i3dm

My Feedback: (51)

Hello guys,

For those who have or are planning to get a FB jets Hawk - please note i flew my friend's new Hawk this weekend and had it snap on a high speed pass when i pulled a little up, managed to roll back up right just to see the left elevator fluttering like crazy, so i lowered throttle immidiately to idle and began slowly decending for a landing.

Slowly but steadily i managed to bring the model in for a soft landing, only to find that the left elevator's bearing block (which is held by 4 M3 bolts to the rear plywood rib in the back of the fuse) was completely loose (all 4 bolts were loose) and every possible bolt which came pre installed in this airplane was NOT loctited and pulled out by hand easily.

This nearly caused us a total loss of the airframe if i didnt lower the throttle immidiately.

PLEASE check yours !!!

Here are a couple vids showing what came loose (Real Player or Quick Time needed to view):

http://www.liorzahavi.com/videos/jets/Nessy%20FB%20Hawk%20elevator%20failure%20(1).mp4
http://www.liorzahavi.com/videos/jet...%20failure.mp4

Spartan Missile

Bravo on saving the jet !

bbagle1

I am no jet expert but I do fly helicopters. Many heli's come pre-assembled but anyone smart always takes them apart and re-loctite's everything. This can double the build time in some cases but is well worth it. Do people not do this with jets?

SJN

Yea, great save [sm=thumbs_up.gif]

tamjets

My Feedback: (2)

This is very important lesson for user end to learn.
ARF kit come from china are not put together by proffesional builder. You paid for what you get.
The person whom put this ARF's kit together must understand what involve to made this plane fly right and things don't come apart. That is common sense if you are flying this kind of high performance jets.
Sorry that your friend had that problem. But that problem can be advoid if done it right and goes over safety lists.
Going online complain about everything happen to your jets is not a solution. Educate your self how to be safe and learn from it what has happen.
Hope the next jet it will be done right and every pilots should be responsible for your own jet when put together.
Hope this thread is not become debating BS whom is at fault.
This is my advise from many years experience building model airplane. Yes I had airplane falling apart from my early year when I start building and learn to fly from wood kit. But I learn from it and built it right since than.

flyexperimental

What Tam is telling us is that ARF jets do not exist,and they are more work than building yourself,since you must go backwards and dissasemble the ARF work that was suposed to be done for you,SO IT CAN BE DONE RIGHT.I do not think i3dm is complaining but is trying to warn the rest of us that have not learned the hard way.I have a 1/6 F16 most of the hardware you are talking about on mine was not very tight,they did use locknuts,but some of them did not have threads protruding far enough for the locknut to work.
Thanks for the warning I3DM,you may have saved some newbys a jet.When will the factories learn that if they do not do it right,just throw the parts in the box and let customer do it right.In the end it saves factory and customer time.

Billy

My Feedback: (15)

First off, thank you i3dm for sharing this. I do think it is common practice with ANY manufacture's kits to go over every bolt and even glue joints. We do pay for what we get and what we get is definatley alots less work than if we were building these jets from scratch. We all should understand that somethings need to be "fitted" at the factory. If the factory had just thrown all the parts in the box, then it would be up to the customer to not only drill the holes but measure and get the placement right. While this would be fine with me, there are alot of people who just want to assemble and go. Thanksfully the jet wasn't loss because of this, but it is a good reminder that EVERY arf needs to be completely gone through. Sometimes even modified to make stronger. I am happy with the way things in the arf world are going. As long as the china arfs come straight and true I am happy to go in and retighten, reglue and refit. It sure beats having to start with "building a plug"[:-]

Again good job on bring'n her home, now go get some Loctite

i3dm

My Feedback: (51)

Tam,

I am NOT complaining, simply trying to warn some guys of the same problem that might hit them as well.

I did not build the model, but one of the most expirienced jet modelers in Israel did ! if it slipped his eyes, it could possibly happen to others as well, so people need to be warned and make sure this doesnt happen to them.

BTW - after landing - the wing's main boom was bent, and the tab holding the left wing mounting bolt was loose inside the wing - just to clarify how dangerous this issue actually become in the sky !! [X(]

In case i didnt catch the flutter on time and lowered throttle immidiately, my bet is that the flutter would have taken the entire airframe apart (this way or the other) and cause a total loss terminal velocity crash. [:@]

causeitflies

We all need to have these reminders, even for the the parts we assemble ourselves. There have been times when I've assembled something loosly, got distracted and gone on to another step only to discover later that I didn't tighten everything up on the previous step. OOPS! [sm=red_smile.gif]Glad I caught it and I better check all of those nuts and bolts.

SAP_2000

How hard can it be to instruct the workers to a drop of locktite on the screews?? Shouldn't be to hard.

