Ultralights

fortunately i am a structures guy by trade, so it wont take long to make up some during my lunch break!

gday, im in the process doing a bit of maintenance on my VG, for its 1000 hrly, i have found lots of surface corrosion, nothing serious, just little spots everywhere, also, the instrument panel is being rewired and upgraded, also part of the 5 year rubber replacement, i have also replace all the rubber fuel lines within the aircraft also.. more worringly i have found corrosion on the lift strut attach plates, the plates between the wing spar and the lift strut, where it is held by the large bolt. i will have to remake the plates, also, the undercarriage material is showing signs of corrosion on top of it where it rests on the rubber mats and blocks under the fuselage, this now brings me to a dilemma, how do you jack and support a Savannah so i can remove the Undercarriage structure, and also remove the lift strut to spar joining plates? I am thinking of large surface area wooden trestles under each wing, and a tail support to remove the undercarriage, any other suggestions??

initial SIDs can be a financial killer, most of the time consumed is in the paperwork! and if any damage has been found, once the initial is done and all repairs completed, the ongoing SIDS inspections are not much more than would normally be done during a 100hrly. and should add little, if any to the costs of those services.

my 19 rego aircraft is based at Bankstown, class D airport. though i am a PPL holder with CTA approval., and the 912ULS is an approved engine, and i have to perpetual approval from CASA.

should be a fun weekend. might bring the Savannah, or the Robin, hmmm

Blame CASA....

could it be valve train with lack of oil?

i stand corrected, just basing my comment on a comment from a fellow RAAF pilot that flew with him.. :)

i dont know, Matt Hall may be a good display pilot, and low level air racing, but i dont think he has won any judged competitions!

there are strips at Cooma, and a glider strip on the monaro hwy between Cooma and canberra, also, there is another strip on the same road about 1/3 out from Canberra. als, might give dick Smith a call, he has hangars and strip at Gundaroo.

Actually, checking your engine monitor is no more time consuming than a usual temp and pressure check that should be done every 10 - 15 mins or so.. just a quick glance is all thats needed. and the information that can be gleaned from such an instrument can save $$thousands in maintenance trouble shooting issues, and can save your life or aircraft by identifying serious issues well before they happen, and could possibly identify issues with Jabiru engines that are causing numerous failures. as for what info you can get from the scenarios earlier.. 1. Exhaust valve leaking.. 2 Injector clogging or an induction leak allowing mixture to lean out to cutoff. (such as a gasket leak. 3 EGT probe failure. 4 Exhaust system leak.... could be a serious issue, (especially if its in a cabin heat muff) watch that CO monitor until you land, and land ASAP. 5 indication of Pre-ignition... the fastest way to destroy your engine, and it could happen within seconds or minutes. ,could lead rapidly to seriously overheated cylinder/s best get mixture to full rich, or power back below about 60% to stop preignition. Land ASAP. (usually caused by cracked plug ceramics creating pre-ignition hotspots) 6 Dead spark plug (1 of the 2 per cylinder) or plug gap out of limits causing poor or no spark, might explain hard starting in the mornings. if you know which mag runs which plug, a mag check will identify the failed plug. (mag check of the dead plug will give a very significantly lower EGT during the mag check compared to the good plug) 7 Failed Ignition system. now operating on one "mag" this will also bee seen at every mag check during runup, or top of descent mag checks, a great way to ensure every plug is working fine during your runup. or identify a bad or fouled plug, or lead. Sadly proper engine management skills are lacking in the training syllabus, but with the info gleaned from such instrumentation, im sure a lot of failures could have been prevented before they happen. not only save a heap of time, as a failed plug etc could be identified and rectified before the next flight, or save heaps in your L2 having to troubleshoot everything to find the issue. without a CHT or EGT on every cylinder, how can you tell if one has been running well over temp every time you fly? or one has been suffering from severe detonation for most of the time? (detonation usually gives a slowly rising CHT with no change in EGT) im sure quite a few Jab failures are the results of these conditions that have gone undetected leading to eventual premature engine failure.

all this talk of sensors, CHT's EGT's etc etc, i try not to fly with anything less than full EGT and CHT monitors, My 912ULS is currently being modded to have all sensors installed. Its nice having all the data from EGTS and CHTS, but, the BIG question, is how to interpret what its telling you! assuming you are in cruise and have been for say, an hour or more.. 1..so, your flying along, all temps normal, EGTs are all equal, and CHT;s the same, then suddenly, EGT starts rising on 1 cylinder, and the CHT is falling.. whats happened? 2 flying along, both EGT and CHT start falling on 1 cylinder at the same time, quite rapidly.. whats happened? 3 EGT falls to zero in 1 cylinder, everything else is normal...including CHT. 4 EGT is significantly lower on 1 cylinder, all others are normal, as is CHT for that cylinder.. 5 alls well,, engine stumbles very slightly for a second, then, CHT starts rising rapidly. EGT is normal, all other indicators are normal.. what will you do? 6 EGT slowly rising in 1 cylinder, everything else is normal, CHT for that cyl is normal. 7 ALL EGT's rise at the same rate without any changes, CHT;s the same on all cylinders. some of the 7 are minor, others can become a fatal situation rapidly if no action is taken with regards to the data.. and this kind of data is of very limited use if you only have 1 EGT/CHT.. Answers this time tomorrow..

