Electric Models Safety Incidents

[Frank Skilbeck]

There was another thread where it was noted that electrical models don't need restraining as they aren't live until the battery is connected, together with the letter in this months RCME where a modeller had accidentally plugged the ESC into the aileron channel on twin, I thought I'd start a thread on electrical safety with an issue we had a couple of weeks ago.

 

It was a couple of new seaplanes myself and a clubmate had built, mine had flown but my clubmates hadn't. Anyway down at the lake first off his ESC wouldn't arm, but this was because he hadn't reduced the trim after that it worked fine and he did some water handling trials. Before the test flight we noticed that he had much more elevator movement than my model had, so he reduced throw to match mine. On plugging in a new battery the motor immediately went to full power and the throttle didn't work, fortunately I was holding the model and he was able to unplug the battery, so no harm done, but if it hadn't have been restrained it could have been a different story. We are not sure why the motor went to full power when we reconnected a battery and this is under investigation (with the prop removed). he could have inadvertently modified the throttle settings on re-programming the elevator we are not sure. 

[Geoff S]

I've recently altered my motor disable switch from one of the toggles to the rotary switch on my Horus.  The rotary switch is almost impossible to operate by accident.  I've also installed my own, quite lengthy warning message when the motor is active. 

 

I have a fairly substantial metal model stand (Model Mate? They're not available now) which I use to install/remove batteries.  I am very careful to keep clear of the prop whenever a battery is installed.

[leccyflyer]

A timely thread Frank.

 

One of the key electric model operating safety measures is to always remove the prop when working on the model. Back before there were readily accessible throttle cut switches I was working on my FW190.  I always say "Don't work with the model on the bench with a prop on" and was just about to remove the prop, but wanted to check everything worked okay. Put the model on the floor in the workshop - the ailerons were reversed - so, into the programming mode on the TX and, as a long time Futaba user, reversed channel 1 in a momentary lapse of reason.

Of course, on the Spektrum transmitter channel 1 is throttle and the model treated me to a leap across two feet of workshop floor at full throttle, taking a chunk out of the door and bending the prop . It could have been much worse - the model could have been on the bench, head on, in a much more dangerous position.. I'd always been careful to only put the prop on when I'd finished setting up the model, but got caught out by not following my own protocols. Lesson learned there.

[Martin Harris - Moderator]

On my transmitter I programme electric models so that the transmitter will not initialise without the lift to operate throttle isolation switch being in the safe position. 
 

Despite this precaution I also handle the model at all times as though it has a running IC engine. 

[leccyflyer]

I also use Throttle Cut on all my models, but this was several years ago, when that wasn't a ready option on that early DX7 transmitter.

[Geoff S]

1 hour ago, leccyflyer said:

A timely thread Frank.

 

One of the key electric model operating safety measures is to always remove the prop when working on the model. Back before there were readily accessible throttle cut switches I was working on my FW190.  I always say "Don't work with the model on the bench with a prop on" and was just about to remove the prop, but wanted to check everything worked okay. Put the model on the floor in the workshop - the ailerons were reversed - so, into the programming mode on the TX and, as a long time Futaba user, reversed channel 1 in a momentary lapse of reason.

Of course, on the Spektrum transmitter channel 1 is throttle and the model treated me to a leap across two feet of workshop floor at full throttle, taking a chunk out of the door and bending the prop . It could have been much worse - the model could have been on the bench, head on, in a much more dangerous position.. I'd always been careful to only put the prop on when I'd finished setting up the model, but got caught out by not following my own protocols. Lesson learned there.

 

I also started out with Futaba and my ailerons are always on Ch1 and 5 - even on my Multiplex 3030 and all my Frsky transmitters.  The joy of flexibility 😛.  Just shows that no matter how experienced or careful we are, things can go wrong.

[PeterF]

1 hour ago, Martin Harris - Moderator said:

On my transmitter I programme electric models so that the transmitter will not initialise without the lift to operate throttle isolation switch being in the safe position. 
 

Despite this precaution I also handle the model at all times as though it has a running IC engine. 

With you here, I swapped my arming switch to one of the lift to operate types to avoid inadvertent operation. Also on my Jeti Tx I have coupled the arm switch with throttle position needing to be at zero. Most ESCs need the zero throttle before starting, but with an arm switch they get the zero throttle at battery connection with the arm switch in the disarm position, so they are ready to go when the arm switch is armed.

[PeterF]

We had a member of our club whos electric model unexpectedly went to full throttle. Fault finding revealed a broken wire in the Tx on the throttle potentiometer which caused a full throttle signal. Whilst restraints and arming switches might not always catch such an issue they would reduce the probability of a fly away. In the incident I refer to it was a helicopter and it rose from the ground cutting him on the face and just missing an eye. It was reported in the BMFA news at the time.

