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The Eagle (EMS) Flys

DaneP

Member
After a six month hiatus, to change over from an Aerosance FADEC to a Precision Airmotive EMS, my aircraft is once again flying. The Aerosance FADEC (now a Continental Motors product) was becoming a liability. Periodically it would skip a beat, for no apparent reason, or give strange readings, that could not be explained. After years of frustration I decided it was time to make a change.

Strangely enough going back to the age of Magnetos and analog fuel injection did not interest me. I had considered the EFII system and was planning to go that way until I met Dennis Wyman of G&N Aircraft (www.gnaircraft.com) at Oshkosh last summer.

Dennis had an engine mockup with the Precision Airmotive, Eagle EMS System installed. Changing over to the the Eagle system would not require any new plumbing, there is no need for a "return to tank" system, and the fuel injectors would install right where the old ones went; no funky fuel rails spraying fuel into the side of the intake tubes. Unlike the old FADEC, The Eagle system is programable by You (meaning Me) the owner. No sending boxes back and forth for the EPROMS to be reprogramed. I can do it with my MacBook Laptop computer using a terminal program. Getting the Aerosance FADEC System to work on my aircraft eventually required removing the engine to the test cell in Mobile Alabama for "Tuning". Looking back at all the trouble I had getting the Arosance FADEC to work, by comparison, getting the Precision Airmotive Eagle system to work was a breeze.

The Installation was not without a few surprises. The biggest one was when I went to install the fuel injectors and they wouldn't screw in all the way. Come to find out, they work perfectly on the 180 horse (Parallel Valve) cylinders, but in order for them to work on the 200 horse (Angle Valve) cylinders, there is a bit of milling required on the cylinders around the fuel injector port. This was easily accomplished with a back-facing tool of the proper diameter, but took a bit of figuring, if you know what I mean. When other issues came up, they were expertly solved by Peter Nielson, Product Support Manager, and Dennis Anttila, Engineer and all over really smart guy. They were both a pleasure to work with.

I installed an O2 sensor, figuring it would help out with the initial mixture adjustments, but so far it was probably a waste of time and effort. The engine ran so well initially, with no adjustments at all on my part, that my first flight went perfectly with no adjustments whatsoever.

In future test flights I will be able to fine tune the mixture as necessary, or change the percentage ratio of fuel to each cylinder by changing the values in the Configuration and Volumetric Efficiency Tables, if necessary. While flying, I can lean the mixture using the Leaning Knob (a potentiometer) that allows the mixture to be leaned during cruse flight for better fuel economy.

While I am far from being completely confident in the Eagle System (talk to me in another year), I am optimistic that Precision Airmotive has a real gem on it's hands. I would not be surprised if they become the new standard for electronic fuel injection and ignition.

Dane Patterson
RV-8, N460DP
 
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That's great to hear Dane. You certainly have been very methodical and diligent in it from what I have seen so it's no surprise that you had a flawless flight!
 
Glad you're happy with your Eagle EMS Dane. Sounds like a quantum leap over the Aerosance which I know others also had problems with.

Just so others know where the competitive EFI systems sit, SDS has a head mounted injector option for parallel valve engines, individual cylinder fuel trim in flight (no clunky laptop required), fuel flow output to your EFIS, LOP ignition advance, is fully user programmable (in flight if desired) and comes with good base mapping.
 
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I'm interested to know if Precision has any concerns or warnings about a returnless fuel system with regards to power interruption with a dry tank situation? We've studied this and came to the conclusion that any air that gets into the system when a tank runs dry must get reprocessed through the pump inlet and keeps going back to the injectors until it's processed through the engine- causing an extended severe lean out or engine stoppage.

I asked the question a couple months ago if anyone had experience with this in real life and didn't receive any replies.

We'd love to incorporate a returnless system as well but only if it's as safe as a return type system.
 
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Interesting, what fuel pressure are you running, is it dead heading the pump or recirculating after? HP FI electric pumps need flow (return) for cooling and less load on motor ya?
 
I don't know about the entrapped air in the fuel lines issue. My guess it that it would clear rather quickly as the air would flow through the fuel injectors at a high rate due to it's (very) low viscosity, clearing the fuel lines of anything but fuel. It doesn't seem to be a problem in the standard analog bendix fuel injection.

The standard engine mounted fuel pump is all that is required for the Eagle system, and the minimum fuel pressure is listed as 20 PSI. There are two Fuel pressure sensors (one for each ECU) and the fuel pressure is used as part of the formula for how long to keep the fuel injectors open.

The Eagle literature describes a "Smart Display" that can be mounted in the cockpit and used to interface the ECU instead of a laptop, but all I have seen is pictures of it. It wasn't offered to me as part of my package.

I know that there is a trick to posting images, on this forum, when I figure it out I'll post some pictures.
 
Can anyone report the time interval it takes for the engine to regain full power with a non-return Bendix system after running a tank dry and switching tanks?
 
