The MD-90 etc might show a little drop in hydraulic pressure during aileron/spoiler check as during preflight (when checking ground spoiler extension).
Still off the topic, but years ago at a "lower budget" civilian repair/overhaul facility at Dothan (DHN), Alabama, a US Navy Reserve CV-580 (one of two based at the Navy side of Andrews AFB) crashed while returning to the runway, following a major overhaul. The facility had failed to thoroughly check the elevator control cables. On climbout, every time the pilots pushed the yoke forward, it could not be pulled back. There was some accidental linkage to either other control cables or other metal parts.
Fortunately for the bean counters, US Naval Aviation saved money using that repair facility-at least until the tragedy during base leg or the crew's "final approach".