Blackhawk Crash Alabama
Wasn't there an accident in the late 1970's that put one aircraft in the water in a similar manner to this latest accident?
It might have been at PAX River....but had two Sikorsky Pilots onboard?
Found it....not at PAX River....but near the Factory.
https://aviation-safety.net/wikibase/77705
It might have been at PAX River....but had two Sikorsky Pilots onboard?
Found it....not at PAX River....but near the Factory.
https://aviation-safety.net/wikibase/77705
Thats the same UH-60 airframe colloquially known as the lumberhawk from the Kentucky incident a few years earlier.
It happened before my time at SA, We were briefed that the aircraft was in a high hover over the Housatonic River. The Stabilizer failed in the full trailing edge down position when the pilots pitched over to accelerate into forward flight. The pilots were not able regain manual control in time to prevent contact with the water. The functionality of Stab manual control switch was brough into question and ultimately secondary control switches were installed in front of each pilots cyclic grips.
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The tail rotor blade failure sometimes colloquially called “blade collapse” could be another crash initiating event. The metallic pitch horn / snubber housing can disbond from the tail blade skins and cause progressive failure as the blade trailing edge unzips, allowing the horn to migrate further outboard, which unzips the skins further and eventually the blade is largely destroyed. Sometimes the horn migrating outboard keeps the tail rotor 1P somewhat in a tolerable zone and the consequence is a loss of tail rotor authority. Sometimes the tail rotor 1P is more severe and the TR gearbox and rotor assy leaves the aircraft.
Hopefully the investigators determine the actual cause instead of us keyboard engineers yammering at each other.
Hopefully the investigators determine the actual cause instead of us keyboard engineers yammering at each other.
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I was going to be mean and rag on an “expert” the local media interviewed on this incident, but then I thought about it and he was doing basically the same thing as we are here, except his speculation wasn’t as informed as ours.
The main comment that I took issue with was this one:
“Helicopters probably don’t have a flight data recorder or a cockpit voice recorder, so what they’ll do is just basically try to… investigate the accident and try to see what, if any, failures of any components,” Williams said. “I would basically look at the main rotor first and of course the tail rotor.”
I guess flight data/CVR isn’t common in the civil rotorcraft world? The H-60 surely does have both, hopefully the IVHMU where they are contained survived.
In the same article it was stated the aircraft was enroute to Madison County Executive airport, I had assumed they had departed from Redstone Arsenal or Huntsville International, I guess because I perceived some forward motion of the aircraft when there wasn’t any.
The main comment that I took issue with was this one:
“Helicopters probably don’t have a flight data recorder or a cockpit voice recorder, so what they’ll do is just basically try to… investigate the accident and try to see what, if any, failures of any components,” Williams said. “I would basically look at the main rotor first and of course the tail rotor.”
I guess flight data/CVR isn’t common in the civil rotorcraft world? The H-60 surely does have both, hopefully the IVHMU where they are contained survived.
In the same article it was stated the aircraft was enroute to Madison County Executive airport, I had assumed they had departed from Redstone Arsenal or Huntsville International, I guess because I perceived some forward motion of the aircraft when there wasn’t any.
Definitely not common in the US and it has been a complaint by the NTSB for years. After they participated in the Finnish Copterline 103 S76 (which did have a CVFDR fitted) accident investigation they formally wrote to the head of the FAA. https://www.ntsb.gov/safety/safety-r.../A06_17_18.pdf
Europe has mandated them for offshore and Part 29 aircraft for many years, and they have been invaluable.
Europe has mandated them for offshore and Part 29 aircraft for many years, and they have been invaluable.
FYI: that changed about 10 -15 years ago. Most GOM twins have CVR/FDRs installed even thought the rules didn't require. Part 135 was updated about 10 years ago to require recorders in certain twins. You even found them in EC135s when they flew the GOM. There is also a move to install in single turbines with some operators doing that now. The problem years ago was there wasn't a recorder that would "fit" in small single turbine helicopters. Now there are several smaller recorder options with STCs which have made their way into some EMS singles.
