Failing KCS-55A gyro

[flyboy0681]

1 hour ago, Godfather said:

Do you have any data to back up that assertion?  That the 55 HSI was the main reason good pilots crashed?  Before you answer thing about the thousands of hours these things have navigated over the years...hell fedex has probably put 50k hours on them in the 208's (obviously a WAG on my part)

Ours is 32 years old and this was the first time the gyro unit was ever opened up and the second time the HSI was serviced.

[Jerry 5TJ]

Well, I worked in avionics engineering at Bendix King for a decade.  The fielded MTBF for the system is known, based on repair data from thousands of systems.  MTBF, as I recall, is on the order of hundreds of hours of run time.  The failure modes are likewise documented, and several are insidious if they occur in IMC. That information is the basis of my guess.  

Loss of attitude reference in IMC is demonstrable (in a sim) to be more than most of us can handle when it occurs slowly and with no annunciation.  Slow, unflagged loss of attitude accuracy is one of the system's failure modes. 

The KCS-55 is a fine system, state of the art of 40 years ago.  If you keep it, I recommend you overhaul the gyro elements on a regular schedule.  I'd suggest every 400 hours.  But that's only my opinion.  

 

 

[Godfather]

1 hour ago, Jerry 5TJ said:

Well, I worked in avionics engineering at Bendix King for a decade...

Slow, unflagged loss of attitude accuracy is one of the system's failure modes. 

I'd suggest every 400 hours.  But that's only my opinion.  

That's what I'm talking about!  You have a lot more experience seeing multiple (thousands) units come  into the service department and have a good idea of the mtbf.

I think almost everyone in this thread is talking about the HSI unit.  I've had the HSI fail on me once (very small sample size) but loss of attitude accuracy is not one of the failure modes that an HSI can display.

Everyone has an opinion but 400 hrs for a 102 & 525 rebuild sounds like a lot.  I was thinking more like 1500 hrs...

Now if you are talking about the attitude indicator (ki256 or ki258) I would agree that a failure could lead to loss of control / death for even good pilots if they were not paying attention.  This is why I have a lifesaver AI (7,500 hr mtbf) 4 inches to the right (same height) to keep things shiny side up!

[PTK]

16 hours ago, Jerry 5TJ said:

Well, I worked in avionics engineering at Bendix King for a decade.  The fielded MTBF for the system is known, based on repair data from thousands of systems.  MTBF, as I recall, is on the order of hundreds of hours of run time.  The failure modes are likewise documented, and several are insidious if they occur in IMC. That information is the basis of my guess.  

Loss of attitude reference in IMC is demonstrable (in a sim) to be more than most of us can handle when it occurs slowly and with no annunciation.  Slow, unflagged loss of attitude accuracy is one of the system's failure modes. 

The KCS-55 is a fine system, state of the art of 40 years ago.  If you keep it, I recommend you overhaul the gyro elements on a regular schedule.  I'd suggest every 400 hours.  But that's only my opinion.  

 

 

Thank you Jerry for your post.

This discussion pertains to the KCS55A. Essentially to the HSI and gyro. Excellent track record and ultra reliable. I looked back through my airplane's logs out of curiosity. Since the day it was born in Kerville there are three entries and all pertain to the AI. None to the KCS55A. One was a swap I believe, the other an  overhaul and one for pump repacement. The only entries pertaining to the KCS55A are mine! One for the gyro and the other for the HSI as I described in earlier post above. 

"Slow, unflagged loss of attitude accuracy..." pertains to the  vaccuum driven AI. This is why I made the suggestion to the op to focus his attention to the AI by considering, when the time comes, the KI300. Remove the vacuum system all together and have an all electric setup. 

Recognizing this is not for everybody. Merely a consideration of existing equipment with a serious and objective eye towards cost and reliability comparison when contemplating glass. 

 

 

[LANCECASPER]

The KCS55A System was the state of the art system for 30 years. I flew behind one in a Mooney 231, 2 Mooney Bravos and one Piper Mirage. I still have one in a Mooney TLS. I lost the AI two different times - once in VFR, once in IFR (very slow loss of attitude - thankfully I caught it and covered up the AI and hand flew it). I've lost a couple vacuum pumps in VFR also, but had standby pumps. 

