Category Archives: Eagle EFI and Ignition System

Throttle cable bracket (and happy new year)

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_DSC0660 _DSC0661 _DSC0663Building has finally resumed! The festive season moves RV building and shop time to “Priority 0” level. I return to building refreshed and tackle a lot of those “put off” jobs.

Take the throttle cable bracket for example. Nothing in the Van’s catalog will work for this particular throttle body so its up to builder to come up with something secure and solid. I made the first bracket, call it the prototype, out of 1/8″ 6061 angle. After initial test fit I found it had too much flex and given that it cantilevers aft about 8 inches I wanted to ensure there would be no chance of failure after a few years of vibration. I increased the bracket arm to 1/4″ 6061 angle and made a few lightening holes along its length. It looks simple but took a good day to complete this item and tune the aft angle to best position the cable end for the throttle body arm.

TC4 Eagle ECU Monitor

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This is the latest release of the TC4 controller which is used to monitor, display and alarm on data and status from both of the Precision Airmotive Eagle ECUs (engine control units). The TC4 also has a GPS module which combines flight data with engine data for the best of tuning information. The data is stored in a micro SD memeory card. The TC4 has ethernet port, USB programming port, USB memory stick port and two serial ports for RS232 and RS485 communications. The pilot interface is a full color touch screen with impressive graphics and screen update times.

The TC4 communicates with both Eagle ECU A and ECU B via a RS485 Modbus data link. Each ECU is polled every two seconds and data is placed in the TC4 memory for processing. I have already bench tested the data link between the ECU and TC4 and now I am working on displays for all the various data types that are available. In addition to the GPS and Eagle ECU data, the TC4 can receive 4 analog inputs from various instruments, 12 digital inputs from switches or sensors and it has 6 relay outputs for driving lights or operating loads such as relays. The TC4 can also be expanded via its CANBUS port to monitor and control a large number of other devices which use this protocol.

I will field test this controller in the CH701 prior to RV9A flight to ensure its screen design and operation is easy and intuitive to use.

Filter Air box wrap up

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A somewhat simple asembly, the horizontal filter air box (FAB) took several hours and a couple of fibreglass sessions to complete. If you had a normal Airflow performance throttle body it would be an easier task as per plans,but with the eagle airflow performance throttle body, its overlength is about 1 1/2″ shorter. This places the inlet, which should line up with the cowl snout about 1 1/2″ too high. It appears that some folks solve this problem with aluminum or teflon spacers, I chose to modify the FAB by cutting it in two locations and making 2 bends to get it to the proper height. The alignment with the snout is perfect now and no spacers were required.

The FAB has an alternate air inlet which is cable operated from the cockpit. I am holding the lever forward to show the normal operating position. Should the air inlet snout become plugged (maybe a seagull found its way past the prop), I would pull the cable which would allow air from the lower cowl air to enter. The air still passes thru the air filter which is directly below the throttle body when the bypass is open.The rubber cowl seal material allows a good seal between the FAB and the inlet snout.

 

 

The last feature of the FAB is the airfilter bypass door. This is provided in case the air filter become plugged. Remember the seagull that got stuck in the snout lost a pile of feathers in the process and plugged the air filter. Another cable operated from the cockpit can be pulled which allows air to flow directly into the throttle body, maintaining power and flight. This bypass door must be reset from ground, assuming a very unusual event caused it to be opened.

I still have cables to install, which will happen once the rest of the firewall forward work is wrapped up.

Ignition wiring

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I received the ignition wire flanges that allow the HV cables to pass thru the engine baffles for the four upper spark plugs. There are four of these installed, two have two holes and two have one hole. I used the two hole flanges for HT leads and and single hole flanges for passing the T/C leads thru. To install these flanges, the baffles had to be removed again. Wish I had these on hand earlier as it would of saved time. While the baffles were off I picked up a couple of odd tasks that were easier to complete without tin work in the way. The bottom spark plug leads were routed to each side of the engine using lots of cable brackets for support and routing.

This wraps up the firewall forward portion of the Eagle System installation. The installation is quite busy, a lot of components in a small area. It would of been even more crowded if I had decided to install the PMU forward of the firewall.