Dual vacuum failure in Ovation

[BorealOne]

So - what was supposed to be an uneventful trip over the mountains - Lethbridge (CYQL) with an anticipated IFR arrival into Abbotsford (CYXX) before continuing MVFR to Upper Valley Aviation in Chilliwack (CYCW) to get GJOG re-painted (pictures will follow) turned into a diversion to Springbank (CYBW) after losing vacuum in the climb over the Rockies.

Advertised tops were at 14, but I encountered higher cloud and obtained a block 16-18 to clear. While climbing in IMC through an icy stratus layer at 16, I the Hi/LO Vac indicator started flashing. Vac Indicator gauge showed zero. Ruh Roh!  I flipped the standby vac on, and the Hi/LO light went off, but the vac indicator remained pegged at zero. I disconnected the A/P and continued the climb, using my Aspen PFD as the horizon. 

Once on top, I troubleshooted and debated options for a good 10-15 minutes. The KI256 spun down as I continued to fly west above the deck. WIth the standby vac on, there was enough vacuum to move the command bars, but the horizon wouldn't move, and the vac gauge remained pegged at zero.

The Fraser Valley airfields from Vancouver to Abbotsford were all reporting a mix of IFR and MVFR with 500-1500' ceilings and 2-5 sm vis, but would require descent through stratus with potential embedded TCU between the rocks and down into the Fraser Valley. Everything enroute was also MVFR,and required similar arrivals through layers and between rocks. An hour behind me, Alberta was severe clear. I opted for Alberta. Hand flying descents through IMC into unfamiliar airspace without an A/P seemed a less fun option.

So GJOG is now on the ramp at Cavalier in Springbank. In the meantime, I have questions:

- I know that the standby vac (tail mounted electric standby, as per M20R FIKI configuration) was operational, as I test it during pre-flight. So why no vacuum? Clogged vac line is the only thing I can think of, but what would have caused that in flight? 

- my Aspen PFD isn't currently connected to the KFC150 autopilot as the AI source - it provides HSI/GNSS only. I've not found it completely reliable in my usual area of operation (north of 60º) as the software doesn't appear to deal well with loss of a reliable magnetic heading (things get weird near the poles) causing it to check-out from time to time, so I want to maintain redundancy. If I installed the EA100, there an option whereby you can flip between the KI256 and EA100 to drive the A/P, depending on which AI source the pilot deems most reliable?

Any suggestions?

Edited December 28, 2019 by BorealOne

[carusoam]

Glad things worked out so well, Boreal.

When you can... remove the pilot side panel of the tail cone... the vac pump and hose are right there...

Flip on the vac pump switch on the panel... the pump should operate.

The pump is an ordinary vacuum pump, attached to an electric motor. If no vacuum is generated... it is possible that the carbon blades have been broken.... typical vac pump failure...

So... the sound of the BU vac system operating doesn’t ensure vac actually being there... did your pre-start checklist include verifying... I got the vac actually being present?

Things to look for... what hose do you have back there? If it is a big clear PVC hose... look for an oily substance that fell out of solution with the PVC substrate... known to ruin vac pumps in other LBs... O1’s originally got a black vac hose....

Also Consider where the broken bits of blades may end up... it is possible, the other vac pump may try to draw stuff away from the back-up system...

Lots o people considering a second alternator lately...

Check on what powers your command bars... they are probably electric parts connected to the failed vac part of the instrument...(?)

Instrument shops can install complex switches... my panel has one for the HSI to AP... It selects either the GPS or Nav1 to supply guidance to the HSI... a similar switch can probably handle AI to AP...  

Interesting challenge considering the 60° latitude...(?)

PP thoughts only, not a mechanic...

Best regards,

-a-

[MIm20c]

I agree about the electric command bars. I thought the h/l vac warning remained on when the standby vac is operational. Not sure if that means a one way valve closes off the sensor and main vac pump or not. Did you test it on the ground after you landed?  Ours was incorrectly installed and the in/out was reversed at the factory. Important to check that vac works with the engine off. The gauge will read correctly with the backup system on. 

[ilovecornfields]

Maybe install a G5 and GAD29B and remove the vacuum system? Hopefully that will work at your latitude.

[LANCECASPER]

Dual vacuum pumps were a great idea in the 80's and 90's but the flaw is that if the instrument that runs on vacuum goes bad it doesn't matter how many pumps you have. From the mid 90's and on Electric Attitude Indicators with battery backups became increasingly reliable and available. It amazes me that when people are tearing out their panels and going all glass that they forget how relatively recent the G5 or likewise devices are.

Disclaimer: I have three Aspens and "legally" I don't need a backup, but I like having a Mid Continent Lifesaver Electric Attitude Indicator with Battery backup in my panel. It does not rely on vacuum or GPS aiding and will rely on its own battery if the ship's electrical system goes dark. It also is not an electronic MEMS sensor providing attitude backing up an EFIS panel with electronic MEMS sensors. It has a rated 7500 hours mean time between failure. I doubt that there are any G5s that have flown 7500 hours. Along with this instrument in my field of view, if I have a second altimeter or even a portable GPS with terrain or iPad talking to a portable AHRS I should be able to keep the wings level and get down safely. I already know that it's highly unlikely that I'll ever really need it, but all it takes is once.

Also field of view of view should not be discounted. The G1000 has backups but they are way over next to the circuit breakers on the right side. That would be a tough transition going from autopilot coupled flight to hand flying and scanning instruments way out of your field of view. If I owned a G1000 airplane I would go up with a safety pilot and cover the G1000 screens and practice that scenario regularly.

 

[FlyingScot]

23 hours ago, BorealOne said:

 

- I know that the standby vac (tail mounted electric standby, as per M20R FIKI configuration) was operational, as I test it during pre-flight. So why no vacuum? Clogged vac line is the only thing I can think of, but what would have caused that in flight? 

 

Any suggestions?

I had a standby vac failure not too long ago in my O2 for no apparent reason - until I found one - this is what carusoam is talking about:

 

After about 20 years the Tygon vac lines that Mooney used in the 2000s start to breakdown and release plasticizer into the line - this looks like a thin, clear oil, which of course fouls a dry vac pump - 

It's why I have an elec backup AI, and why I am going to install G5's.

Hope this helps - sure was a surprise to me.

Happy New Year to you and yours - Bob 

 

 

[Yetti]

If a vac line broke or fell off somewhere in the system, both pumps would not help anything work.

[BorealOne]

Thanks all - My O1 is of the same vintage so is likely suffering the same Tygon issue. Will investigate. 

Also agree strongly with LanceCasper re: need for a non-AHRIS based backup AI.

Is there an electric gyro equivalent of the KI256 (not the Ki300) that can drive a KFC150 with the same functionality?

Edited December 29, 2019 by BorealOne

[tmo]

29 minutes ago, BorealOne said:

Is there an electric gyro equivalent of the KI256 (not the Ki300) that can drive a KFC150 with the same functionality?

The KI-254 I believe, made by Castleberry Instruments for King, but it is both rare and 28V only, not sure what your Ovation is.  I recall there one being for sale around here recently.

[carusoam]

See if one is for sale around here...

I think I saw a KI254 recently...

Or somebody was already looking for one...

Best regards,

-a-

 

[ilovecornfields]

Not sure I understand the argument against AHRS-based backups but then there are lots of things I don’t understand so that’s fine. I guess there are always people who will favor older technology without a clear benefit.

I have an AHRS for the G500, another independent one on my trilogy esi-2000, another one on my flight stream 210, another one my Aera 696 and another one on my Sentry. Not having a vacuum system provides me the added benefit of being amused when The MSC Who Shall Not Be Named writes that they replaced the vacuum filters during the annual. 

[gsxrpilot]

On 12/28/2019 at 9:05 AM, BorealOne said:

If I installed the EA100, there an option whereby you can flip between the KI256 and EA100 to drive the A/P, depending on which AI source the pilot deems most reliable?

I'd install the EA100 and just have the KFC100 run off of the Aspen full time. You'll still need either a backup AI or a second Aspen which will act as the second AI. Solid state AHRS will be more reliable than vacuum driven spinning things.

I have an Aspen/EA100 and a G5 (backup). The Aspen drives the KFC100. I removed the standby vacuum pump out of the tail and the engine driven pump is only connected to my speed brakes. So I'm not dependent on vacuum for anything.

[aviatoreb]

57 minutes ago, gsxrpilot said:

I'd install the EA100 and just have the KFC100 run off of the Aspen full time. You'll still need either a backup AI or a second Aspen which will act as the second AI. Solid state AHRS will be more reliable than vacuum driven spinning things.

