carlsnilsson

Roger: I'm unsure if you have a 912 80 hp or 912S, but I assume ignition layout is similar. On my older 912UL, ignition circuit A goes to plugs (1T, 2T) and (3B, 4B) (one pair per coil) and circuit B goes to (1B, 2B) and (3T, 4T). So, theoretically, all being equal, each circuit supplies a symmetrical set of plugs and should produce same rpm. I assume all your plugs are gapped the same? Does the engine start with the same facility on each circuit separately? On my 912 the power input to the ignition modules flattens off (at about 35V equivalent AC on a multimeter) at around 3000 rpm. If previous answers were "yes", then I would put a multimeter (AC volts) on each of the ignition circuit power input lines (red wires) with the engine running and see if the readings were similar from starting rpm to about 4000 rpm. The mag drop indicates that the plugs on one circuit are not getting the same power as on the other - in your case above 3000 rpm. That's either due to input to the modules or within the modules (expensive) - or maybe one coil has a problem - unlikely but possible - or there is leakage on one or more HT leads - more likely. All this assumes your spark plugs are really identical. However, if this problem has been progressive over time and apparent through changes of plugs and caps, then it would appear to rule out the plugs. Leakage in or around the HT leads is the most likely cause, in my opinion. Carl

G'day JG3 and other contributers: I have read this thread with great interest. I have a vaguely similar problem with my Skyfox CA-22 912 UL in that, after a rest of 15 months, I cannot get the 912 started. After considerable messing about, problem seems to be that the spark from both IGN modules is very weak. This particular problem has plagued me for several years - very difficult starting that has got slowly worse with time. Today I turned the engine over with no compression in any cylinder, but each HT lead going to a properly connected plug externally and producing a very weak spark. All four HT coil secondary windings measure similarly on a DC meter- about 8 K ohms DC, as best I recall - could be more or less, but all about the same and no obvious leakage to ground on ohms X 1K. Not sure of the turning rpm, but more than sufficient from past experience - will measure it in a few days. I note the manual re the "Interference Suppression Box" containing the two IGN circuits says (Sect. 6.18.5 in my 1992 version) "Apply Lithium grease to all cable connections to prevent leakage currents". Like others, I have occasionally been guilty of turning the engine over without every spark plug properly connected. However, if this was the problem, I would expect to have a problem on Circuit A 1T and 2T (usually pull 1T or 2T plug to check spark), rather than the whole shooting match. Maybe excess leakage fits the bill better? Have other owners pulled the leads off and used a Lithium grease to inhibit leakage? What's the latest on your problems, JG3? Also, I don't understand the "dead" or "lazy" stator description - a stator has the 10 coils mounted, but is not magnetized itself - is that not so, or do I have it wrong? I thought the magneto ring had the magnetized bits?

Skyfox wings G'day Brent and Dexter (and all): Just to quote (second hand) from the certification documents, the wing spars are lifed at 4000 hrs, the lift struts and carry-though structure similarly and also the horizontal stab spars the same. The primary aircraft structure is lifed at 8000 hours. We all give a lot of attention to the wings, for good reason, but I suggest in passing that owners take a good look at the tail feathers. The leading tube of the horizontal stab is pretty thin-walled and was not provided with any oiling points, which I think would be a plus. My old 55-765 ( ne VH-APK) was rusted out there when I bought her in 1997. Back to the wings: I am not sure of the powers that our Tech. Manager Stephen Bell has in this regard, but I think he is favorably disposed to extending the life of the wings etc, perhaps based on an examination of the structure and spars at the nominal life. Repair of existing wings is a more immediate and difficult problem. After 12 years of flying CA-22's without a real problem, I did something stupid the other day and relaxed too much three-pointing in an apparently benign cross-wind. Result, I hit some trees and damaged one wing. A reminder that pride cometh before a fall. Fortunately, I have a new Skyfox spar and the wing is repairable, but I won't be flying again until late in the year. The real solution lies in the obtaining of new extruded spars that meet the certification standards. Then you talk to people who are actually expert in working with these structures like Foxworker. I would be most reluctant to lose the 55 or 24 rego and change to experimental - and I too am unsure of the practicability of this, given that the foxes were factory built. I would need to read the regs again and discuss with Stephen Bell. It's not a route I wish to take. Regards all, Carl

Skyfox and Gazelle Dear pylon500: the generic Skyfox, i.e. the CA-21 and CA22 taildraggers (the latter called the "Elan") and the CA25N nosewheel (called the "Gazelle") is NOT a clone of the Avid or Kitfox, nor is the Eurofox a clone of the Skyfox. "Clone" means "identical" and the Skyfox is not identical to the Kitfox and the Eurofox is not the same as a Skyfox. In particular, the wing structures are different. The spars of the Skyfox were one-piece extrusions (including the central web) and were made specifically for that aircraft - as a result somewhat stronger than the Kitfox spars. The spars are currently unobtainable. Most importantly, the Skyfoxes are type-certificated aircraft and you cannot go rebuilding them to different specifications and retain the certification. It's a problem needing a solution. carlsnilsson