The U.S. aircraft register, updated daily
Parts

Extension Frame

No failure report names the extension frame. 4 FAA approvals let 1 company make a replacement extension frame, Basler Turbo Conversions, LLC holding the most (4).

Approved replacement parts 4 parts manufacturer approvals

A parts manufacturer approval (PMA) lets a company other than the aircraft's maker make a extension frame and sell it as an approved part for the models named. These are the companies holding such approvals for a extension frame:

For these models most: Douglas DC-3 (4).

MakerPartReplacesFitsGrantedStatus
Basler Turbo Conversions, LLCExtension Frame F.S. 677 BTC5116388-205112965-20Boeing DC3C-SC3G, -S1C3G, -S4C4G2014-02-13current
Basler Turbo Conversions, LLCExtension Frame Assy. F.S. 636 BTC5116387-105116387-10Boeing DC3C-SC3G, -S1C3G, -S4C4G2014-02-13current
Basler Turbo Conversions, LLCExtension Frame Assembly F.S. 690 BTC5116145-145116145-14Boeing DC3C-SC3G, -S1C3G, -S4C4G2014-02-13current
Basler Turbo Conversions, LLCExtension Frame Assembly F.S. 703 BTC5118108-165118108-16Boeing DC3C-SC3G, -S1C3G, -S4C4G2014-02-13current

Sources: the FAA's service difficulty reports since 1995 (a report is a part that failed and was fixed, as filed by an airline, repair station or owner; the count shows reporting as much as reliability) and the parts manufacturer approvals in the FAA's Dynamic Regulatory System. The part name is the reporters' and the approval holders' own words, reduced to the first plain words so that spellings meet.