Engine Inflight Shutdown - Carburetor ice, maybe?

[jrs14855]

Originally Posted by riobison

Yes, it does sound like it.

The Vans Aircraft are very tightly cowled with lots of heat in the cowling so probably less likely to get carb ice but they are still susceptible.

35 years ago I was taught that whenever I reduce power setting to 2200 rpm or less, I always pull on carb heat first and leave it there until I land or my RPM is over 2200 rpm. It has worked well all of these years

Tim

Absolutely correct on small Continentals, but not on Lycoming per Lycoming 1148C.

[riobison]

Originally Posted by jrs14855

Absolutely correct on small Continentals, but not on Lycoming per Lycoming 1148C.

Specifically what point?

[riobison]

There are a lot of incidents and accidents that are unexplained with no evidence after the fact. In most cases the assumption has been Carb ice. Hard to prove of course as the evidence has already melted.

One time in 1980 during my flight instruction in a C 172 with a 150 HP Lycoming located in dry Central Alberta in the summer on a clear day. During the run up while checking the carb heat we had fairly severe engine roughness for a minute or so before it cleared up (ice melting). Both my instructor and I were shocked at this. This was not a wet plug, vapor lock or anything like that. This was something different and we agreed that it had to have been carb ice. Obviously the conditions were ideal at that time. So it can happen to any of us with any engine.

Tim

[Lionclaw]

My -9 had the same engine with sleeved hoses run over the top of the cylinders as well. The only time I ever had an inflight shutdown was over Lake Michigan after buying mogas at the Manitowoc airport (most likely vapor lock).

It sounds like you've narrowed the issue down to your carb. If you're not confident in your carb, even after rebuild, I'd suggest exchanging it as a core for a new/rebuilt unit from a reputable seller.

[Dave62]

Sounds like a float sticking to me or not closing due to contamination.....it takes very little. Will cause all the issues you are seeing. Get the carb off and to the shop.
Dave62

[Ramiro Silveira]

Andy,

Your photo album about the engine is the greatest source of info about the bad reputation O-320-H2AD that I have ever seen, I love it, I have been watching it many times.
What were the results of your engine quit, did you post it here before?

Dave,

99 % of the people I talk to blame the float or the needle and seat and I fully agree, but how could this remain a problem after the carb have visited the shop 2 times, the first having all parts replaced according to Marvel Schebler standard repair kit including a brand new blue float?

Thanks,

Ramiro

[Lionclaw]

Originally Posted by Ramiro Silveira

Your photo album about the engine is the greatest source of info about the bad reputation O-320-H2AD that I have ever seen, I love it, I have been watching it many times.
What were the results of your engine quit, did you post it here before?

Thanks Ramiro. I was going to write up something of a guide for the H2AD, which is why I took so many pictures. But ultimately I decided against it because I didn't want to encourage others to choose that engine. It worked very well for me, but I don't think the extra 100+ hours of work was worth the savings.

I don't think I posted anything about my experience, and I am almost sure it was vapor lock. Watching the fuel pressure I could see it slowly drop down to almost 0, the engine would die, and the electric pump would bring it back to life again. Fortunately I always kept my right tank full of avgas, which would usually just be used for takeoff, landing, or cross country flight. The fact that I was crossing Lake Michigan is what made it memorable!