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-   -   4th Aug 2018 Junkers JU52 crashed in Switzerland (https://www.pprune.org/accidents-close-calls/611836-4th-aug-2018-junkers-ju52-crashed-switzerland.html)

atakacs 21st Nov 2018 17:19

Thanks. I have missed that part. Surprising that they have managed so little (one device) in 3+ months.

As for the egines I'd be very surprisdd if they could deliver anywhere near their rates output.

wiedehopf 21st Nov 2018 18:51


Originally Posted by atakacs (Post 10316652)
Thanks. I have missed that part. Surprising that they have managed so little (one device) in 3+ months.

As for the egines I'd be very surprisdd if they could deliver anywhere near their rates output.

Nowhere does it say one device.
"Bis zur Veröffentlichung des Zwischenberichts konnten einzelne Datenträger ausgelesen werden. "

"Until the date of this report individual devices could be read out.

That would imply several devices could be read out.

jimjim1 22nd Nov 2018 08:51


Originally Posted by Onceapilot (Post 10315888)
This document is an interim accident report but,
https://www.sust.admin.ch/inhalte/AV...B-HOT_ZB_D.pdf
OAP

I found that a web site[1] that reportedly uses google translate and sorts out large documents for you. I guess it splits the file into suitable bits for google and puts it all back together.

I have not read much of it yet but the first few pages look not bad.

https://drive.google.com/open?id=1Mb...4agLS9VQ931JA_

I think that the link should work - I have tested it from a browser than was not logged on to google.

[1] https://www.onlinedoctranslator.com/en/

jimjim1 22nd Nov 2018 09:26

On the basis that I might at least look at the pictures I used google translate against the Figure captions before I found onlinedoctranslator.

These seem in some cases clearer than those in the whole doc translation I linked to above.

Figure 1: Wing section with the 4 bars (Source: Operating Instructions Ju 52 / 3m, supplemented
by the SUST)

Figure 2: Motor mount of the left or right motor (Source: Operating instructions
Ju 52 / 3m)

Figure 3: Maintenance program of the Ju 52
The engines had a maximum allowable according to the maintenance program
Operating time to overhaul (Time Between Overhaul - TBO) of 1500
Hours with a tolerance of 10%. In the operating manual of the aircraft engine
The manufacturer's BMW 132 from 1939 states the following: «One
Overhaul should rarely be required before 200 to 300 hours of operation ».

Figure 4: Accident site southwest of Piz Segnas. A mesh square has one side length
of a kilometer. Source of the base map: Federal Office of Topography.

Figure 5: End position of the wreck

Figure 6: Repair in the area of ​​the wing center box, recognizable by the greenish yellow

Structural parts and the golden connection elements.

Figure 7: Repair of the structure of a motor carrier. The half shells became direct
riveted on the thick paint layer.

Figure 8: Lower spar tube of spar I of the left wing. The arrow points to the zone
with cracks in the spar tube.

Figure 9: Detailed view of the crack zone at the lower spar tube of the left wing.

Figure 10: Detail view of the inner side of the lower side of the left wing.

Figure 11: Detail view of the cabin structure at the rear right. Striking are the rotten ones
Wooden floor (yellow marked zone) and the corrosion damage (red arrows).

Figure 12: Corrosion in the area of ​​the wing connection (red arrows)

Figure 13: Marked aging damage on a hose

Figure 14: Fuel hose with date (November 11, 1988)

Figure 15: Cylinder positions 1, 2 and 3 of the left engine with piston.

Figure 16: Cam of the middle motor. The machining marks are clearly visible
(regular, finely grooved surface) and the eruptions on the upper tread.

Figure 17: Engine components stored in a cabinet and not identifiable.

atakacs 22nd Nov 2018 09:51


Originally Posted by jimjim1 (Post 10317148)
Figure 3: Maintenance program of the Ju 52
The engines had a maximum allowable according to the maintenance program
Operating time to overhaul (Time Between Overhaul - TBO) of 1500
Hours with a tolerance of 10%. In the operating manual of the aircraft engine
The manufacturer's BMW 132 from 1939 states the following: «One
Overhaul should rarely be required before 200 to 300 hours of operation ».

I am possibly over obsessing about the engines but
  • why did they run those very old engines when much better options are available (while keeping with original / vintage JU 52 specs) ? Is there something unique about those ?
  • they had respectively 946:50 h, 1153:11 h and 457:49 h since TCO - seems a lot (even if formally within tolerance).
  • This is not looking too good https://i.imgur.com/UiiALFZ.jpg
  • overall it would seem that these airplanes were not maintained to top standards, so there would be a suspicion that the engines were probably not able to deliver rated power
This might or might not ultimately be related to the accident but I think we can reasonably assume that they did not have a significant performance margin on that day... if at all.

