Osprey down off Japan, body sighted
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They are probably getting some info from USAF on the material failure, and are likely doing some one time inspections.
PS: Ward Carroll's video is freaking excellent.
PS: Ward Carroll's video is freaking excellent.
This article should raise some questions.
800 Hour Time Life Component based upon what criteria and data?
Engagement issues seen quite differently by the USMC and USAF.....are they sharing information and working off the same sheet of music?
Why the inability to determine what is actually causing the problem seen in all versions of the aircraft that is seen as a "just live with it" kind of problem?
This accident investigation is going to be very closely scrutinized by Safety experts I am thinking.....as much for how the three services have approached the problem.
https://www.wsj.com/politics/nationa...le_email_share
800 Hour Time Life Component based upon what criteria and data?
Engagement issues seen quite differently by the USMC and USAF.....are they sharing information and working off the same sheet of music?
Why the inability to determine what is actually causing the problem seen in all versions of the aircraft that is seen as a "just live with it" kind of problem?
This accident investigation is going to be very closely scrutinized by Safety experts I am thinking.....as much for how the three services have approached the problem.
The official report into that crash said Ospreys suffered 15 hard clutch engagement failures in roughly 680,000 flight hours. The investigation couldn’t find the root cause but found older aircraft tended to be more vulnerable, so the military mandated that a key gearbox part be replaced after 800 flight hours. It said that would reduce the odds of the problem occurring by 99%, without explaining how it reached that figure.
The Pentagon has awarded the joint venture between Textron’s Bell unit and Boeing contracts worth more than $60 million for new gearbox designs and systems to detect vibrations that might lead to failures. The Pentagon has already undertaken a range of design fixes for the Osprey, many of them ongoing, and revised training programs.
The Pentagon has awarded the joint venture between Textron’s Bell unit and Boeing contracts worth more than $60 million for new gearbox designs and systems to detect vibrations that might lead to failures. The Pentagon has already undertaken a range of design fixes for the Osprey, many of them ongoing, and revised training programs.
https://www.wsj.com/politics/nationa...le_email_share
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And range. After that the pro's and con's get more complex. Payload, purchase & operating costs and training and support requirements all move in favour of conventional helicopters. Tiltrotors offer a unique capability but at a high cost. Like everything military, if you need a capability and there's no other way to achieve it the cost can be justified.
SAS: in reading the WSJ article ( and the other stories I’ve seen to date ), I haven’t seen a statement as to how many hours were on the clutches in the Japan fatal.
Not being critical of the folks at Bell/Boeing working on this issue. It is very possible the condition of the crash damaged components has been such that determination of the failure mode is anything but clear. Or something similar. Maybe one or two key pieces have not been found. Whatever it is, it will be very frustrating to the group working the problem. Been involved in one of those….that took 6 months. Pretty sure it had a longevity effect on the good man in charge of that effort.
Not being critical of the folks at Bell/Boeing working on this issue. It is very possible the condition of the crash damaged components has been such that determination of the failure mode is anything but clear. Or something similar. Maybe one or two key pieces have not been found. Whatever it is, it will be very frustrating to the group working the problem. Been involved in one of those….that took 6 months. Pretty sure it had a longevity effect on the good man in charge of that effort.
Salvage vessel now arrived and in place, preparing to lift wreckage. (23 Dec., NHK report in Japanese)
オスプレイ墜落事故 機体主要部分を回収するサルベージ船到着 | NHK | オスプレイ
オスプレイ墜落事故 機体主要部分を回収するサルベージ船到着 | NHK | オスプレイ
I have hopes that the clutch issues will be resolved, the tilt rotor designs need the drive transfer system to be reliable and to be engaged when required. Differential torque transmission is always going to be challenging, whether the engines are fuselage or pod mounted.
Brand, A., Kisor, R., & Blyth, R. (2004). V-22 HIGH RATE OF DESCENT (HROD) TEST PROCEDURES AND LONG RECORD ANALYSIS.
What does VRS have to do with this accident?
The witness reports the aircraft was on fire and a PropRotor departed the aircraft before it impacted the sea.
Not much to support the onset of VRS as being a contributing factor in that being true.
Are we diverging from the topic of this thread?
The witness reports the aircraft was on fire and a PropRotor departed the aircraft before it impacted the sea.
Not much to support the onset of VRS as being a contributing factor in that being true.
Are we diverging from the topic of this thread?
For this accident, VRS is not a likely factor, however, taking eyewitness accounts to narrow the scope of the investigation is not a great plan. The clutch and the VRS-related power fluctuations do have potential to be related. The envelope for VRS is well established, and should not 20 years later be a factor, but it was raised in the posts.
Do you suggest that a Prop-Rotor departed in flight? What is the source of that information? The Japanese PM noted that the left engine was apparently "on fire" and a later report indicated that the aircraft rolled over "180" degrees" to being upside down. Those are consistent with a failure of drive, and that comes back to anything that relatest to torque transfer to the prop rotor, which includes the clutch system. There have been enough hard engagements to be of concern, and the consequences of a hard engagement can include a loss of drive to the rotor, which has a fair chance of spoiling everyone's day.
