A DHC8 CREW ROLLED INTO A GPU ON START. THEY HAD NOT SET THE PARKING BRAKE PER THE CHKLIST.

Narrative

I ASSISTED THE FO IN CONDUCTING THE EXTERIOR PREFLT. UPON ENTERING THE COCKPIT; A NORMAL ORIGINATING FLOW (INCLUDING DAILY ITEMS) AND CHKLIST WAS COMPLETED. THIS WAS FOLLOWED BY A BEFORE START CHKLIST. I RESPONDED 'SET' TO THE PARKING BRAKE CALL AND NOTED TO THE FO THAT 2000 PSI WAS INDICATED ON THE ACCUMULATOR; SUFFICIENT PRESSURE FOR A SAFE START. UPON START; WHEN BRINGING THE CONDITION LEVERS OUT OF FEATHER; WITH HEAD DOWN; I NOTED OR FELT; MOVEMENT. I RAISED MY HEAD AND; RECOGNIZING THE PROB; IMMEDIATELY SET THE PARKING BRAKE. AS A RESULT OF THIS RAPID BRAKING; THE NOSE MOVED DOWNWARD ON THE NOSE STRUT; STRIKING THE GPU SENDER VERTLY. MINIMAL DAMAGE WAS SUSTAINED TO THE NOSE DOOR ASSEMBLY. I CONSIDER MYSELF TO BE RIGID WHEN IT COMES TO PROC AND CHKLIST USAGE; AND IT IS DIFFICULT TO BELIEVE THAT I SAID 'SET' WHEN IN FACT THE PARKING BRAKE WAS NOT SET. THE KEY FACTOR SEEMS TO BE MY INTERJECTION INTO THE CHKLIST; OF A COMMENT ABOUT ACCUMULATOR PRESSURE; THUS DIVERTING BOTH MY OWN AND THE FO'S ATTN FROM THE PARKING BRAKE POS.