Analyzing a repair doubler

[MrHiLok]

Hi,
I am trying to analyse an external repair doubler installed on the horizontal stabilizer of a large aircraft.
Corrosion damage was found on the upper skin of the horizontal stabilizer. the rear spar of the Horizontal stabilizer is attached to this section of the skin. The corroded section of the skin was trimmed out (thickness of the skin is 0.1 inch) and a filler and 0.1 inch thick doubler made of 2024-T3 was installed at the trimmed location.
In original design, on the outboard side of the trim, the upper skin is attached to the rear spar using BACR15FV6KE rivets and on the inboard side of the trim, the upper skin is attached to the rear spar using BACB30NW fasteners. There is a rib installed on the inboard side of the trim.
The repair doubler was installed using 4 rows of fasteners inboard and outboard of trim and two rows in the forward direction of the trim.
All fasteners on the repair doubler are BACB30NW8K*, except the fasteners common to the repair doubler and rear spar on the Outboard side of the trim are as per original BACR15VF^KE rivets. This is going to be a temporary repair for 20 months.
My questions are:
1. Are the fasteners inboard and outboard of the trim installed through the repair doubler, the upper skin and the rear spar in double shear or single shear?
2. How to analyse the fasteners which are installed through the filler at the trim location. There were two rows of BACR15VF6KE rivets in the original design at the trim location. A total of 6 fasteners are installed at the filler (through the external doubler, filler and the rear spar).
3. Apart from the static strength calculation to determine load capability lost due to trim and number of fasteners required to transfer the load across the trim, what other analysis should I consider? Eg torsion case? Fastener bending?

Thanking in advance.

 

[rb1957]

1) since you're specifically tlaking about the rivets between the spar, the skin and the dblr, double shear ... the original skin was shearing load into the spar, now it'll be shearing load into the spar and the dblr.
2) the filler i assume is filling the void between the stringers/spar cap and the dblr ... i'd assume it is non-structural (and not helping the dblr)
3) the obvious is damage tolerance, but i'm curious how you determined static strength (presumably without OEM support) ?

i don't know how you can do this without OEM support, they're the only ones who know the loading on the H. Stab. 0.1" thk skin is PDH so we're clearly talking a large transport.

 

[MrHiLok]

OEM’s approval is being pursued.
This exercise is for my own self. OEM will only say yes or no, but will not provide any justification why it is ok or not ok.