Ashley Briggs wrote:
This aeroplane was operated up until 1972. I have yet to find a Reed and Prince screw in the airframe. And unfortunately she has not copped well since her retirement with extensive corrosion throughout the airframe. Some screws do come out conventionally but a great deal are just shearing the heads off.
Perhaps over the years it's past operators did a reverse DC-10/L-1011. Both the 10 and the 'other' airplane were notable for infesting aviation with that wonder of the modern world, the TRI WING screw and maybe past users of yours removed and pitched all the R&P's as they went just to simplify things.
The only things I've found the TRI WING is good for is to keep some baggy pants from stealing your car stereo since none of them seems to carry a #3 tip in their pocket, and lots of creative vocalizations from some poor mechanic who's just spent 10 minutes squeezing into an all but inaccessible spot to discover that 2/3 of the screws are TRI's~