1001001
Well Known Member
Not in an RV but...
In the interest of safety I want to let you know I had a carburetor failure on my Warrior the other day. It is a Marvel Schebler MA-4SPA. Not sure, but this might be a standard model on RVs as well.
In this carb, the fuel bowl assembly is bolted to the venturi/throttle assembly via four body-bound bolts that mount through holes in the throttle assembly to sockets in the bowl assembly. The bolts are secured with locking tabs and not safety wire.
Due probably to vibration and in spite of the locking tabs, the bolts had loosened and then damaged the threads in the bowl assembly. The carb bowl was separated from the throttle assembly by about 1/32 to 1/16 inch and very wobbly. One bolt was almost completely loose.
I first noticed something was wrong when I shut down the engine on Sunday night at Sarasota. The engine continued Dieseling after I cut off the mixture. It finally coughed to a stop. It was late and dark, and so I decided to check it out in the morning. The mags did ground properly. In the morning we had to reposition from one FBO to another so I started up and taxied across the airport and had the same behavior when I shut down.
I did a close inspection of the engine compartment and found the carburetor wiggling when I pushed on it.
I got a mechanic at the FBO to look at it and he removed the carb from the engine and confirmed permanent damage to the bowl bolt sockets. He said it would not be safe to re-tighten the bolts and I agreed.
So, a new (overhauled) carburetor and a hefty maintenance bill later, I left Sarasota and got back home late Thursday night. The core is being sent back to the manufacturer for a failure analysis. When I receive that report, I will report it here.
Anyway, something to check on your airplane, and to pass around to other folks with carbureted engines. The carb is hard to see with the cowl on and this can only really be detected by grabbing it and shaking.
If this has happened in the past to a carb and the bolts have simply been retightened, it could be a time bomb. I was lucky I found it on the ground.
If you find this, make sure to check the integrity of the gasket and mating surfaces of the fuel bowl and throttle assembly, as pieces of the gasket or metal shavings could be ingested into the engine through the carburetor via this failure mode.
Also, note that if your engine gives you any unusual behavior, it is trying to tell you something. Check it out before further operations.
In the interest of safety I want to let you know I had a carburetor failure on my Warrior the other day. It is a Marvel Schebler MA-4SPA. Not sure, but this might be a standard model on RVs as well.
In this carb, the fuel bowl assembly is bolted to the venturi/throttle assembly via four body-bound bolts that mount through holes in the throttle assembly to sockets in the bowl assembly. The bolts are secured with locking tabs and not safety wire.
Due probably to vibration and in spite of the locking tabs, the bolts had loosened and then damaged the threads in the bowl assembly. The carb bowl was separated from the throttle assembly by about 1/32 to 1/16 inch and very wobbly. One bolt was almost completely loose.
I first noticed something was wrong when I shut down the engine on Sunday night at Sarasota. The engine continued Dieseling after I cut off the mixture. It finally coughed to a stop. It was late and dark, and so I decided to check it out in the morning. The mags did ground properly. In the morning we had to reposition from one FBO to another so I started up and taxied across the airport and had the same behavior when I shut down.
I did a close inspection of the engine compartment and found the carburetor wiggling when I pushed on it.
I got a mechanic at the FBO to look at it and he removed the carb from the engine and confirmed permanent damage to the bowl bolt sockets. He said it would not be safe to re-tighten the bolts and I agreed.
So, a new (overhauled) carburetor and a hefty maintenance bill later, I left Sarasota and got back home late Thursday night. The core is being sent back to the manufacturer for a failure analysis. When I receive that report, I will report it here.
Anyway, something to check on your airplane, and to pass around to other folks with carbureted engines. The carb is hard to see with the cowl on and this can only really be detected by grabbing it and shaking.
If this has happened in the past to a carb and the bolts have simply been retightened, it could be a time bomb. I was lucky I found it on the ground.
If you find this, make sure to check the integrity of the gasket and mating surfaces of the fuel bowl and throttle assembly, as pieces of the gasket or metal shavings could be ingested into the engine through the carburetor via this failure mode.
Also, note that if your engine gives you any unusual behavior, it is trying to tell you something. Check it out before further operations.