Looking for cause of engine quit

[Blain]

Building a -8. Bought an RV -7A through insurance auction for the engine and firewall forward components. Contacted the builder-pilot for details of the incident. Very forthcoming and honest.

Certified IO-360-L2A, slick mags, Precision Airmotive injection. 500 TSN.

Pilot report: crossing Sierra Nevada mnt range west to east. Begins decent from approx. 11,500 into Carson City. Sometime during decent realizes the engine is out. Went thru mag check, has fuel pressure, ran out of options and made a successful forced landing except for pole-vaulting over the nose gear and parking it on the lid. Occupants extracted and walk away.

So FAA enters cause as "Icing", which seams unusual with injection and no visible moisture. Inspector doesn't even remove cowling.

Fast forward to this week.

All I need to do is find the "smoking gun". What was the cause?

Removed cowling.

First check the "P" leads for grounding. Switch functions correctly.

Connect fuel source at wing root bypassing tanks. Fuel pump switch on results in good flow and 30 lbs pressure. Small leak at line entering servo.

Secure ship for test start. Anchored to my farm tractor.

Cranks for just a few seconds then fires. Settles into good idle. Oil pressure good, fuel pressure good. Shut down to check everything out.

Fire up again, this time going up to 1500 for mag check. RPM stable.

So I did this for a total of about 15 minutes of run time allowing for cooling since cowl was off.

Now I can't find the smoking gun. Although I bought it well enough to replace mags and injection if I have to but I'd rather determine the cause then just throw parts at it.

Looking for experienced ideas that might lead me to the cause.

Oh, by the way, Have an RV7a "project" airframe looking for a new home

[acam37]

The "project" sounds tempting. Just finished a -4 project that took almost as long as building one from a kit. Post some pictures of the plane.

[Mike S]

Originally Posted by Blain

Begins decent from approx. 11,500 into Carson City. Sometime during decent realizes the engine is out.

I wonder if he was low enough on fuel that the nose down attitude in the decent (which would be pretty steep to get into Carson) unported the fuel pickup in the tank???

[bret]

Been over that range many times, if....he was leaned out for 11,500 Ft, and descended 5,000 Ft and not richen back up, he could have just starved the engine, too lean.

[Dave62]

Check fuel tank vents. Can cause issues especially at higher altitudes.
Dave 62 Swift driver

[1001001]

What was the temperature at altitude? Could it have been ice crystals forming in the fuel and clogging the filter, then melting and redissolving after the landing? This would depend on the position of the restrict ion relative to the fuel pressure sensor, as you said the fuel pressure indicated normal.

[Flyingleap]

John and Martha, King Schools...Cessna said:

The very kind and competent person on the other end of the line said, ?It?s not in your model year?s handbook, but in subsequent years there?s an explanation of how to prevent this. When an airplane?even one using avgas?flies at altitudes where it?s very cold, the water that is regularly dissolved in the fuel precipitates out in the form of ice crystals, which then can block your fuel system. Then as your fuel system warms up, the ice melts and the water dissolves back into the fuel. When you drain warm fuel from the sumps, you won?t find water, because it is dissolved in the fuel. The solution is to use a fuel system icing inhibitor like the product called Prist, or isopropyl alcohol.?

[flightlogic]

I think John might be right. You probably will never see it happen again... to you anyway. Fly it and have FUN

[Blain]

So I think of icing as in the throttle body. But ice in fuel now starts to make sense. Subject flight was in March so the possibility of condensation in the tanks would be higher then summer, (at least for this area that has more distinct seasons)

At the same time it's very likely that temps at that FL were well below freezing.

As I think about it however I have to question fuel pressure he said was present. Unless the clog was after the mech fuel pump. This seems unlikely with the temps under the cowl?

[Flyfish]

Originally Posted by Blain

Sometime during decent realizes the engine is out.

It sounds like he was at idle power if it took him awhile to "realize" the engine quit. Not much heat under the cowl if that happened?