Ann: New Maintenance Agreement, page-8

The Maldives have all their PT6 engines on Power By The Hour (PBTH). That is PTB provides the engines which, for every hour of engine operation, the Maldives pay a fee to PTB. When an engine is due for a scheduled service PTB sends them a replacement engine (I believe several spare engines are positioned at the Maldives for unfortunate incidences anyway). Instead of the Maldives having a massive cost spike for overhaul or a hot section the engines are already paid for over many weeks of paying PBTH. Accountants enjoy this leveling of the costs. This business model has proved a winner for PTB. Of course, they also have numerous other customers who take the one-time cost.