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Author Topic: U/C casting X-rays, TNS 165  (Read 1070 times)

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Offline Tim Watson

  • Posts: 43
  • Country: gb
U/C casting X-rays, TNS 165
« on: Wednesday November 22, 2017, 17:27:38 UTC »
Does anyone have a suggestion for a firm that can do this?  Preferably in Southern or Eastern England.

Offline qe45 - (Skytrade)

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Re: U/C casting X-rays, TNS 165
« Reply #1 on: Thursday November 23, 2017, 09:33:38 UTC »
Try Brinkley ??

Offline alant

  • Posts: 19
  • Country: gb
Re: U/C casting X-rays, TNS 165
« Reply #2 on: Friday November 24, 2017, 08:48:26 UTC »
Brinkley are very good.

Offline Tim Watson

  • Posts: 43
  • Country: gb
Re: U/C casting X-rays, TNS 165
« Reply #3 on: Sunday December 03, 2017, 13:24:04 UTC »
Many thanks. Brinkley is an excellent suggestion!
Tim

Offline munkrevival

  • Posts: 17
Re: U/C casting X-rays, TNS 165
« Reply #4 on: Friday December 08, 2017, 18:45:40 UTC »
Just curious, what results have these inspections produced? Are cracks found often? Are certain production years more likely to have had a run of weaker parts than other years?

Offline Nigel Stevens

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  • Country: fr
Re: U/C casting X-rays, TNS 165
« Reply #5 on: Saturday December 09, 2017, 14:02:13 UTC »
Munkrevival, at the risk of starting a polemic, here are my thoughts.  I do not know the extend to which cracking is found. What is not stated in the TNS is why the cracking is important. As far as I know there has never been a situation where the undercarriage leg became loose or fell out, let alone cases caused by casting cracking. The castings may crack but so what. There are lots of aeroplanes flying around with cracks in the structure. In fact if you look at what happens where there are accidents, such as ground loops, where the gear leg takes the impact, the casting destroys the spar, but the gear leg remains firmly attached to the casting.  One wonders therefore about the true value of this TNS, and I'm intentionally phrasing this politely! It is another element that make the aeroplane expensive to maintain. Perhaps that is part of the story.
Nigel

Offline john henderson

  • Posts: 257
  • Country: gb
Re: U/C casting X-rays, TNS 165
« Reply #6 on: Saturday December 09, 2017, 18:21:17 UTC »
We have much bitter experience of this TNS and its consequences. Nigel is quite correct that the casting is riveted solidly top and bottom and to the spar and to the adjoining ribs each side.

The cracks BAC were concerned about were age embrittlement cracking running vertically up and down the tube that connects the two heavy section load spreaders at the top and bottom.  Apparently you are allowed one or more cracks provided they do not penetrate beyond the tube section.  Radial cracking is not acceptable.  I agree with Nigel that even if it cracks all the way to the top or bottom it ain't going anywhere and neither is the undercarriage leg.  I know of no case of structural failure resulting from cracked castings 

Note the undercarriage leg is only fastened to the top of the casting by a single stud that has a split pinned nut accessible through the cover on top of the wing.  The leg is held in location by a serrated bush that matches a similar bush on the leg (again at the top). Any side or fore and aft loads are taken initially by the top mounting and if the leg deflection is sufficient (hopefully never!), eventually by the lower spreader which, note has a diameter about 6mm greater than the leg. This clearance is required to allow the serrated collar on the leg to pass through when the leg is being removed.

Therefore, (my teacher told me not to start a paragraph with therefore!), the loads incurred by the leg are transmitted from the top casting into the upper wing structure, and then onwards through the surrounding area and also downwards through the tube section of the casting to the lower spreader and surrounding wing area.

Or aircraft was involved in an accident whereby whilst travelling backwards at slow speed down an embankment (don't ask!), the port leg was stopped by a concrete block. This placed an aft load onto the port undercarriage, which I am sure was never envisaged at the design stage.  In turn, this caused a ripple across the top surface of the wing.  The CAA inspector rightly asked for the wing to be stripped, the casting to be removed and inspected and the spar to be checked for damage or distortion. We did this and had the casting Xrayed.  There was no change from the previous Xray which had showed a vertical crack approximately 4.5 inches long.

