rc plane crash - 68% pitts challenger robbie skipton at raf cosford

[Adrian Smith 1]

That's fine Owdlad, I just wish you had put all that detail in your original post rather than a throwaway comment which needed qualifying. Presumably you know for sure it was a loose spark plug do you? If so a definite maintenance lapse which could have been avoided.

[Owdlad]

Posted by ChrisB on 18/07/2016 21:35:50:

Posted by Barryorbik on 18/07/2016 20:55:53:

Terrible to see such a lovely aircraft destroyed but does anyone know the cause?

and does it really say 'skip' on the aircraft piece being carried to the trailer in the still photograph at the end of the video.

The cause was a spark plug coming loose and the engine dying.

Great shame, but its one of the pitfalls of the hobby unfortunately...those that have and those that will. Robbie will have another monster aerobatic plane in the air soon enough!

 

I bare no ill will towards the pilot.....infact the oposite as it's gut wrenching when this sort of thing happens.

The key issue is that lessons are learned so as to prevent it from happening again. This is why an accident & investigation should be carried out. Let me stress! this type of investigation is in the intrests of safety and not to oportion blame it is to find out the root cause and act upon it, put measures in place to prevent such occurrences.

Let's not forget that this model was bordering on full size (68%), where all sorts of rules and regs apply

Edited By Owdlad on 19/07/2016 22:59:33

[Dave Hopkin]

Posted by Owdlad on 19/07/2016 21:35:27:

The pilot looks nervous............flying in front of paying spectators effects your mindset and it can effect your performance for good or bad.

Reason for the crash........ loose spark plug causing the engine to die.

I'm sorry but that's pilot error due to lack of effective maintenance. Flying a 60+% scale monster with a 400cc motor up front in front of 1000s of spectators all reliant on a radio signal is a recipe for disaster and proper safety measures should be in place

Before every flight a thorough pre-flight maintenance check should be carried out.....every last nut & bolt should be checked over including the engine. Spark plugs don't suddenly become loose.

I will stand by what I say......pilot error... let's hope that people learn lessons from his miss fortune.

I hope the LMA are conducting an accident investigation to prevent such occurrence from happening again and don't brush this crash under the carpet which I suspect will happen.

Assumptions owdlad - this is what the Pilot posted about the accident on the LMA forum.....

Well as you know Dad and I are quite anal about our preparation. but on this occasion a £6 spark plug let me down. you just don't expect one to unwind itself still on the plug cap and hanging there out of the engine. I hadn't had any warning or any problems up to that point. Flight was all OK then all of a sudden i lost all power no real options as i was going down wind. She began to stall so flew away from crowd line, I tried to turn it well the other side of runway to land but in she came. Quite a bang. No damage to prop, engine or electronics on inspection only the plug hanging out on ht cable. But air frame is in a skip. I have to be pragmatic, i've had a good run for 6 years without loss, it had to happen sometime. The engine will be hanging on another Bipe by Christmas. Thank you for all support shown today it was very humbling.

He was down wind and left with very few options, his first thought was crowd safety the second to attempt a recovery - neither to me shows signs of nervousness or lack of preparation.... I wasn't there this year but watched the pair of them prep that aircraft for flight last year and they were extremely careful and thorough

[ChrisB]

"I'm sorry but that's pilot error due to lack of effective maintenance. Flying a 60+% scale monster with a 400cc motor up front in front of 1000s of spectators all reliant on a radio signal is a recipe for disaster and proper safety measures should be in place"

 

Models of that size under-go regular checks. Its very very rare for a plug to come loose.

I'm sure an investigation will take place and to suggest that it will be swept under the carpet is an unfair statement Owdlad.

Lets not forget the crash happened in front of thousands of people on a full size MOD airfield and can't be swept under the carpet. Having been involved in the organisation of such events I can say that much planning goes into safety, including discussions with the CAA.

The aircraft was 68% full size and weighed over 20kg. Anyone wishing to fly it must have been certified on it, as Robbie was. It underwent a build inspection and certification and a series of test flights before being allowed to fly in public and any changes made to it, replacement engine, radio, structure etc would require additional inspection.

Knowing Robbie, he won't have been nervous, having flown it and several others of that size many times.

The fact is that sometimes, no matter how much redundancy is implemented things can go wrong and that's a fact. Twin receiver/powerbox systems multi-ganged servos....only one transmitter, only one engine. Risk cannot ever be eliminated, only mitigated.

