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Originally Posted by wrench1
(Post 11864799)
Looking at an "enhanced" version of the full video posted above, the tailboom folded in the same plane as though the LH mount(s) failed. And with the 5 degree offset of the vert fin it seemed to follow that...
In #97 Obba posted a link to a Juan Browne review of the accident and at 6:10 he is of the opinion that the main rotor with its gearbox parted first, but that differs to what most here interpret as what happened, namely that the tail rotor and part of tail boom separated first. That is how I also interpret the various videos when considered together. But many components, including cowlings, must have separated from the main fuselage on the way down, so hard to say what is actually seen in the footage. |
An enhanced version of the photo from the NY Post article. Original photo Christopher Sadowski
https://cimg7.ibsrv.net/gimg/pprune....e38086e3ea.jpg |
Originally Posted by FH1100 Pilot
(Post 11864841)
We know that the owner of the company did say that the pilot of the L-IV reported that he needed to refuel upon landing. The RUMOR that I heard was that the situation was much more critical than simply "needing to refuel." The RUMOR is that he ran it down and it flamed out, and then he mishandled the engine failure. I know, I know...it's wrong to be casting aspersions like this so soon. But it might fit the scenario and offer some explanation. If the pilot was slow in responding (or responded incorrectly) to the engine failure, a yaw could have occurred and the sideslip might have been `sufficient to break the tail boom off. Why the transmission came off...I don't know. The videos of the crash do seem to show that the airframe yawed (one way or the other - hard to tell) just prior to everything coming apart. |
Originally Posted by helispotter
(Post 11865046)
wrench1: I assume you are referring to an 'enhanced' version of the video posted on Reddit?
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Originally Posted by Kulwin Park
(Post 11865055)
"IF" fuel was critically low....
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Originally Posted by 212man
(Post 11864844)
But in the longer video it is clear that the break up starts before the MGB detaches, so that doesn't really match that theory - does it? Or maybe I misunderstood?
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Originally Posted by TowerDog
(Post 11865032)
This was the pilot, an ex Navy Seal according to New York Post.
https://nypost.com/2025/04/11/us-new...-sean-johnson/ I wonder if he was a Gunners Mate attached (at some time or another) to a support unit in support of a SEAL team or if he actually graduated from BUDS training. |
Originally Posted by Mozella
(Post 11865087)
Some reports imply that he flew helicopters in the Navy, but I'm pretty sure he was an enlisted man, not a Naval Aviator. One report says he learned to fly at Embry Riddle. Someone claiming to be his shipmate says he served with him on an aircraft carrier as a Gunners Mate.
I wonder if he was a Gunners Mate attached (at some time or another) to a support unit in support of a SEAL team or if he actually graduated from BUDS training. Was up shooting some air to air today in a 407 here in Florida and have to say kept thinking back to what happened in NY the other day and for the first time in a long time I had the nerves going. Even at 500ft high its still a long way down. May they Rest in Peace. :( |
One photo of him appeared to be as he sat in the right hand seat of a Blackhawk....might that have been taken during his time in Montana?
There are numerous photos of him at the Billings Face Book page including one of him flying a Chinook during the firefighting season. |
This talk of the fuel call being a disguised mayday is fanciful at best. He called for fuel as he no doubt needed fuel, probably like he would do 10 times or more per day! Presumably to get the fuel guy/gal out at the pad ready to hot-fuel, saving time and money.
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Originally Posted by Kulwin Park
(Post 11865055)
"IF" fuel was critically low, wouldn't the pilot elect to land at that jetty when the fuselage crashed, or opt to inflate the skid fitted float bags, and just land safely on the water or the jetty? (maybe experienced pilots could comment)
I can't see why you would risk losing an aircraft for another 3 minutes flying back to base when there was other landing options. All this is speculation based on the low fuel theory presented. It simply appears that the pilot requested that he might need re-fueling on landing, as one assumes he had another flight. |
Considering the StrechedBanger was made from the 70's through to around 2017, with thousands made, and an enormous amount of flight hours, it is a proven platform.
