John Redman

My Feedback: (8)

Well folks we have been working the issues on the "Low RPM Shut Downs" on the P-120. What we have found is that it seems on the average only people flying at altitudes of 2500 feet or higher have had these rare occurances. They are very sporatic on the average. For example I have gone months without any shutdowns and then in one outing I had 3 "low rpm shutdowns" in one day. This has happened both on my Bobcat's and my Mig-15. These shut downs only occur during taxi out and have never occured in the air. The initial fix was for us to set our idle to 34,000 or even 35,000 and this would routinely solve the problem regardless of field elevation. But the bottom line is it wasn't absolutely right. I do know that Bob Wilcox was amazed to here of the number of these shutdowns that had been happening to guys who hadn't said anything.

Bob Wilcox has worked the issue with the Germany guys to give us a solution. The final version of software I have recieved is down right awesome and has cured the shutdowns entirely as best I can figure. The older version's of software would give me an RPM drop off to approximately 28,000 when I would throttle up to 45,000 and back down to idle (33,000) for a taxi out. Sometimes this would trigger a shut down if the rpm stayed below the programmed settings in the ecu for a period of more than 3 seconds. The programmed settings to trigger a "Low RPM Shut Down" is when the engine rpm drops 15% lower than the set idle rpm for a period of 3 seconds or more. In other words if your rpm is set at 33,000 for idle, then the ecu calculates a 15% drop which would be 4650 rpm lower than your idle setting, 28,350 rpm. If it see's this rpm or lower for 3 seconds it will shut down the engine. This shut down feature is there to prevent potential fires and such from the low rpm operation.

Well after a couple of different ecus with different software they have finally got it set where the rpm never drops more than 1,000 rpm below the set rpm setting. Recaluculating pump voltages and such is the fix in the programming I believe. The end result is no more problems. I feel like I have worn out a starter motor on the front of my engine as well as runnning all of my fuel cans dry to sort this out, but it is worth it. I have recorded rpm readings using the three following fuels: Crown Kero K-1, Jet-A, and JP-8. All have produce the same results with the new software.

I am sure most of you can remember my last post about this with the dirty UAT bag. I believe that was something that just happened to be in the middle of these other issues. I can't retest the old bag as it was cut up to determine what was inside of it. But I have pulled the UAT out of my Mig-15 and believe me it is as dirty as the original I had and to date there have been no problems. End statement here is I don't believe the UAT was the problem.

I am sure you can send your ECU in for the latest software if you choose. I have no idea what Jet Cat USA might charge, I doubt it would be much, as the older software is working very well for most everyone. For us higher elevation guys I highly recommend you send in the ECU for the update. If you elect not to send in your ECU for the update then I recommend you set the idle for either 34,000 or 35,000. I am guessing that any engines sent in for service from now on will recieve this new software as well as all new engines from the factory.

Hope this helps you guys sort some of these shut downs out. You jet jocks lucky enough to fly at sea level probably have never seen this situation. Jet Cat will continue to improve its products by using us field reps as guinea pigs when ever they can <VBG>. I am fortunate to have an unlimited landing area and a Bobcat that will float awhile before coming back down to mother earth, hence why I am the lucky one.I honestly don't mind as I learn more and more about the inside of this thing we call an engine.

Regards,

John Redman
Team BVM, Jet Cat USA, Shultze Chargers

Ehab

My Feedback: (44)

Hi John;

Glad to hear you guys solved this particular problem. What is the latest version of ecu rv 4.0? Is it L or higher?

I just installed a new P120 on my Bobcat and it fired up, as usual, first time. All I had to do is teach it my 10X. The software on this one has a lot more data on the GSU than ever before. It tells you the battery voltage, rpm, and a bunch of things the original rev4 did not. The acceleration is much improved too!! These guys have dialed it almost perfect so far.

Is Rosamond where you fly? and is your elevation 2500 ft?

John Redman

My Feedback: (8)

Hello Ehab,

Here in Rosamond we fly at either the Edwards dry lakebed or at the AV Tailwinds field. Field elevation is right around 2342 msl. But with our nice warmer temperatures we can see density altitude close to 7000 feet during the summer time on certain days.

Do you like hte new display on hte GSU? I think it gives a wealth more info and I am not sure about what the latest version of software is, Bob could answer that.

Going flying again this morning as soon as I get the kids off to school.

Regards,

John Redman
Team BVM, Jet Cat USA, Shultze Chargers

mr_matt

My Feedback: (10)

The firmware is revision M. It has not been released until now (except on a couple of limited cases) as we wanted to get this testing done.

Ehab

My Feedback: (44)

While I respect rcu rules as best as I understand them, I do not feel that this posting should have been moved. John was trying to inform people of a solution to a previous thread. Anyway, I do respect the action and thank Gordon for a good job fighting fires here!