Modest Pilot
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Everything posted by Modest Pilot
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Couple of points about 4 way valves. First the both on position is usually 180 deg from the off position. A number of Cessna's have tried a takeoff in the off position, the engine often cuts at around 50 feet. The Andair fuel valves have a pull up pin before you can go to off, not perfect but maybe a help. On low wing aircraft with no header tank, with low fuel and the selector in the both position un-porting can occur, air can enter the system and cause at airlock. Vans aircraft kits no longer have fuel valves with a both position after a company employee had an engine stop on final and right off his brand new pride and joy. Apart from the draining on the ground problem on Jabs in the air unless you keep the aircraft perfectly trimmed for yaw (no rudder trim on Jabs) fuel will always drain from one tank first and you will fight a wing heavy situation which is a pain on long flights.
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I can't remember the details but Jabiru increased the size of the float cutoff seat in 3300's as some engines showed problems such as yours. Ring Don at Jabiru for the details.
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Moree is a popular stop for those coming from the North. BP card required but the agent usually is there prior and after Natfly and takes cash or Credit cards.. It's around half way if you are coming from YCAB. You will find it a little to the west of the direct track, but this will keep you away from the High terrain and the trees south of Wee Waa.
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Check the brass plug below the butterfly valve. The one you use for the manifold pressure gauge.
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That's it Jaba. Took me all day, it's hardly worth removing the engine, as the time works out greater. The factory have it down to about 3 hours with two guys on the aircraft. Hint: a stud clamp would be handy, saves having to double lock stop nuts to stop the stud turning when you put( or take off) the first nut. I was probably over cautious and did one nut at a time, which meant that you have to wait 10 minutes or so to let the Locktite set up and not let the first nut turn, so that's 2 hours gone. You might be able to set up a sequence that's faster and not risk distortion of the case. I spent the time cleaning the lead build up off the heads! It's worth doing an oil change as the cowls are off, taking off the oil filter and adapter, gives a better swing for the Torque Wrench on the lower forward nut. Also the new ratchet torque wrench's are hopeless for this job; you need to keep the crows foot adapter at the same angle for the correct torque. I would not do this job with a non certified wrench either. Having said all this I must add that this is one of the nicest and easiest engines I have worked on.
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There is also a cheaper Locktite with similar specs available, but beware as the temperature rating is to low. Also the latest 620 containers breathe and have a much longer; if any; use by date.
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To replace the barrel nuts the Heads and the pushrods and their tubes have to come off to reach the lower nuts.
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All bolts stretch it's just a question of how much, it depends on a lot of things including the tempering. A lot of time and money is spent finding out how much! If you think about it, an aircoooled aircraft engine has a whole bunch of different metals madly expanding and contracting a different rates. The pretensioning and a calibrated turn would be ideal. I guess cost will rule it out for low volume production.
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My engineer brother put me on to the new electronic strain gauge activated torque meters. I bought a 3/4" drive certified one (0% to +1/2% error) on the net that does 20ft/lb to 60 ft/lb for $50 bucks. Gives LED warning lights green, orange , red as well as the LCD read out. Stores the last 50 readings. I agree there are better ways to tighten bolts (check a Falcon auto manual on how to tighten the head bolts and you will get the picture) but you may as well start with a decent tool.
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Hope I'm wrong but the plenum chamber still looks on the small size. My J230 is updated as follows: 290 needle jet and new needle to match, flow straightner, and the biggee 3/16" equalizer vent and 3mm emulsion tube holes. The latter brought the EGT range down to 650-680 F at 2800 rpm 20" MP and 23lt/hr with a Senesnich 56" pitch prop. at 2000' and 23 deg OAT. T/O really gets up and goes @ 42 lt/hour F/F and even lower temps. Had to reset the idle down from a little over 1000rpm; Seems smoother from 850 rpm-3300rpm than before. Starts going rough below 800rpm. So unless the new plenum offers a huge improvement I think that wraps up my tuning efforts for a while.
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Be aware that if you change the factory prop you may have to re jet the carb, it's a bit tricky I'd talk to Don at Jabiru first. You need EGT and CHT's to make sure that you don't go to lean, you will probably need to cruse at higher cruise rpm to keep the EGT's down.
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That's exactly what is about to happen. A new rudder is awaiting certification. No more flat sides. A more efficient 12% chord standard NACA airfoil. The J230 will get the same treatment if all goes well. Makes the aircraft feel nicer to fly.
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An unexpected increase in manifold pressure turned out to be a minute crack in the tube at the take off point. It's located right under the butterfly valve. Interestingly the EGT spread narrowed to 10-15F, with a minute increase in overall temp's. Jabiru think it maybe turbulance create on the opposite side of the carb from outlet of the atomizer. It gave a constant 3" less reading accross the cruise/climb range. Jab are still working on the new manifold at this stage you will likely need new or modified inlet pipes to fit it.
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Easy enough to get to Lax. There are heaps of good value airport hotels if you want to take a break. The flights tend arrive early morning giving plenty of time to wander around to Southwest Airlines. They usually stop once so if you get one through a close stop like Las Vagas you can grab a good seat by the overwing exit (lots of legroom) as deplaning pax get off! They have 4 services a day to Gen Mitchell Field Milwaukee, (costs around $500 return) much quieter than O'Hare and cuts an hour and half off the trip to Oshkosh. Also you just walk across the road to get a rental car avoiding the dreaded shuttle bus! This is worth considering as they do road works in summer and the turnpike from O'Hare can be like the harbour bridge in peak hour. I'd also recommend the EAA hotline and stay with an America family, most houses are airconditioned and it can be stinking hot and humid in summer; might even score a swimming pool if you are lucky. The locals are friendly and will more than likely take you to places that you would never find on your own.
