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Jr 28 x , a heads up

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Jr 28 x , a heads up

Old 08-19-2018, 10:51 AM
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David Gladwin
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Default Jr 28 x , a heads up

The following is offered in the hope it may prevent a repetition:

I lost a jet today, a PST Panther JetCat with JR 28x, on its first flight.

Control throws and C of G had been meticulously checked BUT when an independent control check was done one flap was found to be reversed. T/ O setting was symmetrical. This was corrected on x bus and all looked well. Perhaps I had failed to select SET to store the flap settings on final checks at home.

The model was refuelled, started and taxied out, flaps set at t/o. Take off was normal but when flaps up was selected the model went out of control in roll. I THOUGHT I reselected t/ o flap but MAY have selected full flap, resulting in one flap retracted, the other at landing setting, 45 degrees.

The jet was uncontrollable and crashed, total loss.

My best GUESS . Is that after correcting flap setting I had failed to press SET which STORES the setting.

My BIG mistake , perhaps it will prevent a repeat, because it is a trap for the unwary.

Last edited by David Gladwin; 08-19-2018 at 11:10 AM.
Old 08-19-2018, 10:56 AM
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Damn that sux.

Why the heads up on a 28x though, any idea what happened?
Old 08-19-2018, 01:35 PM
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David, sounds like a set up issue as you say, a ground check of all settings should have shown this up though, sorry to hear of a lost model.

Paul
Old 08-20-2018, 12:52 AM
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David Gladwin
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Just another thought.
Looking at the X bus page this morning, I guess I had pressed SET for the neutral , the button for which is just below the reverse box so that when pressing the correct SET button REVERSE is obscured by the finger pressing SET ! The button I should have pressed is the SET button ABOVE reverse.
An expensive human factors error causing my first crash for many years.

Thats aviation, you never stop learning!

Hope this may may just possibly prevent someone else making the same mistake.

David G.

Last edited by David Gladwin; 08-20-2018 at 01:07 AM.
Old 08-20-2018, 03:15 AM
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David,


An expensive lesson, but I have to take issue with "An expensive human factors error causing my first crash for many years."

From all the lessons and experience you have provided over the years from your full-size aviation career, I'm surprised that your pre-flight take off checks of full, free and correct movement of every control surface did not catch this error.

Just like full-scale aviation, a control check should be done before EVERY flight.

My routine before every flight, immediately after power on is;
Up, Down, Left (Aileron), Right (Aileron), Left (Rudder + NWS), Right (Rudder+NWS), Flap Mid, Flap Full, Flap Up.


Sorry for your (avoidable) loss.

Paul
Old 08-20-2018, 03:15 AM
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David thanks for sharing. In full scale we always talk about accidents and how to correct the problems. All to often with model aviation people don't talk about it because of the drama or simply hurt pride. Wish we all could be more open about our accidents and learn from them.
Old 08-20-2018, 04:02 AM
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David I applaud you for coming on here and admitting an error so it could serve as a cautionary tale for the rest of us. I've been in RC for 26 years and I lost track of how many guys got a "radio hit" shortly after take off on the first flight of the day and lost a plane only to find out later that they plugged something in wrong. I take two things for this 1)preflight is critical and 2) the more complex our radios get the more careful we need to be when programing.
Old 08-20-2018, 04:11 AM
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Originally Posted by gunradd View Post
David thanks for sharing. In full scale we always talk about accidents and how to correct the problems. All to often with model aviation people don't talk about it because of the drama or simply hurt pride. Wish we all could be more open about our accidents and learn from them.
Well put Kris!

David, thats for expounding on your initial post so we can all benefit
Old 08-20-2018, 04:27 AM
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David Gladwin
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Thanks Guys, yes, 50 years of professional flying taught me about honesty and the “ just culture” , don’t see why we can’t do it in modelling too.

Paul, we HAD done a full control check, with an independent set of eyes, 2 minutes before start, including flap and gyro, yaw damper, which is when the flap error was spotted and corrected. My independent checker was a retired airline captain. The human error, my mistake, was pressing the wrong SET button, ie pressing SET with the “reverse” window still visible.

Further work this this morning with the surviving electronics, receivers, hub and converter harnesses showed that both flap servos were moving in the same direction, when , as the flap servos were “ handed” they should have moved in opposite directions.

The holes in the Swiss cheese all lined up and got me.

I will leave it at that.
Old 08-20-2018, 10:49 AM
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Sorry to hear of the crash David, it is a sobering reminder that even during pre flight checks it is easy to become so conditioned to going through the motions that sometimes we look but don't actually see. Many times I have caught myself checking all the surfaces to see if they are moving when I wiggle the sticks only to realize I just went through the motions but really didn't notice if they were correct or not. Most recently was a reaction 54 turned it on, did all my normal checks of all surfaces and figured good to go. It was during start up I realized my left aileron was hanging down the servo had died. I could move it to center by hand and it would deflect upwards just fine but if i deflected it downwards that is where it stayed. I suppose it could have failed during my start up and had been ok when I did my control surface check but I feel like I missed it during the first check. This is an airplane that had flown many many times so I got complacent. Fortunately it was caught on the ground.
Old 08-21-2018, 06:11 AM
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There are a lot of variables with the newer radios and all kinds of things that can interact in weird ways, We had a case at our field with a Boomer XL that had been flown many times. A smoke system was added. What did not get caught was that when the smoke was turned on that same switch turned off the elevator function. There was no piece of the aircraft left that was much bigger than a dollar bill. The lesson was that when making any change in the TX all modes and conditions must be checked for unexpected interactions. I do not know how many maiden flights I have seen where the sticks were wiggled to verify that everything is moving but never actually checked for direction of movement.

David, thanks for the reminder.

Last edited by flyinfool1; 08-21-2018 at 06:15 AM.
Old 08-21-2018, 11:16 AM
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ravill
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Crashing sucks, sorry for your loss David!

I've always wondered why I'm the only one I see with a checklist clipped to my belt/pants that I read before EVERY flight. Although, in this case, it seems that even a check list would not have helped.

I wonder if you could have flipped the flaps back to take off position, as that was the last input that caused the offending behavior?
Old 08-21-2018, 11:57 AM
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David Gladwin
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Indeed I have relived the flight a dozen times, or more!
When the aircraft rolled, I immediately reselected t/o flap which brought things under control.

I then trimmed the jet, retracted the gear, climbed to a safe height.

I then reselected flaps up to see if the problem recurred (v v bad decision in hindsight) the same roll recurred.

I was was ready to reselect t/ o flap, though, but may have moved the flap switch too far and gone to land flap. I will never know. ( most of my other jets have Weatronic so the recorded data on the Wea. would have told me exactly what happened )

I then fought the jet BUT. Although the ailerons were powerful enough to overcome the assym. Every time I released ail. deflection it rolled inverted, the process continuing till impact!

My bigtime error. That said when correcting the flap travel during preflight, not pressing SET meant that when the tx was switched off after the control check, the corrected data was not stored.

When the tx was switched on very shortly afterwards the flaps assumed the correct position,and all other flight controls responded normally, deluding me to thinking all was well.


Although it would not have helped on Sunday, my more complex model, such as my F4 and Hawks have the checklist on the access hatches for instant access.

As as a matter of interest I have just finished reading John Farley’ s ( ex BAe chief test pilot) superb book “The View from the Hover” a top read for anyone involved in any aspect of aviation. JF relates some of his big mistakes such as slamming a Harrier throttle shut during transition instead of selecting the correct nozzle angle , and shutting down the engine when just trying to select idle power, both occasions nearly causing loss of the jet.

We never stop learning and I do hope that relating my experience may just, possibly , prevent a similar problem.

That said, it was only a model and no one was hurt, or secondary damage caused. One recent book I have read, Harrier Boys, relates that one RAF Harrier pilot, who spent 17 years on the jet, lost no fewer than 21 pilot colleagues in accidents. Puts it all into perspective!

David.

Last edited by David Gladwin; 08-21-2018 at 12:21 PM.
Old 08-21-2018, 03:25 PM
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I don't know why you put the 28X in the title.. The radio wasn't the problem.
Old 08-21-2018, 03:55 PM
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I don't know why you put the 28X in the title.. The radio wasn't the problem.
totally agree
Old 08-21-2018, 06:09 PM
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Guess the title is OK. I think the 28X radio is one of the finest systems ever made. But like David mentioned, if you are making adjustments and then forget to press the set button, or turning the radio off by sheer habit on using other radios , you may have a big problem.
Old 08-21-2018, 11:41 PM
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David Gladwin
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Originally Posted by Doug Cronkhite View Post
I don't know why you put the 28X in the title.. The radio wasn't the problem.
I thought I made it clear that the radio, per se was not the problem, , it was a user, me, error.

