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Fastest M20F ever....


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I know we all like to wag our... tails... about highest airspeeds. This M20F managed to go 242KIAS (likely straight down, or close to it) and didn't come apart. 

Air transportation safety investigation report A21P0001 - Transportation Safety Board of Canada (bst-tsb.gc.ca)

Makes for interesting reading, and a good reminder on the importance of partial panel skills.

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1 hour ago, blaine beaven said:

I know we all like to wag our... tails... about highest airspeeds. This M20F managed to go 242KIAS (likely straight down, or close to it) and didn't come apart. 

Air transportation safety investigation report A21P0001 - Transportation Safety Board of Canada (bst-tsb.gc.ca)

Makes for interesting reading, and a good reminder on the importance of partial panel skills.

This was a terrifying read that I in know way expected to end well.  Happy to read that everyone including the plane is still flying. The only real positive I can take away from this Is to never stop trying and that airframe will withstand way more than you think. I would be interested in the G force information from the ADI..

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Interesting reading indeed. Yes, partial panel skills are often not given the importance they should have. And even people who are proficient in training and checks have fallen victim to spatial disorientation and not many of those lived to tell the tale.

Apart from the questions asked by the report, I am wondering what can cause 2 GI275 to fail in such a situation at the same time. I think many of us, myself included, tend to think of safety in numbers, so 2 independent EFIS should give redundancy they obviously do not.

So maybe not such a bad idea to keep that old vaccum horizon after all? I still have mine, thanks to the fact that my C needs vaccum to pump up the stairs... Would I have kept it otherwise? Not so sure. But I sure am glad i did after this report.

 

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43 minutes ago, mike_elliott said:

This plane needs to be checked for structural damage. Underwear was ruined for sure.

It was and returned to service per the report.
 

I cannot imagine the terror of multiple aerodynamic stalls in IMC while disoriented and watching the VSI wind around and off the scale.

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29 minutes ago, Shadrach said:

It was and returned to service per the report.
 

I cannot imagine the terror of multiple aerodynamic stalls in IMC while disoriented and watching the VSI wind around and off the scale.

I know I read that it was returned to service after inspected in accordance with Appendix G of Canadian Aviation Regulations Standard 625, for what thats worth. @M20Doc would have a better feel if it involves engineering structural analysis or a "well, that looks ok to me, even tho we now leak a bit from the tanks..." standard. These planes have a redline far below where this was operated at for reason, and this one wasnt made of a super aluminum others were not made of. S=P/A is not a dynamic formula, either the exceeded speed was wrong, the original never exceed speed was miscalculated, or physics are wrong, but something doesnt "compute"

 

 

 

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There is a good discussion of this on Beechtalk. Short version: The GI 275 has a lot of installation options. It can be a primsry ADI, an HSI, a MFD, a backup instrument, or an engine monitor. In this case, one was originally installed to replace the HSI. Later, a second was installed to replace the ADI. Normally, when two GI 275s are installed at the same time, they are set up so that the HSI can revert to an ADI if the primary ADI fails. Apparently, this was not done.

Garmin’s documentation often does not make all this level of detail clear to aircraft owner. Some details are only described in installation manuals which Garmin considers proprietary and prohibits their dealers from supplying to customers. There is a risk that you ask the shop to install something that has options and it doesn’t end up working exactly as you expected because you and the shop miscommunicated about some detail. In this case, the shop likely did exactly what was asked: Install a GI 275 as an ADI. The owner likely didn’t know that this would not give the reversionary capability.

Skip

 

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10 minutes ago, mike_elliott said:

I know I read that it was returned to service after inspected in accordance with Appendix G of Canadian Aviation Regulations Standard 625, for what thats worth. @M20Doc would have a better feel if it involves engineering structural analysis or a "well, that looks ok to me, even tho we now leak a bit from the tanks..." standard. These planes have a redline far below where this was operated at for reason, and this one wasnt made of a super aluminum others were not made of. S=P/A is not a dynamic formula, either the exceeded speed was wrong, the original never exceed speed was miscalculated, or physics are wrong, but something doesnt "compute"

 

 

 

Well @blueontop would be in a better position to discuss how Vne is determined. 
 

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That was indeed a scary story! Happy things turned out okay. I am scheduled to get 2 GI-275s installed in a month or so. What's concerning is AHRS alignment requirements mid-flight. In IMC, how is a pilot expected to maintain level flight and speed? My mental checklist says hit that AP ENG button if not already enabled. But for those that don't have one, or in-op, this is not a good situation. Do we know if AHRS alignment is needed often? "sensor fault within the AHRS that required the instrument to be realigned" - why? Defective unit? Poor quality?

 

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11 minutes ago, PT20J said:

Well @blueontop would be in a better position to discuss how Vne is determined. 
 

yea, Ron could drill down on the engineering. Clarence might be able to opine on what the  Apendix G of the Canadian Air regs spec for return to service

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32 minutes ago, mike_elliott said:

I know I read that it was returned to service after inspected in accordance with Appendix G of Canadian Aviation Regulations Standard 625, for what thats worth. @M20Doc would have a better feel if it involves engineering structural analysis or a "well, that looks ok to me, even tho we now leak a bit from the tanks..." standard. These planes have a redline far below where this was operated at for reason, and this one wasnt made of a super aluminum others were not made of. S=P/A is not a dynamic formula, either the exceeded speed was wrong, the original never exceed speed was miscalculated, or physics are wrong, but something doesnt "compute"

 

 

 

You are correct and I do not know the standard by which it was returned to service. I have read many times that the airframe was dived in excess of 300mph during flight testing. The speed is not so much the concern as the g loads and the rapidity with which I am sure they varied.

