May 2011 – Bulkheads Chapter 4 — Steps 1-3 3 May 2011 – The F22 bulkhead before the leg holes were cut out and the F22, F28 and Instrument Panel Bulkheads. Chapter 4 — Step 4 of 4 4 May 2011 – Firewall after cutting out of 1/4 in. Finnish Birch plywood: