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C210 Carry-Thru Spar.
Has anyone got a recent quote on one of the C210 Carry-Thru Spars?
Last I recall was around $130,000 - $140,000 (USD) and not sure if that was landed. That is on today's exchange rate $185,000 to $199,000 Australian $'s (+GST) I would be looking at around $30,000 to replace one. I would also look at 2 pack painting the current ones, and a big tin of LPS3 for where you could not paint & increased inspections. |
Where were you sourcing the carry through spars?
Cessna may restart production of upgraded CT spars in light of the large numbers of these aircraft that are still flying. That would be a very expensive option versus a unit fabricated under an EO of some sort. Target aircraft could include those on long term survey, aircraft with modified wing tanks or STOL STCs, or aircraft that have not kept up with SIDS |
Deviating slightly but in the same matter.
A design fatigue life is calculated on a perceived typical cycle. I have no exact figures to hand so I am generalising. The manufacturer may suggest the finite life is based upon a typical we'll say 45 min flight at say 7,000 feet. That's Ok, we know where we stand in regards to the finite life of our aircraft. Issues that may complicate the matter are for example, fitting long range fuel tanks to the wing tips of a C210. The wingspan is increased and the bending moment changes; hopefully the STC holder has examined all possible scenario's to ensure on-going airframe safety. But that particular STC is no longer worth the paper it's written on if you then add say a V.G (vortex generator) kit to said aircraft. Result differing loads on wing, not assessed by the fuel tank STC holder. Then go and add a STOL modification?, and the two previous STC's are no longer worth the paper they are written on. The C210 was never designed to fly low level survey work, regardless of tail boom or not. Airframe loadings are significantly higher at low altitudes. Complicating the issue in the C210 (strutless) is the very low Vma at Max weight, and even much lower at a weight such as one pilot and nil baggage and minimum fuel. The C210 must be handled carefully at all design weight/speed limits. When you add more than one (1) STC to cover an aerodynamic modification you are in effect a test pilot every time you fly the aircraft. Flutter testing may have been conducted for a fuel tank mod, but all three. No way! Be careful folks, the aging aircraft issue is a major on-going problem. |
Originally Posted by Led Zeppelin
(Post 10518157)
Where were you sourcing the carry through spars?
Cessna may restart production of upgraded CT spars in light of the large numbers of these aircraft that are still flying. That would be a very expensive option versus a unit fabricated under an EO of some sort. Target aircraft could include those on long term survey, aircraft with modified wing tanks or STOL STCs, or aircraft that have not kept up with SIDS * Cessna may restart production of upgraded CT spars in light of the large numbers of these aircraft that are still flying. - Cessna a long time ago changed their like on strut-less singles. * That would be a very expensive option versus a unit fabricated under an EO of some sort. - Big balls on a low volume EO replacement. Try buy a stall warning vane/switch - and they are on many aircraft. If I previously did a component like a Carry Thru on a EO, I would reconsider lots about now but I doubt any have been made. |
Originally Posted by Office Update
(Post 10518227)
Deviating slightly but in the same matter.
A design fatigue life is calculated on a perceived typical cycle. I have no exact figures to hand so I am generalising. The manufacturer may suggest the finite life is based upon a typical we'll say 45 min flight at say 7,000 feet. That's Ok, we know where we stand in regards to the finite life of our aircraft. Issues that may complicate the matter are for example, fitting long range fuel tanks to the wing tips of a C210. The wingspan is increased and the bending moment changes; hopefully the STC holder has examined all possible scenario's to ensure on-going airframe safety. But that particular STC is no longer worth the paper it's written on if you then add say a V.G (vortex generator) kit to said aircraft. Result differing loads on wing, not assessed by the fuel tank STC holder. Then go and add a STOL modification?, and the two previous STC's are no longer worth the paper they are written on. The C210 was never designed to fly low level survey work, regardless of tail boom or not. Airframe loadings are significantly higher at low altitudes. Complicating the issue in the C210 (strutless) is the very low Vma at Max weight, and even much lower at a weight such as one pilot and nil baggage and minimum fuel. The C210 must be handled carefully at all design weight/speed limits. When you add more than one (1) STC to cover an aerodynamic modification you are in effect a test pilot every time you fly the aircraft. Flutter testing may have been conducted for a fuel tank mod, but all three. No way! Be careful folks, the aging aircraft issue is a major on-going problem. I personally have worked on many C210's in a number of countries that have done low level survey and they age very well. Some countries require X-ray of aircraft after they get "x" years old - but not here in Australia. |
I'd be interested to know how many carry through spars are in need of replacement.
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Management at Cessna these days aren’t interested in Cessna single engine anything (Caravan included) and haven’t been for decades. I wouldn’t hold your breath waiting for Cessna to start cranking out spar carry thru’s after having effectively abandoned the 210 years ago when they destroyed the tooling. If memory serves, one of the reasons they gave at the time for not puting the 210 back into production was that the spar carry thru (amongst other things) did not meet the current certification requirements. It was suggested from an engineering point of view, Cessna couldn’t make it happen. You would’ve thought for a manufacturer to be able to design, certify and then put into production an aircraft like the Citation X, coming up with a solution for the 210 spar carry thru would’ve been relatively easy. Evidently not. Cessna haven’t put any REAL investment into their S/E line up for nearly four decades and aren’t going to start now. They’d be more than happy to let the 210 fleet whither on the vine. Time to start visiting the salvage yards. |
A new carry through isn’t going to be able to be done as an EO either. Machining out of billet is not the same as a forging. You would need an engineer much smarter than me to come up with a solution. Even doing it in steel while perhaps massively stronger and fatigue proof may have unforeseen aeroelastic effects. But i’ll leave the rest to professionals ‘cos I don’t know. |
Time to put some struts back on the old 210 :p |
The ATSB stated that the corrosion pitting caused a crack to quickly develop. It would be interesting to know what the estimates of "quickly" are. 10 flights, 100 flights etc. The carry through mustn't be very damage tolerant though this appears a one off. The break seemed to occur in the radius where the chord starts to thicken.
For a modification, what about a carbon, Kevlar or boron doubler adhered to the lower cap to strengthen it instead of metal. |
Originally Posted by clark y
(Post 10518742)
The ATSB stated that the corrosion pitting caused a crack to quickly develop. It would be interesting to know what the estimates of "quickly" are. 10 flights, 100 flights etc. The carry through mustn't be very damage tolerant though this appears a one off. The break seemed to occur in the radius where the chord starts to thicken.
For a modification, what about a carbon, Kevlar or boron doubler adhered to the lower cap to strengthen it instead of metal. Strength does not seem the issue, several aircraft have over-stressed the wings and the Carry-Thru is not the failure area. |
If the cost of replacement is around $200,000, I'd be exploring all avenues including bonded repairs. It is not the typical solution for a 30 year old strutless Cessna but the design, materials and installation methods are available. Bonding patches to metallics in the aerospace industry is not new, just technical and expensive. Bit of trivia, even the Westgate bridge in Melbourne has tonnes of carbon fibre adhered to the concrete (not steel) structure to toughen it up. . |
Clark, I think you might find that the testing required to certify a boron or carbon patch to an existing crack might be a trifle pricey. There is also the question of changing the loading distribution in the forging that could cause cracking elsewhere or even ending up with a structure “too rigid” that ends up over stressing the wing attachment points on the wing spar. However, I am at least 20 years behind the times and I defer to real Aviation structural engineering professionals. |
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