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JetCat Slipping (?) Starter

Old 12-04-2022, 02:14 PM
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highhorse
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Default JetCat Slipping (?) Starter

Gents, I have a JC 100rx that isn’t coming up to rpm (rpm low signal) during initial start phase. It had fewer than 5 starts since new when the issue developed, but the engine is actually at least 8 years old. Do the starter O-rings harden and lose grip over time, requiring periodic replacement even if nearly new in terms of total time?

How does one analyze/trouble shoot starter issues? I’ve read references alluding to cleaning the O-ring/starter interface, but have no idea how to go about it.

Any help appreciated - thanks all,

Don
Old 12-04-2022, 02:31 PM
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Dave Wilshere
 
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Don

just hold the Spool/Ignition-starter button down, this will run just the starter motor. You will hear if it is slipping and the rpm will not reach the expected 5-6,000 rpm.

My guess is it’s not that, low rpm message is lack of fuel, so it does not go past the initial ignition.
Hold down limit (blue) button and press +
Release both buttons and it should say Url Accl 1 what ever the figure is (0.100. 0.150. 0.175) hold the change value button and use + > to increase this figure a couple of points ( 0.120. 0.170. 0.195) just approximate figures.

try again.
Old 12-04-2022, 03:04 PM
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Thanks Dave. I have already run the starter manually as you suggested. It sounds slow to me, but I don’t consider myself a relatable judge. There is also a slight squeak, possibly slipping sound, but again, I don’t trust my judgement. Also, there’s no fuel obstruction, the manual valve is open. No reason that I can think of for lack of fuel, but I will triple check that aspect.

RCU wouldn’t let me upload the vid, so the best I could do was make iCloud links of failed starts I am getting.

Failed start
Another view of the failed start

Again, any and all help greatly appreciated.

Last edited by highhorse; 12-04-2022 at 03:54 PM.
Old 12-04-2022, 03:15 PM
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Deleted.

Last edited by highhorse; 12-04-2022 at 03:54 PM.
Old 12-04-2022, 08:24 PM
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My P-100 started doing the same thing and I think it is age-related, with the o-ring getting stiff and not gripping well.
I replaced it and now it is good.
I will say that replacing the o-ring was no easy task.
Old 12-04-2022, 09:56 PM
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If it is the O ring, why was it difficult to replace? I think it takes 5 minutes! Pop the start cap off, unscrew the two mounting screws. Use a pen to mark the polarity on the PCB and starter mount. Pull out the starter assembly. Two cuts with a sharp scalpel and dig out the O ring. Clean the mounting cavity with a Q-tip and CA kicker. Squeeze in new O ring, replace the starter, screws, cap and it’s done.

If the turbine is free and the O ring is not slipping it can be the motor brushes are dirty/warn.
Old 12-05-2022, 01:27 AM
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Dave, would you mind viewing those two short vids to see if it looks/sounds like mine is slipping?
Old 12-05-2022, 01:42 AM
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It’s not slipping, but you are right it is turning slowly. You can either order a new motor assembly, or remove it and run 6v directly to the motor to try and clean the brush gear
Old 12-05-2022, 02:17 AM
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Also you should order a new type cable set, that old type you have causes issues

Dave
Old 12-05-2022, 08:06 AM
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I once had to replace the O-ring in my JC 100RX. While I was waiting for the new O-ring, I just added a couple drops of belt dressing in the joint and it started working. If I recall correctly, there is also a bit of tension adjustment available, too. (i.e. adjust the position of the nuts inside the top of the motor.) Also, could it be that the battery is not delivering the current or you have the wrong battery type setting in the turbine? My P100rx has been the most reliable turbine of all that I have had. It has lots of hours, went thru heck as I was learning to fly jets, and it is still ticking! It has got to be about 5 years old. But I have never let it sit for more than a year. Could it be that the startup fuel valve is stuck shut?
Old 12-05-2022, 08:26 AM
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Dave, just to clarify - you can remove the starter assembly w/o removing the starter mount? How do the wires disconnect?
Jim
Old 12-05-2022, 09:08 AM
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My thanks to everyone here. To clarify, the engine ran fine a week before, and although old in shelf-years has perhaps 5 starts and 30 mins total run time. The battery is fine and I have also tried starting from an external DC power supply with no change.

It looks like the starter is the most likely culprit, so diagrams, vids etc which shed light on starter maintenance will be greatly appreciated.

Dave, what were the issues with the prior cable set?

