I can assure you that crew personal equipment such as life jackets, QRB's, harnesses, strops etc (I took this to be the 'aircrew equipment' referred to by the OP) are quite legally serviced by skilled and trained aircrewmen. They hold the appropriate engineering authorisation and use the properly controlled and amended CMM's for each item. These are detailed on the company capability list.
SM please check your facts before flaming a post and avionker most of the CMM's do have ATA25 chapter numbers (Equipment and Furnishings in case you need to look it up). Was simply answering the O/P's query, did not expect to be knocked for that!
'Aircraft' as opposed to crewmen SE is of course serviced using the appropriately authorised outfits.