We cannot tell you for 100% when you will have to change the hose assemblies at your aircraft - to many variables are influencing it like the aircraft manufacturer, the manufacturer of the hose assembly or of the engine - but we can help you to get this info:
Rubber & Teflon hose assemblies
In general the aircraft manufacturer is responsible for the operating times. Check your handbook of the aircraft. If this is not helpful ask the manufacturer directly!
You cannot get a binding answer? Maybe because there is no existing aircraft manufacturer? Ask the STC holder for the aircraft.
Is there no existing STC holder? Ask your responsible aviation authority!
Criteria’s of Inspection and Service
Hose assemblies need to be replaced when following occurs: