Looking for answers/help .
Flying my TB40 today with spirit GT , using Rescue automatic . On the 3rd flight of the day after bringing the heli into a stable, level hover I engaged rescue automatic to set the hard deck .however instead of the helicopter climbing after flipping the switch it descended just as fast as it should have climbed, smashing the helicopter into the ground . The helicopter was blades up the entire time just went straight down .
I just stood there dumbfounded, I checked all my switches to ensure they were in the correct orientation and they were.
There were No abnormalities when initializing the unit. Everything prior to this happening was exactly as it had been on the previous flights .
It simply decended the helicopter instead of climbing when rescue automatic was engaged to set the hard deck altitude at about 30-40 above the ground . Again skids down blades up in normal orientation the whole time .
Please Help me figure out what happened. My assumption is there was a glitch in the spirit GT unit or its firmware .

Things I would check: collective stick movement matches channel movement in spirit diagnostic screen (up is positive), collective direction not incorrectly reversed (radio and spirit advanced tab), unit position matches configuration (not inverted from setting), rescue collective pitch set correctly in stabi tab. If one or multiple of these things are wrong you could get correct stick response on the servos by reversing something elsewhere, but it will cause problems.

A log would probably help as well as more information such as if the rescue has worked correctly before on this setup and bench test results (does rescue correctly move the swash upwards?) to determine if it was a one time thing or something else.

We are sorry to read about your model.
Fortunately the behavior can be perfectly explained and could happen even if model is flying seemingly well.

This page lists reasons and things to check:
https://manual.spirit-system.com/index. ... ise_Rescue

Once they are sorted it will work with 100% reliability.

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Spirit System developer

Thank you for responding.
I built this model and installed this spirit GT this spring and have an over one hundred flights on it . Nothing had changed with the setup or helicopter, I saw nothing out of normal when I preflighted prior to this flight , the initialization was as usual and control direction normal , the take off and hover went as usual and very smooth with no noticeable vibration.
It simply went down instead of up when I engaged rescue level . From my point of view it had to be a glitch in the unit or firmware .
Of course it’s possible that something happened that I missed or didn’t notice .
After the crash I did reboot it and the swash moved up when rescue was engaged on the ground .
I will double check all channel direction etc in diagnostic page , but assume it will be fine .
You mentioned a Log , could you tell me more about what you would be looking for in that log ?
I just want to determine what the cause of this was and if it’s the unit I want it repaired or replaced as it’s only a few months old .
Unfortunately if I can’t figure out the root cause I’m not sure I can trust the unit to not do it again randomly.
Thanks in advance for helping me get to the bottom of this .

Thank you for the details.

Helicopter models and their mechanic is wearing each flight so even that nothing is changing by you, it is common that after hundreds of flights a bearings might need replacement. Sometime just after 20 flights if it was not perfect fitted from the beginning and overheating.

For you model can still fly perfectly, but for Rescue difference could be night and day, because for example faulty bearings could cause exactly what happened to you.
If there is vibration issue you will almost never notice any oscillations of the model. This is usually result of too high gain (settings). Spirit is very tolerant to vibrations so it could fly without any issue. But Rescue works like complex math where all manevers you did at the flight are integrated. So at the beginning of flight possibility for Rescue issue is very small (even if there is something seriously wrong). But at the end of each flight probability is the highest.

For this reason we recommend to check Rescue at the end of each flight immediately after landing. If it will work well there, you can be sure there is no issue. In this way you can avoid any damage and gain confidence.

If there was something wrong in your settings I think you would notice it sooner. But if your flight manevers are noticeably more complex then previously it could show this problem only after these maneuvers.

The highest probability is that something started to fail mechanically. Please verify vibration level with Spectrum Analysis tool (preferably with tail blades on).

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Spirit System developer

Okay , I understand what you are saying, and I agree it’s very possible for everything to be perfect one flight and have a bearing or something fail that goes unnoticed. I also u derstand that the rescue can show this issue much sooner than regular mode .
If we suspect vibrations caused the issue , is there a way to access vibration levels in the flight log for that flight ?
If not I’m not sure what good checking vibrations after the crash would do as the helicopter is now damaged .

Post crash inspection showed nothing other than crash damage .
There was slight looseness in the feathering shaft to blade holder connection , but I would consider it normal , and have certainly flown and seen much looser flown without issue .

I did look over everything in the setup menus and diagnostic page and everything appears to be working as it should .
Every time I engage rescue auto on the bench it works as it should , with the motor running or not .
I checked the vibrations on the analyzer , no main or tail blades ( as the were damaged in crash) while sitting on the bench they were running 47-49 total on the status bar on the RH side , with a notation that said Normal .

So Far I’m not coming up with anything model related to cause the issue .
Please advise further testing/ next steps .
Thanks!

I experienced an unexpected "Rescue" behavior around 8 years ago. Maiden flight. I tested Rescue while hovering at eye level. The helicopter dropped down, instead of lifting up. I was never able to figure out what caused this unexpected "Rescue" behavior. Since that incident, I test "Rescue" at no lower than around 50 feet altitude. At the same time, I have not experienced any unexpected "Rescue" behavior since that incident. I reused that Spirit unit on the rebuild, and no subsequent issues with it either, which makes me think I may have configured it wrong to begin with.

similar experience but after engaging altitude hold with the GPS, the heli simply shot down full negative pitch, and this flight was after 4 previous flights with no issues at all.

I would be great to have some indication/warning to that we get to know this, maybe a fast LED flash after flight or some swash movement during initialisation? to warn that a recent flight had critical vibrations levels and the model is not fit for any rescue/auto level modes until its fixed.

The problem is that each kind of vibration could have different impact on Rescue/Stabilisation modes. Generally vibration level could be extremely high, above mechanical capabilities of the model itself. But if these are resonant vibrations any motion sensor will stop working properly. Then there are autocorrection mechanisms that are doing corrections all the time. But then it depends on what figures you are flying. And then even if your settings are wrong it still can work correctly (even for years), but after flying longer or flying more complex maneuvers it could fail one time.
In other words there are many variables that could affect it, even excess heat of your motor/wrong placement of the unit.

On the other hand we can add check if Rescue/Stabilisation had wrong direction after landing. Simply because models are usually not landing with rotor down.
So you would have chance to at least fix it later.

On a side note, if you are experiencing the Rescue/Stabilisation failed, you can be almost certain that with other FBL unit it would fail much sooner as Spirit Rescue is very tollerant to vibrations and can handle all maneuvers in a normal circumstances.

We recommend to add warning for telemetry vibration level - if your model will exceed usual level then you know something wrong will happen.

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Spirit System developer