Thanks for triggering another of those trips down memory lane, Centaurus. Despite my brief (500 hrs) sojourn as P2 on the Dak, I well remember the attention that was given to the presence of "five locks and two pins" on board prior to engine start. (I think the two L/G pins were normally handed to the skipper.)
What I hadn't remembered (or perhaps never knew) was the secondary role of the aileron locks in stopping the flaps drooping in the absence of hydraulic pressure. I wonder if they all had that feature.
Merry Christmas,
Chris