25-04 -> 05: Mid Fuse Forward Bulkhead / Cover Ribs

I started our by deburring all the required parts for this section, including the side angles, cover ribs and bearing bracket support ribs. The bearing brackets themselves were covered in a previous post.

The bearing bracket supports were 'suicide countersunk' as i could not use a countersinking cage here. 

I was then able to prepare all the cover ribs including dimpling along the bottom, and installing nutplates. Page 25-04 was very complicated with regards to what cover ribs were dimpled on the top, and which nutplates went where, but after going slow and reading it 50 times i think i got it right! 

All the cover ribs have the same holes - but some are ignored.

These are the bearing bracket rib support brackets. 

I then moved onto countersinking the mid fuse bulkhead forward spar flanges - for the dimples in the skin along the bottom flange, and for nutplates along the top. I had some paint left over from spraying the cover ribs the day prior, and was able to cover it and keep it in the fridge, so could prime the countersinks on the spar flanges. Nutplates were installed along the top flange. 

I was now ready to begin riveting things to this spar - i started with the side angles. These are bolted and then riveted. These were riveted on using the gun and bar with the assembly standing up and clamped to the table. 

I was then able to stand the assembly up and using shims clamp to the bench. I clecod on the cover ribs and bolted and torqued each bolt to 38 in/lbs (28 in/lbs plus some running torque). I then riveted on the cover ribs - i was able to use the long straight cupped set for most of these, set at 55psi. For the topmost rivet, the straight set did not fit due to the top flange of the cover ribs - so i had to use the double offset set. 

The long straight set is a great tool. 

The long straight set did not fit.

Here you can see all ribs riveted, but the bearing bracket ribs are not ready to be installed as yet.

Of course, torque seal used on all nuts as soon as the torque is set.

At the completion of this section, i had not received the new bearing brackets as yet, so the riveting of the bearing brackets ribs and support brackets will occur once the new bearing brackets are done. 

I will add the pics of this when it is completed. For now, section 25 is complete pending the arrival of the additional parts, so i will move onto section 26 - Lower Mid Fuselage.