What was found
ILN - AFTER TAKEOFF WITH GEAR SELECTOR UP, ALL THREE UNSAFE LIGHTS AND GEAR DOOR OPEN LIGHTS REMAINED ILLUMINATED. ALL THREE GEARS APPEARED TO REMAIN DOWN. RECYCLED GEAR, RETRACTED NORMALLY WITH NORMAL INDICATIONS. JACKED AIRCRAFT AND PERFORMED SIX GEAR RETRACTIONS AND INDICATIONS WERE NORMAL. CHECKED RIGGING OF LANDING GEAR, CONTROL VALVE AND EMERGENCY EXTENSION AND ALL CHECKED OK IAW DC9 SUPPLEMENTAL MM, CHAPTER 32.