DO-160 Section 16: Every Power Input Condition Your Source Has to Generate

Aviation & 400 Hz · 3 min read · 36 cited facts

DO-160 Section 16 is not one test. It is a category system, and the first thing that determines your bench is which letter your equipment is qualified under. Get the category wrong and you will either buy a source that cannot run the clauses or spend money reaching conditions your programme never has to demonstrate.

Categories decide everything downstream

A(CF) — 400 Hz constant frequency
A(NF) — 360 to 650 Hz narrow variable frequency
A(WF) — 360 to 800 Hz wide variable frequency
A — 28 VDC supplied from a transformer-rectifier unit
B — 14 or 28 VDC with a floating battery
D — 270 VDC
Z — 28 VDC from a variable-speed generator with no battery

A(CF) equipment needs a source that holds 400 Hz precisely. A(WF) equipment needs one that sweeps to 800 Hz and slews between. Those are different instruments, and the difference is not marginal.

Steady state is a matrix, not a setpoint

Parameter	Value	Clause
AC normal steady state	100 V and 122 V, 30 min per point	16.5.1.1
AC abnormal	97 V and 134 V for 30 min; undervoltage 60 V and 10 V for 7 s	16.5.2

AC normal and abnormal steady-state conditions

Each of those points is held for thirty minutes, at each frequency corner for your category. The test time adds up quickly, which is why sequencing and unattended operation matter more here than raw capability.

Modulation is where basic sources fall over

Parameter	Value	Clause
Voltage modulation	envelope to 5.0 V at 115 V, 1–200 Hz	16.5.1.2
Momentary interruptions	19 profiles, 2 ms–200 ms at 0 V, plus partial sags 15/35/50/65%	16.5.1.4

Modulation and interruption requirements

Surges size the instrument

Parameter	Value	Clause
Normal surge	160 V for 30 ms (A(CF)/A(NF)); sag 70 V for 30 ms	16.5.1.5
Abnormal surge	180 V for 100 ms then 148 V for 1 s	16.5.2
DC ripple	<4 Vp-p on 28 V, <16 Vp-p on 270 V, 10 Hz–30 kHz	Ch.18 Fig 18-3/18-4
Engine-start undervoltage	drop to 10 V, ramp 0.3 V/s for 35 s to 20.5 V	16.6.1 (B/Z)

Surge and DC conditions

The engine-start profile is worth dwelling on. It is a slow ramp — 0.3 V per second across 35 seconds — rather than a step. That exercises hold-up and brown-out behaviour in a way no transient does, and it needs a source that can be driven smoothly rather than stepped.

How this differs from MIL-STD-704F

Both describe an aircraft bus, and both demand a programmable source. The practical difference is shape: 704F is organised around normal, abnormal, emergency and starting states for each power type, while DO-160 is organised around equipment categories and a long list of discrete numbered conditions. A bench built for one will usually cover much of the other, but the test sequences do not transfer, and neither do the acceptance criteria.

Building a DO-160 §16 bench?

Tell us your equipment category and which conditions you have to demonstrate. We will come back with what covers them.

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