The final pair of bulkheads in the absolute tail - verify they are not reversed. At one point I believe the drawings actually indicated them reversed, or at least that's what I heard - not confirmed. In any case if that final bulkhead is reversed it LOOKS right but will cause exactly the problem you are fighting.
Ask me how I know...
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2022 dues paid
N16GN flying 1,000 hrs and counting on 91E10; IO360, SDS, WWRV200, Dynon HDX, IFD440, G5
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
Pending Repeat Offender - 10 kit is on order. TDI? Turbine? Stay tuned!