A particular preflight system check and the lack of an indication in the cockpit that could have alerted the pilot of low hydraulic pressure resulting in high pedal loads and a subsequent loss of control after takeoff, was the probable cause of a helicopter crash in Colorado that killed the pilot and seriously injured two flight nurses, according to the National Transportation Safety Board (NTSB).
(In the image above, still frames from Summit Medical Center surveillance video show the accident helicopter engulfed by a fuel-fed fire 20 seconds after impact [left] and at 60 seconds after impact [right].)