| Bulletins
Bob Wilcox
Attention Kero Start Engines Users:
If the engine fails to start, you can get excess kerosene in the engine. YOU CANNOT REMOVE EXCESS KEROSENE BY TILTING THE PLANE WITH THE NOSE UP IN THE AIR. The kerosene will be captured by the exhaust guide vanes and will not run out of the engine. The nose must be tilted down towards the ground. The excess kerosene will then run out the intake. You may need a towel around the intake to absorb the kerosene. You may also need to clean off the starter o-ring afterwards since it may get kerosene on it.
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!!!!
Failsafe and the Auxiliary channel:
DO NOT ASSUME THAT YOU PROGRAM THE AUXILIARY CHANNEL LIKE THE THROTTLE CHANNEL FOR FAILSAFE!
FOR TWO CHANNEL OPERATION ONLY: Do not set the AUX channel in your transmitter for failsafe. Keep it in HOLD MODE only. THE AUX CHANNEL IS DESIGNED TO STOP THE ENGINE INSTANTLY IF COMMANDED TO DO SO.
From the desk of Matt Carroll:
Static discharge
I have been to dozens of events since I started flying jets in 1997 (over 10 years now). I have seen this problem twice. I have never seen it on any of my personal planes after flying hundred and hundreds of flights in some of the most static prone weather in the world (California and Arizona deserts in all seasons). NEVER a problem. Over the gamut of model planes, I would say it is a 99.9% chance against ever seeing a static problem.
Markus Zipperer (JetCat chief engineer) has spent a lot of time and money troubleshooting this static discharge issue over the past several months. He has learned a lot and has since submitted an article on the subject for publication in what should be the next issue of JetPower magazine. So I will not go into any great detail about what static is or how it is being generated. The article will do that.
Briefly, Markus is convinced the offending static electricity is primarily generated by the fuel coming into contact with the non-electrically conductive components of the fuel system. Kevlar tanks are especially bad for this.
So why do we appear to be seeing more problems recently? Well some theories are that the planes are getting bigger and bigger, so the fuel tank size and the fuel flow are increasing as well. Tank manufacturers might now be using a different material formulation that is more susceptible to generating static, or some fuel formulations might be more or less susceptible. One thing we do know for sure is that the JetCat ECU hardware has remained virtually unchanged since it was introduced almost 5 years ago. The only major changes have been in the software from V4.0A to V5.1E currently sold. The software changes would not make the ECU any more or less prone to static charges failures. The potential for "static problems" has always been present with any electronics in our planes since day one!
We have not be able to figure out is what is different between the 0.1% of installs that suffer disruptive static discharge, and the 99.9% of the installs that never have a problem. This might be a phantom, because the complexity of the static discharge might be a problem we can ever figure out in models made as a hobby out of primarily non conductive materials. Full size aircraft use special materials and processes as well as detailed design techniques to manage static electricity build up and control the discharge. Not practical for us, at least based on what we know now.
Therefore, JetCat’s current troubleshooting strategy has been to try to reduce or eliminate the potential for generating static electricity at the source. There are 3 techniques we are exploring (BTW, these would apply to all model turbines):
1.) The first is the use electrically conducting fuel line. This seems to help a bit, but it does not address the sloshing of fuel in the big Kevlar tanks. Bob Wilcox has this line in stock as does BVM.
2.) The second is the development of a material and/or process to be used during the manufacture of the fuel tanks that make them electrically conductive. This is good long term solution, but it does not address the current fuel tank installations that everyone has now.
3.) The third strategy is the development of a simple fuel additive that would reduce the static buildup. We started testing a formulation of this material a couple of days ago. It would be a small amount of additive, less than an ounce per 5 gallons of fuel. We hold out high hopes for this option and we should know more about its effectiveness in the coming days and weeks.
BTW, yesterday I spent some time at the Fresno jet rally discussing this issue with a BVM rep who also reps another highly respected brand turbine. He was trying to monitor static charge with special test equipment that measures electric fields. I can provide his name (and the name of another BVM rep who is having trouble, again who does not fly JetCat) to anyone who privately asks. We have also seen receivers suffer a type of “latch up” (that is, just appearing dead) until their power was cycled. This has nothing to do with the JetCat ECU and to imply otherwise is just wrong, it is the static electricity discharging into the receiver.
With JetCat ECUs we are able to diagnose many types of problems. How many flame outs from other brand ECUs are occurring that are not diagnosable? How many receiver failsafes or “latch ups” (and resulting crashes) are occurring that we cannot diagnose? I do not know, nor do I want to try to find out as that does not help fix the issue!
A new, more durable kerosene start plug is now delivering that works especially well in the P60, SPT-5A and the SPH-5A. $199.95 including updating an existing ECU or $179.95 for the plug alone.
When installing the Kerosene starter in the P60, please note:
The P60 glow plug boss may have damaged threads near the combustion chamber. DO NOT FORCE THE KEROSENE START UNIT IN AS IT WILL SURELY BE DAMAGED. This is due to the fact the P60 glow plug boss is tig welded on instead of being brazed. In some cases the weld penetration distorted the threads deeper then what would affect the glow plug but would damage the longer kerosene start unit. We would suggest that you return the engine to JetCat USA if this is the case.
A new version for Jettronic for Windows is available. Check out downloads for the latest version. If you get an error 1911 when installing, press the ignore button to continue the installation.
In January 2006, JetCat USA will be releasing our new kerosene starter plug that can be retrofitted into almost all our existing turbines (some very old engines may not accept this plug). What is a kerosene starter plug? This plug replaces the glow plug in our turbine and allows for a kerosene only start. No more on board starting gas tank! The startup is smooth and reliable. Our start plug is easy to install and hookup. No engine modifications are necessary but the ECU software must be updated at our service center. The plug comes with all the necessary hardware and instruction manual. The price for the plug and ECU software update is $199.95. A new engine ordered with kerosene start is an additional $179.95 over the engines retail price. Any new engine ordered now already comes with an updated ECU. Only the plug would need to be purchased later for an additional $179.95.
WARNING:
(Note: This "Bug" has been fixed in the 4.0h ECU and newer software)
If you are operating the engine in single channel mode and enable the AUX channel for cruise control, then the following restrictions apply.
In the limits menu, operating with the turbine control off, but AUX channel on [:ON Turb Ctrl OFF] while using the speed sensor for cruise control,you must make sure that the AUX switch is in the middle position (1) when you take off. When the air speed reaches the minimum value to enable cruise control, it will immediately enter the mode your AUX switch is positioned to [e.g.: If you are taking off and have configured the AUX switch position (0) or (2) for speed hold and have the switch in that position, then as soon as you reach the minimum speed (~18MPH) for the cruise control to activate, the engine will no longer accelerate]. This can make for a very slow take off!
If you have a speed sensor, but only use it for limiting maximum airspeed -- and do not use the cruise or smoke functions -- disable the AUX switch [:Not Used]. This setting will not only disable the AUX switch, but free the receiver channel for other functions.
If you use the smoke functions and only employ a speed sensor for limiting the maximum airspeed, disable BOTH positions (0) and (2) of the AUX switch in the limits menu, for cruise control.
If you use the cruise control functions and operate the engine in cruise control mode, you must make sure the AUX switch is in the center position when you take off. An ECU revision will be available in the near future, that will ignore the AUX switch when the cruise control is first enabled at take off -- and will require cycling the switch if it was in position (0) or (1).
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