AFGS�87219B APPENDIX A
h. Indication of battery system malfunctions such as over-temperature, battery discharging, and low battery voltage should be provided to the crew as necessary to meet subsystem safety and reliability requirements.
REQUIREMENT LESSONS LEARNED (A.3.2.9.2)
The horror stories of aircraft battery failures are well known and too numerous to relate individually. Catastrophic failures and loss of power have resulted in the loss of both aircraft and personnel. Countless instances of less severe problems have caused personnel injury, aircraft damage, mission aborts, poor maintainability and reliability, and high replacement costs. The lessons learned from these experiences are reflected in the guidance provided by AFSC Design Handbooks DH 1-6 and DH 2-3.
Some specific lessons learned are:
a. One aircraft required a non-standard battery because of available space and the need for thermal insulation. Several deficiencies were later discovered in the design and installation of the unit.
1) A non-standard cell which was much more costly than an equivalent standard cell was originally selected for the battery. It was later found that the standard cell could be substituted without loss of performance.
2) The thermal insulation was designed as an integral part of the battery case. This not only increased the initial and replacement costs, but also downgraded battery reliability because of susceptibility to cracking and contamination by the electrolyte. Making the insulation (or other thermal conditioning) a part of the aircraft battery compartment rather than a part of the battery would have been a better approach.
3) The original configuration of the battery vent tube allowed rain water to enter the battery and contribute to corrosion of thermal switches. A redesign of the vent was required to correct this problem.
4) Access to the battery required the removal of a structural fuselage panel secured by approximately 50 stubborn screws. This is unsatisfactory for an item which requires frequent maintenance.
b. There have been numerous instances of thermal runaway of nickel-cadmium batteries directly connected to high current DC generators. The loss of one aircraft and one of its crew members was attributed to this cause. Safe limitations on charging current are needed for nickel-cadmium batteries.
49
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business