Airframe ASA/Baker's School FAA Oral Questions

Which species of wood is considered to be standard when comparing other woods for use in aircraft structure? - Answer- Sitka spruce What is the basic difference between plywood and laminated wood? - Answer- The grain in each layer of laminated wood runs in the same direction. The grain in the layers of plywood runs at 90 or 45 degrees. What kind of glue is recommended for making a repair to a wooden structure? - Answer- synthetic resin glue How is pressure applied to the glued joint when splicing a wooden aircraft wing spar? - Answer- cabinetmakers parallel clamps How much pressure must be applied to a glue joint in a piece of soft wood to produce a strong joint? - Answer- 125-150 pounds per square inch What is the correct repair to a wooden aircraft wing spar if the wing-attach bolt holes in the spar are elongated? - Answer- Splice in a new section of the spar and drill new holes What kind of repair is recommended for a hole in the plywood skin of an aircraft wing? - Answer- scarf patch What is the recommended taper for a splayed patch in a plywood aircraft skin? - Answer- 5 to 1 What is the recommended taper for a scarf patch in a plywood aircraft skin? - Answer- 12 to 1 Why should sandpaper never be used when preparing a scarf joint in a wing spar for splicing? - Answer- The dust will clog the pores in the wood and the glue will not form a good bond What is the largest hole in a plywood wing skin that can be repaired with a fabric patch? - Answer- one inch diameter Why are light steel bushings often used in bolt holes in a wooden wing spar? - Answer- The bushing keeps the spar from being crushed when the nut is tightened. How long should a glue joint be kept under pressure when splicing a wooden aircraft wing spar? - Answer- seven hours or longer