What was found
BLI FLIGHT NR 2491: AFTER START, SELECTED STBY HYD PRESS ON AND NO STBY PRESSURE WAS INDICATED. RAN MEL 29-30-2 CHECKLIST AND NO PRESSURE WAS INDICATED ON SYSTEM NR 1 AS PER STEP 3. A/C GEN NR 2 WOULD SHOW A LOAD INCREASE WHEN STBY HYD PRESS WAS SELECTED ON WITH NO PRESSURE INCREASE. HYD QUANTITY NORMAL AND NO CIRCUIT BREAKERS POPPED. MAINTENANCE REMOVED AND REPLACED SYSTEM NR 1 STANDBY POWER UNIT IAW DHC8/400 AMM 29-11-36-000-801/-400-801. C/W OPERATIONAL CHECK IAW 29-11-36-710-801. OPS AND LEAK CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.