Fixing into an open back cougar lintel

[dogfonos]

Possibly a simple answer to this question but I'd appreciate guidance.

I want to hang two roller blinds inside a sliding door recess where one blind sits above the sliding panel and the second blind above the fixed panel. Not all roller blinds have brackets for side wall fixing and besides, the two middle brackets don't have that option anyway. So my options seem to be either to screw the fixing brackets into the aluminum window frame, which I'm very reluctant to do, or into the top of the wall recess.

The sliding door area is part of a recent extension and, from memory, the lintel above the sliding door is of the open back cougar type (may not be this particular one but it looked roughly the same):

https://www.travisperkins.co.uk/ste...all-standard-duty-lintel-cg70100/p/9000173462

The inside section of the lintel is covered by plaster and there's a single row of aerated concrete blocks above.

Question is: Is it OK to drill through the steel lintel into the aerated concrete block to fix the roller blind brackets with screws? Any precautions I should take? Many thanks for your consideration.

 

[Bonni]

Use a 3mm HSS drill bit and a no. 4 or 4.5 screw. It will self tap into the lintel.

 

[dogfonos]

Use a 3mm HSS drill bit and a no. 4 or 4.5 screw. It will self tap into the lintel.

Thanks for the advice. Only potential downside is that I see from the design of similar lintels that many (perhaps all?) have numerous small holes in the steel as a key for plaster - sod's law I'll drill into at least one hole. If that happens, I guess I'll have to resort to a longer screw and rawl plug.