t4flyer

Dafydd, I have very limited (theoretical or practical) knowledge of flutter, but the little I do know agrees with your excellent explanation. My understanding is that aileron flutter would very quickly lead to in-flight breakup or at the very least parts of your aircraft no longer being present on your aircraft! Having experienced the strut vibration issue first hand and knowing how it can shake/vibrate the whole plane and now knowing there is a very simple solution, I thought it best to throw it into the pot as it may help others avoid a very worrying situation. (and maybe the root cause of Ian's problem) Incidentally, my AMO who first told me about the strut vibration issue said he had never experienced it in any of his Jabiru's himself. On a later trip to his workshop he showed me his J430 which now had the vibration strips fitted, apparently on a long cross country trip he experienced strut vibration, why it started up? but it gave him a fright and the strips were installed as soon as he got home! never happened again. There are plenty of older Jabi's flying around here without the vibration strips, but for some time now all factory new Jabi's are fitted with the vibration strips. Personally, I would fit them to any Jabiru I owned if only as a precautionary measure. Cheers,

Ok, I was only trying to give the benefit of my personal experience to a fellow Jabiru pilot in need, not start an argument! So anyway I looked on your AUS Jabiru site, a bit of digging and I found this. http://www.jabiru.net.au/Manuals/Airframe%20Construction/Sections/Pre-Paint_Wings_Fit%20vibration%20damper%20to%20strut_J1702400.pdf What do you know.... instructions on how to fit a strut vibration damper, technical drawings and all, and all in lovely living colour. There you go. According to Jabiru AUS all that's needed is.. Materials required: Vibration damping strips (approx 975 x 11 x 3mm, pack of 2) ► 5-minute Araldite and flock TAPK 3-3 1/16” CSK pop rivets (10 of, 5 per strut) AND of course whatever legal issues your Regs require you to do to be able to fit the bloody things. Cheers,

Andy, the strut is not touched. The strip is attached to the strut fairing. If you want to try it you can easily attach the strips with Duck/Duct tape as I did. (I used white tape and nobody even noticed it) I have no idea how your Reg's work so was not intending to encourage anyone to break any laws. Hell's bell's, I was just sharing some practical experience. Dazza 38, "In my experience" I could not feel any adverse effect on the aircraft handling. Actually no effect at all other than the strut shaking completely disappeared. As I said plenty Jabi's here have these strips fitted. Cheers,

Nev, I was wondering who would fall into that trap. Do you want to win a few beers..... It works for me every time and if we were in a bar you would owe me one right now See below, I won the last bet to the original "Duct tape" was in fact Duck Tape and is still known as Duck Tape in many markets..... Actually he was quite correct... I lost a bet over that some years ago The original was an adhesive applied to a Duck cotton material .... both are used inter changeable these days, and the brand we buy here in USA is DUCK Tape.

When the strut flutter started on my Jabi it varied from mild shaking (still very noticeable) to quite severe (scared the hell out of me) I realised that a sudden gust would set it off, or maybe a turn into the wind or leveling out after a climb, but slowing down (at least 10-15 knots) would always stop the shaking. What initially gave it away as strut flutter and not aileron flutter was that on one early morning flight it stared up quite bad and with the early morning sun on the strut I could clearly see the strut shaking. Anyway, I just thought for the price of 2 x strips of hardware shop extruded aluminum and a bit of Duck tape you would be able to eliminate strut flutter off the list and be 100% sure it was aileron flutter. Cheers,

When my strut issue first reared its ugly head, I asked around on our local Jabiru forum and one of the guys sent me these pictures of the factory fitted strips, so I could see where to stick my wooden temporary strips.

I'm no aerodynamics expert, so I will tell it like I understand it! The strut fairings are shaped equal top & bottom and because of this under some circumstances the airflow over the top and bottom can try to create upward lift on the strut at the same time as it creates downward lift. (sounds like rubbish I know, I didn't believe it myself, but bear with me) under certain circumstances this pulling in both directions can cause the strut to oscillate. On my previous Jabi I would be flying along merrily at 90-95 knots and (sometimes) suddenly the whole wing felt like it was starting to shake itself to hell and gone, scared the crap out of me, slow right down and its gone! I asked my AMO about it he told me he had seen this before and explained about the airflow over the strut fairings and told me the "cure" was to rivet a strip along the bottom trailing edge of strut fairing to disturb the air flow under the strut. I am by nature a skeptic and that sounded to simple to me so I contacted Jabiru SA and they confirmed the problem had been identified and that they do indeed fit a strip of aluminium to the strut to break the airflow. Still not convinced I cut 2 strips of wood 4mm thick x 6 mm wide x not sure of the length now, (but it doesn't have to be the whole length) I carefully duck taped the strips to the trailing edge's of the strut and went flying. As I said I'm no expert but the strips worked 100%, never had the "shakes" again, ever. They stayed duck taped on for almost a year until a trip to the factory where I had them replace my wooden strips with the correct aluminium strips. My new J170 came with the strips factory fitted, (as I think it does on all new Jabiru's from our factory) Cheers.

