Could anyone help me with a material strenght calculation of this operating horn from crashed plane? 10

[RedSnake]

Picture elevator to the left and stabilizer to the right.

The red cirkel is a tourque tube on the rudder and have a diameter of 38 mm and the thickness is 1 mm.
The operating horn was a welded box design using steel sheet AISI 4130 in condition N thickness is 1 mm welded against the tourque tube.
On the uperside and sides (3/4 of the circumference) has 30% of the normal materiels strenght(severe lack of fusion).
The last 1/4 can be brittle or have been sheared.
The red triangle is the mechanical stop maximum up.
The relationship between hinge, tourquetube and elevetor edge ca..
0 --------1 --------------------7
Can this construction hold for 5,7 G ???


[img [URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1604784211/tips/STABH2_lpxbcz.jpg[/URL]


Properties Metric Imperial
Tensile strength, ultimate 560 MPa 81200 psi
Tensile strength, yield 460 MPa 66700 psi
Modulus of elasticity 190-210 GPa 27557-30458 ksi
Bulk modulus (Typical for steel) 140 GPa 20300 ksi
Shear modulus (Typical for steel) 80 GPa 11600 ksi
Poissons ratio 0.27-0.30 0.27-0.30

 

[Alistair_Heaton]

Sorry I have just found a picture of the tail of one of them and you are correct the trimming system does not use a trim tab to adjust the elevator trim.. It must have some tensioning system on the pitch control runs which holds a tension on the cable which is not the best to be honest but is legal. The piper tomahawk had a similar tension system and it doesn't allow you to fly the plane if you have elevator control issues. Which could be another point of failure to be honest. If the CoG goes rearwards and the tension mechanism releases then a fully out of trim aircraft is dumped on the pilot. Maybe point of failure is a bit strong maybe loaded above its operating limits would be better causing it to release which would give a nasty change in control weight. You might not be able to see that it had occurred either depending on the system design and the clutch mechanism applying the tension.

 

[LittleInch]

Alistair,

The manual attached might make more sense to you than me, but I think the elevator control cable is just tightened with a turn buckle.

This does appear to be a pretty "basic" airplane alright.

The stab is able to to be trimmed for sure and on the AIB report was found 90% in the nose down position.

I suppose the question is if the elevator horn started to fail on one side and you ended up with different elevator pitch, is that enough to cause a spin or stall before the pilot could catch it by use of the ailerones?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alistair_Heaton]

ok its a screw jack doing the trim so no clutches to release when you least expect it. I used to hate when the PA30 tomahawk used to do that.

Could you find the Pilot operating handbook as well? that should have the CoG flight envelope in it s we can see how twitchy/limited it was with loading.

90% nose down is quiet an extreme trim setting not much left to play with. You can also get elevator stall which although possible is extremely rare. I have only every had it once on a piper Seminole while doing my initial twin rating. Its usually only a factor in high T tail aircraft which don't get the prop wash going over the elevator.

That side of loss of control is impossible to know without a data recorder. I agree that the lever arm had lateral forces on it when it failed, the action which caused those forces, your guess is as good as mine.

 

[LittleInch]

Available here if you want to register...

https://www.avialogs.com/index.php?option=com_k2&view=item&id=884:2todo&lang=en

Otherwise would the attached help?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alistair_Heaton]

Yes please download it.

Then i will work out how much weight movement is required to take it out of the CoG envelope.

 

[RedSnake]

I think it's the technical lingo that makes it confusing
SHK corrected me all the time when I talked about the elevator trim tab and said that it is on the front of the stabilizer
I have to apologize for being wrongly trained by SHK ;-)

About the Airworthiness directives..
The lever for the elevator are not included in the airworthiness directives and there is no mention of any controll of rust.
In 4-10-00 airframe limitations in the service manual mm_ga8.
There might be a amendments not inkluded in the service manual I don't have.

