The gearbox sits on the barbeque plate to which it is bolted. It is slotted to absorb the horizontal forces from the head/gearbox and it is attached to the upper fuselage structure.

It was visible in one of the photos posted still attached to the gearbox, but I'm not sure where that photo is.

It's not in the pictures (didn't look at the video) but anyway it is a slotted plate that attaches the bottom of the gearbox to the transmission deck. Called the BBQ plate because of its slots. The slots are designed to give the plat some flexibility to allow the bottom of the gearbox to sway a little whilst constraining it in rotation (ie taking the torque).

The barbecue plate is the slang term for the gearbox "flexible mounting plate". It is the interface between the base of the gearbox and the airframe and it is designed to resist the rotational forces acting on the gearbox. It is made from titanium but, as its formal name suggests, it is flexible. It has been in use on the AS332 series and H225 for many years.

Years ago probably late 70s early 80s there was a tragic accident with a Puma in Canada caused by BBQ plate failure.
As I recall - BBQ plate failed while the AC was in the hover picking up a longline load.
Transmission torqued to the right which caused the #1 engine drive shaft to be torn loose.
#1 engine over sped and shut down ( this disabled overspeed protection on # 2 engine )
Transmission then torqued left which took out the #2 engine driveshaft. # 2 engine over sped and, due to disabled protection, exploded causing a large fire and crash.
BBQ plate was redesigned and cycle counts for multiple longline sling ops were imposed.
Just mentioned as I am sure the subject may come up.
I am not speculating that BBQ plate failure is a causal factor in this accident.

and the 330 Puma from 1966; that's fifty years.

Suspension bar front lower pin
 

We suspect the front lower suspension bar pin's diaper pins were never installed.

I think its made of Marvel on the 225.

So who is deleting posts again?

On some fora you get half an hour to reflect on your sins and then it's there forever!

Just to clarify

Many thanks to all for the explanation. :ok:

The people who posted them.

Mitchaa has gone from 28 to 17 posts in total today by deleting all but 3 here (ones where he was proven wrong?) and others on the CHC thread.

Skotty,
You're a brilliant ray of shining light amongst these 500+ posts of poop!

Probably a good idea, if all the dross was deleted the thread would be a damn sight shorter.

I will delete this tomorrow!!!!!

I'm with Skotty. Having seen the end result of a 3 legged lifting sling breaking a single leg I can testify that it doesn't end well. Simple mechanics.

http://bt.mnocdn.no/incoming/article3590196.ece/ALTERNATES/w2048c169/IMG_6661.JPG?updated=030520161246

Flex plate still attached.....is it not? See left side of MGB bottom!

Honestly, I've got no idea. It is simply one theoretical cause amongst multiple. How it could have happened? No securing pins installed on the bolts? corrosion? Wrong bolt? Other ways I didn't come to think of?
If it was a problem with the suspension bar and how it could have come lose we will only know once the experts who have access to the data and wreckage have come to a conclusion. Until then its just possibilities and -yes- speculation.

CHC has filed for Chapter 11 Bankruptcy protection.....what is the next step in this Drama?

Wow . . . . serious first post.

@Tyler
Depending upon who "we" is in that sentence.

CHC bankruptcy was inevitable.

Sir, I think the legends are changed... just saying...

What happened to the Airbus, AIBN and CHC leading us to believe there was no human error/misinterpretations. I would think forgetting to install the diaper pins would be human error ... Just saying. I think "we" is just throwing something out there.

I've heard the same from a number of different people now. Washer, nappy pins and possibly the round fire wall panel still in the hangar.

This is only rumour and not fact yet.

re: suspension strut pins .... whether loose , wrong size , or retaining clips missing I cannot see them falling out in flight ..... they are carrying +20,000 lbs and you could not drive them out with a sledge hammer.

On the ground with just enough lift to equal the MRG and rotor system (no weight on the pin) it could move a bit .... maybe that is what happened .... pin slid partway and only 2 of the 3 eyelets were carrying the load and bracket bent and distorted in flight .... just thinking out loud at possible scenarios.

Not so fast.
Constant vibration with loading and un-loading of the strut pin(s) could certainly move it sideways, slowly but surely.
I sure as hell would not bet my rotor or my life on a guess the pin would not move if not secured.

Like 500 other things!


So the suggestion is that a pile of bits sat in a hangar for HOW LONG?

The front strut also carries dynamic loads. There might even be load changes from tension to compression on large fwd cyclic inputs.