Thanks again,
Don
Old 12-05-2022, 09:46 AM
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If I recall correctly, pry the cap off the motor's cover. Then remove the nuts holding the motor assembly to the main shaft. To remove the wires, I think you have to unsolder them from the board in the top of the motor's cover. I think you have to do this to change the O-ring anyway. Then as you put the thing back together, you have to adjust the nuts on the rods to adjust the tension on the O-ring.

It has been a while since I did this. So maybe Dave can correct me if I have it wrong.
Old 12-05-2022, 10:20 AM
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[QUOTE=highhorse;12753651 I’ve read references alluding to cleaning the O-ring/starter interface, but have no idea how to go about

Don[/QUOTE]
Really ? Are you kidding ?
So simple. Use a small paint brush to apply and brush over acetone to the ring and the face of the starter, No need to replace the O ring., First thing to try.
Worked EVERY time for me, and I have four JetCats 8 years old.

Last edited by David Gladwin; 12-05-2022 at 10:26 AM.
Old 12-05-2022, 10:34 AM
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No David, I obviously wasn’t kidding. My engines -JetCats included- have been trouble free before this and I have never had the pleasure of the problem. Thanks for the tip though, and I will add that to my quiver.

Last edited by highhorse; 12-05-2022 at 10:38 AM.
Old 12-05-2022, 10:40 AM
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The issue of slipping starters is covered in the manual , p39, !
Old 12-05-2022, 11:05 AM
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Sound like a starter issue, is it a brushed or brushless motor?
Old 12-05-2022, 11:16 AM
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The issue of slipping starters is covered in the manual , p39, !
Not in my manual, it isn’t. But on page TWENTY nine it lists the same info you’ve mentioned, and I had already read that.

I stated that I’d read references to the procedure, but that I didn’t know how to go about it, right? That’s because for someone new to the issue like myself it seems like the O-ring is not visible. I looked. I looked again. Nada. I know what O-rings are and have for 50 years, but don’t know how to clean something I can’t see. I don’t know if it is deeply recessed of just barely out of sight. I don’t know if the starter housing needs to be removed for access, and if so I don’t know how to go about that without screwing something up. I don’t even know what else I don’t know.

If you’d like to contribute without further sarcasm or derision, I’d be grateful.

Last edited by highhorse; 12-05-2022 at 02:02 PM.
Old 12-05-2022, 11:20 AM
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Originally Posted by Skunkwrks
Sound like a starter issue, is it a brushed or brushless motor?
Thanks. The engine is older (even though nearly zero-time) so I assume brushed. The starter motor has seen almost no use since new though, so I am hopeful that brushes are not the issue…unless they are prone to age-related corrosion even when stored in a controlled environment?

All help welcome, so thanks again.

Last edited by highhorse; 12-05-2022 at 01:06 PM.
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Old 12-05-2022, 12:07 PM
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Originally Posted by A7Bldr
Dave, just to clarify - you can remove the starter assembly w/o removing the starter mount? How do the wires disconnect?
Jim
German logic, the two mounting screws are the positive/negative connection

no wires!
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Old 12-05-2022, 12:13 PM
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This is what you get after undoing two screws No soldering needed!


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Old 12-05-2022, 12:15 PM
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The o ring is fine, it’s the motor or connections that need sorting. It’s just running slowly
Old 12-05-2022, 12:17 PM
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Don, the or-ring is deeply recessed and hard to see or change from the outside. That is why the starter motor has to come out. Once out I dug my o-ring out with a sharp pick and then pushed the new one in.
I didn't realize there was a starter motor cap so I removed the whole mount, which involved unsoldering some stiff wire 'legs' from a PCB under the cowl cover and made this process a PIA..
Obviously this is not the way to go about it, but I got the job done.
My opinion. Jim
Old 12-05-2022, 01:32 PM
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Originally Posted by Dave Wilshere
The o ring is fine; it’s the motor or connections that need sorting. It’s just running slowly
Are these the older brushed starters, a fellow pilot has a 12-year 140, which he had to replace the starter, it won't fully spin up to speed either, no start.

Forget the Jet service in the US, but he sold a bunch of these starter motors at a great price.

They are from an outsourced company that sells these little motors and probably sells new brushless motors to all the turbine companies.

Just a guess here, but probably worth talking to a service person from JetCat.
Old 12-05-2022, 01:50 PM
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Just a guess here, but probably worth talking to a service person from JetCat.
Well that was my first thought and perhaps I should have gone there first but they seem to be in transition (?) (website isn’t clear on that topic) so I thought RCU was a better starting point.

Last edited by highhorse; 12-05-2022 at 01:59 PM.
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