Thread: 200 hourly strip down & re-assembly of Carburettors

I refer to the revision in the Rotax Maintenance Manual (Oct '09) where Rotax now require that both carburettors be removed every 200 hours T.I.S. and be completely stripped down and re-assembled in accordance with the Rotax Heavy Maintenance Manual.

Does anyone know why they have increased the requirements in this area? Has there been problems and if so what kind?
It certainly adds to the maintenance costs as the procedure is quite time consuming.

This is not a change. This has been this way for quite some time. It is only an inspection and does not require the removal of all the parts. If you strip these all the way down then you ought to replace the "O" rings. Just an inspection shouldn't require this. The inspection isn't hard to do. Do not remove the cables from the throttle arm. Just remove the throttle arm and it will make the carb balance much easier. If you do it as Rotax wants it then you are looking at about 2.5 - 3 hours which would include the carb balance.

Although the carburetor rubber flange and diaphragm can be inspected, access to the carb is limited to an in situ inspection, by the close proximity of the firewall to the choke cable. It is not possible to fully remove the diaphragm chamber and needle as long as the choke cable remains attached here. If you want to fully inspect the carb it looks like you need to strip the heavy heatshrink that goes over the 90 degree choke cable guide and the cable outer, in order to have the carb out onto the bench as you might well expect for a really good look. I checked with the CT agents in UK and find there is no part number for this heatshrink. This is making me think that no-one is disturbing the carb from that location, or are people disconnecting the choke down at the tunnel?

I sent in a query and am waiting for a reply from Flight Design on this point for the past couple of days.

My inference is that there is only a cursory inspection of the carb being generally done, or maybe there is some trick to removing the heatshrink?

I just did one a couple days ago. I remove the upper chamber and then removed the rest of the carb to the bench. You can remove the carb to get it out a little farther to remove the 2 chamber screws. Tom

Does this mean that you were able to pull out an extra length of choke and throttle cable away from the firewall?

I was able to remove the 2 chamber screws easily, using a stubby screwdriver but found that taking the top of the chamber and plunger etc seemed to require excessive force.

I removed the throttle arm and choke cable from the side of the carb. Removed the 2 screws and took off the chamber top and spring. I left the plunger in the carb. You might be able to rotate the carb in the socket to get a better angle for removing the chamber top. Tom