 

Edited By ChrisB on 19/07/2016 23:13:02

Edited By ChrisB on 19/07/2016 23:35:02

[Owdlad]

The key issue is that lessons must learned

[Robbie Skipton - Skip Model Designs]

I have to admit. I do enjoy reading forum posts that are blatently slating people.
Firstly lets get a few facts straight.

If i was nervous, or didnt feel confident in flying such a model, do you think i would fly it infront of 1000's of people every year. No. Unlike some model fliers, i dont need a drink to gain confidence to fly!

Secondly. I love getting the blame as pilot error.... can you explain this... the plug came out still in the plug cap! FYI. Zdz engines have a common issue with this and it can happen at anytime ( even if you check it regular) i have so far had to repair 3 zdz engines because of this problem in the larger engines range ( where a helicoil was needed to put the plugs that are blown out of the engine, back in.

Zdz 160 mine
Zdz 210 ( james morris).
Zdz 80 ( cant remember club members name)

So to blaim the pilot for ppp ( poor prep ) is completely wrong.

If you would like to talk about how long it takes to check these planes over and go through our own checklist and pick faults. Please call me on 07912439473 instead of posting acusations on a forum.

Nastyness over. Thank you all for the kind and concerning comments.
New 65% challenger is well underway. Please look on facebook for me to see updates.

 

Edited By Pete B - Moderator on 20/07/2016 12:44:40

[bigbubba]

If it is a common issue for the plugs to come lose on ZDZ engines then should they be used in such expensive large models?

If someone used a RX that had known reliability issues then would that be acceptable?

Posted by Robbie Skipton on 20/07/2016 00:51:24:

FYI. Zdz engines have a common issue with this and it can happen at anytime ( even if you check it regular) i have so far had to repair 3 zdz engines because of this problem in the larger engines range ( where a helicoil was needed to put the plugs that are blown out of the engine, back in.

[Martin Harris - Moderator]

It's been nagging me that the blame for the accident appears to be put on a plug blowing out of one cylinder leading to insufficient power to maintain flight. Even with the massive drag of a Pitts, shouldn't the remaining cylinder have allowed a safe landing under reduced power? I wonder if there could have been a further problem - does the spark continue to fire via the screened lead perhaps giving interference for example or does the twin ignition system throw a wobbly if one plug's earthing fails leading to total engine failure?

Robbie's info on ZDZ plug problems would prompt me to question whether precautionary helicoiling might be a good idea for these engines?

And in case anyone thinks I'm having a go at Robbie, I have great sympathy as I have to admit to losing my Yak last week in a very similar accident after the exhaust pipe blew out of the cylinder head of its ASP 180 - tank pressure loss led to an instant engine cut and it dropped a wing as I attempted to level out of the curving deadstick approach at about 5 feet - which surprised me greatly as I thought I had plenty of airspeed (or should I say a safe AoA BEB!) in hand...

[cymaz]

Posted by Owdlad on 19/07/2016 23:52:30:

The key issue is that lessons must learned

I lost a plane at an lma show. It is a nasty feeling. By the sounds of it it have flown at a few shows yourself.

Even though mine was not on the scale of Robbies, it still had a careful look over and everything checked. I even took it for a shake down flight two days before hand and double checked everything. Still lost it.. Still hurts

[Robbie Skipton - Skip Model Designs]

The trouble with getting an engine, then modifying it. Is that the warrenty is null and void. When your spending almost 3k on an engine. Wouldnt you want your warrenty?

If the engine was a 4 stroke. It it would have still run fine ( 25% lack of power). But as its a 2 stroke . All crank pressure is lost, thus losing all power

Zdz engines are one if the only companies who offer such large engines and the reliability of these engines is certainly not in question. Just simply an issue that has happened and will be resolved before it going in a new model.

[Robbie Skipton - Skip Model Designs]

I never lost radio signal on the model. So no issue with interference

[ChrisB]

Well said Robbie.

Over the years i've heard a number of of people say things like, "with a model that big, you may as well buy a 'real' one"

Clearly they have no idea, as the cost is of a model is far far less than learning to fly, part/purchasing an aircraft, insurance, storage and running costs.

And

that's not the point. Some people want to fly large rc aircraft and why shouldn't they...its been done for years very safely and with all the appropriate checks and regulations and will continue!

Looking forward to your next one Robbie.

[Owdlad]

Robbie.

First of all my sincere apologies if I come across as though I'm having a go at you. This is not my intention at all and you have my utmost sympathy for loosing such a magnificent flying machine in which a great deal of time and investment is involved with such a model.

Did the model crash because of lack of piloting skill.......No

Nervousness.......is a good thing as it keeps you on your toes and prevents taking things for granted

The key issue of an investigation is not to find blame, quiet the oposite. Its to put measures in place to prevent such occurrences from happening.