I think it is so far out that that the end user is responseible for the faults made by the manufaturer. Of course you have to check your plane, but you can't take every nut, bolt and former appart. IMO

Ehab

My Feedback: (44)

How about we meet in the middle;

Instruct the factory to do a final quality check (and I mean insist on it), Include a single warning sheet in the kit to alert customers to check visiable glue joints and check hardware for proper assembly and finally add a note that the final product is the responsibilty of the end user...or something like that[8D]

Note: hidden glue joints and/or hardware not accessable by user is factory's reponsibilty [&:]

AndyAndrews

Man, you guys are LUCKY. Nice save. Thanks for bringing that up. These things need to be checked. I would say that all bolts on an ARF need to be checked for tighness. I don't expect that they will be done properly the first time after seeing what was sent to me by another fairly well know factory in China.

AFTERBURNER1

My Feedback: (80)

My Hawk flys awesome!!!!! Thanks Tam and Billy for hookin a brotha up!!!

DF

Ehab

My Feedback: (44)

You do not fly as much as Raffy flys [8D][8D], hence you have no problems

Edited for DF only!!!!

ianober

My Feedback: (12)

This sound reasonable to me. And Tam, if you know about these issues then why don't you make up a simple flyer and drop it in the box. I know you don't manufacture the kits but you do distribute them. Don't you think that if someone bought this kit from you they would expect you to advise them of some of these issues? I think that is more than reasonable considering the high level of QC you are normally known for in this business. I dont think anyone was criticizing you, I think i3dm was trying to warn other flyers of the issue which is what the manufacturer and distributors should be doing.

Thats just my .02 as a customer.

Ehab

My Feedback: (44)

Your .02 cents are apprecited, now Get BACK TO WORK ON THE F4!!!!!

Joe C

My Feedback: (23)

Good post Ian, Joe C!!

ira d

Are you saying the jet was not built per the instructions that came with it? Otherwise
if the instructions didnt say to beef up this or locktite that then the builder is not at
fault IMO. Also I think its good this was posted on the internet so other people can
be aware of what may be a potential problem.

Dave Presta

My Feedback: (3)

I put a dab of aeropoxy on the bolts to help with them not vibrating out.....but still expect the stabs to fail! The stab mechanism is crap, but I got what I paid for so I am not complaining. If it makes it 20 flights without failing, I will be happy. I too think it would be a good idea to sell a kit and let people know, seeing that most people who are buying the cheap china arfs are new to turbines and do not know anything about the quality, only that it is a cheap easy way to get a jet in the air. Maybe a little note in the kits should be:
"You need to go through all the work we have done and make sure we did it correct, if it fails and you don't re-do the pre-fab work done at our factory that we charged you for by selling you a plane almost ready to fly.....then shame on you....its your fault"

I'm not pointing the finger at any kit manufacturer, just having a little fun with this subject......remember, I too needed to go through my entire arf and fix everything I could find, but most wont know to do that.

Yeah Duky, all 5 flights you have on that thing at half throttle have made me totally convinced that mine should not have any issues. And you still had to tape up the leading edge (well, have someone else do it for you) prior to the first flight so the crack down the seamline would not open up on you in flight!! Its things that we cant see like your wing that make me nervous.

I am still looking forward to flying my Hawk, they fly really well and I plan on doing some formation smoke party's with Duk Duk at Cali Jets.

This thread does give some good information to others who are building china arfs, and if it helps just one guy find some loose bolts and fix it prior to losing a plane.....it was worth it.

causeitflies

This applies to all ARFs, from 40 sized trainers to jets. The newer guys that were raised on ARFs should know this as their instructors should have told them to check every glue joint, nut and bolt they can get at. I never trust it unless I build it myself

AFTERBURNER1

My Feedback: (80)

Don't get it???

Dave Presta

My Feedback: (3)

Probably a very good rule of thumb!

flyexperimental

The factories building these also need to realize although thier is not a pilot in the plane LIVES are at stake.This poor qaulity control may get someone killed.Our jet flying hobby is at risk.The longer the poor qaulity continues the more the odds will increase one will go down in a bad place.I am not saying we should all build from scratch,but I think some things on these(ARF's) should be left for the builder to do because they do not get everything in staight and true,and if it is going to come apart,then don't bother to put it together.The pros like Tam know what need to be done,but what about the new guy putting one together with little or no instructions.Is he going to know that he needs to redo some of the work that he thought was already done?,because the directions sure do not tell you to.

i3dm

My Feedback: (51)

I agree, and i dont see anybody in their right mind thinking this shouldnt be posted large and bold.

This is a dangerous hobby already, no need to add more dangers due to poor QC.

FB Hawk owners - please check your planes !!

uncljoe

My Feedback: (8)

When you buy cheap expect cheap in return..... Quality Control , like Freedom is NOT Free.

Semper fi
Joe