The U.S. aircraft register, updated daily
Parts

Internal Spline

No failure report names the internal spline. 1 FAA approvals let 1 company make a replacement internal spline, Precision Manufactured Aircraft Parts holding the most (1).

Approved replacement parts 1 parts manufacturer approvals

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

MakerPartReplacesFitsGrantedStatus
Precision Manufactured Aircraft PartsInternal Spline PM-00068Airborne Internal Spline and Aero Accessories...Franklin Engine Co. Any engine series where Airborne...2002-12-22current

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.