Yes 3500 on recurring every 300 hours. This is not in the EAD, but is in the SDB from Enstrom. The FAA EAD does say initial inspection before further flight and before 1500 TIS or any that TIS cannot be determined or over 1500 TIS. The SDB allows 5 hours of flight before inspection, but the EAD does not. For those that do not know, Enstrom, last I heard, was doing the testing for free and will disassemble/reassemble the retention system for a fee.