Thursday, 14 July 2016 12:18

New ASB: Carburetor Float Exchange

A MANDATORY Alert Service Bulletin has been issued which applies to a very limited range of 912, 914, and 2-stroke engines, as well as any engines which have been equipped with ROTAX part number 861185 floats during engine repair, maintenance or general overhaul as of May 09, 2016. 

NOTE: If you have already downloaded the initial issue of this bulletin, please discard that, and download it again. ( Links below are to the latest "Revision 1" edition. )

Due to manufacturing deviations, certain 861185 carburetor floats supplied as spare parts after May 9th, 2016, and/or installed on specific serial number engines and carbs (see the ASBs for specific serial number ranges), may have the outer surface “flake” from engine vibration.

Serial number ranges are detailed in the latest revision of ASB-912-069 / ASB-914-051 (certified engines) and ASB-912-069UL / ASB-914-051UL / ASB-2ST-003 (UL engines).

The affected floats must be replaced with current-issue 861185 floats, which are now marked with three dots for positive identification.

(a current-issue "three-dots" float, part number 861185) 


Floats produced before May 9th, 2016 are not affected by this manufacturing deviation.


Part number 861185 floats were originally marked with two dots.  
But not all of the "two-dots" 861185 floats are affected!

Only those floats which were produced after May 9th, 2016 are affected.  

You should check with your supplier to determine when your floats were produced.

Floats with part number 861185 produced before May 9th, 2016 are not affected by these bulletins. 

Floats with part number 861185 MARKED WITH THREE DOTS are not affected by these bulletins. 

Floats with part number 861184 are not affected by these bulletins.

The alert service bulletins describe the float replacement procedure and specify a range of engine serial numbers and also a range of carburetor serial numbers which are known to contain potentially affected floats.

If you recently acquired one of the affected engines, its carb floats must be exchanged. If you recently acquired one of the affected carburetors, its floats must be exchanged. 

The UL bulletin only applies to a specific serial number range of 582 engines with potentially affected floats, but if you have any model of 2-stroke ROTAX engine equipped with BING carburetors (447, 503, 582, 618) and you recently acquired replacement carburetor floats as spare parts, or had a carburetor rebuilt, then the bulletin applies , and you need to check the production date of your floats, to determine if you might have some of the affected "Two-dots" part number 861185 floats.

Note that this ASB release is not related to a previous (2015) exchange program for 912/914 carburetor floats, which dealt with an entirely different manufacturing deviation.

The issue with this very small run of affected "two dots" 861185 floats is described in the bulletin as "Due to a deviation in the manufacturing process of the floats a partial separation of the outer skin because of resonance vibrations during engine operation may occur. These separated particles might lead to a restriction of the jets in the carburetor. As a consequence the fuel supply to the affected cylinder bank may be reduced or blocked. Possible effects are a rough engine running behavior with reduced fuel flow, up to a major powerloss or engine shut down with blocked fuel flow on the affected carburetor."

Peeling of the outer skin of these floats is a serious issue, and as a safety precaution all carburetor floats identified as coming from this production run must be replaced immediately, whether or not they currently show any symptoms of skin peeling or flaking.

If your floats are affected, contact the authorized ROTAX distributor or service center for the territory your engine is operated in to request replacement floats.
If you don’t know a Rotax retailer you can find one online (Click here for the Service Locator).

CLICK HERE to view a video pertaining to this new Alert Service Bulletin.

DOWNLOAD: ASB-912-069 / ASB-914-051 Rev.1 (certified engines)

DOWNLOAD: ASB-912-069UL / ASB-914-051UL / ASB-2ST-003  Rev.1 (UL engines)

The European Aviation Safety Agency has issued an Airworthiness Directive EASA AD 2016-0144 on this issue.

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