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Js3 jet catastrophic failure.



 
 
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  #61  
Old September 9th 18, 04:46 PM posted to rec.aviation.soaring
AS
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Default Js3 jet catastrophic failure.

On Sunday, September 9, 2018 at 2:41:43 AM UTC-4, Mike Borgelt wrote:
On Sunday, 9 September 2018 14:45:00 UTC+10, AS wrote:
It is 2018. Why are we even talking about winch launching?


Mike


------------

Because not all of us are independently wealthy and can plop down a couple big ones to get a jet retrofitted into our ships or even purchase a new glider with that factory option!

Uli
'AS'


Also very workload intensive and dangerous.

Mike


You are absolutely right - installing a jet is very labor intensive and the operation comes with its set of dangers!

Uli
'AS'
  #62  
Old September 10th 18, 08:39 AM posted to rec.aviation.soaring
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Default Js3 jet catastrophic failure.

One potential problem with multiple jets is if one starts while the other doesn’t but pumps fuel through.
Good engineering may help but there is a known issue there. (PM)
  #63  
Old September 10th 18, 11:56 AM posted to rec.aviation.soaring
AS
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Default Js3 jet catastrophic failure.

On Monday, September 10, 2018 at 3:39:49 AM UTC-4, wrote:
One potential problem with multiple jets is if one starts while the other doesn’t but pumps fuel through.
Good engineering may help but there is a known issue there. (PM)


Tom - good point but each turbine has its own controller monitoring what it is doing. If it doesn't ignite and run within the set parameters, fuel to it is cut off.

Uli
'AS'
  #64  
Old September 10th 18, 07:49 PM posted to rec.aviation.soaring
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Default Js3 jet catastrophic failure.

On Monday, September 10, 2018 at 5:56:11 AM UTC-5, AS wrote:
On Monday, September 10, 2018 at 3:39:49 AM UTC-4, wrote:
One potential problem with multiple jets is if one starts while the other doesn’t but pumps fuel through.
Good engineering may help but there is a known issue there. (PM)


Tom - good point but each turbine has its own controller monitoring what it is doing. If it doesn't ignite and run within the set parameters, fuel to it is cut off.

Uli
'AS'


I have been using the twin Jet Cat P300's for a number of years on my homebuilt experimental HP-18J. I have to say that they can be troublesome, especially if they are not operated according to specifications. I have been using diesel fuel with 5% oil for the bearing lubrication. If you use Jet Cat oil or Aeroshell 500 turbine oil the bearings are reliable for one or two seasons tops. This includes a full summer of self-launches and sustainer starts at our mid-west altitudes. I attended Parowan and Dave was one of my helpers who graciously assisted me retrieve the glider from an out landing. That day the failure was pilot error and not the turbines. I had failed to plug in the CPU's prior to takeoff so the turbines and fuel were just extra ballast that day. During the rest of the event, I used the turbines for sustainer. They started consistently at the airport altitude of 6K and also at flying altitude when needed, sometimes above 10K. With the two turbines, I feel more confident that at least one will start when needed. I typically will do a start sequence for both turbines for a climb and shut one down if I go into sustainer mode to extend my fuel endurance. The problems that I have encountered over the years have been bearing failures, one glow plug ignitor failure and one EGT failure. The turbines are in my opinion good but not great. They still have their issues, two of them are better than one for redundancy and for my application of self-launch. In the mid-west I can take off with a 1K runway roll and climb at 500 FPM. During flight one or both can be started for another climb or for sustainer operations. Operation at high density altitudes and elevated temperatures greatly decreases the performance so I choose to use a tow and use them only for sustainer ops. Here is a link for short clip from our mid-west airport https://www.youtube.com/watch?v=xeQIRrZ7JCU I am currently putting a salvaged ASW-27 back together, I am happy enough with the twin turbines to incorporate them into the rebuild of the glider for the same self-launch and sustainer abilities.

Thanks,
Chris
  #65  
Old September 10th 18, 08:28 PM posted to rec.aviation.soaring
John Seaborn (A8)[_2_]
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Default Js3 jet catastrophic failure.

Beautiful work Chris. Consistently impressed by the talented people in our tiny band of aviators.
  #66  
Old September 10th 18, 08:49 PM posted to rec.aviation.soaring
Nick Kennedy[_3_]
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Default Js3 jet catastrophic failure.

Chris
Thats a nice video, great work on your plane.
When you have to replace your turbine bearings do you do it yourself or send them out?
What does that cost?

  #67  
Old September 10th 18, 09:07 PM posted to rec.aviation.soaring
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Default Js3 jet catastrophic failure.

On Monday, September 10, 2018 at 12:49:08 PM UTC-7, Nick Kennedy wrote:
Chris
Thats a nice video, great work on your plane.
When you have to replace your turbine bearings do you do it yourself or send them out?
What does that cost?


For me, last time I checked JetCat charged about $75 per bearing. Service was $300 to 400 total. The problem with doing it yourself is you need dynamic balancer.
  #68  
Old September 10th 18, 09:16 PM posted to rec.aviation.soaring
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Default Js3 jet catastrophic failure.

On Monday, September 10, 2018 at 2:49:08 PM UTC-5, Nick Kennedy wrote:
Chris
Thats a nice video, great work on your plane.
When you have to replace your turbine bearings do you do it yourself or send them out?
What does that cost?


Nick,

Jet Cat has a support/service center on the east coast that provides the yearly condition inspections and needed parts and service. They have been vary supportive of my installation and typically provide a vary quick turn around. The bearing replacements are provided by Jet Cat as they not only replace the bearings but do a dynamic balance after installation. Most of the bearing replacements and parts have been covered under their 3 year warranty. If I recall correctly the bearing and installation will run around $500 per engine.
  #69  
Old September 10th 18, 11:03 PM posted to rec.aviation.soaring
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Default Js3 jet catastrophic failure.

On Monday, September 10, 2018 at 2:39:49 AM UTC-5, wrote:
One potential problem with multiple jets is if one starts while the other doesn’t but pumps fuel through.
Good engineering may help but there is a known issue there. (PM)


Tom, the key is to install two independent systems. That is two independent fuel pumps, two CPU's, two batteries, two controllers and two engine monitors. Keeping the systems separate provides an added layer of insurance.

Chris
  #70  
Old September 11th 18, 09:08 AM posted to rec.aviation.soaring
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Default Js3 jet catastrophic failure.

Hi Chris, not sure if that would fix every problem. We have had a major fire in Australia possibly caused by a fuel leak from one engine while the other started - creating an ignition source. Although at work I fly with four jets I think the simplicity of simply using a larger jet would be nice, (Jet Arcus etc)
Tom
 




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