Static control w/ belted heli - ground the SK540 housing??

[Carpetbombing]

I just got a Protos 500, and quite a few people have reported static hits that locked out the FBL controller / receivers and made the heli completely unresponsive. Most resulted in crashes, though a few rebooted in three or four seconds and had enough altitude to recover. There are lots of photos of the actual sparks, so I think it's safe to presume this is a genuine problem with the heli. Especially in dry Minnesota winters. I'm running a Skookum SK540 FBL controller with an aluminum housing. So - I'll put silicone spray on the belt, and run grounding / bonding wires from the tail case to the motor, but it occurred to me - if I'm going to have a network of conductive static equalizing wires on the heli, would you WANT to connect a wire to the aluminum housing of the FBL controller? Would this be the best thing to do to prevent ESD to the FBL controller, or the worst?? Or 'it depends'? It'd be easy to loosen one of the screws holding the SK540 case together and attach a small wire to my 'grounding network.' It seems like a spark could sneak in via a servo wire no matter what I do. Any authoritative answers here?

[sctholson]

Is it a carbon frame? The tail box is conductive, so if you are running the carbon version you won't need to ground the boom to the battery. However with the non-carbon version frame you will need the tailbox or boom grounded to the battery.

The tail case I'm not sure. I ran a small wire from the tail case bearing to the boom (inside the tail case - no external wires).
Never needed to ground the 720 blue or black.
Best thing to do is to take the blades off and test it yourself with a multimeter. Static build up and resulting spark was very evident before grounding and the reduction was just as clear. Touch the ground sensor to a bolt on the motor mount and the positive sensor to the outside of the tail case while it's running. The static discharge will be evident and also something you can measure when you try your grounding ideas.
I never lubed/sprayed the belt after the mods.
I ran a 9503 with DSMX sats

[Shogun71]

A staic hit took out my 540 resulting in a crash. I was not high enough for it to recover.

This was on a Compass Atom 500.

The simple solution is to ground the boom. Sand a small portion of the boom and zip tie a wire to bare metal or put a small screw in the boom with a wire wrapped around it.

Then connect the wire to the motor mount so there is effectively a "grounding" point.

Next get a volt meter and check continuity between the tail shaft and the motor mount screws including ones that were not used to hold the wire. If there is continuity then you have "grounded" the boom and in all probability removed the chance of a static kit.

Mikado has come out with a "grounding kit" for some of its models.

[omerco]

Originally Posted by Carpetbombing

I just got a Protos 500, and quite a few people have reported static hits that locked out the FBL controller / receivers and made the heli completely unresponsive. Most resulted in crashes, though a few rebooted in three or four seconds and had enough altitude to recover. There are lots of photos of the actual sparks, so I think it's safe to presume this is a genuine problem with the heli. Especially in dry Minnesota winters. I'm running a Skookum SK540 FBL controller with an aluminum housing. So - I'll put silicone spray on the belt, and run grounding / bonding wires from the tail case to the motor, but it occurred to me - if I'm going to have a network of conductive static equalizing wires on the heli, would you WANT to connect a wire to the aluminum housing of the FBL controller? Would this be the best thing to do to prevent ESD to the FBL controller, or the worst?? Or 'it depends'? It'd be easy to loosen one of the screws holding the SK540 case together and attach a small wire to my 'grounding network.' It seems like a spark could sneak in via a servo wire no matter what I do. Any authoritative answers here?

I fly a logo so the problems are similar.
my solution is this and it also improves glitches in RPM single for the SK governor:
- connect the tail case to the boom (if the boom is anodized there is no continuity unless you sand it or but a screw in it).
- connect the boom to the main pack negative terminal.
-connect all that to SK negative terminal (or to the Rx pack if you have one - its the same).

The connection between the main pack and SK negative (or Rx pack) is needed anyway for the phase sensor to give common ground reference.

If you are using a BEC from the main pack then you only need to connect the boom to SK negative because the BEC brings flight pack negative to the gyro (making wiring the same as described).

[EBrom]

I haven't had the issue, but I don't want to start now. Here's a pic of what I did from some info/ideas I got from the forum.

Hopefully you can see the black wire going from the red yoke connector on the motor mount and the wire is threaded through the side frame and then you can see the wire over the tailboom holder with a screw in the bottom of the tailboom.. Just my way of doing it.
I'm sure there's 100's of ways, maybe some better..

[Carpetbombing]

I'm up to speed with the fixes / mods to control static, my question is if it's advisable to ground the aluminum SK540 case (or maybe the negative bus of the pins on the SK540??) directly to the wire I'm going to use to connect to my tail case to the motor mount. I presume electrical engineering know-how and maybe some detailed knowledge of what the SK540 innards look like is required to know the answer to this. I think it would either be a really bad idea or a really good idea for preventing static hits to the FBL electronics - not sure which. =)

[omerco]

SK negative is the way to go. If you connect it to the case you can create a spark between the case and the internals - which is exactly the opposite of your goal.

look at mikado website they have nice diagrams of how to wire grounding+ phase sensor, but even without the sensor the negative of the Rx pack/SK is the right place.

Without a phase sensor you can skip the gyro - all you really want is to discharge the belt to the motor/main pack negative.

[Rotory30]

I'm installing a sk540 on a goblin 500, is there a problem with static build up on a sab, does it require grounding the boom also