C210 wing spar failure in Aus : C177 inspection recommended as well

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Re: C210 wing spar failure in Aus

Unread post by Carel » Mon Jul 08, 2019 8:39 am

There were SID's for C210's to comply with a year or two ago that checked on the wing spar. Was this not for the same reason?
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Re: C210 wing spar failure in Aus

Unread post by spokes » Mon Jul 08, 2019 10:39 am

I'm not an engineer but where the crack starts a straight line( bottom of carry through) meets a straight line (diagonal section) with a corner not a curve. Shurely if that whole bottom section was curved this wouldn't happen?
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Re: C210 wing spar failure in Aus

Unread post by Ugly Duckling » Mon Jul 08, 2019 11:12 am

Difficult to know what is pre-crash crack leading to the failure and then impact damage.
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Re: C210 wing spar failure in Aus

Unread post by StressMerchant » Mon Jul 08, 2019 12:45 pm

The fatigue zone looks fairly clear, but what I don't see is a clear initiation defect. Often you can see a clear staring point coming from a gouge, or a poor quality holes, or something similar.
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Re: C210 wing spar failure in Aus

Unread post by Starship » Mon Jul 08, 2019 12:50 pm

Ugly Duckling wrote:
Mon Jul 08, 2019 11:12 am
Difficult to know what is pre-crash crack leading to the failure and then impact damage.
The wing departed from the aircraft before it crashed and was found 90m from the initial impact zone. I think it safe to say there was no impact damage to the spar.
VH-SUX Wing.jpg
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Re: C210 wing spar failure in Aus

Unread post by Ugly Duckling » Mon Jul 08, 2019 12:56 pm

Thanks, you are a Star :lol:
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Re: C210 wing spar failure in Aus

Unread post by Starship » Mon Jul 08, 2019 1:12 pm

StressMerchant wrote:
Mon Jul 08, 2019 12:45 pm
The fatigue zone looks fairly clear, but what I don't see is a clear initiation defect. Often you can see a clear staring point coming from a gouge, or a poor quality holes, or something similar.

Here is a highly detailed photo (5288 X 2844 pixels) of the cracked spar. The crack initiated 290mm inboard of right wing fuselage attachment lugs and coincident with a change in section thickness of the lower flange. The crack started on the underside of the flange and grew horizontally before penetrating the vertical part of the structure. (Photo Credits: ATSB)
VH SUX Spar Fatigue Crack.jpg
VH-SUX Diagram.png
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Re: C210 wing spar failure in Aus

Unread post by StressMerchant » Mon Jul 08, 2019 1:27 pm

It is an unusual place to start. Although it is a change in section, the change is fairly smooth. Would not have expected a major stress raiser to form.

They should be able to get an idea of the crack initiation and growth rate, I wonder if this is a manufacturing defect or later damage.
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Re: C210 wing spar failure in Aus

Unread post by heisan » Mon Jul 08, 2019 1:36 pm

StressMerchant wrote:
Mon Jul 08, 2019 1:27 pm
It is an unusual place to start. Although it is a change in section, the change is fairly smooth. Would not have expected a major stress raiser to form.

They should be able to get an idea of the crack initiation and growth rate, I wonder if this is a manufacturing defect or later damage.
Well, I only have one semester of metallurgy, and that was 25 years ago... The coarse structure of the fracture area looks like work hardened metal. Basically just fatigued until the metal was too brittle to hold, then cracked from the highest stress point.
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Re: C210 wing spar failure in Aus