However, it is possible on the 28x , as I found out, that the presentation of the X bus servo/ converter harness page needs extra care from the operator, particularly in strong light conditions ! It is a potential “gotcha” rather like the engine presentation on the original B 737-400 which led a crew to shut down the wrong engine after an engine failure, with dreadful results.

I do agree the 28x is a very fine radio indeed, just off to go flying with it !

I won’t make that mistake again and I made these posts in the hope it will reduce the chances of 28x users making my mistake and being extra careful to use the correct SET button.

Many years ago, at an early IJMC meeting I suggested we create an incident reporting scheme, similar to those which are used in full-size ops. I would collate and publish a quarterly review of such incidents, in the interest of promoting flight safety. It was not taken up.

David.
Old 08-22-2018, 02:06 AM
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David it is a credit to you that you have posted this information.

Most do not have the courage to admit they might have made a mistake but you have done so in the hope that it may help others avoid a similar pitfall. Whilst I am not a JR 28X user or a full size pilot, I do appreciate the importance of learning form mistakes that others have made or encountered and that, from what I understand, is a very important principle employed in the aviation industry. It is a pity that many in our hobby do not employ the same ethos when operating our models.

If there were any idiosyncrasies in the software of the radios I am using, I surely would appreciate being told about them prior to me discovering them the hard way.

It is sometimes only by sheer luck that serious accidents are avoided in our hobby. Best practice, sadly, does not seem to get much of a look in anymore.
Old 08-22-2018, 02:31 AM
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Double Post
Old 08-22-2018, 02:32 AM
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Originally Posted by JP-1 View Post
I wrote this short article for the B.M.F.A. Magazine in the spring of this year:-

Alistair

Flight safetyThe modern 2.4 Transmitter is a great piece of kit, It certainly goes a long way to making our models fly the way we want them to.We can store numerous models within the memory, almost an unlimited scope as to what we can program, however in certain circumstances this can lead to potential model loss unless we adopt a methodical professional approach, and double check any changes made. As in full size aviation a check should be made to ensure full and free movement of all the control surfaces, equally important is to ensure all surfaces are operating in the correct sense, it is easy to make changes when the aircraft is on the ground, less so when airborne, and committed to aviationL.With a complex model you may want to think about a check-list?A new model, with new equipment, Power Box etc, or a new gyro, (Have the Gyro on a separate TX on & off switch) ensure the Bind procedure is successful, Range check, and confirm the fail-safe is set up correctly, ensure the turbine will go to idle / shutdown as per the local rules. Dave Wilshere covered several very good points on Fail-Safes in the April BMFA Magazine.If you have a suspicion that something is not right, it may be the turbine, airframe, or radio, take the time to check it out whilst still on the ground, for those that have travelled a long way to a meeting they may feel a certain pressure to fly, do not fall in to this trap, often when things go wrong (not just in model aviation) it can be traced to a chain of events, each one taken on their own may seem insignificant, however taken together a clear picture emerges of what went wrong.

..
Old 08-23-2018, 12:54 AM
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David Gladwin
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Thank you for your kind comments Craig, you most clearly see my intention.

I was was fortunate in that I was able to pinpoint the exact cause of the crash, so thought it well worth relating it, so many model crashes are unexplained.

Sadly at a small meeting yesterday, just 5 of us, there was a total loss which will never be explained. The jet had been flying normally, then just went out of control and crashed and burned, nothing left. ( My own 8 flights and all others, 28X included, went without incident)

Of course, incident and accident reporting in full-size ops. using various schemes has gone a long way in making aviation safer. I do wish we could have the same in model jet flying, reports could be anonymous as is done on the British human factors scheme, CHIRP. ( Confidential Human Factors Incident Reporting Programme) started in aviation but now adopted by the maritime industry.

Its intersting, too, to see that the medical profession are now adopting some of the safety best practices from aviation.

Thank you ( and the other guys) again for your encouraging and supportive comments.

David.

PS Craig, just about to install the Futaba HPs A 700 servos you recommended in my Mig, thanks for the advice!


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