The baggage compartment shelf on N11018 was a fragile piece of 1/4" plywood at the onset of osteoperosis. Through normal flying and landings and incidental vibrations, it would often slide forward about 1/4" so the back side would no longer be sitting on the main support channel which would cause the shelf to bow in the middle. I replaced it with a sheet of some material that a friend purchased from the Boeing Surplus store several years ago. This is a lightweight balsa wood material sandwiched between two sheets of 0.040" aluminum. I was informed by a former Boeing employee that back in the day this material was sold in 4' x 8' sheets for $2,000.00 per sheet which means N11018 has one seriously strong and expensive baggage compartment. The best part, it weighs only 9 ounces more than the turd it replaced and I've tested it up to 75 lbs. without so much as a bow.