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Oops, darn it...

Had a certain Hawker/Powersafe battery STC holder tell me on Friday about internal shorts and thermal runaways with EarthX batteries. He knew of 5 cases and upon questioning said they all had B&C or Plane Power alternator systems properly wired. :crazyeyes: I would like to see the data.
 
So back in December I posted some pictures of a damaged AOSS that someone sent me and she swore the AOSS failed. Well I found the preliminary report yesterday and that doesn't seem to be what they concurred.
https://app.ntsb.gov/pdfgenerator/R...ID=20191216X53550&AKey=1&RType=Final&IType=LA

Interesting metallurgy report from the NTSB materials lab.
https://dms.ntsb.gov/public/63500-63999/63759/635271.pdf
Then there are the pictures from which I still conclude as I did the day I got 3 photos of the AOSS that it was failure to maintain directional control by the pilot that caused the accident.
https://dms.ntsb.gov/public/63500-63999/63759/635272.pdf
IMG_8108.JPEG


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Not buying it. Lithium iron battery with thermal runaway?! I need the real data on that, too. Especially if it smoked on recharge or while drawing power from it? No one questions a lead acid battery in their aircraft but I don't want that smoke or acid fumes inside either. And when a lead acid battery lets out smoke 99.9% it's due to lack of TLC or knowledge of wiring. I know of only two types/brands of batteries that have had meltdown issues. All the rest have been stories of 'a guy' or self induced.

Web
 
Years ago there was a Cherokee 140 with the back jump seat in Beverly Mass which had someone in the back seat. The seat sagged under the passenger shorting out the battery terminals. They made a hurried landing.
 
Steve Pierce said:
So back in December I posted some pictures of a damaged AOSS that someone sent me and she swore the AOSS failed. Well I found the preliminary report yesterday and that doesn't seem to be what they concurred.
https://app.ntsb.gov/pdfgenerator/R...ID=20191216X53550&AKey=1&RType=Final&IType=LA

Interesting metallurgy report from the NTSB materials lab.
https://dms.ntsb.gov/public/63500-63999/63759/635271.pdf
Then there are the pictures from which I still conclude as I did the day I got 3 photos of the AOSS that it was failure to maintain directional control by the pilot that caused the accident.
https://dms.ntsb.gov/public/63500-63999/63759/635272.pdf
View attachment 48776

View attachment 48777
Click to expand...

Thanks for the pictures. Definitely NOT AOSS issue there!


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Coarse potentially grabby runway surface with tar strips and grooves. Looks like at least 3" gear and 26" tires. Nobody ever looks at the tailwheel for bearing or washer/tension conformity and locking action/spring tension. They can shimmy if not angled right.

Gary
 
original wimpy gear & cabane?

never seen a front gear leg tube broke....... that would be my guess at the weld for the break line clamp....

seen many bent gear legs(rear tube common), but never a broken front one...
 
I know that Cub... Friend of mine rebuilt it after folding the gear under it... Stick came out of the torque tube during take off. Pulled off the power and hit on the nose and mains... pictures are on my website/gascolators page... He replaced the fuselage and had it on 31’s for a while with those AOSS shocks on 3 inch Atlee gear... His son took ownership after he passed and flew it for several years before selling to the current owner... too bad it got bent again..

Brian


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mike mcs repair said:
original wimpy gear & cabane?

never seen a front gear leg tube broke....... that would be my guess at the weld for the break line clamp....

seen many bent gear legs(rear tube common), but never a broken front one...
Click to expand...

976109b26f3831b710ecd47aa205099c.jpg

You mean like that?

Like Steve always said, you can break an anvil if you try hard enough


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It looked in the brief moment the anvil stuck it's horn into the earth, but did not break.

Humm, I wounder how much energy it would take to get my 300# anvil that high up.
 
mike mcs repair said:
But that one broke OFF front tube in the event...... cracked???




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Click to expand...

I'm curious about that too. I've seen welded structure sheared off or just plain torn off, but that missing section looks like it cracked and fell out. Poor welding? Poor heat treat? Flaw in the tube to begin with?

Web
 
When you push something sideways the direction it is not designed to go something gives. Looks like it broke the front tube where the step was clamped on.
IMG_8229.JPEG

And ripped the rear fitting out of the fuselage.
IMG_8228.JPEG
 

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Like Brian, I know this Cub, "Blue Bear" well. My girlfriend and I ferried it from West Texas to Maryland back in September for the owner, a personal friend (he is here on SC.ORG as "Bluebear"). Prior to that I flew along side him to STOL competitions and back country strips. The bird was nice and solid. Best handling Piper Super Cub I ever had the privileged to fly. The year model may have been 1954 but the only original parts were the dataplate, some wing parts and maybe the control sticks. It had an all-new Airframes Alaska fuselage, AOSS gear and the 160hp conversion and many upgrades. It had fresh radios and an EFIS. The AOSS was very nice and solid and could take a beating. And Gary, it had a new ABI 3200 tailwheel assembly installed two annuals back and was and maintained every 50 hours with a complete disassembly and had packed with ABI-specified red synthetic grease.

Dd1GZx9.jpg

As soon as I heard of this accident I knew the airplane well enough that it had to be pilot error. The ferry company's insurance carrier tried to state the problem was with corrosion and the age of the landing gear. I guess they missed the fact everything was new and was the improved AOSS. The insurance carrier sent a photo to the purchaser, who never saw his new airplane in person, stating it had corrosion. It was emailed to me and I looked at that one photo (hard to take everything into consideration with only one photo) and could tell there was zero corrosion and no evidence of fatigue cracking. It was a straight overload structural failure caused by over-stressing the structure. Even though I knew it wasn't the gear's fault it makes me feel good to see Steve Pierce had the same instant conclusion. And more so the NTSB laboratory. The stuff the insurance adjuster was calling corrosion was actually primer applied inside the tube. Again, more evidence of ignorance on the insurance companys' part. They were probably grasping for straws to get out of paying for the mess.

So let me get this straight. A 25 year old pilot with 4 hours in Super Cubs is sent out to fetch one (there is no mention of total tailwheel time) and at his first fuel stop he is nervous enough to decide to fly the pattern and do some touch and goes. Has anybody ever heard of a ferry pilot doing touch and goes enroute? Most seasoned types know it is best to get on down the road and only only land for fuel as necessary and minimize the liability exposure of more landings than necessary. Also, with respect to a new airplane or type I have always maintained that if you are not sure how things might go on landing you might as well wait until your first stop to try one. Especially single seaters with no opportunity for checkout (which does not apply here). You are already in the air flying might as well put some miles on it. Plus if you are going to crash something you ought to be as close to the house as possible and presumably each next stop is closer to your destination.

This whole episode is disheartening as that was such an incredibly nice Super Cub.

Here is a flight log of our delivery flight to Maryland last Sept...

https://eflyer.barnstormers.com/2019/606/featured-article/606-eFLYER-FA01.html

Jim
 

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This is the Cub after the wreck that I mentioned...
bb349e76fd56d8d840e519f2f5f0c5bb.jpg



Mike, the original owner that rebuilt it after that wreck spared no expense.. new fuselage (I actually have the bent one in storage) new landing gear, new spars in the wings. We overhauled that engine and then built him a new one after the oil cooler split open and he threw a rod through the crankcase... That gear failure was due to over stressing, no fault of the airplane at all..

Brian


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cubdriver2 said:
This type of clamp looks like a stress inducer?

Glenn
Click to expand...

Glenn. Not for the damage shown. The gear leg failed in buckling, so had add-on step been lower on the front gear tube it could have actually have helped to stabilize the tube. Not that the outcome would have been any better in this case. Basically the step turns the gear tube column is two shorter columns that each can take far more compression without buckling. Analogous to the action of this step would be the jury struts on the wing. Structurally the jury strut doesn't have to be very strong at all as long as it is there to stabilize the lift strut in compression making it into two stronger shorter sections. So jury struts are designed for durability and ground handling more than flight loads. But what they do with columnar stability is pure magic.

Now, if somebody thought a Super Cub was a Caterpillar tractor and over-tightened the U bolts on the step they could cause a deformation and an associated induced stress concentration. This may or may not have been a factor in the pictured damage as the buckling on the rear gear tube was right at the step mount which means it could have been destabilized by the U bolt. Then again it could have stabilized the step and made that point stronger, with same end result. Without the step the failure may have been at the longeron. Bottom line the loads were to high for anything to either cause or help the situation. Reading that I now feel like a political hack dancing around a definitive answer....
 
Looks like Airframes has addressed the "columnar" strength improvement:
 

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I “heard about” (no involvement by me) a Cub (-18, on 35’s, with a skilled pilot) that came home with that welded lower step , on the picture from BC -12D cracked off from one end. Dunno which end. He didn’t know where, when, or how it happened.

We all know those rear gear tubes flex some.
 
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Which accident did the bolt come out?

I was jacking with my PTT and had my stick in and out several times. Put it in along with the nut and bolt. Took off and going around the pattern I pulled it out. I hadn't gotten it far enough in for the bolt to go in the stub. Got it back down on the stub to land but I was pushing that sucker down the whole time. I double and triple check that thing now.
 
Steve Pierce said:
Which accident did the bolt come out?

I was jacking with my PTT and had my stick in and out several times. Put it in along with the nut and bolt. Took off and going around the pattern I pulled it out. I hadn't gotten it far enough in for the bolt to go in the stub. Got it back down on the stub to land but I was pushing that sucker down the whole time. I double and triple check that thing now.
Click to expand...

The one I posted..

That is almost exactly what happened to Mike except his stick was a bit weird in that it had a pie cutout 90 degrees to the bolt hole on a straight control stick.. He put it in with the cutout and did not have the bolt hole lined up...

Brian


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