darryltarr

My Feedback: (2)

As an experienced RC pilot (and full size pilot), when asked to do the Maiden Flight on a new model there are many things that I scrutinize, the list seems endless. However, there also has to be a small element of trust and faith in the Owner/Builder as you can’t check absolutely everything (after all the model can’t be X-rayed and borescope).

Example: Do I physically test each individual battery to make sure that they have been fully charged, NO, I take his word for it. Do I physically check the CG by picking up the model. YES, nine times out of ten I do, BUT not this time? WHY? Simply because this guy has been flying jets with us for about 2 years and this is his fourth jet, so when I asked:

- Have you checked the CG?
- Yes, many times
- Where is the location?
- Slightly forward of the Wing Tube

Sounds good right. Well this is where my complacency was found wanting. I took his word for it. As soon as the model left the ground (which was way too early and slow), I knew something serious was wrong. With full down elevator the models attitude was dangerously high with what felt like zero airspeed. The only way to reduce the attitude is to apply full down elevator (which I had), reduce thrust, and roll. But I am only 10 feet off the ground, anyway by this time the jet had started to roll as the left wing had stalled so I corrected with rudder (as aileron would have increased the angle of attack of the down going wing), reduced the thrust a little, and relaxed the full down elevator to the neutral position. Then, as the models attitude approached a gentle climb attitude I applied full power again and about half down elevator to maintain the attitude. I eventually ended up in a gentle climb, although still dangerously slow, and managed to climb away but the jet continued to tip stall, so after several recoveries (and at a safe height) I applied takeoff/approach flap, but this had little effect. I battled with the controls for almost 3 minutes hoping to at least be in a position to dump the jet onto the runway or the sand, but eventually the results were disastrous. A complete “Hull Loss” due to "Loss of Control".

Sometime later I asked the owner “How exactly did you check the CG – what method did you use”.

Well it turned out that when he used the wing tube to measure the CG, he made a mark at the wing root, BUT followed a wing panel line towards the wing tip as a reference. As we all know the MB-339 wing is tapered so the panel line does NOT run perpendicular to the lateral axis (fore and aft axis). This meant that the CG was approximately 3” AFT.

So my confidence is low and my ego and pride dented. Never believe everything you hear. After all it is my responsibility to check, check, and check again, and at the end of the day it was my complacency that contributed to this unfortunate and unnecessary event.

I hope that others can learn from this.

Darryl Tarr (Dubai)

Pepperpete

If I ask someone to fly thier plane...I make sure I have an open checkbook ready to go in case I crash it. If someone asks me to fly thier plane for a maiden or any other reason, it's ALL on them in terms of setup and checking proper CG. Of course I will make a cursory inspection. Check that all surfaces are moving the correct way etc and ask if the CG is right but past that...the person who built the plane is responsible completely. So don't feel bad about this at all. Mistakes happen but the responsibility is 100 percent the builder in this case IMO.

siddus74

Bummer sounds like you man should go back to start and grab him self a trainer to build .... not your fault at all ...

Scott.

adamrick

Darryl,

You are way too hard on yourself Mate...! I was there when this incident happend and can categorically state that you executed more than superhman efforts to try return this model to the ground safely. This write-off is NOT YOUR FAULT!

I have known you for many years and know you are the ONLY pilot in the UAE to be completely trusted to perform maiden flightsfor all types of aircraft. You have maidened so many... it's hard to count how many.As has been said earlier, the builder/owner of the model is 100% responsible for ensuring the build is 100% correct BEFORE handing it over to you for the maiden flight. The responsibility for a successfull maiden is 100% with the builder in my opinion. As we all know the old saying... "if you build it right, it will fly right". In this case, the build was not accurate. Does a full sized airplane test pilot get involved with riveting spars to the wing ribs in a 777 or 380? No - he trusts that the manufacturer has built it right before he puts his life on the line to test fly it.