I have an Aspen/EA100 and a G5 (backup). The Aspen drives the KFC100. I removed the standby vacuum pump out of the tail and the engine driven pump is only connected to my speed brakes. So I'm not dependent on vacuum for anything.

KFC200?

[glenn reynolds]

I finally tossed in the towel on my vacuum system and removed the vacuum pump off the engine, removed the standby vacuum pump from the tail and had pacific coast avionics install a garmin g5 for $2,000 (US) installed.  Frankly that display gives me a multi hour built in battery back up, attitude indicator, airspeed, turn coordinator, vertical speed.  Dollar wise I have found this to be an excellent value for the money and the display is really good.  the unit was a slide in fit in the old vacuum driven attitude indicator hole.  And I also drive an ovation.

[Niko182]

32 minutes ago, glenn reynolds said:

I finally tossed in the towel on my vacuum system and removed the vacuum pump off the engine, removed the standby vacuum pump from the tail and had pacific coast avionics install a garmin g5 for $2,000 (US) installed.  Frankly that display gives me a multi hour built in battery back up, attitude indicator, airspeed, turn coordinator, vertical speed.  Dollar wise I have found this to be an excellent value for the money and the display is really good.  the unit was a slide in fit in the old vacuum driven attitude indicator hole.  And I also drive an ovation.

How much useful load did you gain? And did it change your cg?

[carusoam]

Glenn,

What do you have for an AP?

If...I want to follow your your lead..... My KAP150 will be looking for my BK AI for some signal... (i think)

Best regards,

-a-

[glenn reynolds]

Answering the questions (sort of) from carusoam and niko 182: yes there were pounds removed in removing the standby system, (vacuum pump, hoses, regulator, display, gauge, hose to rear of plane, electric standby vacuum and motor assembly) so Pacific Coast Avionics did a new weight and balance for the plane, but I'm sorry I don't remember how many pounds it was but it is a chunky unit with base plate, electric motor and of course the vacuum pump. 

As for carusoam's question this is trickier for me to respond to so I'll provide as much as I know:  The plane has a gns530 and gns 430, TKS and a g500 installed and uses a kfc 150 autopilot.   when shopping for maybe $ynthetic vi$ion and the g5 and a flight stream 210, some of the comments which got thrown my way included: "it is an electric instrument panel and you are REQUIRED to have a vacuum standby attitude indicator, we can't install a G5" from a local avionics shop.  Another item which came up was the TKS stc and redundancy requirements but I don't remember how that effected the options except that the plane has a standby alternator installed on an engine accessory pad already.  I got quotes from four avionics shops and two line items really stuck out: one was the price of upgrading the g500 to synthetic vision (g600) with a delta of almost four thousand dollars between the highest shop quote and pacific coast avionics.  The second was that when pacific coast avionics quoted the installed price for the g5 as less than the in the box price from aircraft spruce.  When I got into the details with pacific coast avionics, they explained that the intent of the requirement to have a back up attitude indicator (I believe this is part of the stc to install the g500, now g600 in the plane) is to have a second, INDEPENDENT attitude indicator which would operate in the event of a total electrical failure, so Pacific Coast Avionics explained that the G5 meets that requirement and they would confirm with the local FAA office to that effect.  two more items are rolling around my memory,  one was that during the install of the garmin flightstream 210, it was seen that with the autopilot, an existing stand alone garmin vor display and the g600, the flightstream needed to push to the gns 430 which is of course paired with the gns530 because all the ports on the gns530 were used (this then requires the extra step of moving flight plans from my ipad to the gns430 and then crossfilling to the gns530 vs direct ipad to gns530, oh well).  lesson observed is that only so many ports are available.   When all is said and done, I found that the G5 had been configured as both an attitude indicator (which is what I bought it for) but also with the soft keys it can then be switched to be a vor navigation display slaved off the gns (I don't remember which one it got slaved to, the gns 530 or the gns 430).  Pacific Coast Avionics explained that the G5 does both functions but is often sold as a "buy one of each" display!  Frankly I got way more for my money than I realized when I signed the install contract.  I credit the service manager at pacific coast avionics for chasing down the options and legalities as this got deeper in the weeds than I had expected.  I know this is a hard thread to follow as i'm not an avionics engineer but feel free to ask follow up questions.  While I felt confident that I couldn't just fly around with the vacuum attitude indicator inoperative (my wallet was sick of replacing pumps and indicators), and two grand was acceptable, It did seem like a lot of back up.... Then one day somewhere over the midwest the left screen of the g600 failed!   G5 worked perfectly.  Pacific coast Avionics put a replacement left screen in and life is good.  Carusoam, During a cross country flight I stopped for garmin service at vip avionics in hartford and they did an awesome job (pacific coast avionics arranged the warranty coverage so as this didn't cost me, I can't speak to their pricing).  hope this helps.  Glenn

[tmo]

Sounds like a big "thumbs up" for Pacific Coast Avionics.

