$429 Dimmer Switch

Oh no! Someone having the audacity to disagree with King Weir!
That'll make him spit out his morning latte! Stand by for the flames.

Good points John, and I agree wholeheartedly, but can you expect every
A&P to fully understand each and every detail? I don't care to pay
for an A&P's education, but it's almost like saying that you obtained
your 30 years in a few months.


Well, I'm truly not looking for a flame war, and I really meant that little
blurb about a "confirmed lingerer"....just couldn't help myself.

It seems that in a discussion group like this there are always very vocal folks
that are always willing to tell you that their way is the better way and that
would have you believe that all mechanics and IA's are crooks or incompetent.

I find it very dangerous that there are folks out there in internet land that
spend their time spouting ways to decieve the FAA and get around the regs,
rather than trying to help folks work within the regs.

Just to clarify a few things, I believe that a good mechanic armed with a
multi-meter and schematic of the Piper instrument light system could do the
same. It does seem, however that many of my brothers and sisters in the biz
just don't have a good grasp on electricity in general and transistors in
particular.

Additionally, in my shop, if I happen to assign a green mechanic to a job such
as this and it takes him/her 5 or 6 hours to trouble shoot and repair.....I
WILL NOT bill the customer this amount. I will bill what I believe is an
adequate and fair amount. The up-side to this is that my mechanic will now be
"trained" and next time around, I won't lose my shirt on the deal. I think
what I was trying to say was that the $429 dimmer was a bit out of line, then
Mr. Weir piped in with his "better way of doing things" which is a tremendous
idea for a home built, but has no place in a certificated ship.

I actually do this on a regular basis. I will assign a green mechanic to a job
like this and with a few well placed nudges and a watchful eye, encourage
him/her to get a copy of the schematic and go troubleshoot. When the job is
done, the customer gets a bill based on what I think it would have taken ME to
fix the problem.

Interestingly enough, there have been times that I've cut a labor bill by
better than 50 percent and still caught hell from a customer. Go figure. (all
you accountants out there must understand that cutting a labor bill by 50% puts
me in the hole, figuring salarys, overhead, etc. etc). I just find it
interesting that nobody complains about the auto dealerships that flat rate
maintenance labor. You know, the guys that fix cars at the local Ford (insert
favorite car type here) dealership take home more pay than my mechanics. They
get about the same hourly rate, but a fair auto mechanic can turn in 60 to 80
hours in a 40 hour work week.....is that fair? Those hours are paid for by
YOU....the consumer.

What makes me so mad about this is the fact that these guys have almost no
liability......I could lose my home, my car, my job and every other thing I own
if a court/jury even THOUGHT I was neglegent......and guess what, jurys don't
make decisions based on regulations. Been there, done that.

We don't flat rate and I think I'd get out of the biz if we did.

The bottom line is....if you feel you're being taken by your mechanic, take
your maintenance dollar somewhere else. Just remember however that a
mechanic/IA that dosen't do his/her job exactly with the regs, isn't doing an
adequate job for you.....You as the PIC (per the regs) have the final
responsibility for the airworthiness of the aircraft you fly. My job as your
mechanic/IA is to keep your aircraft airworthy mechanically as well as
paperwork wise....and I am OBLIGATED under the regs to do both.

I really do understand though, that there must be some give and take, because
if I can't generate a pool of satisified customers, my shop will cease to
exist.

Phew....thanks for this opportunity to vent.......back to lurk mode for me.

The bottom line is....if you feel you're being taken by your mechanic,
take
your maintenance dollar somewhere else.

Thanks for the input, John. (You really *do* need to de-lurk here more
often.... ;-)

I have taken my business elsewhere in the past, when I truly felt I was
being ripped off. However, my current mechanic is an incredible guy, has
taken us out on his boat, has welded things for me, gratis, has helped me
bead-blast P-51 parts for our Mustang Suite, gratis. The list of favors
goes on an on.

He works ten times faster than the "corporate" shop on the field, although
perhaps not in this isolated case.

I will stick with him through one bad experience.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

I've been answering this same exact question for thirty-three years exactly the
same way, and I'm not going to go into the song and dance here again. You can
google the answer if you like, or you can download Applications Note 1 (the one
I wrote back in 1972 as amended through last year) from www.rstengineering.com
if you want the long answer.

Or, I can reproduce it here if you all would like some flame bait.

Jim


"Dan Thompson"
shared these priceless pearls of wisdom:

-Wouldn't replacing an approved dimmer assembly with a home-made one be a
-"major alteration" that would require a Form 337, and field approval of the
-data, for return to service?



