Re: EASA P 145: What mandatory information should on the purchase order of the custom
Assuming you are a Part 145 approved organisation your approved Capability List would reference which CMM or tech Data to use.
There are no clear mandatory items on a list but the organisation sending you the part would be bound by EASA Part-M or similar which states:
M.A.610 Maintenance work orders
Before the commencement of maintenance a written work order shall be agreed between the organisation and the organisation requesting maintenance to clearly establish the maintenance to be carried out.
AMC M.A.610
‘A written work order’ may take the form of, but not limited to, the following:
— A formal document or form specifying the work to be carried out. This form may be provided by the continuing airworthiness management organisation managing the aircraft, or by the maintenance organisation undertaking the work, or by the owner/operator himself;
— An entry in the aircraft log book specifying the defect that needs to be corrected.
Hope that helps