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Interesting ''First Flight',

R

RV-4

Well Known Member
Hello Gents

A friend today did his first flight on his RV-9 and shortly after take-off ( 300 feet) the engine started running very rough to the point that he tought about landing it in a nearby field ..

He is an experience airline pilot so he didn't panic, kept on flying the aircraft and troubleshoot as best as he could at the moment.

He started by leaning the mixture a little ( fuel press went to 32 PSI on a carburated engine (should be around 3.5 to 5 psi ) which improved the engine condition. He did a tight circuit and landed the aircraft without any damages..

On the ground they did check the timing and everything was fine on this point.

They did multiples run-ups and found out that it was impossible to lean the engine at around a 1000 RPM and full power...

A new carburator and mechanical fuel pump is on the way from the overhaul shop..

I also suggested to him to check if he had the proper ''Boost Pump'' for a carburated engine ( could possibly have one for an injected engine )

So anyone with ideas on what may have been the problem??

Thanks you for your feddbacks

Bruno
[email protected]

P.S: Replied via e-mail or PM are fine.
 
Fuel Pump

He is throwing money at the problem instead of taking a step by step approach. First step is to find out if the engine runs differently on the ground with the electric fuel pump off, and verify the fuel pressure in this configuration. Then turn on the electric pump and check again.
IIRC 32 # is higher than the pressure should be with the boost pump for fuel injection.
The low pressure engine driven pump is self regulating but the carb cannot handle high pressure pumps, I.E. injector fuel pumps.
If either of the pumps is the wrong pressure it will flood the carb.
The fact that he got it started and in the air makes me suspect the boost pump, especially if he turned the boost pump on just before starting takeoff.
 
First Flight

Hi Jim

Thanks for the reply.

He's getting the new parts from the overhaul shop on a cost free basis if they are required.

They did check the engine on the ground and with the mechanical fuel pump, the fuel press was 35 PSI and with the boost pump 5 PSI.They taught it might have been an indication problem but if that were the case, he will still be able to lean.

The overhaul shop mentionned that at this pressure, the fuel should have poured out of the carb but there were no trace of fuel around the carb. They are leaning( pun intended ) on a stocked float.

He also did 3 WOT ( with the tail tight down ) and was unable to lean the mixture at all, the engine will quit right away.

He did all the required test prior to first flight ( Tail low, Fuel flow check etc..)

He has a Dynon D-10 installed but doesn't know how to access the info it may have..

Thanks again for the feedback

Bruno
 
RV-4 said:
........ They did check the engine on the ground and with the mechanical fuel pump, the fuel press was 35 PSI and with the boost pump 5 PSI.They taught it might have been an indication problem but if that were the case, he will still be able to lean.........

............He also did 3 WOT ( with the tail tight down ) and was unable to lean the mixture at all, the engine will quit right away.

Bruno
Click to expand...

Two comments: If the mechanical pump pressure is REALLY 35 psi, you have the wrong pump for a carburetor. Should be 4 to 5 psi.

If you can't lean even a little bit without the engine quitting, then something may be wrong with your carburetor. Maybe too small a jet. But, FIRST, fix the fuel pressure. Then run it again, and see if you still have a problem. If you have to, get a mechanical fuel pressure gage and temporarily install it to verify the actual pressure.

There are real engine guru's on this forum that can help, and they would likely want to know the part number on your carburetor, and on your mechanical fuel pump.

Standby........... a genuine expert will be along shortly!! :eek:
 
RV-4 said:
Hi Jim

They did check the engine on the ground and with the mechanical fuel pump, the fuel press was 35 PSI and with the boost pump 5 PSI.They taught it might have been an indication problem but if that were the case, he will still be able to lean.

The overhaul shop mentionned that at this pressure, the fuel should have poured out of the carb but there were no trace of fuel around the carb. They are leaning( pun intended ) on a stocked float.
Click to expand...

Absolutely...there is no way a carbed engine will run if subjected to 35 psi fuel pressure.

My initial engine start (O-320, carb) was with a high pressure, fuel injected pump that was shipped by mistake with the engine. The engine would start and run about three seconds before it quit with fuel pouring out the carb.

The 35 psi indication is bogus if a carbed engine will run for more than a few seconds. That high pressure will overpower even a stuck float valve.

