4-13. TROUBLESHOOTING (CONT)
TEST OR INSPECTION
APU - CONT
APU JUMP START SYSTEM INOPERABLE - CONT
Check APU jump start electrical cables connected to APU (grounding) and battery (positive terminal)
for corrosion, loose clamps and connectors, and fraying.
Clean off corrosion and tighten any loose connections, and/or remove and replace defective electrical
Check that APU jump start electrical box and internal components are working properly by pressing
If an audible clicking sound is not heard and all of above checks/inspections have not corrected
problem, remove and replace APU jump start electrical box (para. 4-113).
GENERAL HYDRAULIC FAILURES
Check that hydraulic tank shut-off valve is open (para. 2-4).
If APU has run longer than 30 seconds, with the hydraulic tank shut-off valve
closed, pump may be damage and the hydraulic system, including filters, may be
contaminated with metal particles.
Indicator should read in green; if not, remove and replace filter (para. 4-89).