FYI: that changed about 10 -15 years ago. Most GOM twins have CVR/FDRs installed even thought the rules didn't require. Part 135 was updated about 10 years ago to require recorders in certain twins. You even found them in EC135s when they flew the GOM. There is also a move to install in single turbines with some operators doing that now. The problem years ago was there wasn't a recorder that would "fit" in small single turbine helicopters. Now there are several smaller recorder options with STCs which have made their way into some EMS singles.
Remember this accident involves a US Army Black Hawk helicopter and the Aircraft Spec is derived from US Army Specifications not the FAA or NTSB.
Also, the NTSB can suggest only and it is up to the FAA to require such devices.
The NTSB has made many such "suggestion" that the FAA has refused/failed to implement.
Also as Wrench rightly points out there are legitimate issues that have been a hinderance.
It is not just the Operators that are the problem.
Also, the NTSB can suggest only and it is up to the FAA to require such devices.
The NTSB has made many such "suggestion" that the FAA has refused/failed to implement.
Also as Wrench rightly points out there are legitimate issues that have been a hinderance.
It is not just the Operators that are the problem.
Re the 8/9/76 11:15PM event at Ft Campbell. Received a call at home 30 min later, and before noon on the 10th a small Sikorsky team led by Bob Zincone (who had taken over development of the UH-60 in January 1975, after three months of flight test) was on the ground at Ft Campbell.
Note: Have three pics that amplify the situation but even though saved as Jpegs-cannot get them to open for transmittal here.
One main blade displayed a peeled back outer surface, initiated at the point where the blade meets the tip cap. That peeling extended maybe 15 ft inboard and some of the Nomex honeycomb was lost with it. Blade aerodynamics changed dramatically.
Crew was flying a simulated infantry lift, with a squad in the cabin with weapons etc.
Flying a a few hundred feet and 145 KIAS or so, the peeling caused immediate and high one per rev vibrations that even made the primary servo caution capsule blink a few times. ( remember, this was prior to availability of NVG’s ). Decision to land immediately was made and they did that, coming down so vertically that the tail rotor took divots out of the same side of a pine tree as they descended. ( Hopefully the picture I have of one of the other three blades having come to a stop against one of the pine trees with a couple of them that had been hit and broken off by the main blades during landing will be available for later viewing-its a saved jpeg and therefore should work here, but doesn’t ).
There was one injury: upon landing the squad leader told the squad to follow him as he was jumping out of the right cabin. BUT, it was dark, and the ship had come down straight alongside one of the pines so the Sgt went about 12 inches and bloodied his nose on the pine tree.
The SA group had brought some gear and did borescoping of the drive train boxes and engines and found no evidence of sudden stoppage. The UTTAS program included a requirement for blade etc replacement capability in the field, so the contingent of Army maintenance folks ( trained by SA-the same sort of group existed on the Boeing side ) unlimbered the portable maintenance crane and started removing/replacing the rotors. Another team of troops from the 101st* arrived with chain saws etc and started clearing the area where the UH-60 main rotor had started a clearing-unintended.
* Ft Campbell is home to the 101st Airborne Division
That work continued into the next day-followed by doing ground runs for main/tail track and balance ( all done by the Army crews ), and on the next morning ( the 11th ) the Army crew flew it back to the cornfield which was the base of operations for the field evaluation. Army flight regulations required a check ride by a standardization pilot for the two aviators involved , so, the Army not yet having same, it was agreed that I play that roie and in order not to mess up their flight schedule, those two checkrides started at midnight ( as I mentioned-this was the 101st ). Those blades and that drivetrain remained with that aircraft.
We found that our manufacturing procedure was at fault. There are three wraps of fiberglass at differing angles which form the outer blade skin. Out at the end of the blade, we had done a straight cut though the skin. The peeling started there. Corrective action was to change the design by folding the skin over and underneath, closing off the edge.
Note: Have three pics that amplify the situation but even though saved as Jpegs-cannot get them to open for transmittal here.
One main blade displayed a peeled back outer surface, initiated at the point where the blade meets the tip cap. That peeling extended maybe 15 ft inboard and some of the Nomex honeycomb was lost with it. Blade aerodynamics changed dramatically.
Crew was flying a simulated infantry lift, with a squad in the cabin with weapons etc.
Flying a a few hundred feet and 145 KIAS or so, the peeling caused immediate and high one per rev vibrations that even made the primary servo caution capsule blink a few times. ( remember, this was prior to availability of NVG’s ). Decision to land immediately was made and they did that, coming down so vertically that the tail rotor took divots out of the same side of a pine tree as they descended. ( Hopefully the picture I have of one of the other three blades having come to a stop against one of the pine trees with a couple of them that had been hit and broken off by the main blades during landing will be available for later viewing-its a saved jpeg and therefore should work here, but doesn’t ).
There was one injury: upon landing the squad leader told the squad to follow him as he was jumping out of the right cabin. BUT, it was dark, and the ship had come down straight alongside one of the pines so the Sgt went about 12 inches and bloodied his nose on the pine tree.
The SA group had brought some gear and did borescoping of the drive train boxes and engines and found no evidence of sudden stoppage. The UTTAS program included a requirement for blade etc replacement capability in the field, so the contingent of Army maintenance folks ( trained by SA-the same sort of group existed on the Boeing side ) unlimbered the portable maintenance crane and started removing/replacing the rotors. Another team of troops from the 101st* arrived with chain saws etc and started clearing the area where the UH-60 main rotor had started a clearing-unintended.
* Ft Campbell is home to the 101st Airborne Division
That work continued into the next day-followed by doing ground runs for main/tail track and balance ( all done by the Army crews ), and on the next morning ( the 11th ) the Army crew flew it back to the cornfield which was the base of operations for the field evaluation. Army flight regulations required a check ride by a standardization pilot for the two aviators involved , so, the Army not yet having same, it was agreed that I play that roie and in order not to mess up their flight schedule, those two checkrides started at midnight ( as I mentioned-this was the 101st ). Those blades and that drivetrain remained with that aircraft.
We found that our manufacturing procedure was at fault. There are three wraps of fiberglass at differing angles which form the outer blade skin. Out at the end of the blade, we had done a straight cut though the skin. The peeling started there. Corrective action was to change the design by folding the skin over and underneath, closing off the edge.
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Pine trees are pretty soft and flexible at that size......Bamboo although flexible is much tougher material.
Good thing it was not mature Oak Trees.
Good thing it was not mature Oak Trees.
The NTSB has no such obligation - they can recommend anything they see as having potential value.
To be fair, the FAA has to follow processes - including a cost/benefit analysis and public comments (can be bypassed only if it's judged to be an air safety emergency). Plus, the FAA moves at the speeds of bureaucracy (i.e., slow, slower, and slowest).
The NTSB has no such obligation - they can recommend anything they see as having potential value.
The NTSB has no such obligation - they can recommend anything they see as having potential value.
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Saw this picture earlier:
Appears to show Tail Rotor Gearbox next to the tail
pylon, so the one theory that some of us had (including myself) of the gearbox departing the aircraft seems to not hold up at this point.
The IVHMU is mounted in the avionics equipment rack in the tailcone, approximately 3 feet aft of the main fuel cells. If the tail pylon is in this condition perhaps the tailcone/aft transition section is in a similar state.
The post crash fire would be the big hurdle the CVR/FDR needed to survive.
Also confirms that was a UH-60L.
Appears to show Tail Rotor Gearbox next to the tail
pylon, so the one theory that some of us had (including myself) of the gearbox departing the aircraft seems to not hold up at this point.
The IVHMU is mounted in the avionics equipment rack in the tailcone, approximately 3 feet aft of the main fuel cells. If the tail pylon is in this condition perhaps the tailcone/aft transition section is in a similar state.
The post crash fire would be the big hurdle the CVR/FDR needed to survive.
Also confirms that was a UH-60L.
Any sign of the Main Rotor Blades?
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Sasless,
I think there might be a piece of one in the larger picture, I had cropped it down for clarity. I couldn’t tell if it was Main or tail rotor fragment honestly.
I think there might be a piece of one in the larger picture, I had cropped it down for clarity. I couldn’t tell if it was Main or tail rotor fragment honestly.
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Screenshot from latest edition of Flight Fax:
I hope this doesn’t mean the end of the investigation, but it appears they don’t have any idea what happened at this point, and may never know.
FltMech
I hope this doesn’t mean the end of the investigation, but it appears they don’t have any idea what happened at this point, and may never know.
FltMech