I'm sure it will end up being a simple fix, but I agree a systematic approach is the way to find the problem. Glad the flight ended without incident!
 
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PCHunt said:
Two comments: If the mechanical pump pressure is REALLY 35 psi, you have the wrong pump for a carburetor. Should be 4 to 5 psi.

--- snip ---

Standby........... a genuine expert will be along shortly!! :eek:
Click to expand...

Pete is correct on checking the fuel pump. I once helped a friend check his NEW fuel pump because the engine would not run correctly. The part number on the box was correct but the part number on the pump did not match the box. The right box had the wrong pump inside.

Check EVERYTHING!
 
First Flight

Gents

Thank you for the info.

The possibility that the wrong pump/carburetor might be installed will be taken care off as soon as the new parts shown up on Saturday..

As Sam mentioned, there is no way this engine should run with this pressure so a faulty pressure sensor/gauge could be a cause.

Using a direct reading gauge to check the fuel pressure is in the cards..

So what can be the problem with leaning the mixture at WOT?? As soon as he leaned it, the engine quit??

How come there is no fuel leaking out of the carb?? where is all that fuel going to?? I think that all that fuel might not be there after all:confused:

Keep the ideas coming,there are much appreciated

Bruno
 
If he has his D10 mis-configured, the pressure reading could be off. Check the "sensor type" is correct for the sensor *installed* not what he thinks he has installed. The pressure range of the sensor is printed on the side.

Second, if he has fuel flow, use that as a sense if too much fuel is flowing, independent of pressure. Idle should be less than 2 GPH.
 
Agree

Agree with dynon

I was showing 35 psi on my AFS3500 O-360, the default is for an injected engine. Once I selected the right carb in the settings all was good.
 
I've had a bad carb (new) before - it does happen.

As previous have said, double check the fuel pump & carb to be sure correct for the engine.

Also keep in mind that the MS carbs have a distinct idle circuit - adjusting the mixture with the engine running at low speed (should probably be north of 1500) is not likely to be productive.

I might have missed which prop you have, but if FP and it turns normal static RPM on the ground, then I'd also check to be sure that when the aircraft pitches up (as in climb), that you don't encounter a situation where air is drawn into the fuel line through the gascolator drain (or other leaking fitting - a situation that, while not common, can happen in a Piper Cherokee and produces a result much like described by the OP).

Dan
 
First Flight

Good Morning Gents

I send the link to this page to my friend and he is monitoring it for suggestions and ideas.

He might post whenever he has a minute.He is at the hangar right now working on possible solution.

I'll try to get the engine Type ( I know it is an 0-320 but don't have the dash # ) and the carburetor and fuel pump models so we can troubleshoot the possibilities of a wrong type being installed.

I will keep you posted.

Thanks

Bruno
 
First Flight

Update

My friend kept on troubleshooting the possibles causes as to what may have cause this behavior and he's starting to corner the culprits..

High Fuel Press: Faulty reading due to a programming error which has been rectified ..

As to the engine coughing on take -off, this behavior as he stated , started at about 90-100 MPH and the possibility right now is that there may have been air entering the fuel system thru the gascolator as suggested by someone here VAF (Thank you very much BTW ) and a local mechanic at his airport.

At the request on the MD-RA ( Cdn local inspector, just like a DAR in the US )he had to install an evacuation tube at the gascolator and this tube was bend forward slightly and may have allowed air to enter the system while under pressure.

This tube has been removed for now.

He will also install a new Carburator on Monday and see if he can lean the mixture with the new one.He says that he is confident it will work.

He told me that he will pipe in later on to share his findings and results with all of us here on VAF.

Once again thank you all for your feedback's and advises, they were very appreciated.

Bruno
[email protected]
 
Don't EVER let anyone tell you a mechanical pump can't fail to high pressure! Our 9A had an O-320 with 885 hours that had been stored for less than a year. It gave a high fuel pressure indication. We did all the right things--checked the gauge, tried with and without the electric boost pump, and had the carb float checked and then rebuilt (it was overflowing.) Five (count 'em) A&Ps told me a pump couldn't fail to the high side, but a new pump cured everything. No, I don't know exactly how high the pressure was, because we would have had to plug the pump outlet as the carb float valve was sort of a "pop-off" valve at that point. I suspect it was 12-20 psi. We knew it was the mechanical pump when we bypassed it with a solid line, and the engine ran great on the electric pump. Theory is that gunk had gotten onto one side of the diaphram when the engine was stored nose-up with old oil. Seven years later, the engine still preforms great, compressions never below 76/80, and never a fuel related problem.