Unread post by Starship » Mon Jul 08, 2019 3:03 pm

When these Cessna 100/200 series aircraft were built, Cessna expected them to have a life span of around 20 years. As things turned out many are now considerably older - in the case of the C210, the youngest is 33 years old, production having ceased in 1986. Thus corrosion has become a factor and the placement of the carry thru spar does not encourage regular inspection. Firstly the upper wing surfaces are riveted to the forward and aft spar flanges and beneath, it is hidden from view by the headliner, fuel pipes, electrical cables and flight control cables. The spars were originally installed without the benefit of any corrosion inhibitor and depending upon the location the aircraft is used, corrosion can become a very real problem. Thus any C210 used in a coastal environment (I'm thinking all those V5 registered C210s doing desolated diamond coast scenic tours) are particular prone to this problem. They also often fly with near maximum payloads of 700kg. An aircraft cabin is like a greenhouse and the spar sits up top where moisture accumulates. So in order to do a videoscope inspection the headliner has to come out and if corrosion is detected, the whole thing will probably have to be removed in order to inspect it properly. Removing the wings and carry-thru spar is about 120 hours of work and once removed there is nothing holding the front and rear of the aircraft together except the floor, so that needs to be properly supported.

As I mentioned in an earlier post these carry-thru spars are no longer available new from Textron. The last price I have from about two years ago was $27,485 (R390,000) in the USA.

A good used carry-thru spar that has been inspected, corrosion treated and epoxy coated such as this 1976 Cessna 177B Cardinal one with appropriate paperwork, will cost $3,950.00 (approximately R55,621).
Cardinal carry thru spar diagonal.jpg
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Re: C210 wing spar failure in Aus

Unread post by Starship » Tue Jul 09, 2019 10:53 am

Back in April 2010, you may recall a Cessna C210N V5-BAT came apart in the air north of Swakopmund. I have to ponder whether metal fatigue and a possible wing spar failure were not the cause? The Namibian CAA does not make public, accident reports and I have no idea if they are willing to send one on request. I did, however, find a news report from some ten months later wherein they state that a definitive cause could not be determined.
Namibian.1.png
Namibian.2.png
In the Avcom topic on the tragedy, a witness claimed to have seen the aircraft rolling. It was a third party report and it didn't state whether it was barrel rolling or a loop and I only state loop because the investigator suggested that the pilot may have pulled back hard on the control column as the speed dropped from 177 knots to 88. That sounded like rubbish to me. Now, what happens if a wing comes off? The aircraft rolls as is evident from this video taken in Argentina.

https://www.youtube.com/watch?v=JrVxp_gyTcI

In the case of V5-BAT would metal fatigue even have been considered? It was a 1982 model which would have made it 28 years old at the time. Those V5 registered C210s work in arduous conditions, where corrosion can be a very real problem.

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Re: C210 wing spar failure in Aus

Unread post by StressMerchant » Fri Jul 12, 2019 10:28 am

The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair.
- Douglas Adams
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Re: C210 wing spar failure in Aus

Unread post by Ugly Duckling » Fri Jul 12, 2019 10:39 am

StressMerchant wrote:
Fri Jul 12, 2019 10:28 am
Some more info.

https://www.casa.gov.au/files/awb-53-01 ... rough-spar
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Re: C210 wing spar failure in Aus : C177 inspection recommended as well

Unread post by Starship » Fri Jul 12, 2019 11:46 am

Cessna built 9,240 C210s of which it would appear 3,165 are still registered in the USA and countless others around the world. There are about 237 on the SA Register. Given that these spars could become a very real problem going forward, what are the chances that they will be put back into production?
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Re: C210 wing spar failure in Aus : C177 inspection recommended as well

Unread post by Christopher » Sat Jul 13, 2019 2:15 am

I do not know whether or not corrosion-proofing was available as an option on C210s; but it certainly <was> available on C310s. The pair of 310s operated by AOC at FAVG were both corrosion-proofed at the factory as an optional extra and I do remember that the wings were always seen as being in <perfect> condition by Comair engineering staff when in for maintenance (or Aero Engineering, previously, when that organization was still extant in the northern-most hanger at Virginia - next to Pikkie Rautenbach) These two aircraft (-FLL was one: I forget the other's reg. -- -FDK, perhaps?) operated over sea, at fairly low-level, on roughly six-hour whale-spotting duties, daily in the season, and consequently were very exposed to salty atmosphere. (They were both equipped, also, with wing-locker tanks). (Edit: second 310 was -FJK)

You would have thought that <all> aircraft should be so treated at the factory, wouldn't you?
Last edited by Christopher on Wed Jul 17, 2019 6:13 am, edited 1 time in total.
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