> . . .message posted by: AAMRELECTR@aol.com
>
>>In a message dated 2/19/00 10:34:54 AM Pacific Standard Time,
>>nuckolls@aeroelectric.com writes:
>>
>> Please don't do this folks. There is no basis either
>> in 30+ years experience on aircraft (Cessna rocker
>> switches) nor in the physics of this wiring technology
>> to shy away from Fast-Ons . . . see:
>Bob:
>I was at the airport in Ellensburg Washington calling on a FOB certified
>aircraft mechanic who was working on a Cessna set of rocker switches in a
>panel.
>
>And as has been true with all the APs I've called on in my capacity with AMP
>and with another company selling Mil Spec Aircraft Rated connectors. His
>couldn't curse those things enough as to what a poor and dangerous choice
>they were for aircraft! His experience...not mine.
Experience or opinion? What were the prevailing conditions that produced
any failures he may have witnessed? Were they conditions that might have
pushed ANY terminal to failure? I've heard many a derogatory remark
about fast-ons, some from folk with a long history aircraft. We have
to insist on knowing the physics behind their opinion or it doesn't
account for much. My hero C.F. Kettering said, "You can know a lot
and yet understand nothing."
If you have reason to discount the fast-on as it applies to the fuse
holders, then you have reason to discount the entire fuse holder.
The same technology is used inside the holder to retain fuses as that
which is used to attach wires to the holder's tabs.
>I sold him some Amp #640917 and #640903 Fastons. Since his regular supplier
>Aircraft parts supplier did not and would not carry this item for usage on
>aircraft.
Again, by what argument of fact does the supplier refuse to carry a
product . . . and was he making his decision based on what he sees
in hardware stores (soft copper, plasti-grip clones) or on PIDG
devices or equal?
>I think we need to look at the generic name of this item "Push Ons...and if
>it will Push On will Pull Off? As I said on the page. Is it hard to come
off,
>YES...Is it impossible that they will come off...NO.
Have you read the piece I published on fast-ons? If your aircraft
is subjected to 1/10th the g-loading required to dislodge one of these
terminals, I'll suggest that loose wiring is the least of your
worries. The last fast-on failure I was told about on a Cessna
rocker was where the pitot-heat switch suffered severe meltdown.
The mechanic thought it was fast-on terminal failure which was
was indeed loose . . . until he took the switch apart and found
badly fried contacts and charing internal to the switch housing
. . . the switch failure killed the fast-on, not the other way
around.
>As usual your opinion is welcome and highly respected. But I really think it
>would be better for you and more informative for us if you addressed from
>what you see wrong with the idea of substituting rings for Push On if it's
an
>easy fix.
>I am not telling folks to "shy away from Fast-Ons", but I am saying there is
>another choice for using ATC Fuse Blocks...Which are a really good simple
>idea. . . . for me I'd rather error on the side of safety.
How is it safer? The joint is now process sensitive to the installer's
"feel" for tightening. You've substituted a threaded fastener with a
definite propensity for loosening under vibration while quality
fast-ons dig in deeper under vibration. You have to be extra careful
not to subject the fuseholder's tabs to mate-up forces (twisting) it
was not designed for . . . if you use metal locknuts, the risk of
damage is still greater.
>Also folks might give AMP a call at 1-800-522-6752 take Que #2 for techical
>service and ask them if the two AMP part #s shown above are spec'd by AMP to
>use on aircraft and then ask them if their rings # 8-36150-1 and # 8-320619-1
> . . .
A tech rep for any company would be foolish to either recommend or
discourage the use of his/her product on "aircraft" or any other
non-quantified application. They should be prepared to offer test
results that qualify their product to some specification but it's
ALWAYS up to the system designer to determine if the intended
use falls inside those criteria. The terms "aircraft quality" and
"suitable for use on aircraft" are meaningless and fraught with
hazard for those who have faith in them.
Bob . . .
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( The only time you don't fail is the last )
( time you try something, and it works. )
( One fails forward toward success. )
( C.F. Kettering )
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http://www.aeroelectric.com
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