Latest from AIBN, not that it adds too much:

"All the components from the helicopter are now moved to the AIBN's facilities in Lillestrøm. The helicopter parts were transported on two trailers, and arrived on Thursday morning. Here, the AIBN will continue its efforts to sort and analyze both components and other information. The participants in the investigation are currently working from their home bases, before the team gathers in Lillestrøm early next week to continue the work together.

The search for components at the accident site will resume tomorrow. The main focus for the search is for parts connected to the main gearbox. The search will continue as long as required."

Dom

More or less the same info:

Norwegian newspaper, VG, reporting this afternoon that the AIBN is still looking for more parts from the gearbox. They say, they "have much of it, but still need more pieces".

Further on they say that "all the parts they've got is all important in this early stage of investigation. A gearbox like this contains many parts - and we are still missing several pieces".

May eat my words on this but not buying the missing diaper pin theory. Mainly due to the length of time between the accident and the MRH/MGB replacements. Having worked in the industry long enough, find it really hard to believe, at this time with all the safety nets, such a critical part would be missed. The first engineer would have to forget, the second engineer (initialing the independent) would either have to have gained enough trust in the first guy not to look, however, I cant imagine he wouldn't at least asked (which is when you would think the first guy would go "oh $#%&"). There would most likely be a checklist/greasy thumb copy of the major component replacement that gets attached to the work card where someone checked installing the pins (again "oh %$^*, I forgot the pins). Now this is just the 2 guys signing for the job, there would be several other engineers involved in replacing either of the above 2 components, possibly even a shift change (maybe not for MRH) where another set of guys would have been involved. After all that, hangar/stand cleanup, I think someone would have noted a firewall panel, washer and 2 diaper pins left over and questioned why.


So all that got missed, the aircraft has been flying for a month (according to the rumors) since the MRH replacement. There would have been a significant amount of daily inspections, preflights and turnarounds in which no engineer picked up of the missing panel. I realize its down in the bottom of the firewall behind the engine but I think it would be picked up on a daily. Engineers minds are trained to pick up on the anomalies not the thing that are correct. Again, after all that time, someone is now just noting the significance of the parts sitting in the hangar ... I don't know guys, really seems far fetched to me.


I guess nothing is impossible but its not like this is HS's first go at a puma. I do not work for HS but I do think they are a probably the most experienced super puma operators out there. CHC like all the other big boys, have all the known safety nets in place and is just hard to think such a small yet critical step creeped through the cracks for so long.


Obviously like everything else on here, this is just my own speculation and in due time we will hopefully find out the true cause so that the chances of it happening again are minimised.

Any unlocked pin that is a sliding fit (not a press fit) in a vibrating environment has a good chance of rotating even if it does this very slowly.
If that happens on a vertical pin ( up down ) it may/should stay in the hole by gravity. On a horizontal pin all bets are off. It can't move any farther in one direction but it sure can go the other way. Could take weeks.

We may assume they mean the crash site and not the maintenance hanger or store room I guess!

So Shell's suspension stands and they are about to start flying with Bristow in Norway.
https://www.energyvoice.com/oilandga...ights-bristow/
Have they revealed anything about the Shell Aircraft review?

Would it be fair to say that the aircraft was just at top of descent, about to make its final approach into the airfield. This is assuming that the crew had made any control input at all that might have precipitated the sudden break-up.

If so, the rotorhead and gearbox were being unloaded, not loaded. The former might lead to the final critical slipping of the strut retaining pin, rather than loading up the head which might lead to gearbox, strut mounting failure.

As I recall, the bottom of the strut feeds into a fork arrangement where the pin is threaded through two eyelets. Assuming (again huge assumptions) that there were no diaper pins and firewall plate, how far would the pin have to move to release the strut. Would coming out of one eyelet be enough to lose the structural strength of the pin?

...they don't add Retention Pins to any design just to add to aesthetics.
They are designed to be there to prevent Pins moving...

Can't be a Sus Bar failure because the Gearbox split in 2 parts.
Sus Bar or Pin failure would see the Barby Plate and whole gearbox leave the scene. Almost has to be major Gear failure internal to the Gbox.
I bet my bottom dollar they are the bits they want to still find.

So many 225 fan boys falling for the Airbus ploy of deflection.

Forget the AH and DGAC noise, they are simply covering their backsides and are totally untrustworthy. The stakes a very high and they are trying to save a product line here.

The truth will come out once it is known. It is NOT known at the moment IMHO.

Not so sure about that, loose one of the three bars, the pull on the remaining two would put massive side/load onto the output shaft and I doubt the gearbox would stand that for many seconds.

buzz66

Let's work the odds here for your bet. Forget the stuff about the split and the barby plate.

Has anything like this happened before? Yes.

Was it the bars or the epicyclic module that failed? Epicyclic module.

Eh? ...