Need help figuring out loss of engine in flight.

[Regatoni5]

Hey all, thanks for taking the time to look at this post. Flying my FMS Yak I’m running into a recurring issue.

Aircraft: Stock FMS Yak-130
Battery: Floureon 6s 45c 3300mah
Receiver: Admiral RX10000
Radio: Spektrum DX8E

On my second flight I was turning in on final and my motor cut out. In my flight video you can hear it just cut out completely but flight control surfaces remained operational and I was able to glide it in. Unfortunately it went into a backstop with very minimal damage and I was able to get it back together with. Foam tac, boiling water and a new nose cone. As soon as i got to it I did a function check and motor spooled up and flight surfaces worked again.

i threw in a capacitor on an empty channel in the receiver thinking that it was a brown out issue. And a week later (today) I took her out for another go. The first two flights were uneventful and great. The third flight on the same circumstance, turning on my final I applied flaps and the motor cut out again with the same operational flight surfaces. I didn’t have enough altitude to recover and lost orientation behind the surrounding fence but I did the best I could to level out and down she sailed into the canyon below. Fortunately for me, she flew into a tree a good 5 feet from a trail. I was able to find it by moving my control surfaces and revving the engine. Damage was minimal with slightly dinged nose cone and leading wing edges taking a brunt of the impact.

it doesn’t seem like I’m having a brown out. Could the system be overloading causing the motor to cut out but still leave me the flight control surfaces as a “fail safe.”

I thought id consult with the more knowledgeable pilots on here since I’m left scratching my head. Thanks for your time.

[RRHandy]

How did the battery check out, what was left?.

[fhhuber]

Consider the reasons the ESCs will shut down.

#1: LVC. That would be a battery that can't deliver the current demanded. Do on ground test at full throttle for a full pack using a wattmeter. If it won't deliver on the ground its not going to deliver in the air.

#2 HEAT. If the ESC overheats 90%+ of those made today will shut down in self preservation. One of the causes of overheat it overloaded BEC section. The ESC will shut down the motor first and if it continues to overheat, some will shut down the BEC.... some will keep trying to operate the radio until they burn out.
Same test as #1. Check the ESC temp with IR thermometer. I don't let mine go above 150 F.

One source of BEC overheat in twins is the BEC's "back feeding" each other. Never parallel BECs without at LEAST a diode to prevent wrong way current on the + lead.(note that diodes drop voltage and might cause issues... like Spektrum Brown Out, reduced servo speed and reduced servo power.) I tend to just disable BEC in twins and go to a separate LiFe RX battery.

#3 Bad connect. If you have marginal solder joints or bad connectors, your ESC is going to see a LVC condition. I have MELTED THE SOLDER JOINT at the bullet connector of a brand new pack because the joint was bad from the factory.
Same test... Check the connectors for heat. (also check the wires because some cheaper PNP and RTF models come with cheap ESCs that have inadequate wire for their rated current demand) Your wires and connectors can feel warm... but if they are hot you have a problem. I've seen the wires melt EPO due to being too light.

#4 Just a bad ESC. And again, it should show in ground tests.

If the plane can't do a 100% power static test on the ground from full pack to LVC, you have something that needs to be fixed. Don't even try to fly it.

A twin or higher engine count model with one (or more) "engine(s) out" causing asymmetric thrust has to be flown with EXTREME care, keeping wings as level as practical (turn on rudder and GENTLE aileron to keep it level) Often its best to just shut down throttle and glide it in. Pulling up is almost always going to lead to a stall and spin with asymmetric thrust. Turning toward the dead engine and banking can easily cause the working engine to pull your nose straight down without warning.

[xviper]

the motor cut out again with the same operational flight surfaces. I didn’t have enough altitude to recover and lost orientation behind the surrounding fence but I did the best I could to level out and down she sailed into the canyon below. Fortunately for me, she flew into a tree a good 5 feet from a trail. I was able to find it by moving my control surfaces and revving the engine.

