As an aside - in the new EU OPS world, which part does actually apply to training organisations during training?
Following hamster's advice, we go to the original source - in this case, initially, the EASA CRD on the OPS Regulation (CRD OPS II) where, in the section titled 'Addendum to the Cover Regulation on Air operations and Annex I - Definitions' on page 10 of 155, we find the statement:
"As regards the applicable operational requirements for approved training organisations, it is proposed that flying training by ATOs is conducted in accordance with either Part-NCC or Part-NCO, depending on whether the aircraft is complex motor-powered or not and regardless of whether it is a commercial or non-commercial activity (Article 1(2) point 9)."
Assuming, therefore, that the training is taking place on a single-pilot, piston engined aircraft with less than 20 seats and weighing less than 5700kg, it is Part-NCO that applies to training organisations.
In relation to minimum equipment lists, Part-NCO, as it was submitted to the EC, states:
NCO.GEN.155 Minimum equipment list
An MEL may be established as specified under 8.a.3. of Annex IV to Regulation (EC) No 216/2008. In that case, the MEL and any amendment thereto shall be approved by the competent authority.
It does not, therefore, mandate a minimum equipment list but allows it as an option. Hamster will also be pleased to note that 'authority' is not capitalised.