Alan

John Avgas for 99% of the time. I have topped up with 40 litres of BP Ultimate on three occassions just to ensure a no diversion home run with reserve. 2900 rpm gives me 21 L/hr and nice cool EGTs. Alan

Engine #1039 - 35o hours to date. Good stable leak downs. Always cruised at 2900 rpm. Funny how Jabiru attracts the "I've been told" comments when the request was addressed to users. Alan

My J230 has the symtoms described, but I have the fuel flow sensor installed in the wrong place! (I could not feed the sensors cables down the central duct - try as I might with all sorts of cable threaders). My fuel pump is in the fuel line between the electric pump and the mechanical pump. This is warned against in the fuel computer installation instructions. As a result, when the electric fuel pump is on my fuel flow appears to increase 2-3 litres per hour at idle and 5-6 litres per hour at 2900 rpm. I never noticed any fuel leakage or engine condition change when the electric pump is switched back on. For example after a long flight when the engine is stable when I switch back on the electric pump in preparation landing, the motor note, revs, CHT, and EGT, remain the same no matter what the pump configuration. So I think it is the pulses after the electric fuel pump unevenly driving the sensor rotor speed; the signal processing must not average out this affect leaving the fuel flow/consumption reading erroneously high (safer than an under reading error). I have never left my electric pump on in the cruise long enough to check whether extra fuel is actually being consumed, but I believe it is not. If running both pumps together caused additional fuel usage then either there is a leak in the pipe work or the Carb needle valve is becoming compramised. If anyone can tell me the trick to threading cables down the central spine of my J230c (it has been done on another J230c with no problem), I would be grateful. My J230c came out without the central tank warning light and I would like to fit one. While not trusting the Jab fuel guages I have never had a problem. Pre flight tank dipping, calibating the fuel flow sensor makes me feel reasonably secure, even when I can end up with one tank indicating almost empty and the other 3/4 full. Regards Alan

Is the fuel sensor between the pumps or anywhere after the electric pump? The electric pump will put pulses in the fuel pressure that affects the fuel flow sensor rotor. Alan

In a Jab 230 it is: Wing tanks are both connected to the central (header?) tank. The fuel then goes through the electric pump, the mechanical fuel pump to the carb. There is no return to tank fuel. The pressure guage sender is between the mechanical fuel pump and the carb. If you have a fuel flow meter it should be in the line before the electrical pump. Start up is. Electrical pump on for a few seconds then off - Primes fuel system and verifies function of electric pump. Start motor, taxi and do checks on mechanical pump only - verifies function of mechanical pump. Switch on electric pump for take off, landing and anywhere else you want to be doubly certain of fuel feed. Alan

Condition Monitoring Services (Vibration, oil and grease analysis). Regards Alan

No noticeable change in cranking or starting after the change to iridium plugs. But it has never been a problem before; it never really gets cold up here (FNQ). Alan

Have only done 14 hours flying since fitting iridium plugs and the same result; there does seem to be an efficiency increase. However, I had forgotten that I had the wheel spats put back on the plane at the same service as the change to iridium plugs. This may explain or contribute to the changes observed. Alan

Just changed to Iridium plugs (engine 330 hrs) out of curiosity. Previous plugs were normal NGKs and had been changed out after about 100 hours with no problems. However, the Iridium plugs have presented some noticeable changes. In the circuit there was no noticeable difference, but when set up to cruise there were distinct changes. Normal Spark Plugs Typically I cruise at 2850 rpm which gives just over 110 knots at 20.5 litres per hour, the EGTs (cyl 3 and 4) were level at about 1250°F - I was happy with this. Use more revs to go faster, fuel burn went up and EGTs reduced slightly. Been like this for 330 hours. Iridium Spark Plugs Setting 2850 rpm still gave about 110+, but the fuel flow was now at 19.2 L/hr, the EGTs Cyl 3 was approaching 1300°F and Cyl 4 was now 1275°F. I was two up close to MTOW. Hmmmmm. Resetting the throttle to give 20.5 L/hr now gave me nearly 2950rpm and 120 knots, the EGTs were back down to normalish but No 3 Cyl still leads by about 25°F. With the change to Iridium plugs I will still adjust the fuel flow to maintain low EGTs (and am currently considering fitting a 2 X six channel temperature monitor), it just means I fly faster or change back to normal plugs. Even though I only have two cylinders with EGT sensors I have always flown setting the fuel flow to keep these below 1250°F and have found that going below 20L/hr will slowly have the EGTs climbing. Are these Iridium plugs really that much more efficient? anybody else experienced this? Gauge error? Any suggestions. Regards Alan

