What was found
IN LEVEL FLIGHT AT 16,000 W/ 6000 NR OF FUEL IN NR 2 TANK THE RT AFT FUEL BOOST PUMP LOW PRESSURE LIGHT ILLUMINATED. NO CB'S WERE OUT. TROUBLESHOT SYSTEM CHECKED WIRING TO PRESSURE SW. WIRING CKS OK. READ PRESSURE SW WITH PUMP ON AND OFF. SW STAYS CLOSED. VERIFIED PUMP RUNNING WHEN SW IN ON POSITION. BACKED OFF B-NUT AT PRESSURE SW. NO PUMP PRESSURE. SUSPECT BAD PUMP IMPELLER. REMOVED AND INSTALLED SERVICEABLE NR 2 TANK AFT RT BOOST PUMP, IAW MM CH NR 28-22-021-4. FOUND CORROSION ON RT AFT PUMP PRESSURE SWITCH, REMOVED AND REPLACED SAME IAW MM, CHAPTER 28-42-001-4 FUNCTIONAL TEST GOOD.