Slow day at work and Im just thinking about the Kero start issues I've had. I speak only about a titan/external plug setup.

When initiating the start sequence, On a normal start the starter engages and as soon as the solonoid begins to click (if you put your ear right next to the engine) you can hear it light and a constant combustion sound as the engine preheats. The light up occurs within 1 to 2 seconds at most after the solonoid opens.

When the engine was new to me, For my first few starts I didn't even realize the engine was lit until roughly 10 to 20 seconds after the solonoid began clicking and the ramp begins, Then you hear the roar/whining sound as it spools up to idle.

What I don't understand is the timeout protocal for a failed light. Ideally, If the kero plug is supposed to ignite and preheat as SOON as the solonoid pulses then why does the kero continue to pump fuel if it failed to light? My titan, In the absence of a light up will continue to pump kerosene for quite a while, Enough were if action is not taken to drain the engine a major fire could result.

Why doesn't the ECU realize quickly that the kerosene has not ignited and abort the start faster?

Just curious..

Pete

Pete, I don't know the answer to your question but what you probably need to do is figure out why it is missing starts in the first place. I have been running kero start on the Jetcat's for a couple of seasons now and it is my experience that failed starts are rare. You may have to bump up the amount of fuel that is being introduced into the turbine on start up, which can be increased in the ECU. I suppose there can be other issues but this is the most common reason for a missed start. Kero start is typically very reliable.

Now why would the engine not start in the first place -

The kero start igniter failed. The automatic glow plug test may not detect a failed igniter! If you put your finger on it while the engine is starting and it feels cool, the igniter has failed. If your tried to start the engine with a failed igniter it will get some kerosene inside the engine. Do not immediately install a new igniter and try again without draining the engine.

The kero start feed line has not been primed. Please refer to the kero start instructions on how to prime the feed line. The fuel should be all the way up to the igniter. If you DID prime the feed line and it gets more than 3" of air after a flight, make sure the fitting is tight on the kero start fuel connection and the festo fitting is not leaking. Also make sure the solenoid is fully shutting off. If the fuel does not get to the kero igniter in a few seconds it may not start.

The fuel system has a high capillary resistance or the pump is a little weak and the kerosene will not get to the igniter. The pump will need to be adjust to a higher start voltage. This is adjusted by holding down the limits key on the GSU and then press the + key. A three item menu will appear. The first selection is for the number of cells in your battery pack. Use the + key alone to index to the next selection, UACCEL 1. This sets the minimum pump voltage to start moving fuel through your fuel system. To increase the voltage, press and hold the change value key and then each press of the + key will advance the UACCEL1 voltage by 0.025V. Try one or two increases at a time. To test the flow to the kero start igniter go to the test functions menu and select the kero start valve test. Press the change value key to flow fuel to the kero start igniter. MAKE SURE YOU DISCONNECT THE LINE TO THE KERO START IGNITER SO YOU DON'T GET FUEL IN THE ENGINE.....

If your igniter fails please call JetCat USA for a replacement. I personally fly with the kerosene start igniter and I am always amazed how smoothly and reliable it starts the JetCat engines. I "grew up" owning mid 90s kero start engines and I know what it is like to have rivers of jet fuel running out the tail pipe 9 out of every 10 start attempts. The JetCat system will not do this if operated correctly!!!!


Copied from the Jetat website.

I am sorry that I did not elaborate on my history with the engine.

I think I heard somewhere that the version 1 ignitor was only good for a few dozen starts, I purchased mine with around 40 on it, Over the next few months the good to bad start ratio became more and more unfavorable. During my last outing the ignitor failed, I don't actually have proof it was the ignitor but I made about 10 start attempts over the course of 5 hours and gave up, Assuming it was. Then Me and BigBri converted to gas start.

When I purchased the engine in Oct 09' I got good starts with an occasional miss, Maybe 1 in 10. This ratio tells me that the system is correct but due to XYZ (perhaps my extra long ECU leads) every once in a while it wouldn't start. Im sure there are others in similar situations that may miss a start here and there. Thats where my interest in the abort logic came from.

It just confuses me, If voltage is allocated to the pump with the ignitor hot but no EGT rise is detected why isn't the start aborted right away? Why pump fuel for so long?

Anyway thanks for the help guys and the document you copied David.

Pete

as allways. a new gadget that can fail.. propane is, safer then a flamed up plane,from a wet start.. "kiss" is the best way to go.. kero start is a, FAD ,to show off and ,say you have one.. no need for them.. propane works fine .. you got a new ,very pricy gadget,sucks battery life,needs to be replace often.. [X(]

I've been using k/s for over 150 flights with absolutely no problems, catch up with the 21st century!

Kero start is not new. It is just new to our micro turbines. There is no simpler method of starting a turbine than using the same fuel and supply that the engine runs on normally. Adding another tank and fuel type is in no way KISS. This is not a FAD so you better get comfortable with it.

I also don't see how this helps Pete737 with his problem at all.

Hi Pete.
I had exactlty the same problem on a 160, if the plug is fulty or the inition egnition dies for what reason so ever, the tcu doesnt detect that and starts pumping fuel and you get a wet start. Pete what I have done was to whatch the ground unit carefully. and if you do not haer the ignion, just stop motor.
Alex

I have had 14 jetcat engines, all with kerostart, currently have 7 engines (all SX types now), I have had 1 (one!) failed V1 plug on one of the first SE engines.
On another hand, I have witnessed 3 or 4 severe hotstarts on engines with gas, and I see people keeping the gas bottles under their jackets during wintertime to warm them up (not exactly "KISS" ?), so guess it swings both ways (have you had any kerostart engines yourself since you're and expert ?)

everything swings to ways if you where boxers

Depends on if there is something that can swing
See you in a few days [8D]

a yes forgot its pretty cold in denmark