ROTAX 912ULS NEW FUEL PUMP

[JUSTNUZZA]

Can anyone offer advise on a good place to route new drain line on the new mechanical pumps or suggest a good catch bottle to run it to ?

 

 

[Guest Maj Millard]

Refer to

 

Can anyone offer advise on a good place to route new drain line on the new mechanical pumps or suggest a good catch bottle to run it to ?

Refer to Rotax instructions, they recommend running a line down away from the exhaust, to within a couple of inches of the bottom of the firewall. Additionally they say you can use a catch bottle which you can monitor the contents of periodically.

 

Rotaxowners.com have a nice video on it that an be watched for additional info.............Maj...

 

 

[JUSTNUZZA]

Thanks Maj, I will see how I go.

 

 

[rgmwa]

Here's one installed in an RV-12. The aluminium tube runs from the pump down under the cylinders to the rear of the engine, and is then connected to the black hose that drops down next to the gascolator. The ends of the tube are flared so the hoses won't slip once the hose clamps are installed above the flare.

 

 

 

[Guest Maj Millard]

Mmmmm nice installation and all, but if you every pass fuel you will be putting it out right by an ignition source IE: the exhaust outlet, which does have the possibility of ejecting small glowing bits of red hot carbon !.........besides Rotax talk about the end of the tube exiting in neutral pressure area, and where it is , it doesn't. You'd be safer running the tube on the other side of then nose gear leg, and ending it about two inches above the bottom of the firewall. Sorry for being picky but you did ask. Do it right the first time and it'll never give any dramas..........plus...the way the exhaust pipe outlet hangs off the end of the exhaust-can, will cause it to crack the can badly ( trust me,...been there, done that !) ...solution:....weld a 1" steel strip from the exit pipe to the little bit of steel by where the front pipe goes into the top,of the can.........end of problem.........Maj...

 

 

[rgmwa]

Thanks Maj. The installation is as per Van's plans, but that's not to say there's no room for improvement. The drain outlet is actually quite a bit further from the exhaust pipe than the angle of the photo might suggest, and terminates inside the cowl outlet duct which I assume would normally be a low pressure area. The exhaust pipe projects about 4" below the bottom of the cowl. I'll see if I can relocate the flexible line to the other side of the nose gear leg though, or at least closer to it. Your tip about supporting the exhaust pipe makes sense. Just need to find someone who can do a decent weld.

 

rgmwa

 

 

[Guest Maj Millard]

Thanks Maj. The installation is as per Van's plans, but that's not to say there's no room for improvement. The drain outlet is actually quite a bit further from the exhaust pipe than the angle of the photo might suggest, and terminates inside the cowl outlet duct which I assume would normally be a low pressure area. The exhaust pipe projects about 4" below the bottom of the cowl. I'll see if I can relocate the flexible line to the other side of the nose gear leg though, or at least closer to it. Your tip about supporting the exhaust pipe makes sense. Just need to find someone who can do a decent weld.rgmwa

Yes always a problem finding a good welder when you need one ! I have one friend who builds large alum boats, plus he also owns a Storch so he does a pretty good jobs with a mig. Then another friend who welds a lot of stainless pipe, he's pretty good also. You do have to keep a good eye on Rotax exhaust systems for fine cracking, usually besides existing weld lines.........cheers Maj.....

 

 

[Downunder]

Any half decent exhaust place can do it. They would be experienced with welding thin wall tube.

 

If your exhaust system is not stainless then you might want to think about getting it coated.....The "before" pic was from only 6 months old. Aircraft always in a hangar. The salty air on our coast doesn't like Austrian steel by the looks.

 

Not a particularly cheap exercise but ALOT cheaper than a new exhaust system......Had mine done here http://www.cicceramic.com.au/

 

Due to the high temps, it does fade a bit.......

 

 

 

 

[rgmwa]

Thanks for the tip. How much did they charge you?

 

rgmwa

 

 

[Guest Maj Millard]

Unfortunatly cracking on Rotax exhausts is generally not caused by rust, but by vibration and internal stresses locked into the system. By their very nature exhaust systems have to be checked regularly for cracking. Also the heating and cooling cycles of operation will do it also. Exhaust systems on GA Lycomings and Contenentals will do the same thing especially on AG aircraft which are worked hard.

 

The majority of fine cracks that I have found, often originate right against the edge of a weld. Coating (or painting) a system makes the detection of fine cracks difficult, or even impossible until the crack is larger and advanced. Then a weld repair would be made more difficult to do well on a coated system..........Chroming of exhaust system components is also unwise as you run the rick of hydrogen embrittlement if the process is not done correctly...............Maj....

 

 

[rgmwa]

Hmm, I do find that rustic look quite attractive too.

 

rgmwa

 

 

[Downunder]

Hmm, I do find that rustic look quite attractive too.rgmwa

Till bits start falling off...........and it's not chrome.....

 

 

[rgmwa]

Good point. Oh well, who needs a muffler anyway. Maybe I'll just leave it off.

 

rgmwa

 

 

[Dafydd Llewellyn]

Pick your stainless. Aircraft exhausts should be type 321; weld with 347 filler.