From the type certificat VA503

Did they give you the mass and balance/performance sections of the flight manual?
I have the complete manual GA-FlightManual-08(b) POH but I'm not sure it's correct, as the planet has been re typed in Australia after it came to Europe and this has not been noticed by the EASA.
It is very messy with all the documentation. :-(

The planes basic weight was 1051.7 kg

I probably know more about that plane than those who owned it.
When I ask CP about something technical, he just laughs, because most of the time he can not answer.
My questions are too difficult.;-)

Best regards Anna

 

[Alistair_Heaton]

there is usually a graph which looks something like this in the mass and balance section with also a description on how to calculate the COG which is dependant where they have set the datum.

If you could upload the POH that would be great.

BTW we are going to be joined by another pilot the Swedish TRE I was talking about.

 

[RedSnake]

Do you mean this one?

The planes basic weight was 1051.7 kg

/A

 

[Alistair_Heaton]

yes..... perfect

I can't sit down just now and run the calcs. I have 12 m3 of fire wood to sort out and put in the barn... before the sun goes down...


Being Swedish I am sure you understand.

Airborne68 as I think he is going to call himself will be able a huge help with the Swedish technical translation stuff.

He is a lot more current than I am on the small aircraft stuff but also used to fly the 747.

 

[RedSnake]

I thought you only used peat for firing ;-)

/A

 

[Alistair_Heaton]

Nah I live in the Baltics and the wife and kid is Estonian... We have a holiday farm near Voru next to the Russian border. Which I have built over the last 2 years. Finished the inside just about.... now doing the out buildings. I think I will fail miserably this evening with my goal....

 

[LittleInch]

The accident report noted this as the C of G.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alistair_Heaton]

That's I suspect the best case situation

I don't have a printer and that load sheet is easy done with a pair of compasses.

first print of few sheets and run various load cases.

First one is with two people in the front and 6 at 1715 arm and 77kg for each pax. I suspect it will come in at what the SHK have published.

Then run it again with a more realistic weight for each pax of 90 kg with jump gear on.

Next case keep two in the front,3 at 1715mm arm and have 2 at 2861mm and 1 at 3763mm so thats the jumpmaster with his bum on the baggage rack at the back and a tandem going out the door.

Now have one in the front go from 965mm arm to 1715mm arm while the load master is sorting out the tandem and doing a buddy check.

The SHK can't put in writing what I have suggested because there is no proof that's what occurred. Even their current chart is extensively outside the envelope.

Although that said they did go a couple of levels up and actually weigh an aircraft with real parachutists onboard.

 

[RedSnake]

There were no tandem jumpers on board.
About half of them were fairly recent graduates.
The usual procedure is to jump out 2 and 2.
My opinion is that, that was the plan, no formation jump would be made where many jump out at the same time.
There was no jump master it is only used in sweden in training jumpers.
And my belief is that the door was never opened.
I have many concrete "proofs of this" it would be an equally long thread if I were to explain them all.
SHK has watched various films from many different jumps from the last years and come to the conclusion that jumpers have been sitting on the luggage rack.
I have probably seen more and have only seen it at a tandem jump, where the same amount of people were in the plane.
There were 2 jumpers in the plane who had ProCams, it was my partner and one other, none of the ProCams were turned on at the accident.
But both jumpers were on the day's first lift.
7 out of the 8 was, the film recording from that jump is not public because it is the property of the relatives.
And and would of course never have been shown by SHK.
But I think that if there was a recording from the first jump, it would have been the most accurate picture of how the jumpers behaved on the plane.
SHK could at least have described it in words.
My partner never turned on the camera until the last sekund ,he never moved a muscle before it was time to jump off.
That is also a indikation for me that they hadn't goten as far, he was sitting behind the co pilot chair.
Now they have taken the worst imaginable film and started from that.
But still written in the report that it can not be sad with certainty that the balance sheet looked like this.
Which, of course, is true when no one knows.

