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Gallery, Projects and General => Gallery => Topic started by: Joules on May 10, 2013, 04:35:08 PM

Title: OS 4st Engine Repair
Post by: Joules on May 10, 2013, 04:35:08 PM

I did this repair a few years ago, but happened on the photo's I took whilst looking for something else  :scratch:
The plane had crashed and ripped out the exhaust manifold.

(http://i7.photobucket.com/albums/y253/joulesbee/OS%20Engine%20Repair/TheDamage.jpg) (http://s7.photobucket.com/user/joulesbee/media/OS%20Engine%20Repair/TheDamage.jpg.html)

First job after getting it cleaned in the ultrasonic bath was to mount the head on a lump of something I could grip and act as a heat sink when I did the repair.

(http://i7.photobucket.com/albums/y253/joulesbee/OS%20Engine%20Repair/Weldprepare.jpg) (http://s7.photobucket.com/user/joulesbee/media/OS%20Engine%20Repair/Weldprepare.jpg.html)

Once mounted I could clean up the damaged areas and prepare the casting for alloy welding/soldering.

(http://i7.photobucket.com/albums/y253/joulesbee/OS%20Engine%20Repair/welded.jpg) (http://s7.photobucket.com/user/joulesbee/media/OS%20Engine%20Repair/welded.jpg.html)

I jammed a thermocouple in the part as I did the weld to monitor how close I got to melting the casting as a fraction too much heat from the blowtorch would cause the whole casting to slump and melt.  I used plaster of paris for dams around the casting and in the exhaust port so the molten metal stayed where I wanted it and played the torch around the casting rather than just at the port.  The above picture is after I re-machined it ready for thread cutting, you can see some porosity in the metal I added.

(http://i7.photobucket.com/albums/y253/joulesbee/OS%20Engine%20Repair/Rethread.jpg) (http://s7.photobucket.com/user/joulesbee/media/OS%20Engine%20Repair/Rethread.jpg.html)

Part re-threaded and cleaned up.  The welding process burned all the gunk off and left me with a lovely clean part.  I didn't have a means to cut metric threads at that time so the thread cutting was done on a friends lathe.

(http://i7.photobucket.com/albums/y253/joulesbee/OS%20Engine%20Repair/Repaired.jpg) (http://s7.photobucket.com/user/joulesbee/media/OS%20Engine%20Repair/Repaired.jpg.html)

Finally back together and you could hardly tell it had been repaired from the outside, just cleaned it up with a needle file.  I was happy with the repair and so was the owner who had this engine flying again.  This was the first time I had really used the alloy welding rods in a real application so pretty impressed.   Didn't work so well on the next engine I tried to repair, and of course didn't bother taking photos that time...  :palm:

                       Joules

Title: Re: OS 4st Engine Repair
Post by: Stilldrillin on May 10, 2013, 05:20:36 PM

Repaired, as new, Joules!  :bugeye:

Very well done!  :thumbup:  :clap: :clap:

David D

Title: Re: OS 4st Engine Repair
Post by: vtsteam on May 10, 2013, 07:01:54 PM

Yes that's pretty tricky work!  :thumbup: :clap:

Title: Re: OS 4st Engine Repair
Post by: Meldonmech on May 11, 2013, 06:09:29 AM

Hi Joules,
                  That is a very good result.

                                                        Well  Done    David

                                                       

Title: Re: OS 4st Engine Repair
Post by: awemawson on May 11, 2013, 07:04:33 AM

Excellent repair. I like the idea of putting a thermo-couple in to monitor the temperature - better than the old trick of rubbing soap on the part  and watching it char  :clap: