Rotax 912 carb drip trays.

[Blueadventures]

Any one made under carb drip trays for carbs with the air filters on the back?

 

I’m looking at making a set out of aluminium with a 6 or 8mm i.d. drain tube. Images appreciated. Cheers.

[skippydiesel]

If your Rotax 912 has drips/overflows, your problem will not be solved by installing "drip trays" - fix the problem(s)

[Blueadventures]

Skippy your comment has nothing to do with my question. For your information the drip trays are fitted in order that should your carby develop a leak it will be prevented from contacting the exhaust system. Your aggressive direction is unfounded and unwelcome.

[Thruster88]

Any one made under carb drip trays for carbs with the air filters on the back?

 

I’m looking at making a set out of aluminium with a 6 or 8mm i.d. drain tube. Images appreciated. Cheers.

If you are going to do it make the sides at least 15mm high and slope it down to the outlet. The ones fitted to this factory machine are completely useless. From memory they are held with a tab underneath the air filter clamp.

 

Dont get me started on the positioning of the coolant recovery tank above the pressure cap, they obviously never removed the cap at the factory.

[Blueadventures]

Thanks T88. I have a template in plastic I did yesterday morning with 10 mm sides. And I’m looking at finding a rectangular container in alloy that I can cut the shape from and then only need at worst to place an end on. Thanks for info. Cheers

[skippydiesel]

Come now Blueadventure - my observation may not have met your question precisely but its hardly aggressive and it is without any doubt closely related.

 

Going further - I can not see how an open "tray" mounted in a highly turbulent, vibrating engine bay and subject to the rough movement of taxi/air turbulence, can have any hope of preventing a fuel rich environment from potentially igniting -again fix the problem.

[Kiwi]

Any one made under carb drip trays for carbs with the air filters on the back?

 

I’m looking at making a set out of aluminium with a 6 or 8mm i.d. drain tube. Images appreciated. Cheers.

 

 

A mate used sardine cans under the carbs with drain tubes braised on to it.

Don't forget they also act as heat shields.

[skippydiesel]

.........................................................

Don't forget they also act as heat shields.

 

Now a heat shield may have some benefits - particularly in long taxi situations.

 

In 500 hrs + of Rotax 91 ULS operation I have never had a carburettor leak - I used to use the cork gaskets on the float bowls - very fiddly & easy to damage. I now use the "Viton" rubber ones, that should also easily last for two or more 100 hour services.

[M61A1]

I can not see how an open "tray" mounted in a highly turbulent, vibrating engine bay and subject to the rough movement of taxi/air turbulence, can have any hope of preventing a fuel rich environment from potentially igniting -again fix the problem.

 

 

Now a heat shield may have some benefits - particularly in long taxi situations.

 

In 500 hrs + of Rotax 91 ULS operation I have never had a carburettor leak - I used to use the cork gaskets on the float bowls - very fiddly & easy to damage. I now use the "Viton" rubber ones, that should also easily last for two or more 100 hour services.

Based on that, you might well discard your CO monitor. Just make sure your exhaust doesn't leak.

The whole purpose is redundancy.

The float bowl gasket is only one place leaks can occur. If the aircraft has pod filters the float bowl vent line is tucked in under the retaining clip. If the float bowl overfills for any reason (vibration or debris) it can leak directly on to the exhaust and you would never know unless you saw it or caught fire.

I have also heard of pressed in pins in the float bowl coming loose allowing fuel to escape.

The drip trays are a Rotax part. I'm guessing that they didn't make them for no reason.

[Downunder]

If you want to remove the float bowls easily, try and space the trays as low as you can or make them easily removable.

It's a pain if you want to check the bowls for any debris but need to remove the carb or tray....

[skippydiesel]

Based on that, you might well discard your CO monitor. Just make sure your exhaust doesn't leak.

The whole purpose is redundancy.

The float bowl gasket is only one place leaks can occur. If the aircraft has pod filters the float bowl vent line is tucked in under the retaining clip. If the float bowl overfills for any reason (vibration or debris) it can leak directly on to the exhaust and you would never know unless you saw it or caught fire.

I have also heard of pressed in pins in the float bowl coming loose allowing fuel to escape.

The drip trays are a Rotax part. I'm guessing that they didn't make them for no reason.

 

I dont have a problem with having/fitting a carbi drip tray as such. Just wouldn't want anyone thinking they are are a reasonable solution to a leaking carbi. Nor do I think that they do a great deal to minimise fire risk but if it makes you feel safer - go for it.

As for Rotax supplying them - why not ? Reason - the customer wants them and is willing to pay, I would offer them too. Doesn't mean they are a good solution BUT I do think they might help , just a little, in reducing carbi heat exposure during extended taxiing/ground running.

Your vent line may be installed that way - mine is not. Mine exits below the exhaust system, into cowling exit air, through a common brass "diffuser" tube. It works. This is not as per Rotax but is from my factory.

 

Problem with CO poisoning as it can be insidious and cumulative. The carriage of a warning system is reassuring but will not prevent the problem, only warn you of its existence (light & sound). I go to great lengths to minimise the chance of CO in the cockpit - my monitor show current and past CO max in ppm. This allows me to check the integrity of my CO prevention strategies - a drip tray may (if you are lucky) show some dry fuel stains but then so will the exterior of the carbi - so what is achieved? False piece of mind?

[M61A1]

a drip tray may (if you are lucky) show some dry fuel stains but then so will the exterior of the carbi - so what is achieved? False piece of mind?

You will have achieved knowing you have a leak without catching fire. That's a win.

They work, I've seen them work.

[JG3]

I found that these sardine tins do the job very well. Fit snugly around the float bowl. Held up by either light bungy cord or tie wire. Drain tube is plastic drip irrigation line forced into slightly undersize hole. Been using them for 10 years no problems. Light weight and the price is right..... I particularly like their heat shield function from the hot exhaust right below.

 

[facthunter]

The smell would put me off. (and they are too small to put all the clips washers and nuts one needs when working on the engine). Right over the exhaust pipe? There should at least be a heatshield for that. Nev

[skippydiesel]

The smell would put me off. (and they are too small to put all the clips washers and nuts one needs when working on the engine). Right over the exhaust pipe? There should at least be a heatshield for that. Nev

We are in agreement - much better to make up a nice neat heat shield around he exhaust pipe. Bit of thin aluminium sheet & a couple of hose clamps. If you are keen - builder aluminium flashing,rock wool bandage/tape/ high temp silicon (for the initial install) and those hose clamps or safety wire - works a treat.