WJaviation
Active Member
Hi everyone,
I finally got my engine started after 10 unsuccessful starts. I thought id give a quick write up of what I saw so that maybe another builder might not stress as much as I did.
Master on, Lane A and B switches on, the fault lights illuminate for 3 seconds each and then extinguish. This is as described in the Rotax Manual. Then I turn on the #1 fuel pump. I get good fuel pressure at 43.5 PSI. Throttle at exactly 50% as indicated on the Engine Display page (Garmin G3X). On engine start the engine fires up immediately and with positive oil pressure. within about 2-3 seconds it reaches 2700 RPM. I release the key before this and the engine is running on its own for about a second.
As it hits 2700 RPM (about 1 second of running), the Lane A fault light illuminates solid. RPM rapidly decreases. Then the Lane B fault light illuminates. Then the engine totally quits. Both Lane lights remain illuminated and the engine is stopped. The CAS also shows an "ENGINE ECU" red Message. The FADEC page shows a "Caution" for both Lane A and Lane B.
Ive included pictures of the displays from after the event. My very basic understanding is that the lane fault may have to do with the generator swaps that take place around 2500 RPM, but I have no idea how to troubleshoot.
After a day of deep dives in the pubs..
I posted to Rotax-Owner forums my entire story and got a response from a guy named Bill. He claimed that the "dual Lane caution" is normal. He said that when the engines are new like this one, the "A side" injectors are full of air. The Engine fires up on the B side injectors only (only one injector per engine). Depending on the engine, this could or could not be enough fuel to get the engine sustained. By repeatedly getting the engine to "swap" to the gen A around 2500 rpm, this brings the A side injectors online and pushes fuel through. But before the fuel gets through, it pushes air in and screws up the mixture. The engine/ECUs panics and shuts itself off because it can't find where this air is coming from.
Bill suggested that I just keep trying to start it. He claimed that if I was making it "past the key/start release" point of the start process, and the engine was running on the generators, Even for a second. Then it will run, it just needs to be given the chance.
He was right! In total I needed 10 starts, with the Lane lights kicking on each time for the fuel injectors to "get purged". It finally started on the 11th attempt. I ran it solid for 3 minutes, shut it down, and then started again with no issues. I think this is a happy engine now!
I think one of the possible key symptoms is the "Lane A and B Caution" warnings. The Lanes can't figure out what's wrong so they simply say "caution".
I couldn't find any specific pages in any of the Pubs to verify Bill's theory, but the fact that he confidently told me it would work, and it did...means something.
Id love it if Scott or any of the other engineer types might be able to offer any other explanations. Maybe even add a note in the PAP suggesting that it may take several start attempts to get working.
If not, then hopefully this post will help someone out in the future.
I finally got my engine started after 10 unsuccessful starts. I thought id give a quick write up of what I saw so that maybe another builder might not stress as much as I did.
Master on, Lane A and B switches on, the fault lights illuminate for 3 seconds each and then extinguish. This is as described in the Rotax Manual. Then I turn on the #1 fuel pump. I get good fuel pressure at 43.5 PSI. Throttle at exactly 50% as indicated on the Engine Display page (Garmin G3X). On engine start the engine fires up immediately and with positive oil pressure. within about 2-3 seconds it reaches 2700 RPM. I release the key before this and the engine is running on its own for about a second.
As it hits 2700 RPM (about 1 second of running), the Lane A fault light illuminates solid. RPM rapidly decreases. Then the Lane B fault light illuminates. Then the engine totally quits. Both Lane lights remain illuminated and the engine is stopped. The CAS also shows an "ENGINE ECU" red Message. The FADEC page shows a "Caution" for both Lane A and Lane B.
Ive included pictures of the displays from after the event. My very basic understanding is that the lane fault may have to do with the generator swaps that take place around 2500 RPM, but I have no idea how to troubleshoot.
After a day of deep dives in the pubs..
I posted to Rotax-Owner forums my entire story and got a response from a guy named Bill. He claimed that the "dual Lane caution" is normal. He said that when the engines are new like this one, the "A side" injectors are full of air. The Engine fires up on the B side injectors only (only one injector per engine). Depending on the engine, this could or could not be enough fuel to get the engine sustained. By repeatedly getting the engine to "swap" to the gen A around 2500 rpm, this brings the A side injectors online and pushes fuel through. But before the fuel gets through, it pushes air in and screws up the mixture. The engine/ECUs panics and shuts itself off because it can't find where this air is coming from.
Bill suggested that I just keep trying to start it. He claimed that if I was making it "past the key/start release" point of the start process, and the engine was running on the generators, Even for a second. Then it will run, it just needs to be given the chance.
He was right! In total I needed 10 starts, with the Lane lights kicking on each time for the fuel injectors to "get purged". It finally started on the 11th attempt. I ran it solid for 3 minutes, shut it down, and then started again with no issues. I think this is a happy engine now!
I think one of the possible key symptoms is the "Lane A and B Caution" warnings. The Lanes can't figure out what's wrong so they simply say "caution".
I couldn't find any specific pages in any of the Pubs to verify Bill's theory, but the fact that he confidently told me it would work, and it did...means something.
Id love it if Scott or any of the other engineer types might be able to offer any other explanations. Maybe even add a note in the PAP suggesting that it may take several start attempts to get working.
If not, then hopefully this post will help someone out in the future.