Fabrication and installation of Columbia Helicopters pylon fittings P/N C54S2022-1 and -2 for replacement of Sikorsky fittings P/N 6420-66341-101 and -102 at the transition of fuselage to the tail boom. View PDF on drs.faa.gov ↗

The STC PDF is authoritative: installation instructions, ICA requirements and limitations.