You say the power plant regularly spits plugs.......... This is the problem........ If this happened on a full size the plane would be grounded until a fix is found.

Your model was at 68% scale, to me that is on the boundaries of full size aviation. Under your own admission the power plant on the model spits plugs...... You flew the model with a known issue without preventative measures in place with the resulting engine failure and crash.......I'm sorry as harsh as it sounds, but that is pilot error (without prejudice) and the crash was preventable.

The key issue is to learn from this and put measures in place to prevent such an occurance from happening on the replacement model.

Kind regards ......Owdlad

[Keith Simmons]

Sorry for your loss of your model and is the spark plug a bespoke for the ZDZ engines?

I don't know anything about that type of engine/spark plug setups and do u think it's a design fault?

Is the spark plug a CM-6?  It looks OK to me and hope u will sort it out soon.

Keith

Edited By Keith Simmons on 20/07/2016 08:57:29

[Denis Watkins]

It matters very little that I was their at RAF Cosford and saw this event and was devastated....

As soon as the motor cut, there was NO way out.

The worse scenario in model flight is a deadstick, low flying bipe going downwind, and I stress BIPE.

Robbie, well done young man to treating us all these years and those to come.

[Robbie Skipton - Skip Model Designs]

As stated. It is an issue with zdz engines. However. What can i do to prevent it from happening with out breaking the warrenty. Nothing. The fact the matter is it can happen not just on zdz, but other engines too.. you can be as careful as you like and check the model as much as you like, you will never know if it is going to happen!. If i didnt mention that it was the plug and it was the ht lead vibrating off the plug, would this have been more acceptable. Or would you still expect me to glue the cap on.i dont think so.

Out of interest what engines do you have? And i will sit here and go through possibe things that can go wrong..eg glow plug fail in flight, exhausts fall off and i would love to see your definive answer to solving issues! This includes electric flight ( speed controller burn out, motor swings a magnet etc)

All my models are checked to the extreme, belt and braces is how we operate. So safety is always paramount.

[Martin Harris - Moderator]

Posted by Robbie Skipton on 20/07/2016 07:25:20:

If the engine was a 4 stroke. It it would have still run fine ( 25% lack of power). But as its a 2 stroke . All crank pressure is lost, thus losing all power

Thanks for the info Robbie - I hadn't considered the loss of crankcase compression! All my multi-cylinder experience is with 4 strokes...

Have ZDZ ever commented on or acknowledged this plug problem?

Posted by Owdlad on 20/07/2016 08:33:06:

You say the power plant regularly spits plugs.......... This is the problem........ If this happened on a full size the plane would be grounded until a fix is found.

Your model was at 68% scale, to me that is on the boundaries of full size aviation. Under your own admission the power plant on the model spits plugs...... You flew the model with a known issue without preventative measures in place with the resulting engine failure and crash.......I'm sorry as harsh as it sounds, but that is pilot error (without prejudice) and the crash was preventable.

The difference between the grounding of a full size aircraft with a known engine weakness and a model is that operated correctly, there is little probable danger to human life and limb - a model of this size will always be flown/demonstrated under controlled conditions - not over people - and it is primarily the unmanned model that is at risk in the case of an engine failure.

Edited By Martin Harris on 20/07/2016 11:20:54

[Bob Cotsford]

I'd also like to think that the plug blowing out is a exceptional but not unknown failure, I don't think Robbie said 'regularly'. If that is the case I'm sure that the LMA are aware of the issue and feel that their procedures provide sufficient safeguards to cover it. If not then maybe they need to consider it, but official investigations and inquiries? A bit OTT perhaps?

I remember a mate's BSA A7 blowing a plug out many years ago, damn nearly embedded itself in his knee on it's way out. Early Jap bikes could do it too. A year or two back I had a plug come loose and blow out of a SuperTigre G61. Doggy-doo happens, as long as it's only a rare occurrence acknowledge the risk, allow for the possibility in future and move on.

Edited By Bob Cotsford on 20/07/2016 11:14:10

[Phil 9]

Posted by Martin Harris on 20/07/2016 10:57:14

The difference between the grounding of a full size aircraft with a known engine weakness and a model is that operated correctly, there is little probable danger to human life and limb - a model of this size will always be flown/demonstrated under controlled conditions - not over people - and it is primarily the unmanned model that is at risk in the case of an engine failure.

Edited By Martin Harris on 20/07/2016 11:20:54

Very good point. You can not build anything perfect so there will always be an element of risk (full size included) but the circumstances the model was flow seek to minimise any risk to the public, The model did come down but it came down in a safe area cordoned off to prevent the public entering. It does seem more scary when you see these big models crash any you would not want to be in the way of an out of control model of this size. But saying that I would not want to be in the way of an out of control 40 or 60 size model either.

Models like this are at the extreme end of the hobby and there are not everybody's cup of tea. I did see this model last year at an LMA event and I remember thinking at the time it was a bit OTT and not to my taste, But I would not want to see a ban on such models or shows. I think its natural and to some extent heathy we hold a post mortem after any model crash in the hope of preventing future mishaps but there is no need for it to turn into a witch hunt

[Robbie Skipton - Skip Model Designs]

Im glad this is all cleared up now. And also happy that other people have steped forward with similar experiances to back up my case.

Zdz achknoledge something.... thay hardley achknowledge emails never mind problems...

Thank you once again for the levels of support i have recieved

[MattyB]

Posted by Robbie Skipton on 20/07/2016 09:20:20:
As stated. It is an issue with zdz engines. However. What can i do to prevent it from happening with out breaking the warrenty. Nothing. The fact the matter is it can happen not just on zdz, but other engines too.. you can be as careful as you like and check the model as much as you like, you will never know if it is going to happen!. If i didnt mention that it was the plug and it was the ht lead vibrating off the plug, would this have been more acceptable. Or would you still expect me to glue the cap on.i dont think so.

 

Posted by Robbie Skipton on 20/07/2016 11:58:59:
Im glad this is all cleared up now. And also happy that other people have steped forward with similar experiances to back up my case.

Zdz acknowledge something.... thay hardley acknowledge emails never mind problems...

Best of luck with your new model Robbie, but if this issue is well known on ZDZs and regular checks and maintenance can't mitigate the risk then I'd be very worried about reinvesting in a new airframe and gear for the same engine. Or are you planning on fitting a different powerplant that is less vulnerable to this type of failure?

Edited By MattyB on 20/07/2016 16:36:23

[Owdlad]

Posted by Martin Harris on 20/07/2016

The difference between the grounding of a full size aircraft with a known engine weakness and a model is that operated correctly, there is little probable danger to human life and limb - a model of this size will always be flown/demonstrated under controlled conditions - not over people - and it is primarily the unmanned model that is at risk in the case of an engine failure.

Edited By Martin Harris on 20/07/2016 11:20:54

Martin I'm sorry but correct me if I'm wrong....... A few years ago, didn't a spectator at a model show in the south of England get hit by an out of control radio controlled model aeroplane and died through injuries sustained.

I have no doubt that Robbies model was in tip top condition an well maintained by those concerned....but something did go wrong. The question I ask is simply was it preventable? We all know the cause, it's finding a solution to prevent another occurrence that is the hardest part of the equation.

[extra slim]

Give it up fellas.. Blimey.. It happened, it is a tragic loss for the lad.. Every show I go to I see a prang.. All safely away.. The hobby is in a decline as it is without the glass half full view.. Safety is paramount YES... But this model has been on the circuit for years... Done 10,s or 100's of flights, and was flown a safe distance away, and sadly got trashed.... There are probably more chances of injury to people when you take off or are stood at your local club....

chill and move on

[bigbubba]

This is a discussion forum, please don't tell people to move on. If you don't want to be part of the discussion then don't be ...

[Martin Harris - Moderator]

Posted by Owdlad on 20/07/2016 17:42:21:

Posted by Martin Harris on 20/07/2016

The difference between the grounding of a full size aircraft with a known engine weakness and a model is that operated correctly, there is little probable danger to human life and limb - a model of this size will always be flown/demonstrated under controlled conditions - not over people - and it is primarily the unmanned model that is at risk in the case of an engine failure.

Edited By Martin Harris on 20/07/2016 11:20:54

Martin I'm sorry but correct me if I'm wrong....... A few years ago, didn't a spectator at a model show in the south of England get hit by an out of control radio controlled model aeroplane and died through injuries sustained.

I have no doubt that Robbies model was in tip top condition an well maintained by those concerned....but something did go wrong. The question I ask is simply was it preventable? We all know the cause, it's finding a solution to prevent another occurrence that is the hardest part of the equation.

I think the incident you're thinking of may have been at a continental airshow and was caused by a local radio transmitter broadcasting from the show which put the model into failsafe and into the crowd.

The point I was trying to make was that an engine failure should not hazard anyone on the ground if normal airshow guidelines are being followed - therefore a possible engine fault is not an unacceptable risk as, for example, would be a poor radio installation or poorly constructed/maintained airframe.