Initial Inspection: This inspection will establish an initial baseline and the present condition of the engine. The earlier the engine is maintained in accordance with the MORE STC the better the engine health will be in the long run.
An FAA Form 337 or foreign equivalent (a sample of front and back can be found here) is required to incorporate the STC along with a notice to the FAA informing them that the engine will be using the STC for the maintenance per FAR 91.409.
When transferring aircraft ownership to a new owner, a notice to the FAA is required at the same time the new owner registers the aircraft. For convenience only, see FAA Note Transfer for details.
Continuing Inspections: Engine inspection intervals are required to keep the engine operating at its peak and to keep the maintenance costs to a minimum.