Mitchaa

If they left one or more oil jets blocked degradation could be quick with no chip warnings.

The Sultan

The whole load of the helicopter is suspended from the rotor head by the outer casing of the gearbox. This design was hailed as a huge advance that saved significant amounts of weight, improved payload capability and fuel economy and simplified some maintenance tasks. The only problem with this design is that the gearbox casing represents a single point of failure with no redundancy.

Her flyr rotoren på egen hånd etter helikopterstyrten

Don't know if this video is working outside Norway.

It is a private video of the rotor 'flying by itself' after detaching from the rest. Scary and shocking.

Video working for me (UK).

the BBC just showed the video of the whole rotor descending/rotating slowly to the ground after the helicopter had crashed

Do you have the link of this video?

It's in post #67

I would expect the PUMA to be equipped with HUMS - Healt and Usage Monitoring System. Accelerometers that will discover non standard vibrations before things get serious.

Chip detectors to detect vibrations? Surely by definition even you can figure out what chip detectors actually detect??? :ugh:

I don't know why, but I didn't succed to open it...

"A new gearbox is unlikely to fail, a newly installed recently overhauled gearbox is unlikely to fail."


not so. The majority of component failures come in the first 25% of component life since new or overhaul, followed by the last 25%. The middle 50% is the least likely to fail. That's why they run all components on the US presidential helicopter for 25% of its life on one of the other aircraft before installing it on the presidents aircraft. At 75% they pull it and scrap it. Sorry I don't have a source, (wish I did) but I've heard it several times and it aligns with what I have witnessed. A good friend of mine lost the C47 on his 407 last year with 80 hours TSN on the engine. #1 bearing was incorrectly pressed.

You are right - not chip detectors, but accelerometers.

Likewise with other complex machines. With cars, a good breakdown technician's first question will be 'Has this car been recently serviced?'

You might want to read this statement about the Helicopter in questions maintenance before you offer any more theory's.


https://www.energyvoice.com/oilandga...replaced-year/


Never let the facts get in the way of a good old lynching .

Exactly lowfat. I don't know where the rest of you come from, but yesterday isn't January where I come from.

I just wish there was another photo of that MR Head taken from the side unobstructed by the blade. It looks like the swashplate drive link has broken off (Swashplate stayed connected to the servos?), but it also looks like the rotor shaft is still there, which is a worry.

And for those saying how this is the first civil fatal for the EC225, that is quite true, but let us not forget the two very close calls that were had when the machines ditched and it was later found that there was a 360 degree crack in the bevel gear shaft weld. G-REDW and G-CHCN I believe. Failure was imminent and possibly could have resulted in the MR Head departing the aircraft complete with MR Shaft.

A sad sad day. I hope that lessons are learned and this never happens again.

My first captain always said: "airplanes are only dangerous when they go to mx and when they come out of mx"....

GOULI you are totally wrong.
The whole load of the helicopter is suspended from the rotor head by the outer casing of the gearbox. This design was hailed as a huge advance that saved significant amounts of weight...

The MGB of the EC225, like the others in the Super Puma family, uses 3 suspension bars which transfer the whole load of the helicopter from the transmission deck directly to the top of the MGB casing. Sikorsky use the method you have described, which is why their MGBs are so heavy.
The attached illustration is from the EC225 Technical Data Manual.

MTF's
 

Jimf671 posted:

Quote:
Originally Posted by Daylite http://www.pprune.org/images/buttons/viewpost.gif
Speaking with chc technical department, it now seems the gearbox in the aircraft was only changed yesterday.


That is consistent with the available flight history showing 5 short local flights 26th and 27th.

Depending on local procedures, then, it is possible that everything from the gearbox mounting structure upwards was removed and replaced. Most ops would take the blades off the head to begin with. Anyhow, in the midst of doing all the removal/replacement, there are opportunities for human error. Reason I mention that is that if it was a gearbox issue which initiated the action, one would assume there wouldn't be vibration problems after the re-install, so what were the 5 maintenance flights for? I made the assumption they were MTF's because Jimf671 wrote that they were short.

Anecdote re a local practice that I ran into at Ft Rucker one day. They had a UH-60A which had driven evryone a bit crazy re vibrations and it had been down awhile. I went down with a dynamics engineer to see if we could help. Put the vib gear on and got ready to fly. Our engineer pulled me aside and told me that all the pushrods had no safety wire on. Asked the civilian test pilot I was to fly with and he told me they always did that and only safetied the rods after they were done. Told him that my insurance agent forbade me to fly without safety wire on the pushrods. There is more to this particular story, but although this would be a long shot, its one of the variations that might have taken place here.