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rjtjrt

Well Known Member
I understand GRT Horizon X has a cooling fan.
What happens if the cooling fan fails? Is there a back up fan? What happens if the cooling fan air flow gets obstructed suddenly or over time?
Are cooling fans a significant vulnerability or am I just neurotic??
Which EFIS other than GRT Horizon X have fans?

Too many questions! Getting a headache. Must stop thinking!

John
 
GRT recomended to me that a second fan (in series, effectively) will do just fine in case of an internal fan failure.

Paul
 
Hmmm - not really worried too much about a fan failure, these usually make enough noise as they are dying that you would notice it on the ground at some point before engine noise covers it up.

It does raise an interesting question in my mind though - do any of the EFIS manufacturers put a temperature sensor in their unit to alert the pilot to an avionics overtemp situation? Don't know that it would do much good to know that in flight, other than to tell you that you might be close to letting the magic smoke out and need to land soon.
 
Thermal protection circuit

rjtjrt said:
I understand GRT Horizon X has a cooling fan.
What happens if the cooling fan fails? Is there a back up fan? What happens if the cooling fan air flow gets obstructed suddenly or over time?
Are cooling fans a significant vulnerability or am I just neurotic??
Which EFIS other than GRT Horizon X have fans?

Too many questions! Getting a headache. Must stop thinking!

John
Click to expand...

John
Home computers used to burn up the CPU (brain) if the CPU's cooling fan failed. Modern machines now have a thermal protection circuit installed in the motherboard. A thermistor (thermally sensitive resistor) senses the heat coming off the CPU. If the CPU gets to hot, the protection circuit shuts down the system. The system will not re-start, until the CPU cools down. Why not ask GRT if they have a thermal protection circuit designed into the system??
If the system has this feature, the EFIS will go dark if it overheats, but at least it won't burn out.
Charlie Kuss
 
airguy said:
Hmmm - not really worried too much about a fan failure, these usually make enough noise as they are dying that you would notice it on the ground at some point before engine noise covers it up.

It does raise an interesting question in my mind though - do any of the EFIS manufacturers put a temperature sensor in their unit to alert the pilot to an avionics overtemp situation? Don't know that it would do much good to know that in flight, other than to tell you that you might be close to letting the magic smoke out and need to land soon.
Click to expand...


I spoke with Dynon guys at Sun n Fun and the said that they have an overtemp alarm install in their system.
 
Hopefully, GRT has a sensor, but doesn't simply shut down based on it. If I'm in the crud (IFR), I want to make the decision to smoke the system for an extra few minutes of use, or reconfigure on my terms to move my guidance.
 
Computers will also often become unstable as they get really hot, so there may be some pre-meltdown glitches that could be an indication of something amiss. Also, most all computers made in the last several years receive feedback from the fan so that they known how fast the fan is spinning. If the fan fails to spin, most (depending on bios version and settings) will alert the user to the problem (some will just shut down or refuse to boot) by default. It is possible that the EFIS systems similarly know what is going on with the fan.
 
Dynon's current systems use no fans.

Our next-gen system has 2 fans. They are fully redundant to one another, and we only run one at once. Each has a speed sensor so we know if it's stalled, and the whole system has multiple temperature sensors inside for early warning. If one fan is dead, we'll warn you gently and then just run the other fan. We would not consider the failure of one fan to be a problem that grounds an aircraft.

The system will operate up to at least 60 degrees C (140 deg F) ambient without any fans. We'll run them before that to keep the thermal wear on the system lower, but the system doesn't need them to operate properly. Even with a complete failure of both fans, chances of the system the overheating in IMC are really low.
 
None of our EFIS systems use or need cooling fans.
This includes our new MGL168 project which manages this feat by using a processor with the current highest mips/power ratio in the industry plus a graphics processor made in sub-100nm technology (amazingly, it does not even get warm).
Our design philosophy is: If it needs a fan, it's wrong - start again.
Reason: Fans draw in moisture and dust and whatever **** is floating around and it ends up inside your unit (and if you filter you end up with a clogged filter and no usefull fan). Fans can and do break. They need power, they need space. They cost money. Rule 1: NO FAN. Enough said.

Rainier
CEO MGL Avionics
 
Rainier Lamers said:
This includes our new MGL168 project which manages this feat by using a processor with the current highest mips/power ratio in the industry plus a graphics processor made in sub-100nm technology (amazingly, it does not even get warm).


Rainier
CEO MGL Avionics
Click to expand...

I know what processor your talking about. I have run or HX software on it. It is just slightly warm while running as hard as it can. It is not ready to replace the processor on our HX yet, maybe in a couple of years. The HX can run at Synthetic at 60 fps compared to 4 fps.

It is the first processor available that has any speed improvements at the same low power draw to replace our processor used in our original units, its been 5 years. It is probably 2 to 4 times faster than our older processor, plus the advantages of the graphics processor.

Todd Stehouwer
Grand Rapids Technologies, Inc.
 
GRT HX fan requirements

rjtjrt said:
I understand GRT Horizon X has a cooling fan.
What happens if the cooling fan fails? Is there a back up fan? What happens if the cooling fan air flow gets obstructed suddenly or over time?
Are cooling fans a significant vulnerability or am I just neurotic??
Which EFIS other than GRT Horizon X have fans?

Too many questions! Getting a headache. Must stop thinking!

John
Click to expand...

The Horizon HX is the only equipment we make that requires a fan. It will operate at 150 degF with the internal fan or air blown on the back of the case from an external fan. We recommend using an avionics fan as a backup.

We monitor the CPU temperature and the internal case temperature. The CPU automatically throttles back to protect itself. We also have control over the throttling. We have the option of turning of the Synthetic Vision and throttling the processor way back without the user noticing any slow down other than not having Synthetic Vision. You would need 2 fans to fail before you would need to turn Synthetic off.

Todd Stehouwer
Grand Rapids Technologies
 
todds said:
I know what processor your talking about. I have run or HX software on it. It is just slightly warm while running as hard as it can. It is not ready to replace the processor on our HX yet, maybe in a couple of years. The HX can run at Synthetic at 60 fps compared to 4 fps.

It is the first processor available that has any speed improvements at the same low power draw to replace our processor used in our original units, its been 5 years. It is probably 2 to 4 times faster than our older processor, plus the advantages of the graphics processor.

Todd Stehouwer
Grand Rapids Technologies, Inc.
Click to expand...

Hi Todd,
Yes, you are right. Adding a graphics processor is worth the effort. Don't know how I managed without in the past. Doing terrain texture mapping using the main processor is hard going - having this done inside the graphics chip at blazing speeds is much more impressive - and it frees up valuable processing time that can be put to much better use...

Keep up the good work !

Rainier
CEO MGL Avionics
 
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