Birtcraft metalized wings

[wstevens]

It was nice meeting those who came to Fredericksburg last month. I'm new, and I need to pick some brains.

I hold a 337 and associated logbook entry from 1968 installing the Birtcraft metal wings. There is a (ratty) diagram and Technical Instruction Number 1401 (4 pages) in good condition, but no STC. These Instructions list two Cessna Letters and one CAA Engineering Branch Approval as the authority to install this mod. Is this all there is to it? I can find no STC holder named "Birtcraft," nor any STC pertinent to the C120 mentioning the term "Birtcraft" when I search the Dynamic Regulatory System, so perhaps so, but I'd feel more comfy if anyone who knows more than I do would corroborate this or steer me in a better direction. Thanks for any help!

[6643]

This modification does not require an STC because it is listed on the Aircraft Specification, item 611. (It pre-dates the STC system).

*611. Metal Plating of Wings
Models 120 and 140 are eligible for certification when wings are covered
with metal skin per Technical Instruction Report No. 1401 by Birtcraft
Engineering Co., 11836 Cherry Ave., Inglewood, California.

Note: Approval for the installation of all items of equipment listed herein has been obtained by the aircraft manufacturer except those items preceded by an asterisk (*). The asterisk denotes that approval has been obtained by other than the aircraft manufacturer. An item marked with an asterisk may not have been manufactured under a CAA monitored or approved quality control system, and therefore attention should be paid to workmanship and conformity with pertinent data called for in this specification.