Pratt & Whitney had an informal historian for many years (50s-90s),
Harvey Lippincott. GE had a cadre of men who had worked on the first GE I-A engine, the
Jet Pioneers Associaton. I'm sure the tin-knockers have similar adjunct functions.
I've found that the retirees and informal archivists manage to present a more honest and balanced picture, than do the ones subject to current corporate whims.