After reading accident reports about people losing the only AI onboard, I think the only sensible way to stay with the KCS55A system today is to make sure you have a some type of standby attitude. There are  a lot of options - replace the electric turn coordinator with an electric AI with slip/skid. Replace the TC with a Sandia Quattro or L-3 Genesis. Even Foreflight or Garmin Pilot with AHRS. But to fly IFR with no attitude backup in the year 2016 seems foolish when there are so many options.

When you read about some accidents you come away thinking that they were put in circumstances that were just beyond their control. In this situation for $1000 - $5000 you at least give yourself a good chance of getting it on the ground safely.

[PTK]

22 hours ago, LANCECASPER said:

The KCS55A System was the state of the art system for 30 years. I flew behind one in a Mooney 231, 2 Mooney Bravos and one Piper Mirage. I still have one in a Mooney TLS. I lost the AI two different times - once in VFR, once in IFR (very slow loss of attitude - thankfully I caught it and covered up the AI and hand flew it). I've lost a couple vacuum pumps in VFR also, but had standby pumps. 

After reading accident reports about people losing the only AI onboard, I think the only sensible way to stay with the KCS55A system today is to make sure you have a some type of standby attitude. There are  a lot of options - replace the electric turn coordinator with an electric AI with slip/skid. Replace the TC with a Sandia Quattro or L-3 Genesis. Even Foreflight or Garmin Pilot with AHRS. But to fly IFR with no attitude backup in the year 2016 seems foolish when there are so many options.

When you read about some accidents you come away thinking that they were put in circumstances that were just beyond their control. In this situation for $1000 - $5000 you at least give yourself a good chance of getting it on the ground safely.

Wow! After flying behind the KCS55A compass system in four different airplanes you sure do seem majorly confused on the systems in your panel!

Although I agree with your AI comments, it is a separate system. The AI is vacuum driven and not part of the KCS55A. I was referring to the electric KCS55A and HSI.

https://www.bendixking.com/HWL/media/Pilot-Guides/006-08256-0004_4.pdf

http://mooneyspace.com/topic/5963-failing-kcs-55a-gyro/?do=findComment&comment=268978

This, folks, is a classic example of how people can jump on a bandwagon and rip things out of their panel blindly without fully appreciating and understanding what they're actually removing or installing! And pay lots of money for the privilege!

[LANCECASPER]

3 hours ago, PTK said:

Wow! After flying behind the KCS55A compass system in four different airplanes you sure do seem majorly confused on the systems in your panel!

Although I agree with your AI comments, it is a separate system. The AI is vacuum driven and not part of the KCS55A. I was referring to the electric KCS55A and HSI.

https://www.bendixking.com/HWL/media/Pilot-Guides/006-08256-0004_4.pdf

http://mooneyspace.com/topic/5963-failing-kcs-55a-gyro/?do=findComment&comment=268978

This, folks, is a classic example of how people can jump on the bandwagon and rip things out of their panel blindly without fully understanding what they're actually removing or installing! And pay lots of money for the privilege!

Wow! After living as many years as you've lived you sure do seem majorly confused on what builds good relationships between other human beings.

Yes, you are correct the compass related items are strictly what make up the KCS-55A system, however there has never been one installed to my knowledge without a King KI256 or 258, so I lumped it all together.  You are right, I am wrong, oh mighty one - I know that's what you were looking for and now you have it. Building people up and allowing them their dignity endears them to you and makes you feel good at the same time, a win-win.

Your constant nitpicking of others is what distances you from others on the forum. I  can only imagine what a joy you are for those close to you. 

[PTK]

On April 13, 2016 at 7:06 PM, LANCECASPER said:

Wow! After living as many years as you've lived you sure do seem majorly confused on what builds good relationships between other human beings.