I've had this happen to me a couple of times. I don't believe it's a "brown out". I think it's an ESC issue. Something caused the ESC to cut out. Then, after you lost the plane, I assume you lowered the throttle while looking for it and then you were able to run the engine again. I had a EDF that did something like this. After it cuts out, I shut down the throttle and then immediately turned it back on again. The motor ran. If I went high throttle again, it would cut out again. So long as I kept the throttle reasonably low, I could fly it to landing. This was not a stock set up. I'm going to bigger ESC with more ventilation. Haven't tried the plane again yet.
Same sort of thing happened with a prop plane. I over-propped it and the ESC couldn't handle it. I've since put in a really big ESC that I had laying around and it's never done it again.
Next time (hopefully there won't be a next time) it happens, shut the throttle off momentarily and try the throttle again. If it works, don't go high throttle and land ASAP.

[chipset35]

I've had this happen to me a couple of times. I don't believe it's a "brown out". I think it's an ESC issue. Something caused the ESC to cut out. Then, after you lost the plane, I assume you lowered the throttle while looking for it and then you were able to run the engine again. I had a EDF that did something like this. After it cuts out, I shut down the throttle and then immediately turned it back on again. The motor ran. If I went high throttle again, it would cut out again. So long as I kept the throttle reasonably low, I could fly it to landing. This was not a stock set up. I'm going to bigger ESC with more ventilation. Haven't tried the plane again yet.
Same sort of thing happened with a prop plane. I over-propped it and the ESC couldn't handle it. I've since put in a really big ESC that I had laying around and it's never done it again.
Next time (hopefully there won't be a next time) it happens, shut the throttle off momentarily and try the throttle again. If it works, don't go high throttle and land ASAP.

Is this an FMS ESC issue? Or an ESC issue in general?

[fhhuber]

Sounds like LVC (Low Voltage Cutoff)

This can occur from other than the battery being depleted.

Bad connection somewhere between battery and ESC will do it.
Loose bullets/T connect.. bad solder joint, wire broken inside the insulation...

You can also get similar result from an ESC's thermal protection. Not all ESCs have this, some will let the magic smoke out before they shut down. If you are running very near the thermal protection temperature, then it can shut you down, cool down a few degrees in seconds and be able to resume power to the motor as fast as you lower throttle then move the stick back up... then shut down again.... repeat until impact because you're trying to figure out the power loss instead of flying the airplane...

[xviper]

Is this an FMS ESC issue? Or an ESC issue in general?

This has happened on 2 of my own "modified" planes and on about 3 planes of a friend of mine. His were all "modified" with different motors, ESCs, etc. I concluded that in all cases, the ESCs hit a voltage cut-off or thermal cut-off and shutting it down did some sort of reset. No, it wasn't an FMS issue. The ESCs involved were of various makes and sizes.

[rifleman_btx]

I will also side with LVC. I have a couple questions, what connector were you using, and how long were you flying? Im using 4500s in both my fms edf planes all with stock components. I get 6 minutes out of my fa18, and 3 from my a10 with throttle management. What is the voltage when you pull your packs? Mine are around 3.8v per cell. I will do temp readings off mine this Sunday when i go flying. Hope you get this figured out

[xviper]

I wish I could answer you with specifics but it’s been a while for me. I can tell you that it was a variety of batteries from 4s to 6s, in prop and EDFs. On those occasions, the plane went about one circuit before quitting. I had RX power and was able to land with one and after “reset”, the other was landed under moderate power. They were good batteries which I’ve used many times since. Don’t recall voltage left but it was not note worthy. After all, with only one circuit, I doubt it used much. After increasing size of ESC, those planes are flying fine now.
My friend, on their hand, it’s still a bit of a mystery as he doesn’t talk much about it. He crashes a lot and for many, many different reasons. He comes back and says, “It just quit on me”.

[rifleman_btx]

Yeah i have had those kind of things happen, but mine turned out to be batteries the reached their retirement stage, bad cells, extreme voltage sag. Stuff like that.

[Quickstop]

My preditor esc in my 80mm hawk never worked from the box, would shut down after ten or so seconds. smartest thing was to replace it with a hobbywing esc and never a problem again. I also have the fms 70 mm f-18, which has always worked perfectly. Moral of the story is you can get a bad one or just have it go bad after a little while. Much cheaper to replace it than to keep experimenting and risk the plane.