Onceapilot 22nd Nov 2018 11:17

Due to the severe loss of life in this accident, I expect that the final report will be comprehensive. At this stage, with the interim report to guide us, it seems that there might be considerable comment upon the regulation and operation of these aircraft. As for the cause of the accident, I am afraid that it must be pure speculation at this time.
As a point of interest, it should be understood that the internal condition and visual appearance of a high time large capacity piston aero-engine can be disappointing and somewhat dirty. However, the true condition can easily be determined by examination and measurement. Of equal interest to me in this instance, is the precise flying performance of the aircraft and its engines and how it was licensed to operate.
There does not seem to be any guidance on the likely time that the final report will be published, can any member help with an estimate from the Swiss authorities on this please?
OAP

clearedtocross 22nd Nov 2018 18:35


There does not seem to be any guidance on the likely time that the final report will be published, can any member help with an estimate from the Swiss authorities on this please?
OAP
Nope. The accident investigation branch will publish the final report when their findings are watertight, no schedule given. They repeated in the interim report that there was no indication of a mechanical failure or lack of fuel. What else, would George Clooney say, if not an act of a pagan God? Within a few weeks, there were three similar fatal accidents in the Swiss Alps in hot and high conditions. So obviously the tactics and decisions of the pilots will be questionned. Weight and balance will be important (with Pax moving in the cabin). But regarding the operational aspect, there are open questions about the operation, maintenance and oversight by the CAA too. Legally, this was a commercial operation (passengers paying a fee) , and even if the final report is not discussing legal matters, it will have a heavy impact on possible liability claims by surviving dependants. There is no reason to distrust the investigators, but they will have to be very careful in the wording of there findings. And the interim report created already quite an echo in the media and Swiss aviation circles, not only by what it said, but mainly what it did not.

atakacs 22nd Nov 2018 20:13


Originally Posted by clearedtocross (Post 10317680)
And the interim report created already quite an echo in the media and Swiss aviation circles, not only by what it said, but mainly what it did not.

Could you expand on that ?

clearedtocross 22nd Nov 2018 22:04

If the investigators know for sure what was not the cause they must have a pretty good idea what the real causes and its contributing factors were. Otherwise they would remain much more fuzzy. And they just reported airwortiness issues, but not how it was possible that they remained uncorrected for quite a while. I refrain from expanding my own conclusions on this.

EDLB 23rd Nov 2018 04:57

It means that the pilots stalled the plane and were unable to recover. Hot, high, changing wind directions on the flight path are most likely contributing factors.

rcsa 23rd Nov 2018 07:29


Originally Posted by EDLB (Post 10318006)
It means that the pilots stalled the plane and were unable to recover. Hot, high, changing wind directions on the flight path are most likely contributing factors.

... and, by inference, all the above exacerbated by weight shift - passengers moving from one side of the cabin to the other, from front of cabin to the rear, drawn by a view of a mountain? a photo-opportunity?

clearedtocross 23rd Nov 2018 10:24

The foto in this post shows the situation when you want to cross the Segnes-Pass at 9200ft (600ft more than the Pass). Sorry guys, I am fogged in in low IMC, so this picture is screenshot from my sim. The Pass is above the ASI and the little lake. The famous Martinsloch (not visible in the sim) is below the peak left of the pass and the place the aircraft crashed is south of the lake. To the right (compass) is Piz Segnes and to the left the mountains extend towards the Vorab region. Not much space to turn around if you get a downdraft from the North. https://cimg7.ibsrv.net/gimg/pprune....01013fea4e.jpg

tdracer 23rd Nov 2018 20:56


Originally Posted by rcsa (Post 10318094)
... and, by inference, all the above exacerbated by weight shift - passengers moving from one side of the cabin to the other, from front of cabin to the rear, drawn by a view of a mountain? a photo-opportunity?

That's been my assumption as well - the movement of SLF upset the aircraft CG sufficiently that the pilot(s) lost control and stalled.
A skydiving aircraft crashed around here about 30 years ago when the pilot lost control and stalled due to the rapidly changing weight and CG while the skydivers were doing their thing. It's been long enough that I don't recall details, but there were several fatalities.

RatherBeFlying 23rd Nov 2018 22:19

Perhaps a Vortex Stalled the Airplane
 

Originally Posted by EDLB (Post 10318006)
It means that the pilots stalled the plane and were unable to recover. Hot, high, changing wind directions on the flight path are most likely contributing factors.

A vortex downwind of a ridge can produce a shear of twice the wind aloft in the blink of an eye.

atakacs 26th Nov 2018 22:00

Not sure how to embed this

A video of the investigators working on the wreckage

http://www.20min.ch/ro/news/suisse/s...videoid=654445

arketip 30th Nov 2018 14:25

Ju 52 crash video
 
There is video of the last seconds

http://www.blick.ch/news/schweiz/exk....html?OneS=yes

glad rag 30th Nov 2018 14:54

Why no flash/fire, nothing at all from the AVGAS in that impact??

pattern_is_full 30th Nov 2018 16:27


Originally Posted by glad rag (Post 10324620)
Why no flash/fire, nothing at all from the AVGAS in that impact??

Just guessing, but 1) owing to the direct impact on the leading edges (no cartwheeling) the wings seem to have maintained a certain amount of structural integrity. See post-crash pix.

Plus 2), I believe the Ju52 fuel tanks are discrete "barrels" (7 per side) lined up down the wing centerline with a meter or more of "crush-zone" in front of/behind them, and may not have been breached.

Timmy Tomkins 1st Dec 2018 11:13

What a shame, beautiful old bird, tragic loss of life. It would be a shame if events like this limit the use of old aircraft.

Kerosene Kraut 1st Dec 2018 11:22

They have already. Their other two Jus are grounded until further notice. Maintenance and structure of the accident bird have been found to be below expectations.
If you use oldies like these airline style you might consider building new ones or take something like Baslers, Twotters or Do 228s instead.


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