We put the aircraft wing and the aircraft back together (a lengthy and expensive process), including a new tiebar, a replacement rear fuselage, re wiring, recovering, a bare metal repaint, etc.  After two years and about to apply for the new C of A, we discovered that the Xray was due again even though we had not flown!  This time, the Xray disclosed a radial crack running around the top of the casting for about two inches.  It reflected exactly the shock load applied by the U/C to the casting when the rearward motion of the aircraft suddenly ceased.  Why it did not show or was not picked up on the previous post accident Xray I have no idea!  This meant de-rivetting the aluminium off the wing again, and replacing the casting with a new one!  I won't describe the anguish this caused.  It also meant re-fabricing the wing!   Had I had a box of matches and a can of petrol to hand then, the story might have ended there!

The plus side is that the port wing now requires no Xrays.  The starboard wing has to be done every few years in accordance with the TNS.  As there has been no propagation since about 1985, like Nigel I question the need to Xray the thing so often, or indeed at all.  If the aircraft was being used for flying training with students planting the thing firmly on the ground 20 or 30 times a day it might be different. 

Incidentally, I have several old material U/C castings removed from wings, both port and starboard if anyone is in desperate need.  They are probably cracked but serviceable and don't underestimate the work required to change them, but it can be done.


john h

Offline Dick Gower

  • Posts: 284
  • Country: au
Re: U/C casting X-rays, TNS 165
« Reply #7 on: Wednesday December 13, 2017, 23:08:03 UTC »
That story brings tears to my eyes John!  What tenacity!
I have a copy of the famous March, 1992 BAe letter stating "It would be a correct interpretation that the casting would be serviceable even if split in two".  Happy to copy it to anybody who needs it.

I wonder whether it might be worth an approach to the LAA on this.
Dick Gower
Melbourne,
Australia.

Offline john henderson

  • Posts: 257
  • Country: gb
Re: U/C casting X-rays, TNS 165
« Reply #8 on: Saturday December 16, 2017, 11:07:55 UTC »
Yes please Dick, i would love to see it and perhaps collectively we can make an approach for further alleviation to the LAA. i think you have my email or failing that you have PPJ's.
john h

Offline Dick Gower

  • Posts: 284
  • Country: au
Re: U/C casting X-rays, TNS 165
« Reply #9 on: Monday December 18, 2017, 22:32:22 UTC »
I would attach it if I knew how John.
Will send a bunch of stuff if you can email.
Cheers,
Dick
Dick Gower
Melbourne,
Australia.

Offline speedbird1

  • Posts: 533
  • Country: us
Re: U/C casting X-rays, TNS 165
« Reply #10 on: Tuesday December 19, 2017, 17:42:43 UTC »
My feelings about a lot of these TNS's etc was a "make work" plan by Bae that backfired when the RAF sold the whole lot off and built the Bulldog.  Now we are left with the good folks at DH Support who have no engineering background to prove or disprove the silliness of the requirements.
It would not be difficult to machine some new landing gear attachment fittings on a CAD machine, but in order to do so would require CAA design and engineering approval.  There are companies around well able to do it but they do not hold the aircraft Type Certificate.
The same applies to engine parts as the Type certificate is held by Deltair who are an overhaul company and do not manufacture parts.
Eventually we will  run out of old stock parts and we will be sunk.  Also the market for the parts after going through the hoops of getting CAA approval is very small as we are not in the same league as the WW2 big iron and deep pocket folks.
Johns story of his wing rebuild brings tears to your eyes and he must have had a sadistic side to even try it, let alone do it twice. You need a medal, John.
As an ending how is it that the British machines need all these AD's/TNS's when the Canadian ones don't???  Maybe the Canadians knew better than the home grown company??
Speedbird 1.

Offline Bob

  • Posts: 346
  • Country: 00
Re: U/C casting X-rays, TNS 165
« Reply #11 on: Wednesday December 20, 2017, 16:55:32 UTC »
I understand DH Support have new castings ( The Shuttleworth Collection fitted a pair last year ) and Mark Miller at DHS tells me they have getting the TNS reviewed on their to do list. Unfortunately one of their staff is long term sick and they are bogged down with the fall out from the Australian DH82 problems.

Offline speedbird1

  • Posts: 533
  • Country: us
Re: U/C casting X-rays, TNS 165
« Reply #12 on: Wednesday December 20, 2017, 17:09:04 UTC »
If indeed they have new castings that is excellent news, but their workload with Bill Taylor being off sick will not help.
We all need a BIG thankyou to Bill for all his unseen and tireless efforts over the years and hopes for a good recovery.
Speedbird 1.

Offline Dick Gower

  • Posts: 284
  • Country: au
Re: U/C casting X-rays, TNS 165
« Reply #13 on: Thursday December 28, 2017, 05:35:48 UTC »
Here here Speedbird.
Dick Gower
Melbourne,
Australia.

 

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