Bob
 
Hi everyone,
I am the one who experienced this less than perfect first flight. First I would like to thank Bruno and all who contributed their help in finding solutions to my problems.
I believe the high fuel pressure is taken care of and I will be contacting Dynon to ascertain the proper sensor setting to be used. At least now, the reading is zero with the engine off. There are seven possible settings on the EMS-D10, I have eliminated the first four and 3 are showing 0 psi now, so will find out which one to use talking to Dynon.
As Bruno has mentioned in a previous post, I strongly believe that the culprit for the rough engine was due to air entering the fuel system through a misaligned gazcolator drain tube. This has been corrected as well.
I will install a different carb to-morrow and hopefully the inability to lean will be taken care of. As it stands now, impossible to adjust the idle mixture (no visible increase in rpm when pulling mixture at idle-cut off.) and when leaning at WOT, the engine would just quit without any sign of leaning.
Thanks again and stay tuned.
Michel
 
Michel,
A correctly tuned fuel system will show almost no increase in RPM at sea level. The increase is because you lean through peak power, but the carb should already be at peak power at idle on the ground at sea level. It may also be already lean if it isn't adjusted right so all you will see is a decrease. So that may be a red herring.

Do you have fuel flow with your D10?
 
dynonsupport said:
Michel,
A correctly tuned fuel system will show almost no increase in RPM at sea level. The increase is because you lean through peak power, but the carb should already be at peak power at idle on the ground at sea level. It may also be already lean if it isn't adjusted right so all you will see is a decrease. So that may be a red herring.

Do you have fuel flow with your D10?
Click to expand...

I believe most engines are set up to be rich of best power at full rich, for detonation margins. Back in my O-470 days the manual was very clear; going to idle cut off should produce a momentary rpm rise.
 
We have a Dynon skyview and ours read 35 PSI when we first ran it and it turned out to be the wrong settings in the skyview set up menu. I don't think the rough running and the 35 PSI are related.
 
Bob,
Totally depends on how your fuel system works. I agree that when producing flight power, they are rich. However, many have a totally independent idle adjustment.

Also, since this is not yet a tuned system, it could be mis-adjusted. I was only pointing out that the lack of the RPM increasing when it was leaned was not an indication that it wasn't leaning at all. Just that you could be starting at peak or lean, and thus an increase is not expected.

You should be able to watch EGT's as well and get a sense if you are leaning successfully or not. You can generally do a peak check pretty effectively at about 2,000 RPM, just above normal MAG check power levels.

--Ian Jordan
Dynon Avionics
 
Mousse said:
Hi everyone,
I am the one who experienced this less than perfect first flight. First I would like to thank Bruno and all who contributed their help in finding solutions to my problems.
I believe the high fuel pressure is taken care of and I will be contacting Dynon to ascertain the proper sensor setting to be used. At least now, the reading is zero with the engine off. There are seven possible settings on the EMS-D10, I have eliminated the first four and 3 are showing 0 psi now, so will find out which one to use talking to Dynon.
As Bruno has mentioned in a previous post, I strongly believe that the culprit for the rough engine was due to air entering the fuel system through a misaligned gazcolator drain tube. This has been corrected as well.
I will install a different carb to-morrow and hopefully the inability to lean will be taken care of. As it stands now, impossible to adjust the idle mixture (no visible increase in rpm when pulling mixture at idle-cut off.) and when leaning at WOT, the engine would just quit without any sign of leaning.
Thanks again and stay tuned.
Michel
Click to expand...

Let's see, you got it built, signed off, had a first flight, and landed safely with a squawk list of issues. All safe and no damage, sounds like a perfect flight to me, albeit it with some tension.

Congratulations on your accomplishment.
 
Hi,
Thanks BillL for your good words.
I got another carburator installed today and it has performed as it should. Clear signs of leaning at shutdown and at WOT. My overhaul shop has supplied me this freshly overhaul carb that I will keep and return the other one at no charge. Good customer service from Aéro-Atelier.
The only other snag left is the carb temp. gauge not working. Talk to Dynon today and it would appear the sensor has gone u/s. Not a big deal.
Next flight possibly to-morrow, weather permitting.

