NOVELTY - The apparatus (1100) has a tubular housing with extended fluid passageway (205). A valve piston moves axially within housing in response to pressure of drilling fluid passing through flow path to control flow of fluid into annular chamber (1330). A push sleeve is located within housing and coupled to expandable feature. The push sleeve is moved axially in response to flow of fluid into chamber extending the expandable feature. The expandable apparatus is configured to generate a signal indicating extension of expandable feature.    USE - Expandable apparatus such as expandable reamer apparatus, expandable stabilizer apparatus, etc., for enlarging subterranean wellbore for oil and gas production, and geothermal energy production.    ADVANTAGE - Since the push sleeve located within tubular housing couples to expandable feature and moves axially in response to flow of fluid into the annular chamber, the expandable apparatus generates signal indicating extension of expandable feature. The status indicator closes the nozzle completely and prevents fluid flow through the nozzle when valve piston is in the distal position and the blades are moved to fully expanded position. Hence significant increase in standpipe pressure can be achieved and change in pressure can be detected by the operator using pressure sensors and the fluid flow can be adjusted to achieve appropriate operating pressure. The stabilizer blocks are provided, so as to facilitate centering of the expandable apparatus within the borehole while drilling and reaming the wellbore. Since the first spring can resist motion of push sleeve towards the upper end of the expandable apparatus, blades can be biased to retracted position. Hence the insertion and removal of the expandable reamer from wellbore can be facilitated without blades.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method of operating expandable apparatus.    DESCRIPTION OF DRAWING(S) - The drawings show the cross-sectional views of expandable apparatus.    Blade (120)    Fluid passageway (205)    Expandable apparatus (1100)    Fluid ports (1320,1321)    Annular chamber (1330)