Might seem a silly question bur are you 100% sure its aileron flutter? Just asking because the strut fairing has caused similar effects on a number of Jabiru's in SA. I had violent shaking from the wings which would occur at about 100 knots, to make it worse it did not occur all the time but once it started the only way to stop it was reduce steed to +-85 then go back up to 95+. I also thought it was aileron flutter, really worried me until I found out that it was the strut that was fluttering and the cure was very simple. (and I think now standard on our factory aircraft, well it was standard on my new J170.) Cheers.

My high backed seats are factory produced here in South Africa, many patterns, materials are available, mine are anthracite leather with door pockets to match, way cool.... but if you don't have the cargo door they will severely limit your ability to load luggage into the rear of the J170/160.

I don't know about drawings but you can try them. Try http://www.jabiru.co.za for contact options. I really don't know why a cargo door is not a standard feature on the Aus factory J170's (come to think of it SP/UL120's to). I stand corrected but I think all the newer European LSA's and most of the American ones have some form of cargo loading door or hatch, Its a small thing but improves the practicality of the J170 tremendously, still I don't know your regulations, maybe its a big thing over there? Cheers.

A cargo door has been offered as an option on our factory Jabi's for a little while now. I would guess most, if not all new South African J170's have the optional cargo door fitted during construction. I had one of the first, bloody fantastic, if you are going to tour with a 160 or 170 this mod is a must have in my humble opinion. I used to struggle to load stuff into my UL120 and touring with the wife was nearly impossible, but on my last tour with the J170 I used to chuckle every time I loaded the plane up... so easy. (not to mention the high back seats. no more go-kart seats for me....)

And in South Africa the J170 is offered with a cargo door and high backed seats make a good aircraft brilliant..... Love mine to bits....

This thread has gone very quiet. At the start of the thread there was talk that a firewall forward kit for Jabiru/Rotax 912 was imminent ! Did anything come of this or was it just someones pipe dream? just wondering

I would have thought the main problem with the Jab motor was the carb and its positioning. Firstly a single carb will never provide optimum fuel distribution and therefore the engine cannot be tuned for maximum performance and the carb positioning on the Jabi is not good at all. Secondly Jabiru carbs have a known icing tendency. Replacing the carb with a TBI might solve the Jabi's icing tendency (I use an Aerocarb TBI on my VW powered Zodiac, no carb heat and no icing) but it wont solve the less than perfect fuel distribution problem. Water cooling and staying with a single carb or a single TBI is "in my opinion" not the answer. The current engines are proven designs with a flaw "the carb and manifold system" a good multi-point EFI system would solve both problems and possibly allow a little more power to be squeezed out of the engine due to a more optimum state of tuning. Cheers, T4Flyer.

Hi Bushpilot, I guessed it wasn't true as its a big jump from 500 to 600 Kg MAUW. Although a smaller increase to say 550 or 560 Kgs would be most appriciated :big_grin: Cheers T4Flyer

Hi all, I only asked the question as I read this on the last page of the post "J170 - First Impressions"

Hi Tomo, Actually very well. I live on the South African highveld so fly hot and high (airfield 5,500ft and summer temps above 30C) so decided to go for the 430 wing for the greater lift. So far the UL120 has performed to expectations, there doesn't seem to be to much speed lose compared to the J120. Roll rate is a little slower than the J120, as you would expect and she responds slower to the controls than I am used to with my Zodiac 601 HD. Overall, so far the UL120 is a beautiful flying machine (although its winter here so I can't comment on hot/high summer flying yet) she is not the easiest flying machine to get back onto the ground, but I have been told that is a Jabiru trait and that all Jabiru models take some getting used to (slowly getting there though!) Cheers, T4Flyer.

Hi all, I read a previous post where someone said the J120 has been uprated to a full 600Kg MAUW, is that true? the Jabiru (AUS) web site still has the J120 at 500Kg MAUW. My interest is that I have recently purchased a new Jabiru "UL120" (South African factory assembled J120 fitted with the 430 wings) it is rated as 500Kg MAUW. If the parent factory has lifted the MAUW to 600Kg "maybe" my UL120's MUAW could be lifted here to... Any info would be appreciated. Cheers, T4Flyer.