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engine stalls in very cold weather when throttle advanced briskly
Modest Pilot replied to a topic in Jabiru
One thing to keep in mind is that if yopu use carb heat, use it for at least a minute as per ops manual. This avoids the posibility of re- freezing. Just how cold the manifold can get was bought home recently on my mates 180HP J250. It has two Bing Carbs and a large x-over balance tube. The temp up here has been in the 30c range but with 90% humidity. The crossover tube gets no Carb Heat and has been freezing to the touch with frost all over it. (and you know how hot a Jab gets under the engine cowl!) -
Garmin have a trade in program. You may be able to get a 295 factory checked at their site fir a very reasonable price.
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Extending the lower cowl back past the firewalled helped, blocking off the gap on the oil cooler inlet shroud was good for another 10F lower head temp. You'll then need a 30mm air inlet to a shroud on the front and bottom of the engine sump exhausting at the muffler, this gets the oil temp back to where you what it. Final figures heads 245-250F oil temp 85-95C. The 30mm inlet has a butterfly valve to allow pilot ajustment for cold OAT. Interestingly increasing the needle jet from 285 to 290 (needs new needle also) got the EGT's to below the 700C I was looking for but the head temperatures went up a little. My 3300 has the latest heads and the T/O fuel flow went from 33 to 36 litres an hour so it could be the engine just works better. With old heads this might not happen and the heads will just get cooler! Just as I thought it was time for a break my hanger mate launched his new 8 cyclinder 180hp J258!!! and we are now starting the process over again.
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The take off point on Bing's is not quite manifold pressure but so close to near enough that it doesn't matter. Manual Manifold Pressure gauges seem to read O K without a damper. Electronic sender units may need a rod (brass?) with a 1/64" hole in the tubing. If you have a fuel flow guage as well you can get meaningfull performance figures.
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Assar: If I read your post correctly you are intending to operate with a prop that exceeds the engine manufacturer's inertia limit. If I may I'd like to counsel you to have a re-think. I recall talking to the "wheels" at Bundy about the weight of this prop. Do yourself a favour and give Don a call at Jabiru 61-7-41552811 and get a second opinion. The forces involved if something goes wrong in this area are truly insane! I may be slightly paranoid on this having flown Lockheed Electra's (prop whirl mode from cracked engine mounts was enough to tear the wings off these aircraft) and I also flew a demo flight in a Sportcruiser (Rotax 912) with a Woodcomp similar to the one you describe the day before a prop failure almost ended it's lifespan. The engine mount broke, the firewall bent, fortunately both carbs were ripped off at the rubber mounts and the engine stop a fractions of a second after the event and a successful forced landing accomplished. Not much room for error in this area.
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I presume Jabiru props in N Z are tracked to 3 mm. I feel this is to much for a light engine like the Jab, under 1mm gives a noticable improvement in vibration. On the orginal Hoop pine prop this was hard to get, but along with a dynamic prop balance; people that flew with me remarked that the engine must have been blueprinted. Until more is understood about the flywheel bolts breaking maybe it would be worth working this area. P S: In the end I fitted a Sensenich prop from the factory.
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No it's not a requirement, but if placed on with the engine still warm; any engine; it can cut internal corrosion by as much as 90%
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If the problem turns out to be the flywheel alloy yielding the bolt tension may not be the fix. The index marks might look O K but the flywheel may still rock. Keyways in the crankshaft in my book are a no-no. Almost a sure way of starting a fatigue crack in high powered aircooled engines!
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The latest EAA Sport Aviation mag has an article by Mike Busch (44 as year an USA A & P) on mag checks and plugs. While saying that fine wire plugs have as much as three times the life of normal plugs I thought his comment worth thinking about before rushing out and buying plugs that cost what they do. Quote: I am not a big fan of fine wireplugs and use conventional massive-electrode plugs in my airplane. In recent years, we’ve seen an epidemic of insulator failures in fine-wire plugs. Mike also hosts free maintenance webinars on the first Wednesday of each month at 8p.m. (Central). To sign up or access the archives, visit www.Savvymx.com/webinar
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Savannah accident in Gladstone
Modest Pilot replied to Kyle Communications's topic in AUS/NZ General Discussion
The aircraft had completed a flight with a friend as pax. The pilot decide to go for a further flight by himself. The aircraft appeared to raise the nose wheel at a lower than normal take off speed veer to the left and become airborne, the left wheel hit a pile of dirt, the left wing tip then struck the ground and the aircraft cartwheeled down the slope away from the airstrip. The witness tried and failed to extract the unconscious pilot from the wreckage, went for help and on return found the pilot had crawled clear. Fuel was escaping from the aircraft. The pilot was taken to hospital banged up a bit but looks like being O K. -
You might consider a Jab 250, there is one in Tasmania coming up for sale shortly I believe. They have 120sq ft of wing so stall is a couple of knots slower. More to the point the ailerons are better (they area bit bigger and wing has a cusp) than J230/J200 so 55 knot approaches are a real possibility. I think you should spring for better brakes and bigger wheels/tyres (Matco?) if you are serious about going into tight strips.
