REFLECTOR: RS-10B1 problems

Tue Oct 2 19:37:54 CDT 2012

Brian,

I have thought a lot about what you wrote, and I wanted to ask, why didn't you choose to T the return line, and plum these two lines, 1ea into each tank? I would think that if you kept the two new lines the same length, that the return volume to each tank should be very close to the same, helping to stop a fuel imbalance. As far as heating your fuel, again this would give a far greater volume to dissipate the heat. The same goes with any vapor or bubbles returned to both tanks. I don't really understand why there would be any vapors returned to the tanks, can you explain what you were seeing. Our two fuel servo systems may be different, I don't know what your system is. I will do a test using my fuel pump to analyze what my return fuel looks like as soon as I get time.

My RS-10B1 fuel servo valve output line uses # 4 AN fittings, which then goes to the input of my T fitting, which is installed on the top of my distribution valve. The inside diameter of the T fitting, is .167 inches. My # 72 bleed (.025 inches), is 6.68 times smaller than the original line and fittings feeding the T'd fitting, which now has the output with the # 72 bleed installed. I have then install approximately 36 inches of #4 braided stainless steel Teflon line and #4 AN fittings to get me through the firewall. I was going to plum it into my sump tank, but now I may T my line coming through the fire wall and plum a single 1/4" line to each fuel cell, since there may be, like you are saying a vapor or bubbling of the fuel.

If my gage was correct, I was seeing 55PSI at this same T fitting before I installed the # 72 bleed. I haven't done the calculations as to what volume of fuel will be returning to the tank. My operators manual for my engine says that the fuel consumption for its rated power at take off, is 24.6 gal per hour. 75% should get me in the 16.5 gal per hour range.

Andy Ellzey

>________________________________
> From: Brian Michalk <michalk at awpi.com>
>To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org> 
>Sent: Monday, October 1, 2012 9:57 PM
>Subject: Re: REFLECTOR: RS-10B1 problems
>   
>How much fuel returns to the sump?  Also, how much fuel is too much to attempt to return to the sump?  At some point the vapor amount will be too much as well as heating for the sump to handle.  I ask, because I was using my sump for fuel return.  I did max fuel return tests and decided to add an additional one gallon liquid/vapor separator tank above the sump.    It's plumbed with fuel exit on the left that tees into a sump inlet.  The opposite side is (foamy) return from the fuel pressure regulator.  It is vented to a fuel tank vent.  It fits in the main spar, so it's at the same height as the tanks.  With testing max bypass flow, it accumulates vapor till about half vapor, and does not fill up completely with vapor.  My hope is that with the electric pump off, it will be able to separate vapor indefinitely.  The reason why I did this, is because one of the failure scenarios for my incident was fuel starvation due to vapor lock.  I do not
 think this was the cause, but it's hopefully more safety.  Oh, and it gives me one more gallon of useful fuel.  On 10/01/2012 09:21 PM, Andrew Ellzey wrote:  
>John,  Just wanted to thank you for getting me the contact information for Don Rrivera at Airflow Performance, Don told me that I needed to install a .025 inch, #72 bleed in the T fitting on the top side of my distributor valve. Then install a new return line to my sump tank. I made the modification on Saturday, and my engine ran like a champ.  Thanks again for your help,  Andy Ellzey  By the way, I replaced all of the aluminum fittings with steel, for everyone that e-mailed me about their concerns.      
>> 
>>
>>________________________________
>> From:  John Tvedte mailto:johnt at comp-sol.com; 
>>To:  ajlz72756 at yahoo.com mailto:ajlz72756 at yahoo.com; 
>>Subject:  RS-10B1 problems 
>>Sent:  Thu, Sep 27, 2012 3:05:12 PM 
>>  
>>Andy, 
>>  
>>I would contact Don @ Airflow Performance – see website, and contact info below.  Don worked at Bendix under Elmer Haasse, the inventor of the RS and RSA Fuel injection systems. 
>>  
>>I would plan on replacing those aluminum fittings with steel.  Just too many fuel problems / fires caused by fatigue.  They are likely AN4, which is really small – steel fittings won’t add much weight.  I’m talking specifically about the ones on the fuel spider that you have hoses connected. 
>>  
>>Don Rivera  don at airflowperformance.com 
>>(864)576-4512 
>>  
>>http://www.airflowperformance.com/html/site_html.html 
>>  
>>Be safe, 
>>John 
>>           
>> 
>>
>>_______________________________________________
To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector Visit the gallery! www.tvbf.org/gallery user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail Check old archives: http://www.tvbf.org/archives/velocity/maillist.html    _______________________________________________To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflectorVisit the gallery!  www.tvbf.org/galleryuser:pw = tvbf:jamaicangooseCheck new archives: www.tvbf.org/pipermailCheck old archives: http://www.tvbf.org/archives/velocity/maillist.html    
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20121002/3a10aa27/attachment-0001.html>