Sigmatek DG

Hello -

This weekend, I noticed that our DG is starting to fail.. The indicated
heading sways off after making a couple 90 degree turns.. Vacuum source
seems to be OK, as the AI is still working good, and the vacuum gauge reads
normal. So I'm pretty sure this is isolated to the DG.

It has the original DG. (Airitalia, I believe). The local shop quoted low
700's for a brand new Sigmatek. (No autopilot, flags, or lighting). That
does not include labor.. I think the price is right - but is the brand OK?

--
Ben
C-172 - N13258 @ 87Y

Ben Smith wrote:
: Hello -

: This weekend, I noticed that our DG is starting to fail.. The indicated
: heading sways off after making a couple 90 degree turns.. Vacuum source
: seems to be OK, as the AI is still working good, and the vacuum gauge reads
: normal. So I'm pretty sure this is isolated to the DG.

: It has the original DG. (Airitalia, I believe). The local shop quoted low
: 700's for a brand new Sigmatek. (No autopilot, flags, or lighting). That
: does not include labor.. I think the price is right - but is the brand OK?

When my AI died last summer, I had both the AI and DG overhauled
by Kelly Instruments in Kansas. They did a top-notch job, with new
bearings, painted face, calibration... both are now rock solid. Cost
something like $300 each.

From what I've heard (both directly from Kelley and indirectly
from newsgroups, etc) is that the RC-Allen gyros are a bit more
troublesome from a failure-rate perspective. I was even thinking that the
older stuff is probably built better than the newer stuff... thus the
decision to overhaul the old one.

Make *sure* when you do this that you put in a new filter, and
probably new vac hoses... no sense in cheaping out on $30 when you're
replacing a gyro for $300-$700.

FWIW
-Cory


--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

All great info, but I think that Spruce has new DG's for about $550.

If the DG currently in your plane is an older one (12+ years old), it
might pay for you to look into having it overhauled. The newer
generation of instruments seem to have a considerable amount of
internal plastic that actually warps after sitting in the everyday
summer heat. These newer ones are best served by trashing them, as
the gauge lasts about 18 months before another o/h is needed. Either
way, as normal, your wallet dictates your decision.



On Mon, 10 Nov 2003 16:47:00 +0000 (UTC),
wrote:

Ben Smith wrote:
: Hello -

: This weekend, I noticed that our DG is starting to fail.. The indicated
: heading sways off after making a couple 90 degree turns.. Vacuum source
: seems to be OK, as the AI is still working good, and the vacuum gauge reads
: normal. So I'm pretty sure this is isolated to the DG.

: It has the original DG. (Airitalia, I believe). The local shop quoted low
: 700's for a brand new Sigmatek. (No autopilot, flags, or lighting). That
: does not include labor.. I think the price is right - but is the brand OK?

When my AI died last summer, I had both the AI and DG overhauled
by Kelly Instruments in Kansas. They did a top-notch job, with new
bearings, painted face, calibration... both are now rock solid. Cost
something like $300 each.

From what I've heard (both directly from Kelley and indirectly
from newsgroups, etc) is that the RC-Allen gyros are a bit more
troublesome from a failure-rate perspective. I was even thinking that the
older stuff is probably built better than the newer stuff... thus the
decision to overhaul the old one.

Make *sure* when you do this that you put in a new filter, and
probably new vac hoses... no sense in cheaping out on $30 when you're
replacing a gyro for $300-$700.

FWIW
-Cory

Ben Smith wrote:
Hello -

This weekend, I noticed that our DG is starting to fail.. The indicated
heading sways off after making a couple 90 degree turns.. Vacuum source
seems to be OK, as the AI is still working good, and the vacuum gauge reads
normal. So I'm pretty sure this is isolated to the DG.

It has the original DG. (Airitalia, I believe). The local shop quoted low
700's for a brand new Sigmatek. (No autopilot, flags, or lighting). That
does not include labor.. I think the price is right - but is the brand OK?

Sigma Tek gyros are generally pretty good. We got one earlier this year
that must have been dropped or shipped improperly, since it precessed
almost as badly as the 30 year old gyro it replaced.

SigmaTek replaced the gyro with another new unit (because I insisted on
it) and that unit has been as rock solid as I've come to expect from a
SigmaTek (precession of about 5 degrees per HOUR).

Price of the gyro depends on what type of gyro it is (regular w/wo
heading bug, autopilot, and bootstrap). For a brief rundown of the
differences, read the article on my site. Click through:

Aviation-Articles-DG Upgrade: The SigmaTek Bootstrap Gyro

-Doug

--
--------------------
Doug Vetter, CFIMEIA

http://www.dvcfi.com
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