What was found
ON CLIMB OUT ABOVE 16,000 NOTICED A VIBRATION THAT SEEMED STRONGEST ON THE FO NEAR OUTBOARD CUP HOLDER VIBRATION WENT AWAY AFTER DESCENDING BELOW 16000 ON WALK AROUND FOUND THE GPU DOOR OPEN. PERFORMED WALK AROUND IAW AMM 05-41-01-210-801 CONFIRMED WITH GROUND CREW THAT DOOR FOR GPU WAS OPEN ON ARRIVAL PERFORMED OPS CHECK OF GPU DOOR IAW AMM 52-49-02-400-801 OPS CHECKS GOOD. NO DAMAGE NOTED A/C OK FOR CONTINUED SERVICE.