Saturday, June 20, 2015

SB-12-09-26 … Drilling Holes Into The Bottom Fuselage Skin

Service bulletin SB-12-09-26 involves the landing gear. A bolt length was changed along with an inspection procedure and included is creating two 3/8" holes in the F-1276 bottom skin on each side of the fuselage. The purpose of the holes are two fold …. A drift can be placed up through the holes to tap on the heads of the landing gear bolts to insure they are fully seated. Plus, the holes can be used to slip a socket extension up through the hole to make it easier to check the proper torque on the landing gear bolts. Unfortunately, my bottom skin was manufactured prior to the holes being added by the factory … so the bottom skin needed to be drilled. The photo below shows the drawing for the placement of the two holes that need to be drilled in both sides of the bottom skin. Also in the top right of the photo is shows the HW-00003 plugs that are to be installed in the holes after the landing gear is installed.
Photo of the drill guide in SB-12-09-26 along with the plans showing already showing the holes and plugs.

Once again Mike’s creeper came in handy to roll under the fuselage and carefully mark the hole locations. The two hole locations on the right side were drilled using a tiny drill bit for a lead hole then bumping it up to #30. A step drill bit was used to enlarge both #30 holes to the required size of 3/8".
Using a metal ruler to mark the locations for the two required holes located directly under the right landing gear bolts.
About to use the step drill to enlarge the two #30 holes to 3/8".

Only got the right side finished because would prefer help sliding the workbench under the fuselage over enough to expose the bottom skin's left side for drilling.