[carusoam]

Great details Glenn!

Thanks for sharing them all.

Best regards,

-a-

[ArtVandelay]

On 12/29/2019 at 7:55 PM, Niko182 said:

How much useful load did you gain? And did it change your cg?

 

In my case it was close to 20lbs, electric backup was 12 alone, little change to CG since firewall is close to 0 arm, not like removing stuff from the tail.


Tom

 

[BorealOne]

On 12/29/2019 at 2:50 PM, ilovecornfields said:

Not sure I understand the argument against AHRS-based backups but then there are lots of things I don’t understand so that’s fine. I guess there are always people who will favor older technology without a clear benefit...

Thanks all for the insights and opinions on options.

Re: arguments against AHRS-based backups. I'm usually an enthusiastic adopter of the next shiny new things. However, real life experience with my Aspen PFD in my area of operation (Northern Canada) has made me very happy to have a spinning gyroscope that doesn't care where North is. Recall that compasses get wonky near the poles. In my experience, AHRS devices don't do any better. When magnetic signal degrades, my Aspen first shows an error message to "Cross-Check". Sometimes a few s-turns will get it back on-line, but in other cases it decides that it isn't getting good signal and displays the Big Red X. 

The older gyro-based AI technology doesn't care where North is, so until the AHRS providers can figure out a better way to deal with magnetic anomalies, I'm stuck with it as the best backup option.

[carusoam]

Boreal,

Any answer to what disabled your lost back up-vac system?

Best regards,

-a-

[ilovecornfields]

6 hours ago, BorealOne said:

Thanks all for the insights and opinions on options.

Re: arguments against AHRS-based backups. I'm usually an enthusiastic adopter of the next shiny new things. However, real life experience with my Aspen PFD in my area of operation (Northern Canada) has made me very happy to have a spinning gyroscope that doesn't care where North is. Recall that compasses get wonky near the poles. In my experience, AHRS devices don't do any better. When magnetic signal degrades, my Aspen first shows an error message to "Cross-Check". Sometimes a few s-turns will get it back on-line, but in other cases it decides that it isn't getting good signal and displays the Big Red X. 

The older gyro-based AI technology doesn't care where North is, so until the AHRS providers can figure out a better way to deal with magnetic anomalies, I'm stuck with it as the best backup option.

I had not heard of AHRS malfunctioning in Northern Canada. That’s unfortunate if it’s true for all AHRS. Is your Aspen the only one affected by this or do other people have this issue as well? Seems like all the G1000 planes would be affected. You could still have a king HSI and electric AI which would eliminate the vacuum system.

[Jerry 5TJ]

A magnetic sensor’s heading accuracy is degraded near the magnetic poles.
From G500 Pilot’s Guide:

 

 

[LANCECASPER]

14 hours ago, BorealOne said:

Thanks all for the insights and opinions on options.

Re: arguments against AHRS-based backups. I'm usually an enthusiastic adopter of the next shiny new things. However, real life experience with my Aspen PFD in my area of operation (Northern Canada) has made me very happy to have a spinning gyroscope that doesn't care where North is. Recall that compasses get wonky near the poles. In my experience, AHRS devices don't do any better. When magnetic signal degrades, my Aspen first shows an error message to "Cross-Check". Sometimes a few s-turns will get it back on-line, but in other cases it decides that it isn't getting good signal and displays the Big Red X. 

The older gyro-based AI technology doesn't care where North is, so until the AHRS providers can figure out a better way to deal with magnetic anomalies, I'm stuck with it as the best backup option.

Even though the Electronic AHRS backups look nice and "match" the glass panels, I'll hang on to my spinning Mid-Continent Lifesaver Electric AI with battery backup.

https://www.lifesavergyro.com/pdfs/Flier_4300Lifesaver_English.pdf