[GaryW]

18 hours ago, PeterF said:

We had a member of our club whos electric model unexpectedly went to full throttle. Fault finding revealed a broken wire in the Tx on the throttle potentiometer which caused a full throttle signal. Whilst restraints and arming switches might not always catch such an issue they would reduce the probability of a fly away. In the incident I refer to it was a helicopter and it rose from the ground cutting him on the face and just missing an eye. It was reported in the BMFA news at the time.

 

Being a heli flier myself ... only real way to restrain a heli when starting the engine ( IC ) or arming the ESC ( electric ) is to hold the main head block or put your foot on one of the landing skids to prevent either the main blades turning or inadvertently lifting off the ground.. or with helis especially set a throttle kill/hold switch which wud be switched on while connecting the flight battery or starting the engine

Edited August 1, 2023 by GaryWebb

[Simon Chaddock]

If full power is the result of an electronic fault putting in further electronic based safety systems does not automatically reduce that risk and may even increase it.

If the full power situation is the result of a human error by one person then further safety stages means that risk is still thematically there.

I do wonder how many errors result from a single user using radio systems with different and more complex setup protocols. 

 

[kc]

Some years ago I setup my new vintage electric model fuselage in a stand on the bench indoors with the prop removed and connected the Lipo.   I adjusted everything to be the way I wanted then replaced the prop all ready to fly.   Then I decided to look into the Tx memory to note what items I had changed - instantly the model went to full throttle as soon as I went into the memory, pulled itself out of the bench stand ( no wings to hold it back ) and chewed into the carpet  and whatever was in it's way.    Fortunately I had moved from in front of the model to alongside!    Shook me a lot when I realised where it would have hit me if I had been in front rather than alongside the model!

The point here is that this was a Futaba 6EX 2.4 and explains a mystery similar accident at the flightline that happened to someone else with a Futaba 6EX.   He took hold of his Tx did something ( he couldn't remember what) and the model started up charged along in the pits missed about 6 people and only stopped when the prop hit a leg and chewed a chunk out  -  fortunately just a chair leg not a human!    The very shaken modeller couldn't remember what he did  but said he didn't open the throttle.    I reckon he went into the menu to look at settings just as I did.  Lucky escape. 

Maybe it's just Futaba?   People often seem to look at Spektrum memory without encountering problems.

So a lesson learnt  -  use a Nicad to the Rx not the Lipo when adjusting the Tx for a new model and always point the model away from people when connecting  the lipo.

 

Frank - I wonder if your friend used Futaba and perhaps tried to look into the memory or did something similar?

[Frank Skilbeck]

KC no it was an Open Tx transmitter. But it was fine when he was doing the adjustments, it went to full throttle when he subsequently plugged in a fully charged battery.

 

But also I've quite often seen models with an inappropriate set failsafe, so if the radio interups the transmission when entering setup the rx will go into failsafe.

[Paul De Tourtoulon]

No Kc, not only Futaba, I have 2 EX 6 radios, it is so easy to go into the memory and change the model, of course no one will admit that it's their fault 🤢

[Chris Walby]

Spektrum TX's notify you that you are about to leave the model menu and go to model select/TX settings (it then turns the RF off), but it does not stop you from continuing. 

 

It will be based on the owner knowing that they need to have removed the flight battery (electric) and/or set the correct fail safe's up. 

 

The newer TX's remind you to rebind the RX after certain functions have been changed like throttle reversal, but then again the owner can ignore doing it.

 

As the say "nothing is idiot proof to a suitable igneous idiot"  

 

PS I was watching an air accident investigate. The commercial aircraft started its stick shaker, both pilots pulled back on the stick and did not increase throttles. The aircraft stalled and crashed. My point is that their training was incorrect, but who trains us on complex (to me!) transmitter equipment?

 

Perhaps the BMFA A and B certs should have a section on evidencing TX control checks as well as model checks pre-flight? 

[PeterF]

The Futaba Tx incidents listed above going into full throttle on going into memory settings. Could this be related to Futaba having reversed throttle direction to other makes and perhaps the Rx failsafe not being set if the transmission is shut down on going into model settings. It is many years since I flew with Futaba radio equipment so I can not recall this in detail.

[kc]

Peter,    The throttle on my Futaba was correctly set ( opposite to other sets ) and didn't need resetting after the incident.   Same with my fellow club member - the model had flown earlier that day so was correctly set.   Of course it could be that going into the memory means that the Tx starts up but ignores any servo reversing that has been set, but when turning on normally it notices the servo settings that have been made.

[Trevor]

I have seen this type of incident before with Futaba users, caused by the transmitter throttle channel being (correctly) reversed to align with the needs of the ESC, but this reversal has not been carried through to the receiver's failsafe setting, as PeterF surmised above. The result is that any interruption to signal, whether range-related or due to Tx programming, will result in the receiver going into failsafe and applying full throttle. This is why, when helping to check out somebody's new model, I always insist on a failsafe check before doing a range check!