What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

912ULS Carb Bowl Defect

Jim Gries

I'm New Here
Two days ago on take off I experienced an uncommanded engine power reduction. Long story short, I removed the carburetor bowls to inspect for possible contamination. It appears that the coating/plating inside the bowl is breaking down, flaking off. I showed the bowls to an A&P on the field and he was very concerned and thought it was a manufacturing defect. Attached are some pictures. Any feedback is welcome.
1I9ZrUweoRO2-Zz_fY71r7HVI4QBqarVLmuTh6SKgl_TQOCXGpQAPJIk0lALcq31vNGxfPXBWoFUqURduopH2ceAI5-mPwwJCLMQ6KPqcEXy0c2JtyUe5Bccs8TQUKg6fzKIzfPUdcKMwMZ1CLVwDiYKyvsbnETesiu283rSt1I1hb31XmR4x3e1dYuzcs4UDrLNZmMDlnJR44DVgw_iIc05YCJPWnyamncr9fRQ6jJSIhWVeZGrnSlJi4RjfgK-OYrqZ7eUPd28E-yfg4HvtYFn_7u61FaV6pu8TSGSzuSSdshBrI2b7C1BNnIYei8V1959so05PVs_d7fOktlRwrN0lZ15tMb2l2GTcCljF0LtlwzOlzHB3AMcGF87hbUeZRMQCSVW3eKYNHcEaExoW-SBqb6KeLdJrbAestHvhLuAosSGgAB7mVMrUKWSkxq8ayqLF-2NYtDCZkm0zLXk3Wnhi2D51AGHhegAvhfpKwcbADHBn_cUgispaUOkNi_0AdkHPZixmFzOxBzv07rI8Xr-TZi69fi_OiACYyQ6-TzWpPnYSYnhsKvC1hsEQTvaGi-2ADfWrglEjnCx_Lfd96ZsMQwK8dZ74-Cgu6Mgu9emEcZuwPMQT8lLnhuVLcwoO6cKoYJa9OtP75mDp_QfyMxsKNEPWYDMLtsRUfnQJVPa6S3ex7E-soZP0uKgIw=w579-h772-no


n95Qdre8gxmdm05mD3cSsZqlxu9mK4IM-xxSzeLceCBQ8XmL8meR_QZq0iOvwwc3Gm4oSX2v85ICDPDNWplkNEaLcXZOfI9LRnj9gWnwNWXdzLTH69qHpL7K5uYMiEMSnIjxvekVKBqDK2rE7qvjX2S7HXO2_1iWz3RKzokilaFT_uLhdDPzt3VALyKy64pt4Enzfw8E616dNf7dPxLQsHsnfjUwrzFQ0dK4QL30qo7SjNe2KSfiSnhtyGboRLu9E99BcCI4H4ZloS-2Tn6xR7iE0ciu36Rp8AOEvn9plticqh4YvSoOvm93YCeUpTkwotp8glYhjeYfgWYHGFv-o627wNOS94bdnSPyzXwS5BzPnmddnGiJpRPzBZMW3EdTerM7xey5Z9OUf1W3FB2rZ_qneLzHyKibFzDAqi9RFzsluEBgqSMFhvo91fhfBW9UwY8w68gsX3zbwi2un_ktRr5zXmAo0LIsOOx5wyrWQEo8yCUJVdnaMnzTxSdTaOZ3K7tQSKmrZl-Q83mDl4ayE_klmSMde1FmYbSSDOVCrEyqI0QWq-Db1qoJXj6wvN6EgaL-VllbozanoYDpHJsWsEtAHRHYQE-hLb3s4A1o5DPete-Da2Y1wl-4XbcyfpvskyGxZ6d0VGMKbelipxJkH2ckiR83Cngu92mvcOWNpij0poUcja-Z8mm6goVJsg=w579-h772-no


VVO7C6fSmtY2UuFHouJIRZxnZNIBN7b2Vt5nR3rcFEas3NZZszkCs71SFadKcsgKtHNGG9HNj6SH5g7YwL0zGlO3biQfeU7CKtXHNfO52bjfAIECF9_WAEpakElN6Y5ckdSbdHp3p_68i9zlaIL-XH2dZiw9lTldDkKt3Rqb_HaEo_ZxgDD11JWxmfVQq0hcv4609OtX6DbQ_hrCXr1xfn9YhGuxpdxs17OVB1JLJLJn_C7gxqcJnUXfKXZ5mZxsOHIQ8sg1zCnky_Jul9xZ4vu3f4QHmRkUZyBWStM4McDVkVLBu5_rx-e2bz2ZVe2yPUCQHIXcozEBUGaWZy5P0PjjMkYpPkZOGlmNqx0jj9PHV1UQeE2Cz8xbnzzZ5DTT-w8PfwLRZJnUqcUcA1W5mcMC1mBwNDVLkWUx7zkdU-fBZR6KciOXgoNBZZRjD4gyDxkqg5ISnftoYlpkJp17xwAUyzqTLUmi6iJwwItglnMQJjmjO6YRP-2NAjXjcm0HEzjPA0IWdMzOm5XdujKu34onxOpEgLaRdnyS7dTsVbhXdO-GNIgC89rmJ73MfwRK3m0bJGJbEI48E4x98RMXS6os-zq5fjrweZRqaALTeWZEeLdtGnMjLScb5_Z-moTWm6KJKEPvIWSLTWf6TB3vkuMgiNqgmGKhdaS1b4wHn-REgy_kuelO20U1mpvFzA=w1030-h772-no
 

Attachments

  • Carb Bowl plating crack.JPG
    Carb Bowl plating crack.JPG
    159.4 KB · Views: 235
Jim - First time seeing that on the forum. Looks like plating that is flaking off the carb bowl. Also looks as though there are a couple of more bubbles forming and beginning to crack.

Not something we want happening to be sure. It will be interesting to see if others have seen this too.

Edit: Regardless, this is very troubling and should be brought to the attention of Rotax.
 
Last edited:
I doubt if its plated. Most likely a zinc die-casting. Maybe anodized. Almost looks like spalling of some sort. Manufacturing defect?
 
Yikes! Have not seen or heard of anything like that.
My next call would be to Lockwood.
Thanks for letting us know to be on the lookout.

BTW Jim, how many hours and years on your engine? What fuel?
 
Last edited:
Dave;

Special Airworthiness certificate issued three years ago. Hobbs time 175 hours. 92 Octane fuel. Aircraft hangared in a dry environment.
 
92 Octane fuel.

Jim - Assuming that implies you are running an E-10 auto fuel??? ... just as many of us RV-12 owners do.

The black area underneath where the flakes of metal came off is troubling to me ... looks as though there may have been a reaction with ethanol. Have seen photos of fuel pumps pulled out of auto fuel tanks that have dark areas like that which were said to be an artifact of ethanol and moisture (either in the fuel or in the air).

If you are using E10 and purchasing it primarily from the same source, it would be interesting to do the testing for ethanol content. Don't know how one would test for water content ... but based on reading, a gallon of E10 will suspend about 3 teaspoons of water at 70°, so suppose one could scale down to make test tube testing possible.

It will be very interesting to hear what Lockwood and/or Rotax has to say about the metal flaking and the bubbles forming.
 
Last edited:
Just reworked a SuperStol with same symptoms. Found similar damage in fuel bowls which lead me to get carbs overhauled (lots of new parts) which lead to new fuel pump, which lead to full fuel system do over, which lead to tanks power flushed...
Look at the bigger picture.
 
Back
Top