deadstick

Hi Geoff, do you have some pics? id expect the barrels to be out of round but am interested mainly in the ring issue. Do the pistons have fly cut valve reliefs in the crown? The reason I ask is the ring lands were enlarged to prevent Carbon deposits from causing the rings to stick IIRC. A pic of the head recession would be good too, will give an idea if its been hot around the exhaust valve's ( mixture, leaking seat, worn guide) or from inadequate cooling. Unfortunately Jabiru's in the ab-initio training environment cop a hammering, not intentionally but nevertheless its a harsh environment for any engine. Without warming orbits and constant monitoring its easy to shock cool! With full monitoring, watch the CHT plummet during a PFL or EFATO evolution, its not uncommon to see less than 60 degrees C if not managed correctly. Then imagine the strain on components as the differing expansion rates between the case to barrels to heads plays its hand when the throttle is advanced to max and the nose raised to VY, they really need a soft touch in these circumstances.

Hi Geoff, does sound like she has been hot, just about all the head and valve train issues you describe point in that direction, the cylinder length should be 107.0 mm nominal and surprisingly Jabiru still allow shorter cylinders to be used with a shim under the base ( never seen one that seals and causes allow barrel to case chaffing ). May be economical to buy a short change over engine and transfer your ancillaries over.

Hi geoffreywh, where are you located? Can you provide a little more detail? Did th engine have 4 channel CHT? What airframe was it in? ( J170?). What oil was being used? (Aeroshell W100 or multi grade). Cylinder blue around the top? Are the exhaust valve guides worn? What is the roller surface on the cam like? Sorry for the questions!

Let him experiment I say, who knows what he might stumble upon. After all isn't that what this category of flying is all about? Stand fast LSA! I know of a few 'Camaru' engines floating about at the moment.

Freedom of information, is there such a thing? LOL. Oscar, What do you mean by "you might not want to go there"? Cost prohibitive? Or a long process to get the information? Still don't understand why it's not released.

Has CASA made the information available? Would like to see what it was based on.

Awe aren't confusing harmonics with resonant frequency here are we?

Based on my experience balancing helicopter rotor heads and my Uni days, a harmonics in reference to balance is represented as an integer of that being referenced. For example a vibration/ balance run would involve me setting up the Vibro gear to measure a spectrum spread from the slowest rotational frequency to the fastest. The rotor head would spin at 203 rpm of which being the reference it's called a 1R or 1 per Revolution the next harmonic from that reference would be 406 RPM and be a 2R or 2 per revolution and so on and so on. A print out of the complete spectrum would show differing harmonics of all rotating components, say for instance I had an IPS spike at a set frequency, a quick glance at the known rotating speed chart of components allows you to ID the failing component. A few data inputs and you could accurately predict which blades required a track adjustment to effect a better balance solution.

No one mentioned 'the assembly' Oscar! In fact Ian stated that it was not required, go figure I trust he knows better than I in this topic. Are you ever positive or helpful? You come across as downright nasty and spiteful, though it can be hard to accurately read tone in a typed statement.

Hi Nev, it's not my work mate it from Camit, I don't have the gear and a little bit out of my comfort zone to be playing around with flywheel balance on an engine that's been plagued with issues. And yes Oscar it's dynamically balanced! or am I missing the physics and all? LOL

Lol, no mate just the flywheel! Seriously and no jokes!!! Your basing that statement on your 'in depth' and 'vast' experience in jabiru aero engine building I take it?

One dynamically balanced 2200 flywheel for a friend.

Very nice.

Yeah I was hoping to have a chat with the minister and Mark skidmore but didn't eventuate. I hope the ministers comments weren't just hot air. I listened to Jabiru's lecture and heard some good positive stuff and some bad. It was great to speak with Ian and Jenny bent and see their power plant and products in the flesh.

Yeah I'm suspicious also, especially when they describe a clear cut fuel starvation incident as an engine failure!

Hi Oscar, no that one was my J160, different circumstances.

Hi Keith, what was the cause of the complete failure?

It's in a J230-D, I don't know about extra power but it runs cooler than my previous flat hyd lifter. Only had 2 issues thus far, a leaking mechanical fuel pump, and a lifter that pumped up holding the exhaust valve off its seat slightly.

Sorry Stuart, on topic yes I have a roller cam 3300, got just over 100hours on it and looking good. They are a breed away from the last iteration, run smoother and have less engine noise. If your any where near Tamworth I'm happy to take you for a local flight.

Hi Bruce, exact same thing happened to one of my Jabs, was a J160 with full CHT monitoring. Was being used at an FTF and during the pre take off power checks started running rough. Interestingly three heads had cracks in the intake runners if I recall correctly!

Hi Ricky m, have you checked the carburettor out? I do recall similar symptoms to yours from a friend some time ago and think it had something to do with the density sense line on the carby ( small tube from the side of your carb to the filter box) Might be worth overhauling your carbons well.

Hi Ricky m, check that you have the alloy tube directing air from the cooling ducts to the coils. They will behave this way if they get hot! Also check the gap between your coils and the flywheel, I use a piece of paper to set them up. Don't think it would still make good power if a valve was sticking, though I would recommend fitting CHT to each cylinder if you can afford it.

Rudder discipline is the big priority when this slow.

Love the plane, it's on my list to build one day. However let's give the guy a break here, sure things could have been better but they could have been a lot worse! I don't think he was deliberately 'hotdogging' and I would think he has flown this same approach many times before but as we all know nothing and no one is infallible and conditions change instantly and without notice. I have met the pilot and owner at Avalon and he seemed very passionate about our sport, I think he deserves our support not criticism he is after all part of the family! I would bet he is beating himself up enough right now. I hope he gets back in the air quickly and keeps on displaying his aircraft for others to see.

Wings off and on isn't a big job, however you need the help of another person at least preferably two others. I have transported a few always on a car trailer and with the wings stacked under the fuselage. Longest trip was 700km without an issue however all it would take is a rock etc to Damage it. One consideration is do you have someone to act as an indipendent inspector once you refit the wings? Definitely a requirement, if you will be wings on and off all the time.