had issues, but the huge majority haven't. Maybe aircraft cowl design and installation plays a part and the owner not knowing what to do or how to handle it probably leads to an issue. Just speculating other factors may be at play and it's not just the fuel.

I have had some vaporization after flying into a place and coming out after eating and have the fuel pressure drop to 1.8 psi, but letting it idle at some higher rpms and taxi to the runway it always disappears. Running it at higher rpms before you depart allows cooler fuel to circulate through the engine compartment fuel lines. I've never had to run Avgas in 2K hours in a CT because of vaporization and that's at all outside temps and altitudes to 11.5K.

 

 

[Anticept]

Please remember that different states have different fuel standards. We don't have a one standard fits all in the US, and some states standards are barely standards at all.

[FlyingMonkey]

17 minutes ago, Roger Lee said:

Rotax has them in their diagrams. They prefer to have them.

Not sure what you're referring to...They prefer to have what?

Your experience is similar to mine...ten years flying a CT in the hot & humid Southeast and never had a single hiccup with ethanol mogas...so I'm confused what changed.  Maybe it really is as simple as a failing fuel pump (I hope)...?

[FlyingMonkey]

2 minutes ago, Anticept said:

Please remember that different states have different fuel standards. We don't have a one standard fits all in the US, and some states standards are barely standards at all.

According to the map posted earlier, my area has much less volatile blends than some other areas.  That doesn't mean "no problem", but it's a data point. 

[Roger Lee]

By-pass and check valve

[Roger Lee]

Andy,

Is that new fuel hose you put on 1/4" ID or 5/16" ID?

[FlyingMonkey]

13 minutes ago, Roger Lee said:

Andy,

Is that new fuel hose you put on 1/4" ID or 5/16" ID?

I'll have to ask the manufacturer, he has standard sizes he uses for Rotax.  I do know the return to the gascolator is a smaller diameter than the feed hoses from the firewall and to the fuel pump.

So Rotax prefers a bypass and a check valve to be installed...do they also prefer an aux pump?  Any idea why FD airplanes have none of this?

[Roger Lee]

"do they also prefer an aux pump?"

Yes, but some high wing Mfg's don't install them. Most low wings have them.

"the return to the gascolator is a smaller diameter than the feed hoses "

Then they probably used 1/4" for the returns and 5/16" for the feed.

[FlyingMonkey]

1 hour ago, Roger Lee said:

Then they probably used 1/4" for the returns and 5/16" for the feed.

The smaller hoses are AN-4 (7/32") and the larger ones are AN-6 (11/32").  So the larger hoses are 1/32" larger than 5/16", and the smaller return & carb hoses are 1/32" smaller than 1/4".  

[Roger Lee]

2 hours ago, FlyingMonkey said:

The smaller hoses are AN-4 (7/32") and the larger ones are AN-6 (11/32").  So the larger hoses are 1/32" larger than 5/16", and the smaller return & carb hoses are 1/32" smaller than 1/4".  

That shouldn't be an issue then. Replace that 8 year old fuel pump.

[Warmi]

4 hours ago, Roger Lee said:

"do they also prefer an aux pump?"

Yes, but some high wing Mfg's don't install them. Most low wings have them.

"the return to the gascolator is a smaller diameter than the feed hoses "

Then they probably used 1/4" for the returns and 5/16" for the feed.

Is there a significant downside to installing/using a backup electric pump? 
Every SP I have flown ( admittedly not that many , maybe 5 or 6 ) had one installed and furthermore required to have it running during takeoffs ( Remos POH stated to have it running all the time )

[FlyingMonkey]

1 hour ago, Warmi said:

Is there a significant downside to installing/using a backup electric pump? 
Every SP I have flown ( admittedly not that many , maybe 5 or 6 ) had one installed and furthermore required to have it running during takeoffs ( Remos POH stated to have it running all the time )

Only downsides are added complexity and more components to fail...I tend to like things as simple as possible.  In my case it also adds significant design and re-engineering work on an airplane where I just replaced the entire fuel system at a not-insignificant cost.

That said, if that's were I need to go to resolve this, then, that's where I'll go.  But you can be sure I'll try everything else first.

[Madhatter]

AN 6 is 3/8 hose ID, AN5 is 5/16, and AN4 is 1/4.

 

[FlyingMonkey]

After some research and discussion with Steve at Aviation Specialty, we identified that the upper fuel valve to firewall hose has a vertical rise in it that could possibly act as a vapor trap. Steve offered to make a new shorter hose at no charge (great service!).  I'll probably need to put a 90° fitting on the upper fuel valve connection in order to get the geometry correct.  So that is in process.  The actions taken to try to solve my issue are:

1. Replace 8 year old fuel pump. (completed)

2. Trim back the fuel pump vent line to approximately 1.5-2" above the bottom of the firewall.  It was about even with the bottom of the firewall and I want to make sure it's not exposed to low pressure slipstream air that could create a vacuum condition, especially in climb. (completed)

3. Use a shorter hose with angle fitting behind the panel to eliminate potential vapor trap. (in progress)

After the above is complete I'll test fly it again, if it still has issues I'll try using some 100LL to reduce the fuel volatility.  If that fails I'll start looking at check valves, pumps, and all that stuff.

[Madhatter]

37 minutes ago, FlyingMonkey said:

After some research and discussion with Steve at Aviation Specialty, we identified that the upper fuel valve to firewall hose has a vertical rise in it that could possibly act as a vapor trap. Steve offered to make a new shorter hose at no charge (great service!).  I'll probably need to put a 90° fitting on the upper fuel valve connection in order to get the geometry correct.  So that is in process.  The actions taken to try to solve my issue are:

1. Replace 8 year old fuel pump. (completed)

2. Trim back the fuel pump vent line to approximately 1.5-2" above the bottom of the firewall.  It was about even with the bottom of the firewall and I want to make sure it's not exposed to low pressure slipstream air that could create a vacuum condition, especially in climb. (completed)

3. Use a shorter hose with angle fitting behind the panel to eliminate potential vapor trap. (in progress)

After the above is complete I'll test fly it again, if it still has issues I'll try using some 100LL to reduce the fuel volatility.  If that fails I'll start looking at check valves, pumps, and all that stuff.

I had to use a 120 degree fitting for the fuel valve connection to prevent a water trap. The total length of the hose assembly is very critical in order to fit properly. That's why I used AN hose push fittings and Gates injector hose to be able to make many length adjustments to get it right the same goes for the other end of the fuel valve. I used Gates injection hose and AN hose push fittings inside the cabin and teflon in the engine compartment. 

[Roger Lee]

If it's been working all these years then it isn't the system. It didn't happen until after your maint. if I remember right so you need to find out what changed. Our fuel system in the CT isn't complicated so it should be easy to diagnose. Flush all hoses and any fittings, replace the old pump.

Something changed and that's what you need to find and not try and just throw an electric pump in the system.

[FlyingMonkey]

1 hour ago, Roger Lee said:

If it's been working all these years then it isn't the system. It didn't happen until after your maint. if I remember right so you need to find out what changed. Our fuel system in the CT isn't complicated so it should be easy to diagnose. Flush all hoses and any fittings, replace the old pump.

Something changed and that's what you need to find and not try and just throw an electric pump in the system.

I I tend to agree.  However, the previous hose laid mostly horizontally, while the new one sits vertically:

The additional stiffness of the braided hose just can't really lay down, so the hose needs to be shorter, and the bend should be managed with an angle fitting at the valve.  The orange silicone tape is to provide some abrasion resistance in case the line contacts the radio tray.