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It Couldn't Happen---But It Did


donkaye

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16 minutes ago, jlunseth said:

I just had them installed. The first thing I need to do is figure out how everything works.:o

The problem with checking them though, is that batteries are never as good after say 5 years, as the day they were born. There is a requirement in the AFMS to test every 392 days and the procedure is described for the test, that probably helps. I just decided I am not ready to risk my life on the backup batteries in the 275s. I am keeping my vac AI backup just because I then don’t have a single point of failure. I ditched the old King Flight Director/AI and bought an inexpensive vac AI without the director. When the 275s first came out we had a poster on this site who had both 275s go to “red x” mode, something about the system that the two form that failed. Never heard what they figured out with that. Garmin became involved I believe. Could have been an install error, but then who here with more than a few hours has not had an install error cause some kind of problem. That’s why we have redundant systems.

I agree with that.  My g5 batteries are about 4 years old and still work well, but I will keep track by testing them iaw the instructions as well.

The vac system is good as a backup if you don’t mind keeping it.  I don’t likit as a primary since it can (more easily) roll over without notification, but it’s a good backup choice.

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On 11/11/2022 at 5:48 AM, jlunseth said:

When the 275s first came out we had a poster on this site who had both 275s go to “red x” mode, something about the system that the two form that failed. Never heard what they figured out with that.

Here you go -

Transport Safety Board of Canada report. Have a look at the pictorial flight path following loss of control at what must have been a terrifying ride. Glad it was a successful outcome and not a tragedy.

https://www.tsb.gc.ca/eng/rapports-reports/aviation/2021/A21P0001/A21P0001.html

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Oz- Thank you. So the problem apparently was that two 275s were installed but they were not installed in reversionary mode so the HSI could not act as a backup ADI and the pilot was not aware of that. I believe there is a way to “fail” the ADI to see if reversionary mode is working, I am going to test that in my installation next chance. Mine is supposed to be the reversionary installation and my avionics shop is really good, but “trust but verify” applies. The Report sort of implies that a reversionary switch needs to be installed for a reversionary installation. It does not. The HSI can simply be switched to ADI mode by using the controls on the unit.

Having read that report I applaud the occurrence pilot’s ability to get out of the situation, if it happens to me ever I hope I am that good. There is some chiding in the report about needing to stay current with partial panel skills. That is a good idea in general but the fact that the outcome is not smooth is not the result of rusty skills. Partial panel in IMC especially turbulent is not an ideal situation under the best of circumstances. There are some notes in the report to the effect that the 275 takes a little getting used to. I can attest to that, there is a need to practice to make sure the pilot does not misread what the instrument is saying simply because of lack of familiarity. Also, in my installation the GTN750 causes the 275 to switch to various headings during an approach and it is going to require flying a bunch to make sure I understand exactly what it is going to do. So far it appears to be seamless where GPS and ILS approaches are concerned, but not so much for VOR approaches.

All that said, I am keeping my vac AI.

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LAC in San Jose towed my plane to their hangar last Monday.  I got it back late Friday.  All issues seem to be resolved including my problem with the avionics master always being on, as of a few weeks ago.  The problems were probably inter-related. but I won't know exactly until I see the work order.  From verbally talking to them, it appears a strap became loose along with screws on some circuit breakers.  The issue is still very disconcerting, but probably shouldn't be, as the plane does only have a single bus.  Still, I am amazed that the whole electrical system can be taken out so easily.

This whole thing confirms the decision to put the Aera 760 on the yoke with its battery, and the GDL 52 on the glareshield with its battery.  With the G5, the Aera 760 and the GDL 52, I have Attitude, Navigation, ADS-B In with traffic and weather (although not Out), and SXM Weather.  I performed the G5 Battery test, and with a 3 year old battery it indicated over 7 hours available power.  At the time of my upgrade I was talked out of putting in a Comm antenna switch for a Handheld, since it would add a point of failure to Comm 2.  That's out the window in my mind, and I had LAC order the Kit to add it.  So, that would add extended range on the Handheld Comm I have.

If it was going to happen at some time, I'm glad it happened when it did--on the ground.  It called my attention to the possibility and gave clarity to the process I would need to follow to orderly transition to the backups I have and safely and comfortably land.

BTW, all databases updated properly after the fact.

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FWIW it pays to wiggle those wires and the bus bars going to the Circuit breakers, the aux bus with all the lights and fuel pump, and both master switches.  Further, pull and wiggle on all those high current connections at the starter, alternator, starter solenoid, and main solenoid. You’d be surprised how many we find loose and arcing. 

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On the M20J, there is a row of circuit breaker rocker switches at the bottom of the panel that are powered from the AUX Bus. There is a copper bus bar that connects the hot side of all the switches and it runs near the bottom tube that supports the panel. There isn't much clearance there. Also, the circuit breakers behind the angled panel have very little clearance from metal parts. It's good to take a look under the panel and into the circuit breaker area with the glare shield removed every once in a while. We took a lot of care making sure everything was tight and insulated when my panel was redone.

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22 hours ago, jlunseth said:

Oz- Thank you. So the problem apparently was that two 275s were installed but they were not installed in reversionary mode so the HSI could not act as a backup ADI and the pilot was not aware of that. I believe there is a way to “fail” the ADI to see if reversionary mode is working, I am going to test that in my installation next chance. Mine is supposed to be the reversionary installation and my avionics shop is really good, but “trust but verify” applies. The Report sort of implies that a reversionary switch needs to be installed for a reversionary installation. It does not. The HSI can simply be switched to ADI mode by using the controls on the unit.

Having read that report I applaud the occurrence pilot’s ability to get out of the situation, if it happens to me ever I hope I am that good. There is some chiding in the report about needing to stay current with partial panel skills. That is a good idea in general but the fact that the outcome is not smooth is not the result of rusty skills. Partial panel in IMC especially turbulent is not an ideal situation under the best of circumstances. There are some notes in the report to the effect that the 275 takes a little getting used to. I can attest to that, there is a need to practice to make sure the pilot does not misread what the instrument is saying simply because of lack of familiarity. Also, in my installation the GTN750 causes the 275 to switch to various headings during an approach and it is going to require flying a bunch to make sure I understand exactly what it is going to do. So far it appears to be seamless where GPS and ILS approaches are concerned, but not so much for VOR approaches.

All that said, I am keeping my vac AI.

The two 275s were installed months apart, the HSI first.  When the second ADI was installed, the HSI installation was not changed to be a standby ADI.  This meant the HSI would not and could not be changed by the pilot to display as a standby ADI, either automatically or by a reversionary switch (not installed).  The pilot flying did not know this.  Backup instruments were required but the pilot lost control of the airplane in the clouds. 

In this particular case, the HSI failed at the same time the ADI because the HSI's Air Data Source and the XXX (old man memory) Source were set to #1, the ADI's ADAHRS.

Installation setup was legal, not smart.

Some of the above came from the investigator, not necessarily in the report.

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23 hours ago, Mooney in Oz said:

Here you go -

Transport Safety Board of Canada report. Have a look at the pictorial flight path following loss of control at what must have been a terrifying ride. Glad it was a successful outcome and not a tragedy.

https://www.tsb.gc.ca/eng/rapports-reports/aviation/2021/A21P0001/A21P0001.html

This event was presented to us as a case study at the Mooney Summit in Sept.   This happened to a very experienced pilot.  Scary stuff.

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This GI275 case played out, then was described by the MSer, right after the fact….

Incredibly scary…

He is around here somewhere….  :)

Some of the best MSers have gained some incredibly horrible experience, and shared it with everyone…. So we don’t have to experience it ourselves….

As DK is doing here…   :)

Best regards,

-a-

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3 hours ago, 0TreeLemur said:

This event was presented to us as a case study at the Mooney Summit in Sept.   This happened to a very experienced pilot.  Scary stuff.

As a last resort, if you have lost all attitude information and all backups to attitude information in IMC, the magnetic compass would be your only salvation, and a very poor one at that.  It might be good to do a little training with it.  No heading change > level flight.  As an ATP, I'm surprised he didn't try that.  He would only have had to do it for a couple of minutes to let the GI275 realign.  If the airplane had been trimmed for hands off, a light touch on the controls would have maintained altitude.

Here's a question: Assuming no power changes, what headings would be best to fly in such a circumstance and why?  Also, why did I make that assumption?

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My instrument CFI suggested that if you ever had a dual electric and vacuum failure in the clouds, assuming you were trimmed hands-off prior to that, to take your hands off the controls, reduce power for descent, adjust airspeed with the trim wheel only (some nose up will be required once it settles into the descent), and hold your compass heading +/- 10 degrees with light pressure on the rudders.  Then ignore what your senses are telling you and hope you have enough room to maneuver when you come out of the clouds.

The idea is that a properly rigged, certified aircraft is stable in flight.  It will settle at a speed within the green arc and descend more or less wings-level.  It will not stall itself even at max nose up trim, nor roll over inverted.  A disoriented pilot yanking on the controls without instruments is more dangerous than an uncontrolled aircraft.  It should exit IMC in a controllable attitude and airspeed and enable you to regain visual navigation.

We demonstrated this a few times in VMC.  It does appear to work, at least in smooth air.  The plane will wander and hunt a bit, both in pitch and roll, but descend in a stable fashion on a heading.  It works less well with an iPad or other device mounted on the yoke, which is part of the reason I no longer fly with anything mounted there.

This was before battery-powered backup devices like the G5 existed.  They are probably a far better plan.  But I've always considered the above to be a final option.  I suppose it would be harder now that we no longer have a separate altimeter or VSI in the panel.

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3 hours ago, bluehighwayflyer said:

The Aera must be hard-mounted perpendicular to the flight path for it’s “3D Vision” AHRS to work properly. This obviously isn’t the case with it mounted on the yoke. If I remember correctly you ran into this same issue several years ago prior to getting your 760 when you had your mechanic mount your GDL 52 on a suction cup on your copilot side rear window parallel to the direction of flight. The Aera is no different. You might be able to bypass the Aera’s AHRS, though, in the yoke-mounted configuration you suggest and instead rely on the GDL 52’s AHRS, assuming it is hard-mounted perpendicular to the flight path on your glare shield, but I wouldn’t recommend even that as a serious attitude reference backup.  My experience has been that it is unreliable.  It would certainly be better than relying on the compass, though.  
 

