AFGS-87219 Electrical Power Systems, AircraftThis specification establishes the performance requirements and verifications for electric power subsystems EPS for aerospace vehicles, including aircraft, helicopters, and missiles.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - 30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 - 38 - 39 - 40 - 41 - 42 - 43 - 44 - 45 - 46 - 47 - 48 - 49 - 50 - 51 - 52 - 53 - 54 - 55 - 56 - 57 - 58 - 59 - 60 - 61 - 62 - 63 - 64 - 65 - 66 - 67 - 68 - 69 - 70

AFGS�87219B APPENDIX A

c. Flight critical loads shall have first priority to primary power and shall be supplied from the emergency power source when primary power is not available.

d. The power quality requirements of 3.2.1 shall be maintained.

e. Convenient means shall be provided for disconnecting ground power from equipment not requiring power during ground operation.

f. Other requirements for electric power distribution are as follows: ------------.

REQUIREMENT RATIONALE (A.3.2.7)

An effective distribution system is needed to transmit electric power to the using equipment in a safe and reliable manner. Factors to be considered include power quality, load priorities, reliability, vulnerability, and safety. AFSC Design Handbooks DH 1-6 and DH 2-3 have requirements for power distribution design and performance.

REQUIREMENT GUIDANCE (A.3.2.7)

The requirements of paragraph 3.2.7 are applicable to all aircraft. Additional requirements for a particular application should be added as needed.

REQUIREMENT LESSONS LEARNED (A.3.2.7)

Automatic load shedding is required in the event of a partial loss of the electrical system. This assures that the entire system is not lost due to one item failing. The crew cannot be expected to shut down equipment in time to prevent a total electrical system failure. Some aircraft without load shedding have lost total electrical power due to one small failure that could have been automatically detected and isolated.

A.4.2.7 Power distribution.

Compliance with the power distribution requirements of 3.2.7 shall be verified by analyses and tests as follows: ------------.

VERIFICATION RATIONALE (A.4.2.7)

Analyses and tests are the appropriate means of verifying compliance with this requirement.

VERIFICATION GUIDANCE (A.4.2.7)

a. Analyses appropriate for this requirement include electrical load analyses per

MIL-E-7016, hazard analyses, failure mode and effect analyses, and circuit analyses.

b. Testing should be applied to verify distribution system performance in the laboratory and on the vehicle. The laboratory testing should duplicate actual electrical loads and simulate normal and fault conditions.