nuckolls.bob(at)aeroelect
Guest
|
 Posted: Wed Jul 01, 2026 11:07 am Post subject: DO-160 |
 |
|
At 07:47 PM 6/30/2026, you wrote:
| Quote: | One topic of interest, last year on AOPA's Ask the A&Ps podcast I questioned
the validity of needing to have avionics off for startup because of
"voltage spikes" and all three experts were sincere in their insistence
that these spikes could damage avionics despite thousands of recorded
starts never showing a single "spike". They said the one second sample
rate was too long an interval to record the spike. |
Yeeaahh but . . .
True, the sample rate for panel mounted
data gathering is indeed too slow to
to quantify any 'spike' . . . but they
failed to consider the what we've learned
over the past 50 or 60 years.
After my earlier post this morning I went
to the archives to refresh (and correct)
my recollections: Here's an article I wrote
a few years back that speaks to contemporary
performance protocols and definitions of
various stimuli:
Your browser may balk at downloading
this from an 'insecure' site but be
aware that Matt decided not to
spend buckets of cash for the certification
that pronounces his servers 'golden'.
Go ahead and hit the 'download anyhow'
button.
https://tinyurl.com/DO-160Story
This is a compendium of tests I was
asked to conduct on every device I
was offering to the TC aircraft
industry.
I mis-spoke about the nature of the
inductive field collapse spike.
The unloaded 'spike' intensity was 300
volts for 100 MICROseconds delivered
through a 50 ohm resistor.
A stupidly easy test to pass. We built
a fixture to generate this stimulus
and was chagrined to find that
including a little capacitor
across the supply line quashes
the stress.
Always included the capacitor and never
ran the test again.
The high energy events were based
on worst case stresses generated
by runaway alternator or generator
where some allowances were made
for response times typical of
overvoltage protection schemes
of the time. These SURGE values
for the 14v system were 20 v for
1 second, 40v for 100 MILIseconds.
What is missing from this well crafted
series of tests is any stimulus that
one might identify as a starter-generated
'spike'. What DO-160 DOES test for
is (C) Interruptions. This was exactly
the stress that was killing Cessna's
pride-n-joy, NavCom 300's right off
the production line.
NOT a problem with the airplanes.
The problem was with the radio design
for not proving that various
kinds of missing or low voltage
was deleterious to their product.
Bob . . .
////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================
In the interest of creative evolution
for the-best-we-know-how-to-do based
on physics and repeatable experiment.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