actually, aluminium, most specifically 7075 series (used quite a lot in older aircraft)is heat treated from o condition to T6 hardness by heating to 493degC then quenching. then age hardening at 121 deg for 24 hours. at approx 400deF, aluminium will start to loose a portion of its structural strength, and starts molecular changes in the metal, is the reason why 400DegF is the crucial number when it comes to CHT's and shortening engine life. If shock cooling as most think of it, that being idle power for a period of time, then why dont we see the same damage with almost every twin engines aircraft that are used for training? cooling of the metals at the rates seen in aircraft, does not cause significant changes in relation to excessive heating(dunking in large volume of water from high temps will) . now a glider towing aircraft, sky dive aircraft,etc the engine will be working hard with low forward speed, generating a lot of heat, what are the CHT's of these aircraft? how accurate are the CHT monitors, if they have any? im sure climbing all day with CHT's over the 400def, or up to even 500deg as seen on some aircraft on hot days will be doing far more damage than the cooling on descent.. there is a CHT data on the web taken from a IO540 engine in a single engine RV10, from top of climb at 13,000ft, to sea level in 10NM. idle power from long cruise. the CHT temperature trace dropped, but at a far slower rate that could possibly do any damage.. as in cruise, the engine temp should be relatively cool already(if all is normal) now rapid heating from ground taxi speeds, full power to height and under load will generate a lot of heat, and effectively age hardening the materials, causing increase in the metals brittleness. eg, cracks..

from some of the data i have seen, shock cooling is far less a problem than most make out. as cylinder head temps have more to do with internal cylinder pressures than exhaust gas temps, or the amount of fuel burnt. at idle, fuel is still being combusted, and still generating heat. low throttle settings, mean less cylinder pressures, less cylinder temps.. but when you look at the changes in temperature ranges that could be considered shock cooling, they are relatively small and of no real consequence when it comes to metals failing. full power, with blocked cooling inlets, then flying into a near frozen lake might do something that could be described as shock cooling.. but consider that most aircraft metals are hardened at 500 deg C, then dunked into room temp water within the allowed time limit of 10 seconds Max!, a small change of a 50 to 100 deg wont worry it. a nice little graph derived from real time engine testing with live data feeds, notice the ICP, internal cylinder pressures, and CHT, are almost perfectly matched, regardless of the EGT.

mines an older model with the old bed type engine mount. pictures or plans would be awesome for the bungee changer.. or how much to buy one from you?? as unfortunately i dont have easy access to welding facilities, but if it could be bolted together, then i can make one.

yep, expensive, but the same aircraft had a similar incident just the weekend prior at warnervale, ran off the end of runway, but fortunately didnt hit anything, and he managed to turn it around and get back onto the sealed surface. An empty Cessna Caravan with reversible prop should never run off the end of a 1000mtr long runway!! unless of course you try to land after floating half the runway distance, and refuse to go-around.

i have to do the same in the next week or so, replace the bungee on the nose gear, its almost 1000 hrs old, still in pretty good condition, but would rather replace it anyway. mine sits on its tail esily as well, but i do put supports under the firewall just to be safe. as for actually removing and replacing the bungee, im not so sure yet myself.

for all you guys that saw, or were at the scene today, i strongly recommend getting some help to cope with the days events, you might feel fine, now, and in a week or so, but it will do an enormous amount of good to get some professional help. even just to talk about it, and dont be surprised if you get a call from an investigator. even talking to them can help not only yourself, but find closure for those more personally involved.

a nice Savannah will do you two nicely

thats what im thinking, how do you keep the compression and combustion gas pressures in check with a moving cylinder and fixed head?

last time i was there there is fuel, credit card bowser, though last time i was there was 12 months ago, a relatively large fleet of aircraft there, plenty of croppies. im sure ERSA still has details though

i was flying that day in the sydney basin, winds at 3000ft were approx 40kts! at some points we were flying with a drift correction angle of about 20 to 30 degrees, in a 120 kt machine! given the weather report, the scene of the crash, i would put it right in the middle of rotor turbulence hot spot.

the shell Aviation supplier at Bankstown sells the aeroshel sport plus 4, in 10 bottle cases for $120.

congratulations, now the fisrst phase of your real learning begins

who are you flying with at Sydney?