Nasty incident

[Erfolg]

We all seem to agree, that it is not sensible to not attach the prop with power available until in a safe area and arranged so that the operative is also safe. Which, which for most of us outside. There will be some who have for instance a large double car garage which is empty, for me it is increasingly outside.

I personally break the setting up into a number of phases.

• centre servos, set ESC, using servo tester and program card using a Rx battery for power.
• Only then is the equipment installed in the model. I check the practicalities of accessing motor wires, that servo arms are at 90 degrees to the control linkages (easily checked again with servo tester) etc I do put the motor and propeller combination together in the model. There is no need for power, I am just checking the fit and maintenance aspects.
• When everything is installed and supposably finished, I do a check of the RC side of the system, via the ESC Lipo. Again no need for the motor to be connected.
• It is only now, when I need to do a proper system check do I put on the propeller and do my rotation and power checks. The failsafe check, is now the second part of the rotation check when on 2.4. These checks are done in a suitable location, which is increasingly outside. I have and do checks in the kitchen of my indoor models and in the past small (by current standards) set ups about 100w.
• There is one check that I have started doing, which I trusted to programming now as a separate test and that is the voltage cut off, which I normally set at a high value and set to a description of soft/reduced power. This is after I forgot to set my Tx timer and the motor did not go onto reduced power. As the voltage check came in at 30% ish.

By using the power down facility of all my current ESCs, there should never be a dead stick event. This is a back up to using my timer. Before having a Tx with a timer, I kept models close (as they were small electrics) and relied on observation that the motor was starting to sag. Not the ideal solution, thought the low power setting acts as backstop. I have always considered running the lipo to the point of below 30% as very bad news and going dead stick as failure of good operation.

I personally think the important thing is to disconnect the Lipo when doing anything other than running the motor. All my adjustments are done at home, not at the field, which I do see, for a variety of reasons.

I never, ever, adjust my Tx functionality with the Rx live. It may seem inconvenient to reconnect the Lipo, it is for me a way of ensuring safe working, in any eventuality.

What is apparent that some modellers, and I will not go into details, as I do not want to be personal, and for people to recognise the events, do not do any power checks. Which I can say ( again without the details) has lead to the demise of two models quite recently. In other cases, it was apparent that the model had never been run until readied for flight. I personally believe it is important that the model has been thoroughly checked and set up as far is practical in a controlled environment, free of pressures, by a predefined, structured procedure, not necessarily written down, but thought through (my own is not written down). I see this aspect of great importance from a safety aspect. You may not loose a finger, but possibly damage property or persons as a consequence of system failure, damaged Lipo, burnt out motor, leading to other electrical damage. These checks for me are mandatory for safe operation.

I do find it interesting that there appears to be a subtle but important shift, in the definition of a secured model, which now appears to be moving from the devices as used with IC aircraft, to one which can be argued could be as (BEB) restrained appropriately which could be by being held, as is appropriate to indoor type models.

My final concern, is how many times I have recently seen electric models being worked on, with the Lipo connected. I always (that is my believe) disconnect the Lipo whenever I do anything, other than readying for immediate flight, or a check.

I

[Andy48]

I don't understand why you do a failsafe check after attaching the propellor. This can be quite happily done before. The few seconds a motor might run at full speed with no prop on should not damage the motor.

[Erfolg]

I know that the failsafe will work under operational conditions.

No doubt, I have learnt the lesson of Unilever and Persil Power, with their washing powder, there would be no problem segregating the testing, that was until the public got there hands on the product. There have been many examples where testing under conditions other than operational, have failed to identify issues.

[Peter Beeney]

Yes indeed, Erfolg, I too know from some practical interfering with mechanical and electrical gadgets you never believe anything that anyone tells you, you do a complete check on everything until it works properly to your satisfaction.

And so breaking that rule straightaway, I can say that in this case though, you would only be checking the failsafe setting, which is a function of the transmitter and the receiver. So a servo plonked in the throttle channel would tell you exactly the same thing. That’s how you’d check an i/c failsafe condition. Testing the ESC with the prop on/off is simply telling you that the ESC will shut the motor down. So the test would be equally as valid with the prop on or off, and the motor turning at full speed or only slowly.
This is only my take on it, though, if you’re happy with your procedures then that’s what really counts.

