Given the current rate of growth of gas turbine engines in the aerospace industry, the development of efficient and advanced sealing technology to cater to the harsh operating conditions of the aero-engines is crucial. In addition to developing low-leakage, long lasting and well-performing seals, it is essential to maintain them. Seals play an integral role in improving engine efficiency at a high performance to cost ratio and failure of this part results in a trifecta of hazards: safety, environmental and cost, all three of which are discussed. Efficient maintenance repair and overhaul (MRO) of engines is paramount to ensure compliance with air worthiness standards put forth by regulatory bodies. Data suggests that engine MRO accounts for ~30% of direct engine operating costs and so it is necessary to reduce unscheduled maintenance and failure of components. A review of aero-engine sealing technology is presented in this paper from an MRO aspect and current state-of-the-art sealing technology in the aerospace industry is discussed alongside. It is clear based on the review work that sound MRO practices of seals is just as vital as design and development of them. The future outlook of MRO and overcoming the challenges faced in the industry have also been outlined.