Definitely this 206, identifying feature is the gray paint trim on the rear door.


https://cimg6.ibsrv.net/gimg/pprune....0322e74461.jpg

The cabin door was a small hint as to what type helicopter it was....yes a Bell...but not a Bell Huey.

VH-ZMF
 

For any owners or operators of the 206, you might like to keep an eye on this investigation. Early days, obviously, but the ATSB is reporting it as an in-flight breakup. I haven't heard of a 206 suffering in-flight structural failure before...

Could be why that rear door pair was out there on its own.

AC, does the attached provide any insight?


https://cimg7.ibsrv.net/gimg/pprune....ba7b453299.jpg

Off the top of my head I know of one fatal 206 crash in the UK some years ago caused most likely by mast bumping in turbulence ( can't find an online reference), and another caused by fatigue / loss of torque of the tail fin fasteners ( https://www.gov.uk/aaib-reports/bell...-december-2005 ). And Googling found a mast bumping related crash on the Isle of Man more recently ( https://www.gov.uk/aaib-reports/aaib...nger-ii-g-ramy )

This one may be of interest - https://www.casa.gov.au/content-sear...tor-separation

I have series of photographs which someone sent me from Canada of the mast failure. So lucky they weren’t a bit higher.

Mast bumping would have the rotors some distance from the fuselage, can't see that in the pic. The door pair looks undamaged, so the scenario of the doors coming off and hitting the main rotor or the tail rotor would be unlikely.

There was a case in the 90s involving a B206 with the ambulance kit fitted. This kit has made the rigid pillar behind the copilot door into a removable item, operated by a handle on the inside of the pillar, but supposedly done in such a way that the handle cannot be turned if the copilot door is shut - i.e. it can operate on the ground with the door open. Break the safety wire, turn the handle and the pillar slides out, still attached to the rear door, which now "hinges" on two hooks on its rear edge. These hooks fit into two loops on the fuselage. The whole left side is now open, and the stretcher can be loaded in on top of the rear seat, the copilot seat, and into the footwell. Close the rear door by sliding the pillar back into place and turning the handle. Re-wire the handle after the stretcher is removed.

On this occasion, the 206 had pilot plus 3, watching the Bridge-to-Bridge boat race on the Hawkesbury. A person sitting in the rear left seat wanted to lean forward and shout to the occupant of the copilot seat. He grasped the door pillar for leverage, but managed to operate the handle, which was installed backwards, opening into the cabin. The pilot was somewhat surprised when the door pillar and rear door departed the aircraft into the Hawkesbury. This pillar is an essential part of the fuselage, so he should have landed as ASAP as possible, but instead chose to make a breezy, wobbly trip back to Bankstown.

Seems a design change from the Huey style short shaft free wheeling unit may have created a new and different failure mode.

Those were greased units not requiring constant supply of pressurized oil for lubrication.

A question that springs to mind is why there is but a single injection port rather than two....but such a redundancy would add expense and complexity to the design.

As there is no back up....are there any warning systems that would indicate the loss of lubrication to the free wheel unit?

Why has the subject of short shaft failure come up?
I recall an incident caused by a grease lubricated freewheel failure leading to a bad crash in the mid 70s / early 80s. There was no grease in the newly overhauled, freshly installed unit. The badly injured pilot, a friend, ended up still in his seat 25 feet ahead of the aircraft. Fortunately he recovered and had along flying career in the business.
I also recall, in the same time period, there were some substandard boots that failed leading to loss of grease and actual short shaft failure. One led to an auto into a shallow lake ( water was up to back corner of the sliding doors, the aircraft was repaired in the lake, a drum of fuel placed in the cabin and connected direct to the engine as the fuel tanks were under water) They fired it up and air taxied to shore for further repairs.) and another that ended up with an auto terminating between 2 20,000 gallon fuel tanks with less than 6 feet blade clearance on either side.

So....which design is better...safer?

I recall looking at the short shaft on every preflight and maintenance break....checking for correct installation, condition of the boot, correctness of the locking wire and witness marks on the bolts on the couplings, signs of grease being slung....and turning it by hand to make sure it was right way to.....can you do that on the one in question on the 206L?

