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| Just wanted to clear up some misinformation that I posted June 1. After Bob Pastusek pointed out that 1/4" clearance in static conditions (on ground, engine off) is probably not enough, and that interference with the oil pan could cause a catastrophic oil leak, I re-checked and found that I have about 1/2" clearance. Without going back to my logs, I believe that after "correcting" the problem as described, I also found that the overcenter links shipped with the kit were too long and got Lancair to send the correcton ones which I installed prior to first flight; so I have never flown with less that 1/2 inch clearance (plus/minus engine motion).
Charley
On Jun 3, 2014, at 7:19 AM, Robert R Pastusek wrote: Charlie, To answer your specific question, there are no “moving parts” in the bottom of the -550 crankcase that can be brought into contact with the oil pan…part of the engine crankcase is a cast aluminum “web” across the bottom of the engine that separates the crankshaft and similar from the oil pan itself. There is a steel pipe oil pickup that runs forward from the back right side (looking forward at the prop) of the crankcase, goes down, and makes a 90 degree left turn to sit at the bottom of the pan and parallel to the cylinders. I can measure it if desired, but I’d estimate it to be approximately 12” forward from the back of the pan at the lowest point where it runs “across” the pan. It’s positioned very close to the bottom, of course, and has multiple 1/8” holes on the bottom side to pick up oil. Having said that, 1/10” inch is not enough clearance between the fixed structure of the airplane and the engine…especially the oil pan…IMHO. The engine moves around a LOT more than 1/10”…at least ¼”, probably more. You’re likely getting away with your pan mod because the engine moves forward and just a bit up when the prop is pulling--thereby increasing clearance over the static…but it’s dangerous to count on it. The aluminum pan is very thin, as you noted, and a few minutes of contact with steel will put a hole in it…then quickly, no oil. Hope this helps. Bob Dennis, I've had excellent results with that quick-drain system on my Legacy / 550 also, over 300 hrs and a half-dozen oil changes. I also had the oil pan clearance problem with the nosegear over-center links, in fact my links actually retracted into contact (just barely) with the oil pan. Being in a hurry to get flying, and thinking that the oil pan is fairly thin and flexible, I did a redneck cure: taped two stirring sticks, layerwise, on the bottom of the pan at the point of interference, and manually retracted the nose gear (i.e., by lifting it with my hands) a few times, thus using the O/C links themselves to bend the oil pan to provide about 1/10 inch clearance in ground-retract conditions. I painted the pan and looked for witness marks, but there haven't been any in 350 hours. Perhaps someone who's been inside a 550 could comment on whether there's anything immed inside the pan, or any other risk of bending it inward/upward 1/10 inch near the center... I assume it's an ordinary reservoir with an inch or so at least of clearance above it, give or take non-structural items like a baffle.
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