Engine quit while practicing stalls

[scottmillhouse]

Also consider bad fuel especially if you are using auto fuel with alcohol. I was always careful to use my fuel in a couple of weeks but one time bad weather caused the fuel to age to close to 6 weeks. Engine did not quit but went to mostly the right cylinder bank causing loss of most power and a lot of shaking. Shut off engine when close enough to airport for a little glider time with a dead stick landing. A fuel system flush and a switch to 100LL took care of it.

[Strappe]

Originally Posted by rsr3

How hard are you pushing on the recovery? Enough for negative g?

No, and the engine issue occurs before recovery begins.

[Strappe]

Originally Posted by Sam Buchanan

What?

The engine stops twice for unknown reasons leaving you in glider mode and you left an airport a couple miles away to fly 30 miles to another airport?????

Wow........glad you had a safe return.

I circled at 4500 MSL for long enough to be sure. The issue only occurs when in a steep, nose-up attitude.

[BobTurner]

I have no idea about cause and effect, but since you just had the fuel tank out, I?d look hard at any connections that were undone.

[Strappe]

Originally Posted by tomkk

How much fuel did you have in the tank?

As written, full tank. 19.5 gal 91 octane, ethanol-free, winter version.

[Strappe]

Originally Posted by Sue

6500 feet and full rich, really?

That is the setting on the HACman to shut it off and allow the carbs on the 912ULS to do its normal automatic adjustment. SOP of the HACman is to only adjust it out of full rich when in level cruise flight.

[Strappe]

Originally Posted by DaleB

Bet that got your attention. By sheer coincidence, I was also out in that same ares (assuming south of Wahoo) also doing fairly high AoA stalls in an RV-12 that day. Didn't manage to log any glider time though.

If I understand the HACman system correctly, "full rich" simply shuts off the added vent system and allows the Bing carbs to operate as if there were no added mixture control. Assuming you installed it correctly, I suppose a leak could lead to an overly lean condition -- don't suppose you noticed the EGT at the time, or have data logged from that flight? Of course there could be something wrong with one or both carbs that would cause it with or without the HACman. I'm guessing you haven't spent a lot of time flying at very low throttle settings at that altitude; I know I haven't. I wonder how much, if anything, the high AoA had to do with the engine not performing as expected.

Dave, the Bings do some altitude compensation, but they seem to always be a bit on the rich side. There is no manual mixture control, it's all "automatic" by means of a diaphragm. There is another RV-12 at our airport that's had that system installed for a few years now; the only real difference is higher EGTs and lower fuel consumption when it's leaned out from the normal non-adjusted state. They don't seem to be super common on RV-12s, but I've heard about them on other airplanes that use 912 series engines.

EGT fine in cruise, and after recovery. I did not check actual temp readings during stall and engine stoppage, but they were not out of green area.

[Strappe]

I was over farmland in Fremont area

[Strappe]

Originally Posted by BobTurner

I have no idea about cause and effect, but since you just had the fuel tank out, I’d look hard at any connections that were undone.

I removed the access panel where fuel tank connects to fuel lines. Those are the only connections touched when removing tank. No leaks.

This was the first time I’ve done stalls after installation of HACman.

I’m mostly looking for others who may have had issues with HACman for any reason.

[bobnoffs]

i had a hacman on a jab 3300. the jab had an altitude compensating bing. it would ''compensate '' to 4 or 5000 feet as i remember. when the op said ''full rich'' he meant the hacman valve was closed and it was as if the system wasn't even there, the engine was operating only with what the carb was doing [leaning] . as someone else mentioned it is possible there is a leak in the hacman plumbing, that would simulate leaning with the hacman.
i never had an issue with how the hacman performed .