Love my Eagle EMS

Dane

I have been flying an Eagle EMS for three years and just over 330 hours in my RV 9A. It has been perfect on every flight since day one. I am very happy with the system and my average fuel burn of 7gph at wide open throttle. I am running a Lycoming IO-320 D2EMS, built by areosport power.
 
Left ECU reboots on the Eagle

I've got about 50 hours on my Eagle ECU now and I have had a couple of scares in the last few that I'd like to share with you. I made my usual preflight radio calls and after take off and climb hard to downwind, I made a radio call and my left ECU faulted. I cycled power on the ECU and it returned to service. Once I determined I was running solid on both Left and Right, I made a test radio call and the same thing happened. Time to land and stop talking. Once on the ramp I could repeat this problem.
I contacted Precision and was advised to tie the ECU off switches to the positive terminal of the Eagle Battery when in the run position. This would eliminate the "antenna effect" which was causing an ECU reset (voltage spike??). This fix worked for a couple of hours of flight but on my last flight it returned with the same abrupt power loss.
I'm talking to Precision now about what to do next but thought other users of this system should be aware of a potential power loss that could suddenly hit you.
I'm using a PAR100EX radio which appears to transmit and receive normally.
Regards
Cam Andres
C-FTLL RV9A with Aerosport IO360
 
Eagle - EMS dry tank response time

Hi all,

I realize that this is an old thread, but as the question remains unanswered I will share my experience on this. I am running an IO-375 with the Eagle EMS and have about 140 hrs on it. It has been excellent. I have run one tank all the way dry and then switched over to a new tank. There is loss of power (as one would expect) as the tank is exhausted. Once switching over to the new tank there is no delay in the return of power. It is pretty much instantaneous and it is really a non-event.

-Dan
 
Another data point, from the alternative engine community: Some of those flying automotive style injection with 'deadend' fuel systems (where the regulator is on the cold side of the firewall) have dealt with the tank-dry concern by creating an intentional bleed in the regulator. The regulator's seal plunger is modified to always 'leak' a bit into the bypass port even if pressure is below setpoint. Idea is to let any air clear the pump quickly as it tries to re-prime. Extra fuel being bypassed is insignificant relative to the normal volume of bypassed fuel.

One personal friend did have an 'airlock' experience after a tank-dry (on the ground), and modifying his regulator cured his problem.
 
Contacted Precision about one of these systems earlier this year and was told they are no longer available.
Seems the designer/engineer/tech retired and the product could no longer be supported.
 
I can confirm that. I heard from them today. No longer in production. Very unfortunate, as it is an excellent system.
 
Regarding the concept of returning fuel to tanks, it is a fantastic way to avoid vapor lock.

I have the EAGLE EMS, and I return fuel to tanks, but that is only the starting point. I have one high-pressure, high-volume electric fuel pump connected to each tank, mounted on the wind spar, connected to wet tank fuel with about 18 inches of 3/8" fuel injection hose. The output from the two pumps meets at the center in a tee, and runs to a large Andair gascolator on the firewall that feeds the engine-driven fuel pump. A tap at the top of the gascolator is the return path for fuel, going thru a check valve that also acts as an orifice to hold the fuel pressure at the gascolator between 24 and 30 PSIG, depending on fuel flow to the engine. (The EAGLE automatically adjusts for varying fuel pressure at the injectors). The return fuel can be sent to either tank thru the Vans fuel selector. I have a magnetic switch circuit to light a big LED when the fuel is not being returned ot the pumped tank. Advantages: ability to transfer fuel to the opposite tank, ability to completely drain an almost-empty tank (the fuel-air mixture gets separated at the gascolator, and the air gets returned to a tank), and absolutely no chance of vapor lock. When the fuel is very hot (125F, all day out in the sun), the fuel pump is sucking a fuel and vapor mixture, resulting in the fuel pressure at the gascolator as low as 14 PSIG, but at 14 PSIG, only solid fuel reaches the engine-driven fuel pump, and it gets boosted to 20 PSIG going to the injectors. I have 1400 hours on this system (and on the EAGLE) since July, 2009, and has all been proven to be reliable. However, the two pressure senders on the injector fuel manifold that were supplied by Precision Airmotive have a temperature failure problem -- a very hot engine after landing (it happens) can cause them to fail after landing, and you find out on the next engine run-up, where the EAGLE thinks the fuel pressure is much higher than actual, and it uses its minimum fuel pressure setting, which only allows the engine to develop maybe 40% power. I am now using fuel pressure senders with a higher temperature rating, and have had no problems since. As for playing with the various tables and settings that the EAGLE allows, I have not done much, as the EAGLE system seemed to work just fine the way it came. However, I have a wide band oxygen sensor that I use to adjust the mixture once I get to cruise. I have the EAGLE automatically set full rich when RPM is above 2400 or below 1300 - and then it remains at full rich until the CHTs are below a limit, where it allows the LEAN POT to control the leaner mixture. I put the Lean Pot at 6 o'clock and when the CHTs get down, I see the wide band oxygen go up to above 14.5. I somewhat ignore the EGTs, as they don't tell me much.
 
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