The motor will run indefinitely at no-load speed without damage; unless it’s taken way out of spec. If it is damaged in any way then it’s likely to be rejected by the scrap yard as even second class rubbish!

PB

[Erfolg]

The reluctance to test equipment under operational conditions, raises the prospect in the event of a malfunction the challenge, how would you know that the system operated in the required manner? Your honour there is no reason that it should not, it was just a logic function. Really, how do you know that is all that it is, because it did not operate as you suggested. Have you the manufactures basis of design? Where is your safety documentation and design documentation which verifies this proposition?

I have never seen yet where it is not a requirement of an industrial safety system where the system is not as far as is practicable full sytem testing under operational conditions. Partial tests may be acceptable as stepping stones to full tests During operation partial tests may be acceptable where full testing raises substantial issues, though full tests will be required on an agreed regular basis. During commissioning it will be a requirement to replicate as near as practical the actual operating conditions, particularly where a licence to operate is required. That if a conversation along the lines above is to be avoided in a court of law or with a regulator, who will probably object to plant operation.

We obviously are not in quite the same position, other than if something were to go badly wrong, then the same ideas/concepts would be rolled out.

There is no additional safety issue which cannot be managed during setting up, that justifies not undertaking a practical test when setting and recording the drive train performance. I would suggest any practical test of the failsafe at the flying field, will take place under operating conditions, propellers will not be removed.

For me the irony has been I have normally had to resist the desire of others to undertake in-depth testing without a good cause. Here I find we do not want to undertake a full test, because it is felt that managing the risks is to inconvenient. Or maybe the checks on watts drawn etc are being avoided as not being of any consequence, having no potential safety implications.

At some point the propeller has to go on, to me it is logical that its rotation is verified under controlled conditions. It is also logical, that there is no argument that a system is verified as being fully operable under operational conditions. Then there is no argument that you could and should have done more to ensure that the Rx and ESC goes to the off condition, when there is loss of signal.

I do find as certain irony, that I seem to be the extremist with respect to ensuring safe operation, after working in two industries, where I used to think that some safety aspects were extreme and very costly, for no or little gain. Although a believer in CDM and Risk Management, much else about shoving a protective book down the pants.

[Pete B]

Posted by Erfolg on 23/07/2013 22:23:59:

At some point the propeller has to go on, to me it is logical that its rotation is verified under controlled conditions. It is also logical, that there is no argument that a system is verified as being fully operable under operational conditions. Then there is no argument that you could and should have done more to ensure that the Rx and ESC goes to the off condition, when there is loss of signal.

Following that logic, Erfolg, should you not be advocating testing the system by having a helper walk the model away from the Tx until it goes out of range (a low-power test not being 'operational conditions', of course)?

Pete

[WolstonFlyer]

Oh now now! This is getting silly

[Biggles' Elder Brother - Moderator]

Helper needs to be on stilts to simulate altitude as well.

BEB

[Martin Harris - Moderator]

Seldom has so much been written to argue such an obscure point.

Test failsafe under operational conditions by all means - which should really be done prior to each flight but please don't dilute the message that when you're working on a live model, having the propeller attached to the motor is an accident waiting to happen!

[stevejet66]

Dont you think this thread is well and truley blown out! Guy made a mistake ok! like we all do with models and we learn by it, He was trying to express his view about his model and it truley shook him up what happened. Instead of the simple conclusion over the matter this as been blown out of proportion like a house of commons back benchers debate.

[PatMc]

...and running at 50mph with an occasionaly somersault to simulate aerobatics.

[stevejet66]

Lol its a bit of a shock but ive been there wore the Tshirt as most of us have! As i say we live and learn.

[David Tweddle]

Posted by stevejet66 on 23/07/2013 23:25:01:

blown out of proportion like a house of commons back benchers debate.

Oh did I nod of sorry, can I put in my expenses now...