/ Anna

 

[Alistair_Heaton]

This is the major issue without a data recorder which is only required over 7.5tons there is no evidence only presumptions,

From the little I know about UK para drops its quiet different about the control.

This is historical with RAF jump master instructors writing the manuals. As a herk mate of mine said I love flying with bang onboard (explosives)... hate paras because the JPI is the boss of the aircraft and I do think they believe they can instruct us to ignore the laws of physics. Which has ended up with the captain of the aircraft telling the loadmaster smack that prick please this is not an order.. Reply from the load master was my pleasure Sir.

There was what we call dit of a herk load master after a trip to Cyprus telling the whole load to double round the airframe while the trash was cleared out inside by 2... A major came rocking up in a land rover with a requested permission to fall the colonel out... Reply negative until the aircraft is in the same state as when they got on.... from the depth of 100 odd blokes doing brpee'sv "piss off bob don't make matters worse"

I honestly think if you want to prevent anyone else going through the same bereavement you should tackle the command and control side of things of paradropping in Sweden to prevent a repeat occurrence.

 

[Alistair_Heaton]

But honestly that aircraft is so far out of its flight envelope I would be surprised if the insurance company would pay.... If this is the reason could you be honest please. Because I know a Swedish new qualified CPL will be over 100K plus in debt so not worth suing his estate even thought technically it is their complete and utter legal responsibility to ensure the safe conduct of the flight.

 

[RedSnake]

Now you totally lost me with all the military lingo LOL
In Sweden, the pilot is the boss! end of story ...
The jump master (load master) (which they now want to reintroduce) is the pilot's extended arm read flight attendant.
And then there is one called a jump leader on the ground who will make sure to produce calculations and data and inform the tower about number of parachutes and jumpers etc and inform the pilot about which rules apply.
But it is the pilot's responsibility to do the risk analysis and he decides everything!

It was one of SHK's points that he was too new and inexperienced to handle the analysis and say no.

/A

 

[RedSnake]

They have already got a new plan, how they have financed it, I have no idea.

https://www.svt.se/nyheter/lokalt/v...der-fallskarmsklubbens-nya-flygplan-till-umea

I have never been a member of the club and have only set foot there once before the accident happened, when they had an open house on the day of flight.
After the accident I have only been there at memorial services etc maybe 4 times.
I did not know a single person there before the accident, more than by name after all the stories that my partner told me.

I actually feel a little offended by that.
But because I myself am reluctant to post things about myself online and I know that it is a jungle of scams etc. out there I can respect that you ask.

I really hope you believe me when I say it has nothing to do with that.

Best regards Anna

 

[Alistair_Heaton]

The pilot in command is always the legal responsible for the flight and that's international law.

Multi crew wise when we sign off a new captain I always pushed them into a situation which they have to say "NO" and then stick to it. I have actually walked out of jobs due to being pressurised to do a flight which was illegal and or dodgy in normal speak.

Jump master is a different entity in the Uk to load master which is a defined qualification jumpmaster is an associated technical qualification. They have the authorisations of flight attendants being delegated cabin control but they have the ability to call no drop legally but have absolutely zero control or input for the flight safety.

As for them getting a new plane I would start by asking your local politician and about oversight. They have the joker card as a charity... This is why i suggested the pilots union earlier. They are extremely powerful in Sweden. Know the local laws and have influence. By rights a 200 hour cpl should not have been put in that situation

 

[RedSnake]

From the report.

During flight, the pilot is responsible for the parachutists remaining within the predetermined areas so that the aircraft's center of mass position remains within the approved limits. To ensure this, the pilot has the help of the accompanying "loadmaster" (cf. jumping master) and by conveying the information required before flight to the parachutists on board.

2.9 Collaboration between pilot and jumping master.
The pilot has no practical possibilities to monitor the jumps' movement in the cabin.
Inappropriate movements in the cabin must thus be prevented by the jumpers' awareness of the problem in combination with the jump master's supervision.

/A