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I have a hard time believing the numbers that were reported.  Looking at the flight path in the report it pears to have been going down hill at 23000 rpm or 240 kts, pulls out the bottom to go up hill at 8500 rpm. And it didn’t pull the wings off?  I think the data from the failed unit is as reliable as the unit.

Strangely Garmin didn’t want to share any data.

The investigation attempted to determine more precisely the source of the initial fault. However, no supplemental information about the instrument, possible reasons it would require realignment while the aircraft was in flight, or analysis of the occurrence aircraft’s recorded fault logs were provided to the investigation by Garmin

Clarence

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48 minutes ago, whiskytango said:

Question: If the aircraft had a GFC-500 autopilot would the Level function operate without a functional ADI?

Not sure how the GI 275s work. The G3X Pilot's Guide says:

"In a GMC 507 installation, in the event of display failure(s), basic autopilot functionality remains as long as a ADAHRS unit is still available. The FD is no longer available, but LVL, AP, ALT, and YD ae available."

Skip

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1 hour ago, whiskytango said:

Question: If the aircraft had a GFC-500 autopilot would the Level function operate without a functional ADI?

I don’t know, but generally faults within the system cause a disconnect to force the pilot to recognize and fix the problem.  Especially with ahrs realign, I seriously doubt autopilot would work.  Now if the gi275s were properly configured and the second ahrs was ok, then it might, but no guarantees.  I fly a pa46t with g1000 and 2 ahrs.  Yeah it’s a different system, but if 1 ahrs fails, the autopilot disconnects and cannot be engaged until the fault is cleared up.

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The Transport Canada report is what happened, not why or what could have been.  The reason for the initial realignment of the ADI is unknown at this time. The reason for the HSI not being a backup is a configuration decision by the install shop and backup owner.  The reason for the HSI realignment is the AHRS sensor was set to the ADI, not a normal setting (known, but not in the report).  This could have been done by the shop, owner or pilot.   The big picture for Transport Canada was the ADI failed, and the pilot lost control of the airplane despite the required and working backup instruments.

I have spent a lot of time reading about this, speaking with others and feel very good about my dual GI-275 system consisting of Primary ADI + AP with ADAHRS and backup battery, Standby ADI/MFD with ADAHRS and backup battery.  These technological marvels may replace a vacuum driven AI and mechanical HSI but will do so much more.  If one of those fail, dealing with the failure is pretty straightforward.  If you have a G1000, G500/600/ G3X, GI-275, G5, EIS-500, Aspen XXX, Dynon Skyview: you absolutely must read and study the Pilot Guide and Flight Manual Supplement to understand how to use them when everything works.  It is life-or-death to understand what to do when something does not work.

Skip said something about documentation.  I have read the GI-275 Pilot Guide thoroughly.  Then I read thru the FMS.  Heck, there is stuff in there barely mentioned in the PG.  I have no doubt there are things in the installation manual that could be useful to know.  Look at the configuration,  you do have a copy of that, don't you?  What does each menu item do?  Etc.

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Reading this, I'm loving my steam gauges and new vacuum pump right now.  

The bit about workload increase when things go to hell and the pilot doesn't know what button to push because of lack of familiarity with the system, misunderstanding of the configuration, and/or unread "proprietary" documentation scares the bejeezees out of me.  With my steam gauge setup I just revert to training.  I don't push buttons, except to activate one of the two alternative AHRS sources on board, the AV-20 or the Stratus AHRS display on the iPad.

It seems that big G has a problem at least with that equipment and they don't want to let it be known.

I read complaints about "ancient" gyro technology and 2 lb vacuum pumps.  They don't require software or specialized understanding of configuration.

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8 minutes ago, 0TreeLemur said:

Reading this, I'm loving my steam gauges and new vacuum pump right now.  

The bit about workload increase when things go to hell and the pilot doesn't know what button to push because of lack of familiarity with the system, misunderstanding of the configuration, and/or unread "proprietary" documentation scares the bejeezus out of me.  With my steam gauge setup I just revert to training.  I don't push buttons, except to activate one of the two alternative AHRS sources on board, the AV-20 or the Stratus AHRS display on the iPad.

It seems that big G has a problem at least with that equipment and they don't want to let it be known.

I read complaints about "ancient" gyro technology and 2 lb vacuum pumps.  They don't require software or specialized understanding of configuration.

I'm in the steam gauge camp too.  I might replace my AI with a digital unit but that's it.  Even when I browse newer aircraft for sale, if I see all glass, I hit cancel and look for an older model with steam gauges on the pilots side.  I'm getting old; not interested in all the newer technology.  A nice engine monitor and a nice NAVCOM is enough for me.  

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43 minutes ago, M20Doc said:

I found this picture of the panel, it still had the standard 4 instruments.  Enough to maintain straight and level flight for an ATPL with 6000 hours.

Clarence

8844F0A2-38FF-4514-9A93-DDC799E3B9FE.jpeg

Whoa…he had T&B, alt, VSI, ASI and a whiskey compass? That should be enough for just about anyone to keep it right side up.

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2 hours ago, David Lloyd said:

The reason for the HSI realignment is the AHRS sensor was set to the ADI, not a normal setting (known, but not in the report).  This could have been done by the shop, owner or pilot.  

 

Spot on. If the two -275's didn't have independent AHRS, the second unit would have been rendered useless. My partners and I are now looking into a second GI 275 for the HSI and we are insisting that the unit have its own AHRS separate from the current ADI.

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I found this picture of the panel, it still had the standard 4 instruments.  Enough to maintain straight and level flight for an ATPL with 6000 hours.
Clarence
8844F0A2-38FF-4514-9A93-DDC799E3B9FE.thumb.jpeg.795e291555fecd7c4c3e4fb3196b118c.jpeg

That’s from the EBay listing, post incident, where it stated “no damage history” if I recall…


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