The U.S. aircraft register, updated daily
Parts

External Spline

No failure report names the external spline. 1 FAA approvals let 1 company make a replacement external 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 external spline and sell it as an approved part for the models named. These are the companies holding such approvals for a external spline:

MakerPartReplacesFitsGrantedStatus
Precision Manufactured Aircraft PartsExternal Spline PM-00069Airborne External 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.