Single-engine Endurance and Performance

[hharney]

Single Engine Trials
Sunday June 6, 2010
C337 N712JF C Model N/A

Main Fuel Tanks - 90%
Occupants - 2 adult male
Misc items in baggage area
Estimate the load to be 50% of gross


Rear Engine Power - Front Engine Feathered
2500 RPM - WOT
5500' MSL - 48 F - 100 FPM - 112 IAS -
6000' MSL - 48 F - 200 FPM - 107 IAS

Front Engine Power - Rear Engine Feathered
2500 RPM - WOT
7000' MSL - 47 F - 200 FPM - 90 IAS

We continued to climb to 7500' MSL and then decided to re-start the rear, would not start. After trying several times I looked over at the AMPS and they were pushing 30. I am not sure why the rear would not turn over. When I engaged the starter it would only move the prop 1/2 a turn and stop. I waited at 7000' MSL until the battery came back to a balanced level and tried it again but no good. It would not turn over out of feather. By this time we have been flying along on the front for about 25 or 30 miles at 7000' MSL. We turned right 90 degrees to a 012 heading for Newman's field and started a descent through a hole in the clouds. The single engine approach was uneventful. Given the front engine was the only engine making power the gear was normal and retracted without using the hand pump. It was a great landing on the turf field at Newman's and taxied up to Larry's hanger with only the front engine. After pulling the cowl on the rear and not seeing any red flags I buttoned her up and jumped in the left seat. Started the front, OK no problem. Voltage and AMPS look fine, started the rear, OK no problem, fired right up like normal.

What happened? Why would I not be able to start the rear in flight? The front started fine. I have the MT props, don't know if this has anything to do with it. Starter is getting compromised maybe? Battery lead is weak? It was really surprising when this happened but a good exercise and everything turned out OK. If anyone has had this happen please let me know your thoughts.

[skymstr02]

Herb, did you advance the prop lever to the high RPM stop from the feather position on the altitude re-start?

I've caged both of mine at altitude, with sucessful re-starts, but I have the stock McCauleys and unfeathering accumulators.

If you can get the prop out of feather, it should windmill enough that the starter is not necessary for a re-start.

Dave

[WebMaster]

I'll bet you were 500 pounds under gross. Not a lot more than that.

[JeffAxel]

Hey Herb, it's a Skymaster....you can center the ball with an engine out....might climb a little better!! : - )

[WebMaster]

Parallax. It was the camera angle.

[hharney]

Winds, we had a real stiff wind out of the north. Might be some of the reason it looks that way.

[Learjetter]

Hi fellas! slight re-vector on the thread: searched the whole internet, this and the UK forum, but didn't find an answer: anyone know the engine-out performance degradation with the underbelly cargo pod installed? I'm looking at buying skymaster (there goes the kids' college education $$, which they don't need because the only people making money these days are plumbers and mechanics!). Anyway, I'm fairly comfortable with the SE performance numbers, but can't find the cargo pod penalty. Since I'll be flying out of high pressure alt locations in the mountain west, I'd like to know how bad the SE performance is with the pod installed. Thanks in advance for your knowledge.

Fly Safe!