I recall some failures on UH-1's but after all we were flying millions of hours on them at one point in their service life in the US Military.

It is a fair question Albatross....did the change improve safety or did it bring along some new and different issues?

Noting is failure proof....unless you are suggesting this new design is.....is that why you ask the question you did?

The 206 drive shaft was susceptible to a boot split and loss of grease, had one happen to me but I found it between flights and grounded the machine. The tel-a-temp stickers were usually an indication of overheating, as long as a clumsy mechanic hadn't knocked it with a spanner and turned it black.

The all-metal Meccano-style replacement has also had some failures, but not from lack of grease.

I do not know which design is safer.
I posted as the subject came up out of nowhere when no cause for this tragic accident has been found.
I will say that we always took a very good look at shaft and boots during the DI and at every refuelling during the day.
I never had a short shaft or FW unit problem with any 204, 205, 206 or 212/412 but still the incident history prompted a good look. We will not speak of the old “Oil Heads” remember those?

Yup you can do that on a 206L.
Long time since I flew any Bell product but always luved flying them ( best years of my career - flying was fun and ops manuals were thin, management was 100s if not 1000s of miles away.) .

Wire locked freewheels
 

Can someone please clarify which part of the 206 MDS installation was wire locked and also any similarities between the 206 and 205/Huey freewheel systems?
I must be getting old and stupid as I remember the 206 freewheel residing in the Allison engine gearbox and the 205 freewheel being located forward of the MDS in the Main Transmission.
I'm not stating these as facts as I probably don't have the experience and knowledge of some on this page as I only had 30 years on Bells.

Looks like the ATSB is focussing on a birdstrike of all things? I don't think anyone considered that possibility before - though it has happened previously, when an Osprey came through the left windscreen of a 206 at Southport. The ATSB report doesn't give much insight though one has to wonder what could have happened if it came through the right side...

It's not the first and it won't be the last. Many years ago a chap in the US was flying a 206 at night over a city and a bird strike rendered him unconscious for an unkown length of time, woke up and landed, fortunately his 206 had some sort of autopilot looking after the office. Again in the US was a fatal to all on board a S-76 which had a bird come through the windscreen. Where I spent most of my time wedge tails were prominent, along with large number of Ibis and the odd pelican, one of our S-76 aircraft had a strike with a large bird of unkown description, hit at the top of the windscreen divider, knocked both fire handles out of the detent causing both generators to drop off line which then caused loss of the SAS, bird then went up into the rotor which then slapped the bird down through the cabin roof into the passengers laps. Be careful out there.

This PA-28 survived an encounter with an eagle in the Melbourne area some years ago. Many other types would have been uncontrollable after such an impact. It missed the windscreen, glanced off the wing and hit the horizontal stabilizer. Buckles in the rear fuselage skin RHS.
https://cimg8.ibsrv.net/gimg/pprune....c5eff22c0c.jpg

Wedgies being at the top of the heap will not get out of the way. You can even fly right up alongside them in formation and they are not really concerned.

After they released calicivirus to kill rabbits in Australia it took away some of the food chain for Wedgies and the easier option for them was "road kill". Some horror stories of them being run over by vehicles for the same reason.

Not relevant in this case so much but with later types of helicopter that are much quieter it is a bit disconcerting how close you can get to some birds before they move out of the way to the point where you actually need to change the way you operate in some areas and/or be aware of it.

KRviator listed extracts from the ATSB preliminary report but not this sentence: "The carcass and samples taken from the helicopter’s main transmission cowling were identified as Aquila audax (commonly known as a wedge-tailed eagle)". I wonder if this is any indication that the eagle struck near the rotorhead? Not sure how blades cope with birdstrikes, but you would certainly have to wonder how a pitch control linkage would cope with such an impact. If it was bent, blade would experience sudden pitch increase.

Just came across this footage on YouTube of a bird strike (or near miss) of what is apparently Robinson R44 Clipper VH-ROO flying at 700 ft near Lake Macquarie in Australia. Still photo at start of the video seems to indicate bird was flying in generally the same direction as the helicopter(?). The footage shows just how rapidly the bird comes into view. In this case, the pilot appears to have reacted swiftly in an effort to prevent a strike: