Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain SAFT America Inc., P/N 021929-000 (McDonnell Douglas P/N 43B034LB02) and P/N 021904-000 (McDonnell Douglas P/N 43B034LB03) nickel cadmium batteries. The existing AD currently requires replacing all battery terminal screws, verifying that the battery contains design specification cells, and replacing the cells if the battery contains non-design specification cells. This proposed AD would require an inspection for certain nickel cadmium batteries and, if necessary, replacing battery terminal screws with new hex head bolts and adding shims. This proposed AD is prompted by a report of battery screws shearing off while under normal torque loads. We are proposing this AD to prevent internal shorting, arcing, and loss of emergency battery power due to failed battery screws, which could result in loss of emergency power to electrical flight components or other emergency power systems required in the event of loss of the aircraft primary power source.