Please share the story on the sinking float. M/S has a 15 year old SB on that issue that is slow to be complied with. Mandatory IMO.
Absolutely. It has some useful lessons that I'm happy to pass along. Four of us were headed from a grass strip over to the Floatplane Mecca for lunch. We were all on skis. Preheat, warmup, runup etc. all went well. Taxied out and departed. I was the last in the flight to take off. All normal. As I climbed out and was just starting to catch up things got really, really quiet. I pushed over to 55 and started to run the basic restart checklist. Nothing. I started a gentle turn back to the field. I was a half mile or so away. I let the boys know I was without power and returning to the field and they wheeled around to watch the fun.
Here's where I made a mistake. I had the field made and was plenty high. So, I started a 360 to shake a bit of altitude so I'd land closer to the hangar. Dumb idea. As I came halfway through the turn the landing spot was fading out into the distance. I was still in the turn and starting to unconsciously pull as the ground neared. The left wing started to wobble a bit as I tightened up the turn. I pushed and leveled and set up for my alternate landing spot.
Seconds later I set down in a farmer's field across the road from the airfield. When I clambered out there was fuel spilling out of the carb. The other boys landed and walked over to the airplane. We started it up and taxied down to the road, put it on dollies, rolled it down the street 100 yards, popped it over the snowbank and taxied back in to the hangar. The engine ran fine at low throttle--anymore and it would bog out.
The next day we pulled the carb and hauled it over to the shop for further examination. Upon disassembly it was clear that there was gas in the metal float. Further examination revealed a pinprick hole in same that caused it to fill up and sink. The best guess is that it was already partially sunk and sank the rest of the way in operation, flooding out the engine with an unrestricted fuel flow once aloft.
The great, great thing about the MS carbs is that they are otherwise pretty bulletproof and overhaul kits are readily available (since we had it apart we overhauled it, too). We opted to repair the float with silver solder and leak tested in gasoline (do not leak test in water as it has a different viscosity). We set up a head test tube and followed the MS instructions for setting the float height. Pretty straightforward. Static check, flight check, returned to service.
At the end of the day the simplicity and general reliability of the MS carb outweigh the inherent fuel inefficiencies of such an ancient carb. Very few moving parts. And, certainly, a bit of an achilles heel with the float. So keep an eye on them.
Oh, and one more thing. All of this occurred on skis. My first takeoff and landing on skis. Good fun and a learning experience all the way around. And, yes, somewhere there are pics of us dollying the airplane down the road....