 

The Aera 760 would be used for Navigation only.  As I mentioned, the G5 battery backup provides Attitude.

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7 hours ago, donkaye said:

Here's a question: Assuming no power changes, what headings would be best to fly in such a circumstance and why?  Also, why did I make that assumption?

Ah, old school! No power changes implies no acceleration or deceleration compass errors on easterly or westerly headings, so those headings would be best. Worst choice would be northerly or southerly headings due to lead/lag caused by northerly turning error which is worse the farther north you are.

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13 minutes ago, bluehighwayflyer said:

Yes. Copy. I see what you meant now.  That’s a hell of a lot of backup capability.  I guess the G5’s limited  back up battery capacity is the weakest link, but knowing that you can plan and take action accordingly.  Amazing technology.  

In doing the battery test this week, it showed over 7 hours of battery capacity.  Garmin says 4 hours, but that's what it said.

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6 hours ago, Z W said:

My instrument CFI suggested that if you ever had a dual electric and vacuum failure in the clouds, assuming you were trimmed hands-off prior to that, to take your hands off the controls, reduce power for descent, adjust airspeed with the trim wheel only (some nose up will be required once it settles into the descent), and hold your compass heading +/- 10 degrees with light pressure on the rudders.  Then ignore what your senses are telling you and hope you have enough room to maneuver when you come out of the clouds.

The idea is that a properly rigged, certified aircraft is stable in flight.  It will settle at a speed within the green arc and descend more or less wings-level.  It will not stall itself even at max nose up trim, nor roll over inverted.  A disoriented pilot yanking on the controls without instruments is more dangerous than an uncontrolled aircraft.  It should exit IMC in a controllable attitude and airspeed and enable you to regain visual navigation.

We demonstrated this a few times in VMC.  It does appear to work, at least in smooth air.  The plane will wander and hunt a bit, both in pitch and roll, but descend in a stable fashion on a heading.  It works less well with an iPad or other device mounted on the yoke, which is part of the reason I no longer fly with anything mounted there.

This was before battery-powered backup devices like the G5 existed.  They are probably a far better plan.  But I've always considered the above to be a final option.  I suppose it would be harder now that we no longer have a separate altimeter or VSI in the panel.

I've heard this as well and my recollection was that trim full nose up with the flaps down, which is the maximum stability condition.   I've not tried it in my airplane, but it's something I have been wanting to try.   It does seem like it'd be better to try it once or twice to know what to expect.

I've also heard that in the old days (like, biplane stuff), one tactic was to put it in a spin and hold it, which is a stable condition in many old airplanes, and then recover once out of the clouds.    That's not an option in a Mooney, but does seem a lot better than flopping around and potentially overstressing the airplane.

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1 hour ago, EricJ said:

I've heard this as well and my recollection was that trim full nose up with the flaps down, which is the maximum stability condition.   

Part of my training was to avoid major configuration changes made blind.  Dropping the gear and/or flaps would seem like a good plan, especially to keep you from overspeeding the aircraft, but it's hard to imagine a faster way to disorient yourself and maybe put the plane into an unusual attitude.  It might take a lot of discipline not to grab the controls while the plane settles into a descent after doing all that, even though I think it should eventually.  Maybe I should go try it that way under the hood sometime and see.

I also heard that when spins were a mandatory part of the curriculum, they were taught as a method to descend through a cloud layer in a stable maneuver.  Initiate and establish the spin above the deck, recover below it.  Probably part of why they killed so many pilots in training.  Definitely not a Mooney option.

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On 11/15/2022 at 10:36 AM, EricJ said:

I've heard this as well and my recollection was that trim full nose up with the flaps down, which is the maximum stability condition.   I've not tried it in my airplane, but it's something I have been wanting to try.   It does seem like it'd be better to try it once or twice to know what to expect.

I've also heard that in the old days (like, biplane stuff), one tactic was to put it in a spin and hold it, which is a stable condition in many old airplanes, and then recover once out of the clouds.    That's not an option in a Mooney, but does seem a lot better than flopping around and potentially overstressing the airplane.

Not sure about the full nose up trim since in my J that’s quite a bit more nose up than a normal full flap approach. Also, I don’t think flaps have much effect on stability and stability generally decreases with airspeed due to increased tendency of the controls to float under lower dynamic pressure.

But, the general technique is sound. Trimmed for lowest possible airspeed makes a crash more survivable. I might leave the flaps up for a higher nose attitude. Hands off the controls and keeping the ball centered with rudders will prevent entering a spiral. 

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Fuel imbalance always made me wonder about…

What happens in the clouds without an AI….

My M20C would be quick to roll towards the heavy wing… fuel status drives this…

The LB has rudder trim to lift the heavy wing…

Staying trimmed certainly helps…

Best regards,

-a-

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