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Author Topic: Gear Collapse Scenario  (Read 8766 times)

Tarver330

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Gear Collapse Scenario
« on: July 29, 2018, 07:43:50 pm »
What would cause a gear to fold up on 560 Commander?

Has anyone heard of 4 new bungees falling off?

Adam Frisch

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Re: Gear Collapse Scenario
« Reply #1 on: July 30, 2018, 12:07:02 pm »
It is possible scenario. If the brace hasn't locked over center, it can collapse.

The bungees are exchanged each year, normally. In my experience, they need it by then. I just exchanged all mine and that's after they were replaced about a year ago (but not flying much). On was even snapped, and often they can look good but have "structural" damage.
Slumming it in the turboprop world - so you don't have to.

Jfelipe.rojasr

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Re: Gear Collapse Scenario
« Reply #2 on: July 30, 2018, 01:18:22 pm »
Hi

I agree with Adam, Bungees is better to be changed during 150 hour inspection or annually whatever comes first. Since itís an elastic component is better to change it and never re use it from my point of view.

Regards

Tarver330

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Re: Gear Collapse Scenario
« Reply #3 on: July 31, 2018, 07:37:33 pm »
How critical are the bungees in preventing a gear collapse?  Critical I guess. Please call or text me at 863-899-1617 with any advice on this issue if you don't want to post.  My poor 560 is totaled because of the right gear folding up.  I'm pretty sad!

Adam Frisch

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Re: Gear Collapse Scenario
« Reply #4 on: July 31, 2018, 11:19:28 pm »
Very sad to hear that, Michael.

They're pretty critical. In fact, they're the only things that pulls the brace over center and locks them in the case of lost hydraulics. Without them being over center, or without hydraulics maintains the down lock pressure, they will collapse.

Did you have a hydraulic loss on your 560?
Slumming it in the turboprop world - so you don't have to.

Bruce Byerly

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Re: Gear Collapse Scenario
« Reply #5 on: August 01, 2018, 12:27:16 am »
In my experience, gear collapse is almost exclusively mis-rigging and poor or non-existent maintenance and why the gear needs to be looked at by a knowledgeable Commander mechanic. Bungees arenít holding the plane up.  Obviously they help pull it over center particularly important if in case of hydraulic pressure loss. Itís an extremely robust main gear compared to many planes (such as Twin Cessnas) but parts under load wear and thatís why there are scheduled gear inspections, clevis inspections, etc. Looking at many piston Commanders itís amazing to me how many show no evidence  of a real gear inspection in the last 20+ years yet still do their job. IIRC, itís 3,000 hours but No calendar limit in the 50ís/60ís maintenance manuals.  Given the 5 year interval on 690 series, I think it prudent to check the gear adjustments and look for cracks/corrosion every year. Itís just not happening out there.

As a practical pilot suggestion, I recommend a wipe down of the actuators and oleos every pre flight.  I use lemon pledge. Learned that from the most respected forestry operator. Works well and smells good.  :D If you see any drips off the actuators, itís time for immediate maintenance. If you let them get dirty and roll an O-ring, you lose pressure. Then you really need that nitrogen pressure and those bungees!
« Last Edit: August 01, 2018, 12:37:22 am by Bruce Byerly »

Dhavillandpilot

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Re: Gear Collapse Scenario
« Reply #6 on: August 01, 2018, 09:47:51 pm »
Not quiet correct the 685 manual states 3000 hours or 5 years. I've just done mine.

I got the LAME to pull them out and disassemble then re assemble after NDT. I did all the dirt work of de grease and paint strip and then re paint.

All we found after a tototal of 4000 hours was one cracked scissor link bolt.

But when doing it the one thing that doesn't come out easily had has to be replaced is the tapered AN386-1-16 tapered locator pins.

Bruce Byerly

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Re: Gear Collapse Scenario
« Reply #7 on: August 01, 2018, 11:30:35 pm »
Not quiet correct the 685 manual states 3000 hours or 5 years. I've just done mine.

I got the LAME to pull them out and disassemble then re assemble after NDT. I did all the dirt work of de grease and paint strip and then re paint.

All we found after a tototal of 4000 hours was one cracked scissor link bolt.

But when doing it the one thing that doesn't come out easily had has to be replaced is the tapered AN386-1-16 tapered locator pins.

Whatís not quite correct? I said the 50ís and 60ís 500 series not the 70ís 685.

Lose the scissor and you can quickly total your plane WITHOUT a gear collapse.

Tarver330

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Re: Gear Collapse Scenario
« Reply #8 on: August 03, 2018, 08:24:15 pm »
Very sad to hear that, Michael.

They're pretty critical. In fact, they're the only things that pulls the brace over center and locks them in the case of lost hydraulics. Without them being over center, or without hydraulics maintains the down lock pressure, they will collapse.

Did you have a hydraulic loss on your 560?

No hydraulic loss, just a collapsed right gear and no bungees despite a bill for 4 new ones....  I really can't wrap my head around it.  It's very sad.  I'm getting my MV prop rebuilt with new blades and it's painfully expensive. 

Adam Frisch

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Re: Gear Collapse Scenario
« Reply #9 on: August 04, 2018, 11:47:19 am »
Hmm, strange... You must have had a hydraulic actuator failure or a structural failure somewhere in gear train for it to collapse. I can't think of anything else.

I hope you can repair it and I feel your pain.  :-\
Slumming it in the turboprop world - so you don't have to.

SKYFLYER

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Re: Gear Collapse Scenario
« Reply #10 on: August 04, 2018, 02:55:52 pm »
Not sure I understand what happened... Did you take-off with all four (4) bungies missing???  You did not see or inspect them during pre-flight???

Bruce Byerly

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Re: Gear Collapse Scenario
« Reply #11 on: August 04, 2018, 08:30:58 pm »
Maybe this the planeís way of telling you it would rather commit suicide than be parted out in favor of a Widge?  ;D

Tarver330

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Re: Gear Collapse Scenario
« Reply #12 on: August 09, 2018, 06:13:32 pm »
No, the Bungees fell off on the last leg of this ferry journey.  They were there on the previous fuel stop.   I really like this airplane and had no idea how cool they were.  I get it now and wouldn't mind another one.  The issue with the 560 is the Hartzell MV props are more valuable than the entire airframe.  MT is rounding third base with SAE20 props so perhaps more of these will be brought back from the dead. 


Adam Frisch

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Re: Gear Collapse Scenario
« Reply #13 on: August 10, 2018, 02:11:02 pm »
Hartzell been running their little money-making scheme on all the oldest Commanders/Twin Bonanzas/Widgeons via the MV-hubs. My 520 had 250hr AD, which was insane.
Slumming it in the turboprop world - so you don't have to.

donv

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Re: Gear Collapse Scenario
« Reply #14 on: August 23, 2018, 01:17:59 am »
Interesting to hear all this about the bungees. Are they supposed to have a time or calendar life?

I have a spare one in my baggage, just in case.