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Folks my Rotax 912 F had a category 1 prop strike in December. I've checked run-out (well within limits) and am fitting another 3 blade 72" WarpDrive Prop. My old one was set at 9.5 degrees and gave good RPM static (5300). The new one is set to 6.5 and only giving me 5100 rpm.:eek:
field alt: 5300ft
Temp averages 28 decgees C
Any ideas would be very much appreciated.
Best
Zeke
That's a big difference in pitch with a smaller change of rpm.
A bit obvious,but are you using the same point on the prop to measure or is there a miscalculation on the pitch guage?
You checked the "run out" of what? The prop flange? Was a crank shaft inspection done? This is a complicated procedure, but can be done without tearing down the engine.
I just finished setting the pitch on my 3 blade, 70" Tapered Blade Warp Drive Prop with a 912 UL.
First a few questions; where are you placing the protractor in relation to the prop blade tip?; do you have straight or tapered blades?; do you have the nickel leading edge?
I am almost at sea level, however, I started at 11 degrees and my static WOT RPM exceeded 5800. I then went to 14 degrees and had A static WPT RPM of 5200. I placed the protractor at the tip as recommended by Warp Drive.
Ralph
Many Thanks for the useful feedback all. I have been tinkering and came up with the following:
1) Dirt in the jets...
2) One Prop blade slightly out of true
3) The digital gauge we used for the pitch setting was for a different prop... So we got even pitch but not a true angle. Yes, we measured the distance from the hub, and this was right out out at the tip.
4) I re-checked the angles using a protractor (Warp Drive) flush with the tip and got similar results and 8.5 degrees after adjusting for the 12 degree rake-back angle my 26" Airstreaks generate. I also compared this to two other KF's in the hangars and got similar results. So I think I'm within range (?).
So static is similar 5100, and Full Bore in the cruise is 5300. I want a little more if possible tho. But hesitant to fine out the pitch any more - any thoughts? Take off power was all there and the pre-take-off roll was as I am used to it, about 250/300 M odd.
I cruised up around Mount Kenya yesterday and back again. About 3 hours with a break half way. All went well and the view was worth all the effort of keeping this little bird up and safe! The Photo attached is looking down from around 9000 feet on t he MT Kenya Forest Canopy about 1500 ft below. Those are Big Trees!
When I landed back at my base strip neat Nairobi, OH Boy, She was running rough again, between 3000 and 4000 rpm. And not so good at idle either (1750). So back to checking Jets again tomorrow before we go flying over the Masaai Mara looking for a lost lion with a collar on... !!
Anyhow, we have a lot of issues with fuel quality here in Kenya, even from reputable (?) sellers like Shell. So I'll be switching out the inline filters from the wing tanks before the lion flight too.
All thoughts welcome and thanks again
Zeke
https://1drv.ms/i/s!Agw03vsxyd32hTGar4vDq8qLHQZV
The Flange yes. Interested to know how the crank can be done without a tear down please.Quote:
Originally Posted by Av8r3400
As far a dirty fuel goes, I try to always pour my fuel through a 'Mr Funnel' That will even filter out water supposedly. I'm almost always refueling at home out of fuel cans. JImChuk
https://www.amazon.com/s/?ie=UTF8&ke...l_7iaccrm5ei_e
Line Maintenance Manual
The above link is to the line maintenance manual. Chapter 5 goes through the prop strike procedure. It refers to the "heavy maintenance manual" for the procedure of the inspection.
Heavy Maintenance Manual
The heavy maintenance manual (link above), chapter 72, section 3.9 give the step by step procedure.
California Power sells the crankshaft distortion measuring tool for about $250-$300 .Most common dial indicators with appropriate fittings can be used to measure crankshaft runout Rotax has adequate instructions for use of the distortion tool.
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