Ignition, Thanks for the sentiment about the cyclone. All prepared and battened down - it a case of wait and "what will be will be" now. As far as the window is concerned (and assuming the hanger stays up) it is the removal of the old window that looks like it may be a bit tedious. Alan

Anybody replaced a door window on a Jab (230) - don't ask:beg:. Interested in any helpful hints as to removing the old window. Currently thinking of having it ground out of the frame to leave room for the new +plus epoxy glue and then filler. Alan

I have a Jab J230 and have vibration analysis experience through work. Next time I am home I will attempt to measure the static natural torsional resonce of the propellor/crank/flywheel assembly. It will not be excactly the same as the dynamic torsional resonance but will give some guidance. I am intrigued enough now to put inthe effort. Regs Alan

EGT - Temperature Spread My 230 has EGTs on Nos 3 and 4 Cylinders only, but even when cruising throttled way back because of FNQ turbulence the EGT temps never go above 1300°F. However, my No 4 is always some 50°F below No 3. On those two cylinders anyway I don not seem to get the high EGTs we are warned about at low rpm. NB Weather permitting I use 2850-2900rpm most of the time. Just wondering what others had experienced as a typical EGT temperature spread for the Jab 3300 cylinders and for those with six EGTs whether there is a consensus as to which cylinder positions run hotter (leaner) than others (possible as a result of the different paths lengths in the inlet manifold to the single carb). Many years ago I rode a trials bike (Greeves Scottish) this had two inlet manifolds,a short one for road work and a long one for trials; the long one increased the torque. So I assume the manifold length must change the mixture or charge somehow, as the jab has three different inlet manifold lengths. I wondered whether this was contributing to the reported Jab EGT temperature spread - Anybody? Alan

Where do people keep their EPIRBs Slightly off topic but where do other people keep their EPIRBs? In my J230 it lives in a safety grab bag (Water, First aid, torch, spare GPS etc) just behind the passenger seat where I can just reach it in flight. But I feel this is a compromise as I also keep the ERSA here and have found that retrieving the ERSA in turbulence troublesome. Any other thought? Engine out in smooth air, OK reset the transponder, but flying out west up here (FNQ) in the typical turbulence after about 10am and then having an engine out you are going to be pretty busy just keeping the plane steady; trying to fiddle with the small buttons and knobs on the Microair is not going to be easy and would just adds to the stress. I suppose I should consider presetting the distress code in the standby memory, but as Maj offers this would enhance the risk of false alarms. Alan

Er excuse the stupidity in the previous entry about indexing the prop around. This of course will controlled by your bolt spacing. Alan

I analyse vibration spectra of machinery as part of my job. The fact that the vibration exists in an rpm band suggests it is a resonance problem. That is not to discount the unbalance offering from Maj as there may well be an underlying unbalance. Think of a resonance as a mechanical amplifier that only works at certain speeds, so a small unbalance can really offend if it hits a resonance. The balance of reciprocating machines is a black art, but it is normally sorted during the design stage. But it could be that where you have now indexed your prop through the 3:1 gearbox the unbalance and there always is some (aerdynamic and mass) is in phase with a directional engine vibration. You could try moving your prop on the hub - given the 3:1 gb I would try moving it 15 degrees from where it is. The other thing that can drive a vibration resonance is mounting stiffness - to move a resonance vibration frequency up either increase stiffness or reduce mass, the opposite actions moves it down. Generally you try to have all resonances above normal operation. Did you use new engine mounts with your new motor? We have fixed a multi million dollar boat by adding washers that allow us to pre-compress the mounting rubbers. Alan