Yes, you can check and check and check, but as you stated - this was the owner's 4th turbine jet, so naturally one would assume the build was correct. You are not there to scrutinise every last detail from a builder on his 4th turbine. You are there to set up the flight characteristics so that the builder's dream comes to life at the last step.

Darryl, you taught me to fly and you taught me to build. Your standards are legendary, as is your honesty and knowledge of RC airplanes and heli's. And lets not forget, you do these maiden flights out of the goodness of your heart, and because you love to see the hobby flourish.

You have maidened ALL my models to date, and I certainly hope you will continue to do so Mate. Your help and insight is invaluable.

(I'm damn sure the Dubai Peanut Gallery agree with me too..!!)

luv2flyrc

My Feedback: (6)

+1 , you did everything that you reasonably could, there's no complacency here at all. Had the owner chose to fly it, it would have most certainly crashed as well.

Mike

Dr Honda

My Feedback: (4)

Yep... not your fault at all, and I don't care how good of a pilot you are... that plane wasn't going to fly with a CG 3" rear.

Because of things like this... I generally don't ask people to trim my models... and I don't trim other people's. The one exception in the past 30 years for me, was with my first jet, and I had the CD trim it for me.

Anyway... at the club I fly at... I've seen it a bunch of times. The last time was a very nice .60 sized war-bird. Everything was checked by the owner... but we found that the elevator was backward. Unfortunately, it was after take-off. (total loss)

-JC-

My Feedback: (26)

Darryl,

There is absolutely no reason for a dented ego here. You offered a service to the owner and it is 100% his responsibility that the jet is in flyable condition for the maiden. You asked the right questions about CG and I'm sure you inspected the jet before take-off.

You are a world class pilot and a meticulous builder. So, the guys in your area are lucky to have you to maiden their equipment if they don't want to do it themselves. The builder made a costly mistake... Hopefully he learned a lesson for next time. As you said, he had previous experience, so you were correct to assume that he would know something as basic and simple as balancing a plane.

No reason for lost sleep. From now on you are going to check CG 10 out of 10 I'm sure, but only as a courtesy... Not your responsibility at all if you are told that the plane is ready to fly.

Hope things are well... It's been too long

Wayne22

My Feedback: (2)

I think you guys are missing the point... It was an unnecessary event and could have been prevented (20/20 hindsight). Darryl never stated he was accepting 100% of the responsibility for the consequences, but using this as an example to all of us to learn from this unfortunate experience - don't get complancent!

JohnMac

Darryl,
It is easly to blame your self for this, but how would you have checked the CG anyway? Most jets are too big to balance on your fingertips and unless you just happened to have a balancer with you, what could you do? At our club we insist on scrutinising every model that comes to fly there, even if it has flown elsewhere before. And still we have incidents.
Like the guy who turned up with a second hand F16 he had bought. I scrutinised the model.
It looked really nice until he took of and performed his first turn. Both wings fell off! ( No, seriously, both wings fell off!) I could not believe my eyes. I got there with a foam extinguisher but there was not must left to extinguish. Both wing panels had come down close by and inspected the vertical aluminium wing joiners. They had both sheared off about 1/2 out from the root, and not suprisingley as they had been drilled and tapped vertically, right the way through!
When I talked to the owner he told me that the wings were held on by a thin bolt right throught he joiner. This meant that of the 6mm thicknes of the metal, about 1.5 mm was left in total at this point. I asked the owner if he did not think that this was not a very sensible arrangement and he said he had not seen nothing wrong with it.
I was incredulous that someone could have designed it this way, and that the new owner thought it would be OK.
I did not check the wing joiner system as it never occurred to me that do anything so stupid.
In the end, how far can you go to satisfy yourself that a model is fit to fly?
John

SCALECRAFT

My Feedback: (13)

I never fly other people's aircraft.

I will let others fly my stuff I can replace.

Poop happens.

Steve