Yes, you are correct the compass related items are strictly what make up the KCS-55A system, however there has never been one installed to my knowledge without a King KI256 or 258, so I lumped it all together.  You are right, I am wrong, oh mighty one - I know that's what you were looking for and now you have it. Building people up and allowing them their dignity endears them to you and makes you feel good at the same time, a win-win.

Your constant nitpicking of others is what distances you from others on the forum. I  can only imagine what a joy you are for those close to you. 

Let's try and focus. You can't just "lump it all together." Two different systems, powered differently.  That's the ingenuity and beauty in this setup. And soon you'll be able to improve upon it tremendously by removing the vacuum component, i.e. KI300. Retain the KCS55A if you so desire. This in contrast to all your eggs in one basket approach as posted earlier.

That's the point. 

On another note, it would be remiss of me if I didn't at least mention to you that ad hominem attacks are self-defeating. By resorting to such attacks you are admitting that you have lost your argument.

Nevertheless, I sincerely thank you for your opinions.

[Godfather]

The only recent installs w/o the ki256 would be the ones with the kap 140 rate based autopilots ... 2000 ish Cessna and Diamond.

However, I agree with PTK that the rest of the system is very durable. 

[LANCECASPER]

1 hour ago, Hyett6420 said:

FYI I spoke to Bendix at friedrichshafen (aero-expo) last week.  Had a long chat about HSIs and AIs .  You CAN buy a NEW hsi (same model as you existing) from bendix King and they have a lovely new glass AI.  

Price was approx 7k euros so about the same in dollars.  Gets you a NEW HSI for the price of two overhauled ones.  If the overhauled ones only have a one year warranty (which appears to be the norm) you get a new one for the price of two overhauled ones.  Seems like a good deal to me.  I think! . 

The new glass AI (KI-300) is not available yet and with their recent track record on getting things certified for General Aviation, no one is holding their breath.

At the current exchange rate 7000 euros for an HSI is 7856 US dollars. That's just the HSI and not the remote gyro (KG-102A), flux gate, slaving accessory - all potential failure points. That is throwing good money after bad. If this was 1980 that would be a reasonable option. Nearly 40 years later, there are better alternatives.

[LANCECASPER]

5 hours ago, Hyett6420 said:

If all I have to do is plug and play then I can do that myself and get the a and p to sign off.  EASA approval is expected by July on the KI300, so as an European, if my AI fails then I'll be ok   Regarding the HSI it is the unit in the instrument panel that fails the most, hence my comment.  

Regarding failure points there are thousands on the aircraft, where do you stop.  The servos that drive the flying parts are not duplicated, nor are the cables that send the signals etc  

Whenever I read posts one of the things that always springs to mind is that cost is a very big issue.  The fact that you can replace this and that to remove possible points of failure doesn't weigh well with the cost issue.  

King may have EASA approval by July, they just aren't committing to which July. 

[Marauder]

5 hours ago, LANCECASPER said: King may have EASA approval by July, they just aren't committing to which July. 

Ah ye of little faith.  

LOL, here is an announcement of the KSN 770. Look at the article date and look at when BK said it would be shipping:

http://www.planeandpilotmag.com/article/apex-edge-series-ksn-770/#.Vx4E2dT3arU

Now read the date when it was certified in this article:

http://www.flyingmag.com/avionics-gear/instrumentaccessories/bendixking-ksn-770-navigator-certified

At least they kept their promise on price.

[Awful_Charlie]

Interesting that they told you EASA approval in July - I went to them for a KI300 for installation in my N-reg in July and they told me there was no chance! Their recommendation was an overhauled KI256, and they got a bit uneasy when I asked for other alternatives, although they grudgingly acknowledged that an Aspen adapter would do the job

[Marauder]

1 hour ago, Marauder said: LOL, here is an announcement of the KSN 770. Look at the article date and look at when BK said it would be shipping:

http://www.planeandpilotmag.com/article/apex-edge-series-ksn-770/#.Vx4E2dT3arU

Now read the date when it was certified in this article:

http://www.flyingmag.com/avionics-gear/instrumentaccessories/bendixking-ksn-770-navigator-certified

At least they kept their promise on price.

