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matsgone

Lts101-700 Astar B2/D2 - Overspeed Vs. Flame Out?

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Hi!

 

I was recently made aware that a pilot flying an Astar B2/D2 for the same company, had an overspeed on final approach which ended up in a flame out... and autorotation.

 

I heard of at least one similar occurance...

 

When I tested the overspeed limiter on the machine I flew a few months ago, following the procedure, the engine flamed out instead of just spinning down to prevent overspeeding.

 

My understanding of this system is that when an overspeed is detected, a signal is sent to decrease the amount of fuel sent to the engine to prevent such an overspeed......but no flame out should occur....

 

I ask myself if it would be safer to fly with the overspeed limiter breaker pulled out....

 

I would appreciate feedback on this, whether anybody has heard anything about flame out caused by this system.

 

Cheers!

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I've heard about something like that and believe the fault lay in the overspeed control box. I'm not 100% on the details, but I believe there was a flaw in the hardware programming.

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yes.....its designed to reduce the amount of fuel in the "system" but it doesn't mean it always works correctly !! its not the first one to quit either.....not sure if pulling the breaker is the "fix".......you survived Mordor so what you worried about !!

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yes.....its designed to reduce the amount of fuel in the "system" but it doesn't mean it always works correctly !! its not the first one to quit either.....not sure if pulling the breaker is the "fix".......you survived Mordor so what you worried about !!

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I flew the FX with the 101 conversion from helilynx and found the governor slow, and not as responsive at the same heli with the 1D1. Guess that what ya get! It is a less expensive engine by about a 100K+- It didnt seem as though it had as much jam either!

 

2 Cents P5

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It closes the flow fence. Reducing air flow, slowing the engine. Hopefully preventing it from flying apart and blowing the tail rotor drive shaft apart.

 

 

When doing the test. It usually failed. Causing the engine to flame out. Some days it did work but not many That was my experience.

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matsgone, like I said, we've had this issue in the past where the overspeed test resulted in a decel and / or shutdown. we traced the flaw back to a faulty control box. May I suggest you contact the provider of your conversion kit. Who knows, maybe there's a revision on the box or a firmware update or what have you. PM me if you want more details.

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matsgone, like I said, we've had this issue in the past where the overspeed test resulted in a decel and / or shutdown. we traced the flaw back to a faulty control box. May I suggest you contact the provider of your conversion kit. Who knows, maybe there's a revision on the box or a firmware update or what have you. PM me if you want more details.

 

 

The flame outs are not caused by the control box. The control box detects an Np over speed of 108.8 which it then bleed off PY air which then causes engine to decel. There is a small orifice in the fuel pump, that if it is a certain size (which could still be limits), it can cause the engine to flame out when you do your EOS test. I have heard that the fuel pump manufacture is working on a modification to the fuel pump to stop that. Apprently they are being tested, not sure when they are going to be available. I believe that this is why soloy calls for the EOS to be done at the last flight of the day, as you are shutting down anyways.

 

If you where to have an actual overspeed failure the EOS deceled the engine with out a flame out, as soon as your NG gets below 100%( i think that is the number)the engine would just overspeed agian and again. So you would throttle back to idle anyways in the event of an overspeed.

 

This is on a 700D2 engine, a 600 A-3A uses a mechanical overspeed.

 

Hope that helps.

 

If you have any questions call Bob Southward at intermountain turbine. Guys a LTS 101 genius

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Superwrench has it right, Its a fuel pump issue that they have been working on for at least 2 years. We had a modified pump on an engine in PNG that seemed to work that we were trialing when I was there.

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