Directional Gyro on M20K 231

[Aspen2013]

I have the Century 41 A/P with Garmin 430W and DG (Mitchell/century style). The DG stopped responding to any turn about 1 month ago and then it started working again. Today it stopped turning and about 10 minutes into the flight it started working however it would not stay on the correct magnetic heading. The HDG bug would cause the aircraft to turn in response to the selection but would not hold heading as DG sometimes did not give correct heading. The NAV mode would not fly any direct to waypoint or hold on a track. It would fly RNAV approach with correct glideslope but unable to stay on FAC.  I believe the DG may be failing. The Vacuum hoses appear in good shape and are not leaking at the attachment end to the DG not sure about up higher next to glare shield. The VAC light does not come on unless the engine is shutting down. The AI appears to respond normally but appears to erect slower on the ground at idle settings but nothing significant. Any ideas or others

with similar experiences before I replace DG? Thanks

 

 

Edited June 14, 2020 by Aspen2013
add info

[carusoam]

It isn’t going to fix itself...

So...

What does your vac gauge say? (In case there is a drive problem)
How old is the DG?  Years and hours  (It could be worn out)

What do you want to do next?   (The future is coming)

Replace with the same?   (Buy time)

Get OH’d   (Spend a lot of dough)

Replace with something modern?   (Spend more dough and get something better at the same time)

We have a guy...

PP thoughts only...

Best regards,

-a-

[Aspen2013]

No VAC gauge just light. VAC pump 340 hrs. DG who knows maybe 1979 version?

Buy Time - Found one on eBay for $250.00  LASAR $562.00. 

 

Ultimately It needs Two Garmin G5 units (AI and DG/HSI) with adapter to connect to Century 41. One quote for $15,000

Edited June 14, 2020 by Aspen2013
add info

[carusoam]

Assume the one on eBay is no better than the one you have...

Lasar can tell you honestly about the quality of what they are selling...  (yellow tagged Or is that a new price?)

2k hrs on instruments is pretty good... bearings wear out.... OH is the next typical step...

@Alan Fox has used instruments... can test them so you know they are working... (May have better options to meet your needs)

Is the DG being used for the AP at all? (Adds to the cost)

Best regards,

-a-
 

 

 

[Aspen2013]

Yes the DG is used by the autopilot. Thanks for the info on where to get used instruments. 

LASAR is not new. Maybe yellow tagged but it was $1062 and they marked it down to $562

[N231BN]

When was your instrument filter last replaced? I have the exact setup in my 231, 15k is a lot for 2 G5s. Perhaps they were quoting you the GI-275? A G5 ADI will not run your autopilot.

 

$562 for a tagged unit is pretty good. I replaced mine with one that had sat on a shelf for who knows how long and it has worked fine for 5 years now.

 

 

[Aspen2013]

Filter replaced in April 2020 at annual. 

G5 AI = $2299

G5 HSI with GPS interface = $3125

GAD 29B adapter = $  699.99   Century 41 autopilot is on the list of approved legacy autopilots

  $6123 for units

 

Labor  = close to $9000 

 

Edited June 15, 2020 by Aspen2013
edit

[N231BN]

Filter replaced in April 2020 at annual. 
G5 AI = $2299
G5 HSI with GPS interface = $3125
GAD 29B autopilot adapter = $  ???   Century 41 autopilot is on the list of approved legacy autopilots
Labor  ??
 

It will only provide heading and course inputs from the HSI, the G5 cannot replace the attitude indicator.

[N231BN]

Filter replaced in April 2020 at annual. 
G5 AI = $2299
G5 HSI with GPS interface = $3125
GAD 29B autopilot adapter = $  ???   Century 41 autopilot is on the list of approved legacy autopilots
Labor  ??
 

Also, $3125 for the HSI includes the GAD-29B so they are basically charging you 10k in labor.

I have decided to save up for the GI-275, it is a little more money but is a higher-quality product. It will also replace both Gyros and provide a Flight Director for the C41.

[ArtVandelay]

Filter replaced in April 2020 at annual. 
G5 AI = $2299
G5 HSI with GPS interface = $3125
GAD 29B autopilot adapter = $  ???   Century 41 autopilot is on the list of approved legacy autopilots
Labor  ??
 

There should be a GMU 11 in there somewhere. Rule of thumb is labor = 50% of hardware costs. So you’re looking at $6k of hardware, means $9k is what I would expect.
Removing and reinstalling interior is probably 4-6 hours of labor, plus another 4-6 to remove old equipment, so they can literally spend a full day before the tech can actually do the work necessary to install it.

[N231BN]

There should be a GMU 11 in there somewhere. Rule of thumb is labor = 50% of hardware costs. So you’re looking at $6k of hardware, means $9k is what I would expect.
Removing and reinstalling interior is probably 4-6 hours of labor, plus another 4-6 to remove old equipment, so they can literally spend a full day before the tech can actually do the work necessary to install it.

The GMU11 should also be included for $3125.

[Aspen2013]

Thanks for that info. I will look more at the GI-275. 

[Aspen2013]

I just researched the GI-275. So what you are telling me is in order to truly remove the vacuum pump and AI and DG you cannot do that with G5's?

 

I see the GI-275 says it will provide precise attitude information to select autopilots. 

AI = $3995

HSI = $4295

And that's all the cost for the units?

[N231BN]

I just researched the GI-275. So what you are telling me is in order to truly remove the vacuum pump and AI and DG you cannot do that with G5's?
 
I see the GI-275 says it will provide precise attitude information to select autopilots. 
AI = $3995
HSI = $4295
And that's all the cost for the units?

That is correct. Also, the price for the ADI with autopilot is an additional 1k.