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  #1  
Old 06-08-2012, 12:02 PM
DocThrock DocThrock is offline
 
Join Date: Mar 2007
Location: Indiana
Posts: 67
Default RV-7A engine near failure?

My buddy has a 7A with 180, cs, AFP pump, filter and injection. He took off relatively cold and the engine went to rough idle shortly on climb out and he made a safe landing. On touch down, then engine caught up and ran perfectly.

Test flight. No problems up to 8K altitude (from 580 Ft). This time, on pitch over, the engine did the same thing. Mags, fuel selector, boost pump, no effect. Negative Gs, positive Gs, hard banking, no effect. No frank indications on any gauges. Had to land again at rough idle. Got on the ground, tapped the brakes, engine caught back on and ran fine.

His A&P is baffled, and so am I. Any ideas?

Thanks!

CONCLUSION: Turned out to be contamination beyond the filter screen inside the Airflow Performance fuel controller. Some fibers had evidently slipped through the pores in the filter and clogged the inlet. When you pulled the filter out, nothing was in it. Up inside where it seated, a glob of clog blocked the fuel flow. The controller had to be completely disassembled (by Don @ AP) and returned to service. Very weird. No signs of any debris ANYWHERE in the entire fuel system. Hopefully pictures are forthcoming.

Last edited by DocThrock : 07-04-2012 at 11:13 AM. Reason: Engine starvation problem solved.
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  #2  
Old 06-08-2012, 12:19 PM
attson attson is offline
 
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Location: CA
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How about checking the engine air intake to make sure there is plenty of air for proper fuel burned
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  #3  
Old 06-08-2012, 12:26 PM
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Ron Lee Ron Lee is offline
 
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New plane?

Has anything been worked on since it last operated normally?
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  #4  
Old 06-08-2012, 12:26 PM
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Don Jones Don Jones is offline
 
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Default Hours?

How many hours on the engine?
Sounds a lot like the classic Lycoming sticky valve guide to me.
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  #5  
Old 06-09-2012, 09:45 PM
yakdriver yakdriver is offline
 
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Default

Does he have the purge valve. Make sure all the fittings from the purge valve back are tight and there are no cracks in any of the flare fittings that would allow air in the system. I had the same thing happen on mine after I had the baffle off and I had only finger tightened the purge valve fitting. Don
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  #6  
Old 06-10-2012, 12:15 AM
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Mike S Mike S is offline
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Default

Quote:
Originally Posted by DocThrock View Post
On touch down, then engine caught up and ran perfectly.


Got on the ground, tapped the brakes, engine caught back on and ran fine.

His A&P is baffled, and so am I. Any ideas?

Thanks!
There is a story here, ----- what is the common feature that landing will effect.

I would look closely at the fuel system.

Is there anything in the fuel tank floating around that could block the pickup???

Is there a flop tube than could be in the wrong position??

I have seen the same symptoms in a R/V aircraft that had the fuel pickup in the wrong location.
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  #7  
Old 06-10-2012, 07:17 AM
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Walt Walt is online now
 
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Quote:
Originally Posted by Don Jones View Post
How many hours on the engine?
Sounds a lot like the classic Lycoming sticky valve guide to me.
I would have to agree with Don, sounds like typical Lycoming "morning sickness".
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  #8  
Old 06-10-2012, 07:40 AM
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N395V N395V is offline
 
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Location: Mendon South Carolina
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Default

Quote:
AFP pump, filter and injection.
Just as the fuel line enters the AFP fuel controller there is a very small very fine filter. If it is starting to get clogged it will cause those exact symptoms.

It should be pulled and cleaned at every oil change.
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  #9  
Old 06-10-2012, 08:01 AM
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Walt Walt is online now
 
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Quote:
Originally Posted by N395V View Post
Just as the fuel line enters the AFP fuel controller there is a very small very fine filter. If it is starting to get clogged it will cause those exact symptoms.

It should be pulled and cleaned at every oil change.
This why I don't like to do blind "internet troubleshooting".

Doc said in his first post that he and his A&P are baffled, this would lead me to "assume" that they have done some preliminary troubleshooting which "to me", would normally include checking pressures, making sure there are no obstructions, cleaning/checking filters, checking fitting security etc etc..
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EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
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  #10  
Old 06-10-2012, 08:01 AM
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AltonD AltonD is offline
 
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Default

Don't forget the issue with the flop tube coming off inside the tank. I didn't see that he switched tanks.
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