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.

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AFGS�87219B APPENDIX A

If specific auxiliary power requirements are known, they should be specified accordingly. Otherwise performance should be as necessary to meet aircraft operational requirements. Auxiliary power requirements for ground maintenance, system checkout, manned alert,

lighting, cargo loading, starting, emergency power, etc., should be specified as determined from analysis of aircraft operational requirements.

REQUIREMENT LESSONS LEARNED (A.3.2.6)

APUs have proven to be beneficial to most aircraft.  They eliminate the need to connect external electrical power for any maintenance, checkouts, etc.  They can also provide electrical power for alert situations, emergency power, and hot turns.

A.4.2.6    Auxiliary power.

Compliance with the requirements of 3.2.6 for EPS operation with on-board auxiliary power shall be verified by analyses and tests as follows: ------------.

VERIFICATION RATIONALE (A.4.2.6)

The performance of the EPS with respect to auxiliary power requires verification by analyses and test.

VERIFICATION GUIDANCE (A.4.2.6)

a.   Use electrical load analyses in accordance with MIL-E-7016 to aid in determining the quantity of auxiliary power required for various modes of operation.

b.   Verify performance of the EPS by testing in the laboratory and on the aircraft.

VERIFICATION LESSONS LEARNED (A.4.2.6)

Testing is the only viable means to demonstrate that the auxiliary power unit comes on as designed and picks up the electrical loads.  Laboratory testing followed by on-aircraft testing is required, to demonstrate the entire system function.

A.3.2.7    Power distribution.

Electric power shall be distributed from the various power sources to the aircraft loads in a safe and effective manner.

a.   The buses and distribution circuits shall be configured so that normal EPS operation loads receive power from the aircraft primary power source(s), ground power, or an auxiliary power source as applicable.

b.   In the event of an EPS failure that reduces the amount of available power below total aircraft requirements, non-flight critical and/or preselected loads shall be automatically disconnected as required.

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