Next time I am at the hanger I will measure the angle and chord width of the deflector plates. I have to climb under the AC anyway to replace the transponder antenna which came away in my sponge during a wash session! Watch these as they are a very light construction and now having seen what little was holding it together i am surprised it lasted this long! The actual angle I used for the deflectors was a fluke. We exposure test aircraft materials up here - primarily composites, but I had some bits of an "alloy" we had left over from some adhesive bonding tests many years back. I cut the deflectors from this alloy and the "shallow" angle was the limited bend I could put in with my wooden bench mounted vice! Boy was that stuff stiff. Must look up what it was at some stage. So I cannot claim any real science in choosing the angle, but years of being around aircraft and model making suggested my low angle would be worth trying. Alan

Carlo Prete up here in Innisfail does Float Plane Endorsements. Alan

JR, Before the factory kits came out, following I think Brentc's example, we put cowl exit deflectors or "tabs" on three J230s here and got very variable results; one actually had more high temperature problems. Mine had only a shallow angle deflection and showed a huge improvement. Make sure your angle of deflection is not too high. Even operating up here in Far North Queensland we don't have any normal operation engine temperature problems now that all the Jabiru cooling mods are in. Alan

HEON, I have had a Mizer for a couple of years now and it has worked fine as an additional fuel indicator. (Can scan the Instructions if anybody requires). Sounds like your unit has a problem if it shows remaining fuel OK but no flow figures. You could try a recalibration which might jog it back into action. The Mizer flow sensor should to be fitted prior to the fuel pumps. Mine is between the electric and mechanical pumps and reads high when the electric pump is on - I think the pressure pulses in the fuel line cause the rotor to speed up. Alan

Does anyone know what paint to use to match the Jabiru factory built white finish? My elevator tape departed yesterday and took a fair proportion of the paint layer with it :raise_eyebrow: Alan

Apologies- Cannot find reference in POH OK Sorry chaps but I also cannot find any reference to a 85Kg seat limit in the POH. Just got back from a stint out in the very wet bush up here and have since been through POH at least four times. Perhaps I am loosing my marbles or dreamed it, but I am convinced I have read it somewhere. However, what started this was a discussion with another 230c owner. He concurs he has read it somewhere also. So perhaps we are both having senior moments together. In a desperate attempt to prove we are both mentally fit, we are still looking into this. Again, sorry for ringing the false alarm. Alan

Chris. Most resin systems continue to cure for a fairly long time after the recommended time. A simple analogy is lots of little short molecules are present in the liquid resin, adding a catalyst causes these to cross link to form bigger networks of molecules and form a solid. Like musical chairs not all the monomer (little molecules) can find partners or a nich to bond onto, so these slowly diffuse through the solid until they meet up with an active site or another monomer. Heating increases the reaction rate and the diffusion rate so a higher temperature will help the cure. But go too high and the heat becomes destructive to the resin system. The strength of a composite comes almost all from the fibres, the matric (resin) holds the fibres together and provides form and stiffness. Alan

Glenn, I am away from my 230 for the next few days. Will look up the details then and get back to you. Alan

Heating or soaking composites I would go with Brentc on this; to go outside the conditions in the POH is I believe operating illegally, even if demonstrated and indicated safe verbally by the manufacturer it is still a "no go" area. I think the only way out of this dilemma is to obey the POH or get Jabiru to issue an amended POH. I ask a similar operating question about my J230 seat loading being limited in the POH to 85Kg and the ramifications of exceeding this relatively low limit. Just a quick point on composite materials and heat. We exposure test aircraft composite materials and structures here in FNQ (Not commercially, so I am not advertising). and yes strength is lost with temperature increase, but not linearly, there is a transition point that depends on the resin system, weave, direction of loading etc. It is more realistic to think of the composite having a recoverable loss of modulus (stiffness) with temperature increase. Interestingly many composites actually increase in strength with heating and time as any left over monomer in the resin cross link. Moisture absorption also effects the modulus of many plastics. Hence being in Innisfail for this testing! Alan