[Terence Lynock]

well, this afternoon after finishing the electrics installation I had exactly this problem of inadvertant start-up, not through programming fault or anything else, just a total split-second accident that could have ended in the operating theatre.

Having done everything needed with a new trainer type model and getting it ready to maiden tomorrow hopefully I turned to put the transmitter down,hooked the throttle stick in a fold of my tee shirt and went to full power, an APC 9x5 at full throttle is a very efficient mincer, it sliced through seven sheets of paper and the plastic document sleeve they were in, chewed up the plan under it turning it to confetti.

This was one of those very rare moments when you have a model that is live, during an electrics test and although everything is set up properly and doing as it says on the can things happen and usually so quickly you dont have time to react, I did make sure hands and movable objects were behind the prop at all times but it is so easy to become complacent about electrics, with i/c when the motor is running you can see it but with electrics it can go from zero to flat out meat mincer in a second.

Anybody want to put this lot back together for me?

[001]

I think that the 'normal' person would never start their I.C. engine in the lounge or kitchen or bedroom for obvious reasons. Shed or garage, maybe with ventilation etc.

It is so tempting do do that 'last check',( bit like that 'last flight' with an electric motor indoors 'because there is no smoke, no oily spray and very little noise'.

My own experience was that I was checking some control function or other on a 0.40 size brushless motor plane and decided to do it indoors whilst swmbo was out. I actually loosened the prop right off. The motor started unexpectedly at full throttle. The plane didn't move, but the prop spun up very fast, shot forwards and up and one tip embedded itself about 6mm into the ceiling 3" away from a flourescent tube light fitting. I had to remove it and fill the hole pretty rapidly. Now, that could have been my eye that the prop hit.

It could also have smashed the tube and brought it down on my head or face.

So, whenever I have changed anything, battery, transmitter function, between flights or if I have any doubts or second thoughts, brief distraction, I always take the prop completely off.

If I had been working on an I.C. engine, I would have had to physically start the thing and I have had 55+ years of practice and ingrained habit keeping clear of them, partly because they are noisy..

[andyh]

Posted by Martin Phillips on 18/07/2013 20:02:23:

Not if you fit a safety plug.

apologies for the stupid newbie question (the stupid question is the one you don't ask, etc...), but could someone explain/post a link to a safety plug? I'd be very keen to have way to make a model safe whilst fafing about with wire, hatches, etc. I quite like my fingers beung attached to my hand

[andyh]

Posted by PB on 19/07/2013 17:23:12:

Is there a case growing for an EP A test and an IC A test which restricts the candidate to that type of flight only.... ......or is that another thread?

sorry to go OT - did another thread get spawned for this?

does an Elecrirc A test let you fly IC to A-test standard (ie solo) too? I had rather inferred by the existence of the two separate tests that they qualified you to fly only that type - seems like a bit of a waste of time to have separate tests otherwise ...

[PatMc]

The BMFA "tests" are personal achivements not qualifying tests. Some, but not all, clubs use them to decide if a pilot is OK to fly solo. This would be the clubs' own decision so they will also have to decide on whether Electric & ic "A" tests are equal or not.

[Pete B]

Martin Phillips posted good info re safety plugs here a couple of days ago.

pete

[Erfolg]

Link arming plug, one of many

[WolstonFlyer]

Andyh - there isn't two fixed wing A tests. There is just the one test and it does not say how the model should be powered. Even if your model is electric you could get asked questions about IC model safety when you take the test.

There is the 'slient flight electric -A test" but that is for powered gliders and has an element of thermal soaring in the test as well as powered flight.
**Link**

[andyh]

thanks gents

I have seen a safety plug before after all, just wasn't familiar with the terminology, think I will be putting these on my electric models from now on

re. the A test, apologies, I was sure I had seen separate tests but maybe I was confusing it with the silent electric one

as you were

[Tim Cheal]

Along with the other electrickery safety precautions I have taken to a very simple solution which has helped me, I use an elastic band to keep the throttle closed on the TX.

This prevents any inadvertent throttle opening and gives me some piece of mind.

Tim

[Tony Bennett]

i do the same as tim.

simple and effective.