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On Thu, 08 Apr 2004 16:31:40 GMT, ET wrote:
As I've thought more and more about getting my PPL and building a plane, it's these engine failure on takeoff accidents that bother me the most. It's been mentioned here that statistically, flying GA is about as dangerous as driving a motorcycle. Statistics can be misleading, of course. I used to ride motorcycles, and have done my share of "stupid" things, but the most danger in riding a motorcycle is more the stupid actions of other drivers, especially regarding the decreased visibility of the MC to other drivers. So to increase safety in driving a motorcycle, you constantly have to imagine your invisible and that every car that has the potential to intersect your course probably will, and act accordingly (in other words "ride paranoid") It seems that a pilot has alot of control over "most" of the risks of dying in his plane.... fuel exhaustion, flying into IMC, landing in crosswinds beyond pilot/plane capability... etc., but For awhile I've thought these were engine failure on takeoff were the most unavoidable accidents, since it's basically instant failure and can happen at any time in an engines life. I don't like feeling that there is a risk of dying that careful planning and/or technique cannot reduce. As I've done more research (yes I'm sure alot of this will be covered in PPL training.. but..) I've learned and inferred some things. Obviously, during takeoff is the time when the engine is under the most stress, that's why, I assume, a good run-up is done before takeoff, so hopefully if something is "about to fail" it will fail then and not on climbout. Your suggestion of best angle of climb, I believe mirrors my recent mental processes about the takeoff and engine failure risks. I assume that best "angle" of climb will give the aircraft the best compromise between rate of climb and engine output/stress? In thinking about engine choices for my (hopefully) upcoming Sonex project, this has lead me to lean more toward the (much) more expensive Jabiru 330, rather then the AeroVee or Jab 220. With more power available, the plane will climb to above my "no return" altitude quicker, and/or at a lower % power setting. I have communicated with one Sonex pilot who totaled his airplane after a prob hub failure (using a GreatPlanes VW setup, a faulty hub attachment that has since been re-designed) and an attempted turnback (roled the plane after a wingtip strike... fortunately lived to tell about it). Very scary stuff.... I was also taught in my first GA plane ride (sr-22) by a CFI to use every foot of available runway. We pulled onto a 5300 ft runway off the taxiway that was about 100ft or so from the beginning of the runway and he still turned, and looped around to use all of that 100 feet. He reasoned to me that in the event of an issue at takeoff that 100 feet of runway could be the difference between life and death, even though the sr-22 only needed less than 1000 feet to takeoff.... I know this is very basic stuff to this group, but in my very short time of "hanging around" 2 different small airports I have seen many folks jump in there plane without doing "any" inspection, takeoff with no runup, etc. I wonder how many of these statistics are a result of these breakdowns of procedure....? -- ET ![]() ET, I also have your concerns, and I'm building a homebuilt airplane. In addition, I'll be using a non certified auto conversion. Since the majority of fatal accidents in homebuilts occur during the initial flight, I am paying particular attention to this detail. To that end, I intend to run the engine on a test stand I've fabricated for many hours. I need to test the engine at full power for at least ten to fifteen minutes a number of times. I also feel I should document this so that the DAR can see that this testing has been done. It's surprising to hear of the number of first flights that occur without extensive ground testing of the engine. In addition, once the engine is installed in the airplane and all systems are hooked up as they would be for normal flight, I intend to further test the engine with the fuselage jacked up in a nose high attitude to make sure that fuel flow and engine cooling are adaquate for the climbout. Further, because I'll be using electronic ignition and I'm trying to reduce the single point failure mode possiblities, I'm doubling up on the ignition systems. The distributer has two pickups inside it and will lead to two completely independent ignition systems. Both will run simultaneously so that should one fail, the other is already running. This is what the Nascar racers run in their race cars. Yes the distributer represents a single point failure in and of itself, but since the distributer drive is also the oil pump drive, should that fail the engine is history anyway. The wiring will conform to aircraft standards. Every external and a number of internal bolts and nuts have been safety wired, including the oil pan bolts. The oil filter is safety wired in place. The oil pump bolts are all safety wired. The intake manifold bolts and the exhaust manifold bolts are safety wired. Cooling system hose clamps will be safety wired. All these things I can control and many are the result of actual experience. Single electronic ignition systems have failed. Oil filters have spun off. Carb hold down nuts have backed off. The oil pickup tube hold down bolts have backed off. All that has failed in the past has been addressed. That's all I can do. The airplane itself is a high wing monoplane with STOL performance. I decided on that type while flying around the Vermont/New Hampshire/Maine area. There are precious few flat places to set down should the engine fail so I decided that I should build an airplane that can land very slowly, if necessary. Corky Scott |
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