I'll assume that you're looking into buying a hangar which is approved to do heavy maintenance on small jets.
you need to get an EASA 145 approval and for this you'll need to go through a complex procedure.
Here is some useful info I found after googling.
2. INTRODUCTION• An organisation that intend to secure jobs from Europe has to have EASA 145 approval. The approval means that the organisation has met the minimum standard as listed.
3. ROAD TO GET EASA 145 APPROVAL• One of the actions items required for companies applying for 145, is to train their staff on 145 awareness. Some of the learning points are shared below.• You may get more information from EASA official website.
4. ABOUT EASA• EASA stands for European
Aviation Safety Agency.• Its responsibilities includes – Act as an advisory body to EU in matters related to civil aviation. – Monitor the aviation safety and ensure its compliant. – Issue Type certificate for companies in Europe – Issue Design approval for manufacturing and modification. – Authorize non EU companies to operate on EASA guidelines.
5. VARIOUS PART OF EASA• In order for EASA to perform its roles, various regulations were laid down. The big ones are as follows:• Part 145 – MRO – These are regulation related to the setting and operation a maintenance, repair and overhaul of aircrafts of components.• Part M - continuous airworthiness. This provide the guides and process to ensure the civil aircrafts continue its airworthiness status.• Eu Operation – AOC – The air operators certificate are given to airlines when the airline had met the minimum standard and requirement to set up a civil airline.• Part 66 – licensing. This is the section giving guides and approval in matters relating to certifying the maintenance personnel.• Part 147 – training organization
6. REQUIREMENTS TO GET EASA 145• The followings are the requirements that an organisation must have at the time when the application is made: – Approved facilities with controlled environment – Tools and equipments. – Approved processes as laid in MOE – maintenance organisation exposition.
7. More Requirements to get 145• Approved parts. A system to ensure that the parts received are genuine.• Approved documentations – Manufacturers – AMM,MPD, CMM,IPC,WDM,SB – Regulatory – AD,AN – Companies – job cards, check list, report, manufacturing orders, Tags• Release documents – CRS EASA form1
8. More Requirements to get 145• Qualified personnel – sufficient licensed personnel – Quality assurance personnel• Auditor• Accountable manager• Moe – Maintenance Organisation Exposition giving details of the management personnel, processes and the control.
9. MOE Contents• Management organization• Maintenance Procedures• Line Maintenance Procedures• Quality System Procedures• Procedures for operators• Appendies
10. CATEGORIES OF 145• Part 145 categories• A1 aircraft > 5700kg• A2 aircraft <5700kg
11. ENGINE APPROVAL• Approval: For repairing & overhaul Engine – B1-turbo-jet – B2-Recipocating – B3-Apu (auxiliary
power unit) – D1-NDT
12. WHO CAN ISSUE CRS is the certificate release to service.• B1 Certifying staff• B2 Certifying staff for his scope.• Certifying staff for his scope of Authorization
13. INFORMATION GIVEN IN CRS The following information shall be available• Companys approval number• Name, approval number• Date and place of issue• Reference
Ensure that all these requirments are fullfilled in the maintenance hangar you're looking to buy + The personnel in there are appropriately qualified lincensed B1 or B2 engineers, Have a look at thier MOE, Thier procedures, The infrastructure of the shop and capabilities of the hangar and I advise you to do some more reading on 145 organizations before involving yourself in this bussiness.
It appears from your post that you have no idea on what you're about to embark on which is no good when it comes to such businesses so do your research.