Summary: The article analyzes the cause of damage to the PR-9 aircraft generator-starters. Measures are given to avoid the failure of generators and starters during engine operation, i.e. when starting the turbojet engine of the "Iryda" aircraft. The article is a reprint of a publication published in No. 52 of the journal "Maszyny Elektryczne – Zeszyty Problemowe" from 1996.