Quest and YS 1.10.

[Henderson,Eric]

With beautiful weather granted us in NJ this weekend we got to do a lot of pre-winter flying. Joe Lachowski was defying all vertical gravity limits with his Temptation. My newest Quest was given an airing and to my dismay managed to spit the prop off in flight. This was the second time this engine has done this. 

The first time it did the "prop-spit" I serviced the regulator and founds some debris. The 1.10 (and the .91) uses a one piece gasket and combined diaphragm. This time it was given closer inspection. It left me with the impression that there could be an issue with the diaphragm. It was definitely not flat and may have been the problem. 

So this time I decided to go a bit more radical and fitted a complete replacement regulator from a YS 1.40. The regulator bolt and fuel hole pattern is the same but the design is different. With the 1.40 version I used a leak-free gasket and a "round" diaphragm.

The result was that the engine ran perfectly thereafter. It sounded a lot better as it was opened-up and it idled very steadily.

I have heard of quite a few problems with 91's spitting props and could not help wondering if there was perhaps a more 
generic problem with these one piece gasket/diaphragms. Either way I was pleased that parts could be interchanged and that there is a fix.

 
Regards,

Eric.
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