912S shutdown on Final

[catz631]

I had my engine quit on me 3 times on final when I first bought the aircraft. In fact I think it was 3 of the 6 landings I made. Fortunately I was high enough and it does a reasonable glide.
The problem was too low an idle. I adjusted that and have not had a problem since but always think about it happening again and try to adjust my flight path accordingly.
Not nice to have this happen when you are new to the aircraft ! (or any time)
Dick Maddux
Fox 4
912UL
Milton,Fl

[HighWing]

Interesting topic. I have a friend that typically sets his idle to stop at full back throttle. He does it for short field work - he had a 700 ft. strip at his house with a mountain of cow manure just short of the threshold. He flew it that way for years and never had a problem. I always had my idle set much higher than that but never tried to get into his place. My guess is that if I flew his airplane, It probably would not have been pretty on final. As Dick and others suggest, it may have more to do with what you are used to than the absolute idle numbers. My thought always was, these engines don't windmill given the gearbox and I don't want to deal with the potential need for an engine start in that situation.

Lowell

[DesertFox4]

If it's running good in all other power settings then it's idle setting.
Raising the idle setting 100 or 200 rpms makes all the difference. One of my friends has his set lower than mine and I can kill that engine every time if I pull back on the throttle firmly on short final. Happens when the load is removed from the prop. Most set for 1800 to 2000 rpms on idle. I like 1200 to 1400 on mine. Allows for much shorter landings, less float. Like Slyfox and Av8r3400, at touch down I advance the throttle to the 1800 rpm range to keep out of the gearbox "chatter" . Slyfox, Av8r3400, my friend and myself know our aircraft very well and can do this without thinking about it anymore.
We can all set our aircraft to our own particular likings. Of course this brings to mind letting some one unfamiliar with your aircraft fly it without knowing how you have it set it up. If buying an experimental aircraft from someone it might be a question that needs to be asked before you fly it.

[SaintAero]

I'm not sure if this is applicable to this topic, but I sure wish I had this info with my Rotec Radial/Bing Carb.
Certain electric pumps are known to flood the carbs on Rotax 912s. See the Special Airworthiness Information Bulletin on page 2 of the EAA Flight Advisor and Tech Counselor news, Safety Wire. http://www.eaa.org/safetywire/july10.pdf
Don

[kmach]

Sounds like idle set a little low.

That's what I am thinking too, I think I read awhile ago that an idle of 1800rpm is good , any lower and your putting stress on the gearbox,if I remember the article correct. The rotax engine manual I think shows a minimum rpm of 1400, and I think that was around where this aircraft was idling at with throttle right out.