AW139 Crash in Bahamas - 7 Killed
Thank you for inserting bold type John - very kind of you to point out my dopey error.
I read it again and as far as I can see FH is asserting that there are people here insinuating that the accident was caused by inept pilots screwing up. I am one who suggested that a possible cause of the accident due to the circumstances is one of loss of control due to loss of situational awareness and that can happen to anyone. The only person who has used those terms in FH himself.
Paco - note above.
I read it again and as far as I can see FH is asserting that there are people here insinuating that the accident was caused by inept pilots screwing up. I am one who suggested that a possible cause of the accident due to the circumstances is one of loss of control due to loss of situational awareness and that can happen to anyone. The only person who has used those terms in FH himself.
Paco - note above.
That while no human is perfect (hence the repeated mention of "it can happen to all of us", it actually mustn't happen to none of us.
One obvious hypothesis arises from the report along these lines; loss of one tail rotor blade, a huge resultant one per tail vibration which in turn results in the tail rotor, tail rotor head and associated structure separating from the aircraft. CG shifts forward, perhaps beyond the capability of the available at cyclic range to correct etc etc.
That is indeed the first picture that comes to ones mind when reading the prelim. All four blades detached, one completely missing and the TRGB torn off matches all too well a situation where one blade departs.
When considering that the tail was found 500ft away and the wreckage was in only 16ft of water plus the Eye witness report of spinning lights (basically ruling out extreme forward velocity which could otherwise explain the tail ending up 500ft away) it is very hard to conceive that all this would be the mere result of the impact. Can't be completely ruled out, but Occam's razor would have a pretty clear verdict here...
I think I will also send my jury away to gather more evidence. If there is a mechanical failure which cannot be isolated to that particular aircraft or a run of MSNs, it could be a large exercise to potentially inspect the whole 139 fleet.
At some point if it is reasonably suspected that a Tail Rotor Blade did depart the aircraft and cause the accident....there will in all likelihood be an AD issued to inspect the Tail Rotor for certain defects or evidence of a pending failure.
If I owned some 139's I would consider getting a head start on that possibility and undertake a one time fleet-wide inspection as a purely precautionary action.
Not knowing what exactly to look for....just some added emphasis to the existing maintenance actions in place could not hurt.
Just Saying!
If I owned some 139's I would consider getting a head start on that possibility and undertake a one time fleet-wide inspection as a purely precautionary action.
Not knowing what exactly to look for....just some added emphasis to the existing maintenance actions in place could not hurt.
Just Saying!
Right about the inspection SAS. Be nice to know the TR head and blades hours too. If there was a separation, and they have the TR head hardware, determining if there was a separation and the cause etc will hopefully be straightforward metal fatigue analysis etc, but one never knows. If it goes down this road the NTSB should be out with inspection guidance and/or other related instructions before too long.....you’d expect. To be honest, I’m still very interested in the mechanism resulting in the main blade stubs and their attaching hardware not still being attached to the hub ( yes, I saw the dampers hanging there ).
GB: good input and thanks for that data point. Would appear to contradict the hypothesis I postulated. In the case you cited, was any of the tail fin and cone structure separated, as has been reported in this case?
GB: good input and thanks for that data point. Would appear to contradict the hypothesis I postulated. In the case you cited, was any of the tail fin and cone structure separated, as has been reported in this case?
Last edited by JohnDixson; 28th Jul 2019 at 15:33. Reason: Additional info and question
I know most anything is possible when rotor blades, main or tail, depart the aircraft.
We seem to isolate the events when there is a chance a Main Rotor blade departing could lead to the other Main Rotor blade leaving too....and perhaps one of them taking out a Tail Rotor blade in the process thus kicking off the loss of the other Tail Rotor blades.
Hopefully, the missing TR blade will be found and the NTSB can determine what components failed or were catastrophically damaged should all this be caused from a mechanical failure.
We seem to isolate the events when there is a chance a Main Rotor blade departing could lead to the other Main Rotor blade leaving too....and perhaps one of them taking out a Tail Rotor blade in the process thus kicking off the loss of the other Tail Rotor blades.
Hopefully, the missing TR blade will be found and the NTSB can determine what components failed or were catastrophically damaged should all this be caused from a mechanical failure.
There were 13 POB so that is a lot of forward CofG with all those bits missing off the back end. As I mentioned, the aircraft was controllable and a successful landing on the water was carried out with no injuries to any passengers.
Thanks. Just had a look at that machine on floats in the harbor right after the landing. Whoever was flying did all of the right things-fantastic effort.
The question of the controllability/CG would, in the Bahamas case, then rest on whether the separate pieces of that tail cone came off in the air or at water impact. Associated with that question is the physical evidence of the ripped metal edges shown in the rear of the main fuselage in the pictures taken at the recovery of wreckage. The structure in that area has to be quite substantial and strong due to the flight loads and hard landing loads design requirements. Never say never in aviation, but I’m having difficulty convincing myself that the water impact alone did all that. Well, we’ll see, one of these days.
The question of the controllability/CG would, in the Bahamas case, then rest on whether the separate pieces of that tail cone came off in the air or at water impact. Associated with that question is the physical evidence of the ripped metal edges shown in the rear of the main fuselage in the pictures taken at the recovery of wreckage. The structure in that area has to be quite substantial and strong due to the flight loads and hard landing loads design requirements. Never say never in aviation, but I’m having difficulty convincing myself that the water impact alone did all that. Well, we’ll see, one of these days.
Wait...what? The t/r gearbox separated from the fin? And one of the four t/r blades has not been found? Hmm. I know that a lot of you had leapt to the conclusion that two inept pilots screwed up. And I know it's tempting to use our vast knowledge of helicopters to pontificate on meaningless internet forums so we can prove to others how smart we are... But maybe we shouldn't be so quick to judge? My personal jury is still out on this one.
FH1100, where are you reading that the TGB separated? I can't find that anywhere.
Ohhhhh, I dunno. Maybe because the NTSB preliminary report said: "The tail rotor assembly, which was also separated was subsequently recovered." I guess I assumed that to mean the t/r gearbox came off, but now that I think about it, maybe just the tail rotor itself came off and not the whole gearbox? Beats me.
Yeah. To me, Tail Rotor Assy means just that. The Tail Rotor. And their definition of that may also be a bit hazy. How much of the tail rotor? Was the hub left on the output shaft or was the output shaft broken off and still attached to the tail rotor?
I've not seen any photos of the tailboom to see what is still attached. And as for the boom being 500ft away from the wreckage..... It weighs practically nothing for the size of it. It should float for quite a while, drifting away from the main wreckage and of course the fuselage doesn't come to rest at the point of impact. It too is travelling at speed.
And seeing as I'm here
I'll address all the posts about the "new" tailbooms that came out after the Qatar incident. They aren't new. The AIN news bulletin is wrong. It says "The new boom will employ a different composite technique and use an aluminum skin bonded to honeycomb, according to one U.S.-based AW139 customer who spoke to AIN."That is not correct. The tailboom always had an external Alloy skin. What changed was the honeycomb. They went from nomex honeycomb to alloy honeycomb. There is an Optional bulletin to change your tailboom over from nomex to alloy honeycomb but boy oh boy is it expensive. The other relevant bulletin is the one that has the external longerons put on (which this aircraft has). That removes all the repetitive inspections and AD's for the boom.
There is now a new boom on the 7000kg machines. They wanted to reduce weight and complexity so went with the same honeycomb fin but a conventional boom of sheet metal, frames and stringers, with no honeycomb. Looks exactly the same on the outside.
The boom failing in flight is an extremely remote possibility. Same with a TR Blade failing in flight. The new blades have had no issues since coming into service many years ago.
Need more info from NTSB to rule out possible scenarios.
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 413 Likes
on
218 Posts
Surely, if a MR blade was shed in flight, the resulting out of balance forces would dislodge the main rotor gearbox attachments.
In the two 225/332 events....did the gearbox depart either or both aircraft prior to final impact?
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 413 Likes
on
218 Posts
If you mean the tragic accident where the top of the main gearbox departed, complete with the rotor head and all four blades still attached, there wouldn't be the same out of balance forces as if a single blade came off.
Whoever was flying did all of the right things-fantastic effort.
That would be Richard Moffat, exceptional pilot that I’ve had the pleasure to crew with. And he did that ditching directing a low time national copilot to correctly manage the throttles.
Last edited by malabo; 29th Jul 2019 at 19:04.
You are quite right Shy....but there would have been some very unusual forces for sure....and the question was actually about the stress damage to the gearbox mounts.
My question was not clear enough upon re-thinking it.
There was the third crash where a main blade did let go....and I cannot recall if that gear box departed following the one blade.
I am looking for that video....but am having trouble remembering where that occurred.
Found it......it appears the gearbox stayed with the aircraft but the video is very short and the aircraft falls behind a building immediately after the blade separates and the rest of the rotor head departs.
My question was not clear enough upon re-thinking it.
There was the third crash where a main blade did let go....and I cannot recall if that gear box departed following the one blade.
I am looking for that video....but am having trouble remembering where that occurred.
Found it......it appears the gearbox stayed with the aircraft but the video is very short and the aircraft falls behind a building immediately after the blade separates and the rest of the rotor head departs.
Noooby, the report reads:
”The helicopter was found inverted and the tailboom was separated from the aft fuselage and was recovered in multiple pieces.”
This begs an explanation for the “multiple pieces “.
”The helicopter was found inverted and the tailboom was separated from the aft fuselage and was recovered in multiple pieces.”
This begs an explanation for the “multiple pieces “.
Watch this video.....and count the pieces!
I wonder where the tail rotor blades wound up after this tragedy?
I wonder where the tail rotor blades wound up after this tragedy?
Join Date: Jan 2007
Location: here and there
Age: 67
Posts: 139
Likes: 0
Received 0 Likes
on
0 Posts
Latest letter issued from Leonardo, does not appear they think there was any mechanical failure !!
Following AW139 accident that occurred near Big Grand Cay Island, Bahamas on July 4th, 2019, Leonardo Helicopters immediately dispatched a team to offer support to the recovery and investigation and continues to work closely with the Investigating Authorities.
At this point, Leonardo Helicopters do not envisage the need to take any airworthiness actions as a result of present investigation outcomes
Following AW139 accident that occurred near Big Grand Cay Island, Bahamas on July 4th, 2019, Leonardo Helicopters immediately dispatched a team to offer support to the recovery and investigation and continues to work closely with the Investigating Authorities.
At this point, Leonardo Helicopters do not envisage the need to take any airworthiness actions as a result of present investigation outcomes
