The use of unmanned aerial vehicles (UAV) is becoming increasingly popular in many industrial fields like power utilities and oil and gas. The needs of such industries for reducing maintenance costs and increasing safety led to opening a new market for the UAV in these industries. This thesis focuses on the oil and gas industries, and studies the opportunity of using an unmanned aerial system for detecting gas leaks along the pipeline systems used in these industries to transport gas very long distances. Since this master thesis has been developed at Venturi Unmanned Technologies, the gas leak sensor has been integrated into their vertical take-off and landing (VTOL) UAV platform. This drone combines the easiness of taking-off and landing of a multicopter with the long range capabilities of fixed-wing aircraft. The versatility of this VTOL platform permits the implementation of various types of sensors and it allows to perform different types of tasks. The gas leak sensor finally integrated in Venturi's VTOL has been selected after going through a market research and is based on TDLAS technology. This technology can detect gas leaks from distances up to one hundred meters and is tuned to have high sensitivity to methane, as this is the main component of the natural gas transported via pipelines. The main part of the thesis consists in the structural integration of the sensor into the given UAV platform. A mount system is designed after going through several iterations in which stress analyses are performed seeking for weight optimization. The electronic integration is studied to prove the complete compatibility between the sensor and the drone. Furthermore, after the integration is realized, a prototype of the sensor is manufactured. The prototype is used to do tests on the newly developed gas leak sensor mount system. To have a complete integration of the system, a new cover for the rear payload compartment is designed to be able to accommodate the gas leak sensor. Finally, the developed gas leak sensor mount system proved to be an adequate solution for the sensor integration into the UAV drone platform.