As written on AirMech:
"There are two (2) OJT requirements:
1. On completion of a Type Rating Theoretical Course the student should complete a Practical Element followed by Structured OJT in the Part 145 environment. A part 145 signatory (Type Rated) signs off the Structured OJT and passes the list to the Part 147 Assessor who must himself be Type Rated as previously stated. The assessor can then supply a Practical Element Certificate to the Student.
2. To supplement the Part 147 OJT - AND for the FIRST Type Rating only - The student must also supply a second record of OJT demonstrating the students Part 145 work experience over the past two years AND covering approx 50% of the Part 145 List (The List can be tailored by the Part 145 Company but (and this is where I think it falls down) must be acceptable to "the CAA") the list is also supervised and signed off by a T/R Engineer but then Assessed by the Signatory mentioned in the MOE/CAME - often the QAM or a QA Eng.
Unfortunately the two parts of the CAA (your local Surveyor and the ELD) don't appear to have the same briefing on what is required and so the list may be acceptable to one but not the other!
I hope this explains some of the pain the latest changes have brought."
...and you're welcome.