Ah yes but...... The first article says they will be taking orders inthe fall, not shipping. . Also didn't say which fall. . Sorry just doing British government spin. . 

To give these guys a little break, Avidyne also took "orders" years before delivering as well.

[ZamF16]

OK, so here we go again.  After replacing the KG-102 in 2012, with an overhauled gyro, I now have a problem with the HSI not staying slaved.  It slaves to the correct heading at power-up , but then after a little maneuvering the heading wanders off.  If I deselect slave and reselect it, the heading corrects itself, but then wanders off again as soon as I start maneuvering.  Does this sound like the gyro again?

[jetdriven]

The KI-300 is vapor ware.  You can buy a Aspen Pro for 7k at avionics source. 

[PTK]

2 hours ago, ZamF16 said:

OK, so here we go again.  After replacing the KG-102 in 2012, with an overhauled gyro, I now have a problem with the HSI not staying slaved.  It slaves to the correct heading at power-up , but then after a little maneuvering the heading wanders off.  If I deselect slave and reselect it, the heading corrects itself, but then wanders off again as soon as I start maneuvering.  Does this sound like the gyro again?

Yes. Had same issue a few years ago. It was in the gyro. It cost me about 300$. Take it to a good avionics shop. May also want to speak with Bob Bramble, (913)680-4169. Very knowledgeable on King and honest gentleman.

 

[LANCECASPER]

3 hours ago, ZamF16 said:

OK, so here we go again.  After replacing the KG-102 in 2012, with an overhauled gyro, I now have a problem with the HSI not staying slaved.  It slaves to the correct heading at power-up , but then after a little maneuvering the heading wanders off.  If I deselect slave and reselect it, the heading corrects itself, but then wanders off again as soon as I start maneuvering.  Does this sound like the gyro again?

 

Jerry at Porter Strait in Tulsa is a good choice.

I asked them to do an "Inspect and Repair as Necessary" on the KG-102A Gyro. It needed one capacitor and the optical switch needed to be re-calibrated. It cost $320 plus shipping. If it had needed a complete overhaul it would have been $1595. 

[ZamF16]

6 hours ago, LANCECASPER said:

 

Jerry at Porter Strait in Tulsa is a good choice.

I asked them to do an "Inspect and Repair as Necessary" on the KG-102A Gyro. It needed one capacitor and the optical switch needed to be re-calibrated. It cost $320 plus shipping. If it had needed a complete overhaul it would have been $1595. 

Called Porter Strait this afternoon based on your previous post.  I am pulling the gyro and getting it in the mail to them.

[LANCECASPER]

It's very easy to remove - two minutes maybe. Undo the two screws that sit at the front of the unit (toward the front of the airplane), undo the connector in back and it comes right out.

[ZamF16]

Sent the KG-102 gyro to Porter Strait in Tulsa.  The main culprit of my problem was the optics out of calibration.  However, they found a lot wear on the gyro bearings, so it ended up needing a complete overhaul.  It lasted 4 years and about 400 hours.

I considered transitioning to a solid state option, but for the cost I am going forward with overhaul of my mechanical gyro.  I will consider an upgrade next time the gyro goes out.

[LANCECASPER]

How much for the overhaul?

[ZamF16]

It would have been about $300 if I could have gotten by with a recalibration, but the worn bearings will start to cause problems soon.  The cost for the overhaul is $1595.

Edited October 1, 2016 by ZamF16

[Tony Armour]

Another vote for Bob based on my experience with him. He was "THE" man at King for many years. I seriously doubt anyone knows more about them than Bob. My bill was (without checking) $450

 

 

[ZamF16]

Porter Strait did a fantastic job overhauling the KG-102.  In addition to completely overhauling and repainting the whole gyro, they added a shock indicator to the outside of it and the packaging in which they sent it.  The optics were out of calibration and the bearings showed significant wear, which they attributed to excessive vibration.  I am not sure where the vibration is coming from.   None is apparent in the cockpit, although it might feel completely different in the tail of the airplane.

It is reinstalled and working great.  Hopefully this one will last longer than 4 years and 400 hours.  

Edited October 9, 2016 by ZamF16