There is no indication what actually happened nor the root cause. It is not used for scheduled passenger services, nor can it carry hundreds of people, which authorities tend to treat with much greater caution. You could speculate that one of the mounts failed, as was made further up in this discussion. If that were the case, there have been 3 previous accidents, all which survived, two landed in one piece, one rolled over, and were ultimately attributed to inadequate maintenance. They all involved partial loss of control, and reports of the nose pitching up and a roll to the left. On such a mature type, It is highly unlikely that this an inherent flaw, or something previously undiscovered. |
"It is not used for scheduled passenger services"
Oddly enough, it has been, in what was then the largest helicopter network, between Glasgow and various destinations in the west of Scotland, including Fort William, Oban, Rothesay, etc. with a list of exemptions as long as your arm. It was a safe machine then and it is now - this I feel is a one-off, like the incidents with the 212 and TT straps. As bell ringer says, it is a proven platform and I believe it was at one time (if not still) the safest single engined aircraft, based on hours flown. |
You’d need to ask yourself, which is more likely?
1. Tail boom folds and subsequently the main gearbox disconnects 2, The main gearbox disconnected and the tail boom folded |
Some will assume, because it is the first thing we see, that the tailboom failure was the cause. However, it's what we can't see that matters.
My feeling is that the tail folding was secondary to the transmission, or mountings, letting go. (But if you are a follower of British tabloids, it was definitely the Jesus nut) :suspect: |
Originally Posted by Bell_ringer
(Post 11865231)
My feeling is that the tail folding was secondary to the transmission, or mountings, letting go.
What I’m wondering is if it was a catastrophic transmission failure, would the blades keep spinning for an auto rotation, as once the blades and transmission left the fuselage, they were freely rotating with the transmission hanging below, so the transmission wasn’t seized? It’s not possible surely that the blades AND transmission were spinning through the air is it? (Thinking of a child’s toy here) What about the engine, quite often in these events, something let’s go and the engine rpm goes through the roof; does anyone hear an engine in any of the videos? Mike Pateys turbine Lancair went from cruise RPM to zero in about a second, I fully expected that to at least tear the engine off the mounts or at least some torsional damage, but seemingly nothing. |
Originally Posted by Squawk7700
(Post 11865228)
You’d need to ask yourself, which is more likely?
1. Tail boom folds and subsequently the main gearbox disconnects 2, The main gearbox disconnected and the tail boom folded https://asn.flightsafety.org/wikibase/188940 |
If the MRGB is allowed to move (as a result of one of the nodal beams or other fixings giving way), it would twist the TR drive out put which could, feasibly, create enough imbalance and drag along the TRD shaft to overstress the boom and cause it to fail.
What is puzzling is that it looks like the rotors take only the top part of the MRGB with them when they separate rather than ripping the whole gearbox out. Whatever the initial trigger, it rapidly becomes a catastrophic in flight breakup which even the best pilot in the world wouldn't survive. |
Originally Posted by SilsoeSid
(Post 11865251)
A case, (re post 80 above)…
https://asn.flightsafety.org/wikibase/188940 |
Squawk7000 - I guess this is the paragraph you are referring to in that report
Although the precise forces and moments involved in failing the helicopter structure have not been quantified, calculation has shown that, if the engine affected is neither automatically nor (rapidly) manually shutdown, rapid re-engagement of a slipping freewheel has the potential to cause structural failure of the tail boom. Defining such forces is difficult because the exact timeframe over which the re-engagement occurs has a significant effect on the torque felt through the transmission and by the airframe; an instantaneous re‑engagement would theoretically generate an infinite load. Physical examination of the components could not refine the time parameter, but calculations suggested that a re-engagement occurring over a fraction of a second could cause structural airframe damage. Re-introducing two components turning at different speeds when they are designed to drive at the same speeds is a recipe for disaster - see the Wessex crash in the Welsh lake back in the early 90s - that was a disconnect coupling allowing the TR to slow down and then taking up the drive again as the yaw input was changed. |
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