  The Cherenkov Telescope Array (CTA) is a future ground-based gamma-ray
observatory that will provide unprecedented sensitivity and angular resolution
for the detection of gamma rays with energies above a few tens of GeV. In
comparison to existing instruments (like H.E.S.S., MAGIC, and VERITAS) the
sensitivity will be improved by installing two extended arrays of telescopes in
the northern and southern hemisphere, respectively. A large number of planned
telescopes (>100 in total) motivates the application of predictive maintenance
techniques to the individual telescopes. A constant and automatic condition
monitoring of the mechanical telescope structure and of the drive system
(motors, gears) is considered for this purpose. The condition monitoring system
aims at detecting degradations well before critical errors occur; it should
help to ensure long-term operation and to reduce the maintenance efforts of the
observatory. We present approaches for the condition monitoring of the
structure and the drive system of Medium-Sized Telescopes (MSTs), respectively.
The overall concept has been developed and tested at the MST prototype for CTA
in Berlin. The sensors used, the joint data acquisition system, possible
analysis methods (like Operational Modal Analysis, OMA, and Experimental Modal
Analysis, EMA) and first performance results are discussed.