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Any body that understands
-that tranistorized dimming system (and its just not that complicated) SHOULD
-KNOW to verify that the light chain is not shorted before sticking in a new
-transistor. A short is about the only thing I've ever seen that will kill the
-otherwise beefy 2N3055 transistor.

And any engineer that designs a dimming circuit without short circuit protection
of the output device should be staked out with ants and honey.



-
-And to Mr. Weir......the 337 is for Major repair and Major ALTERATIONS.

And reasonable men interpret MAJOR differently. I have my sources that I've
published with a Chief Counsel's opinion. They are yours to google as you see
fit.



As
-the chief inspector for a large repair station, if I see an aircraft for an
-annual with some kind of aftermarket or home made dimmer system....it better
-have a 337 associated with it....not because I'm a jerk or an a**hole, but
-because that is what the regulations require.

And again, I beg to differ with your interpretation, as does the Chief Counsel.


Unfortunately, if I ignore that
-or miss that and the owner rolls the aircraft into a ball, even if it had
-nothing to do with the accident, I could be in big trouble with the feds or
-possibly be sued by the estate and loose every thing I've worked so hard for
-these last 30 plus years.

Them's the breaks, ain't they? Both of us have our respective hineys on the
line.


I've been the biz long enough

As have I, and we can disagree without being disagreeable.



"You seek your god in rule books and idols made by men, and all the while that
god is within you. Safety is that which you know, not what somebody else thinks
it would be nice for you to comply with. Ask your FAA inspector for the
approved definition of safety. There is none. How can any agency guide toward
that which it can't even define?" (Richard Bach, "Found At Pharisee")

Jim



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Had a double helping of bitch flakes this morning, did we Stu?

Jim


Stu Gotts
shared these priceless pearls of wisdom:

-Oh no! Someone having the audacity to disagree with King Weir!
-That'll make him spit out his morning latte! Stand by for the flames.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Three words...

Newly graduated engineer.



I wonder why
-Piper made it so complex later on,



Jim



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Actually, they are a little simpler to design than the old analog beasts, in
that you don't have to do a lot of thermal worst-case analysis. And, the
current limiting is a hell of a lot easier to do.

Watch out, though, that the person who designed it understands RFI and how close
to the noise margin the Loran is. You'd be surprised how many designs have
their switching frequency a submultiple of 100 kHz. and wonder why the loran
(and everything else harmonically related) goes Tango Uniform when the lights
come to life.

Also, you need to understand that switching frequencies on the order of 30 Hz,
90 Hz., 150 Hz., and 9960 Hz. will honk up the avionics also. The hell of it is
that radio manufacturers do a great job of shielding their product against this
sort of RFI, but then run a wire from the dimmer port directly to the lights,
letting any crap on the dimmer wire merrily radiate throughout the radio.

Jim

When my dimmer does
-go, or I add more lighting to the panel, I'll probably opt for one of the
pulse
-width modulated ones (those are much more complicated than the piper pass
-transistor, but they also dissipate very little power).



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

The next step in the evolution is to get rid of all those incandescant
bulbs and replace them with LEDs. Lower power consumption for the same
light output, and they never burn out.

Has anyone got an STC for this kind of set-up yet?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

A friend of mine did their Stinson 108 with LEDs with appropriate Canadian
paperwork and it works incredibly well. As soon as I get my ac in May
it will be one of the first mods I get done to it. Easy to read, easy on the
eyes
and very cost effective.

Brendan


"Jay Honeck" wrote in message
news:iQJ4c.6688$1p.158527@attbi_s54...
The next step in the evolution is to get rid of all those incandescant
bulbs and replace them with LEDs. Lower power consumption for the same
light output, and they never burn out.

Has anyone got an STC for this kind of set-up yet?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Ray Andraka wrote:

Err, that transistor is there so that the rheostat doesn't double as a space
heater. It is there for a very good reason, although today there are better
ways to dim rather than a pass transistor. For that price, you could have
installed one of the pulse width modulated dimmers and done away with the old
fashioned piper circuit. Would have required a 337, but then it would be the
last time you'd ever have to deal with it. You might have even been able to
get separate dimmer circuits for instrument and overhead lights out of the
deal.

Be a bit carefull with PWM dimmers., if they get placed near the avionics
you might have problems with RFI .

Have a look at the circuitry for the alternator-fail annunciator
on the Piper Arrow. It wastes 4 watts just to keep a globe off.
(I'd always wondered why the comm-panel switches were always hot)