Rack'n Roll

Last couple of days, I really experienced the benefits of my fuselage support. Once I removed the gear with the help of my friend Marc, I could swivel the fuse around to reach areas that would have been difficult to access without it. Wx was nice outside so I could make some progress on the tube cutting:

I tried various cutting methods and the best compromise I found between precision and efficiency was using a Dremel with 1 1/2 in diameter cutting disk for metal. I even tried a buffer tool but it is too big to perform the precision cutting when getting around a tube to be preserved and is not much faster than the Dremel.

 The following is the status of what I cut from the structure and what remains to be removed:

1. Gear support diagonal - Done LH - RH to be removed
2. Nut plate attachment lug - Done both LH and RH
3. Bottom central gear support - Done
4. Bottom gear support reinforcements - Done both LH and RH

Here's a CAD view to better visualize what parts I removed. I highlighted in blue the members in question. Note: I didn't model the nutplate attachment lug (#2):

...and here are the reasons for the removal of each member, again with the same numbering convention:

1. The LH diagonal was terrifying and I intend to comply with the Steen S1 drawings i.e. replace them with 3/4 in 0.035 wall tubing (was 5/8 0.035). Also, removing these will help getting access to install the lower longeron reinforcement sleeves:
2. Also need to remove the nutplate lugs to allow the installation of the longeron reinforcement. 
3. The welds were bad and the gear bolt bushing were welded to it. Since I will not need the inboard bushings (passing from 4 bolts per side to only 2), I decided to replace this member and remove everything I don't need anymore.
4. Same reasons as 3.

The CAD picture above also doesn't show the gear support flat plates in between which the gear was held. Here are a few pictures that progressively show the parts removed:


Before the removal of RH#4 and a part of #3:

Another view.. This one is very interesting: the crack due to the torsion of the gear is obvious. The crack propagation  is close to 45° which is a typical failure mode for round elements in torsion. ATTENTION PITTS OWNERS WITH SPRING GEARS WITHOUT RADIUS PLATES: THIS IS THE CRACK YOU DON'T WANT!!

Finally got the RH assembly removed:

Same cuts on the LH side (one of your last chances to admire the masterpiece (of shit) of an unknown welder):

Another interesting picture here.When I removed the RH nutplate support lug (#2) another crack was hidden under! This one seems also due to torsion, but aft of the spring gear. With time, the longeron section sitting on top of the gear would have probably broke, which is most likely what happened on the LH side. Makes sense doesn't it?

AGAIN SPRING GEAR PITTS OWNERS, CAREFULLY INSPECT YOUR LONGERONS HERE!!

Big thanks to my friend Scott who helped me pull the fuse back inside:

And last but not the least, a picture of some acro with Marc in the Citabria before my grinding Sunday : )

Coming up next: the removal of diagonal #1 RHS!