Regards
Michel
 
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First Flight

Bonsoir Michel

Glad to see that things are starting to fall back in place...

Too bad I have a medical tomorrow otherwise I would have come to CSE4 to have a look.

Bonne chance on the second try..

Bruno
[email protected]
 
This is an update to my first flight. I managed 1.5 hr of smooth flying yesterday. Did some stalls and some slow flying. The airplane handles very well. I am very happy with the results of my work of the last 18 months. I did get the RV grin.
Thanks to all who have contributed to this post. You are an incredible source of knowledge.
Keep the blue side up.
Michel

PS: Bruno, give me a call when at CSE4 next.
 
Michel,

Congratulations! I did not find this thread until now. Glad you got all issues resolved. Martin just came back here for a few days and flew with me this morning. I will tell him your status.


Ted
 
Bravo Michel!

I am happy to know that you resolved your problem.
I hope the short flight we had last month helped you on your first flights.

Welcome to the RV grin club!

I"ll see you at the airport.
 
TC1234c: Thanks Ted again for introducing me to the RV-9 and please, give my regards to Martin. And you are both welcome to visit anytime.
PS: I will send you some pictures if you pm me an email address.

DLussier: Salut Denis. Yes I had a good practice with you and it gave me confidence that I could do the first flight. My ac is as docile as yours in stall. Thanks again for the practice. See you at the airport.

Michel
 
First Flight

Salut Michel

I'm really happy to know that it all turned out ok on your ''second'' flight..

Can't wait to see it live..

Will let you know next time I stop in Lachute ( probably next saturday if the Wx is good)..

A+

Bruno

P.S: Salut Denis..
 
The aircraft was showing good flight behaviour and wanted to confirm the stall speed. Better to do it in a controlled environnement than on approach.

Michel
 
too soon

Mousse said:
The aircraft was showing good flight behaviour and wanted to confirm the stall speed. Better to do it in a controlled environnement than on approach.
Michel
Click to expand...
It is better not to do it until its time!


I'll stick with flight two being way too soon to be testing stalls :eek:
See below:

AC 90-89A - Amateur-Built Aircraft and Ultralight Flight Testing Handbook
Document Information

http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 90-89A.pdf

"SECTION 1. THE SECOND FLIGHT
1. OBJECTIVE.
To re-affirm the first flight findings.
...
c. The second flight, again lasting approxi-
mately an hour, should be a carbon copy of the first
one, with the exception that all first flight discrep-
ancies are corrected. If problems are not corrected,
all further flight testing should be canceled until solu-
tions are found.
"

"SECTION 2. THE THIRD FLIGHT

b. Resist the temptation to explore the more
exciting dimensions of flight. Stick to the FLIGHT
TEST PLAN and perform a conscientious evaluation
of the engine. After landing, review the data with
the crew members. Make adjustments as needed, per-
form another post-flight inspection of the aircraft,
and record oil and fuel consumption.
c. After three hours of flight testing, the pilot
should be able to make the initial determination that
the aircraft is stable and engine is reliable in cruise
configuration."

"2. GENERAL. These next seven 1-hour test seg-
ments should confirm the results of the first 3 hours
and explore the following areas:
a. Gear retraction (if applicable)
b. Climbs and descents to preselected altitudes.
(monitor engine performance)
c. Airspeed indicator in-flight accuracy check"


"HOURS 11 THROUGH 20
1. OBJECTIVE. To focus the next 10 hours of
flight testing on the following: stall speed, best rate
of climb speed, best angle of climb speed, and slow
flight. It is recommended that stall speed tests be
conducted with the aircraft’s fuel tanks full. (CG). "
 
Last edited:
Dave and Trina, you are right, It is better not to do it until it is time. And it is up to you to determine when it is time. Naturally it depends on your personal flying experience, your confidence in your equipment and whether your are flying a new design or a proven model like a RV-9. The FAA document adresses all basic amateur built aircraft. An RV-9 built as per Van's plans and equipped with conventional aviation engine and equipment is more of a known value, safety wise than your basic amateur built aircraft. And it is your prerogative to follow this FAA document to the letter if you so wish.

Fly safe.

Michel
 
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