Autorotation is not covered in the MV22 NATOPS or PCL, Perhaps the dash-1 covers something in that area. The suggested power-off sink rate of 18 m/sec is fairly impressive. The 609 and XV-3 were autorotated, the XV-15 had the blade tested in the wind tunnel at NASA Ames, and was estimated to have a sink of 2400 fpm... At 60-80 kias, 18 m/sec is a mighty steep descent. Auto is moot if they are upside down, which suggests a transmission failure assuming that in straight and level cruise it is pretty hard to get into VRS. A drive failure spoils their day and is consistent with reported events.
I think that the V-22 is a neat aircraft, but it has issues, the transmission/clutch is one matter, and the remote possibility of autorotation doesn't make for comfort in a combat aircraft. The IFR handling is tolerable and while it may occasionally be marginal according to the flight test reports early on in some phases, it is within acceptable standards.
[1] Maisel, M. D., Giulianetti, D. J., & Dugan, D. C. (2000). The History of the XV-15 Tilt Rotor Research Aircraft: From Concept to Flight.
[2] REPORT 301-099-005 NASA CONTRACT NAS2-8580. (1976). WIND TUNNEL TEST RESULTS OF 25-FOOT TILT ROTOR DURING AUTOROTATION.
[3] A1-V22AB-NFM-000 NATOPS FLIGHT MANUAL NAVY MODEL MV-22B TILTROTOR
[4] A1-V22AB-NFM-500 NATOPS PILOT’S/ AIRCREW POCKET CHECKLIST MV-22B TILTROTOR
[5] Trail, S. B. (2006). Evaluation of V-22 Tiltrotor Handling Qualities in the Instrument Evaluation of V-22 Tiltrotor Handling Qualities in the Instrument Meteorological Environment Meteorological Environment.
[5] 1-V22AB-NFM-500A1-V22AB-NFM-500
Do you suggest that a Prop-Rotor departed in flight? What is the source of that information? The Japanese PM noted that the left engine was apparently "on fire" and a later report indicated that the aircraft rolled over "180" degrees" to being upside down. Those are consistent with a failure of drive, and that comes back to anything that relatest to torque transfer to the prop rotor, which includes the clutch system. There have been enough hard engagements to be of concern, and the consequences of a hard engagement can include a loss of drive to the rotor, which has a fair chance of spoiling everyone's day.
Autorotation is not covered in the MV22 NATOPS or PCL, Perhaps the dash-1 covers something in that area. The suggested power-off sink rate of 18 m/sec is fairly impressive. The 609 and XV-3 were autorotated, the XV-15 had the blade tested in the wind tunnel at NASA Ames, and was estimated to have a sink of 2400 fpm... At 60-80 kias, 18 m/sec is a mighty steep descent. Auto is moot if they are upside down, which suggests a transmission failure assuming that in straight and level cruise it is pretty hard to get into VRS. A drive failure spoils their day and is consistent with reported events.
I think that the V-22 is a neat aircraft, but it has issues, the transmission/clutch is one matter, and the remote possibility of autorotation doesn't make for comfort in a combat aircraft. The IFR handling is tolerable and while it may occasionally be marginal according to the flight test reports early on in some phases, it is within acceptable standards.
[1] Maisel, M. D., Giulianetti, D. J., & Dugan, D. C. (2000). The History of the XV-15 Tilt Rotor Research Aircraft: From Concept to Flight.
[2] REPORT 301-099-005 NASA CONTRACT NAS2-8580. (1976). WIND TUNNEL TEST RESULTS OF 25-FOOT TILT ROTOR DURING AUTOROTATION.
[3] A1-V22AB-NFM-000 NATOPS FLIGHT MANUAL NAVY MODEL MV-22B TILTROTOR
[4] A1-V22AB-NFM-500 NATOPS PILOT’S/ AIRCREW POCKET CHECKLIST MV-22B TILTROTOR
[5] Trail, S. B. (2006). Evaluation of V-22 Tiltrotor Handling Qualities in the Instrument Evaluation of V-22 Tiltrotor Handling Qualities in the Instrument Meteorological Environment Meteorological Environment.
[5] 1-V22AB-NFM-500A1-V22AB-NFM-500
Last edited by fdr; 24th Dec 2023 at 07:51.
Ecce Homo! Loquitur...
Do you suggest that a Prop-Rotor departed in flight? What is the source of that information?
For what it’s worth I just watched the interview and the local bloke said the left engine (which was on fire) exploded with a ‘bang’ and he witnessed the propellor spinning off and away as the aircraft went down.
Osprey black box from fatal Japan crash found with data intact, U.S. Air Force says - Japan Today
WASHINGTON
The Air Force has recovered the flight data recorder from a CV-22B Osprey that crashed off the coast of Japan in late November with its data intact, which could provide valuable clues for investigators as to what caused the fatal accident. Eight Air Force Special Operations Command service members were killed in the Nov 29 crash, which occurred off the coast of Yakushima Island in southwestern Japan. The Osprey was on a routine training flight enroute to Okinawa. Finding the voice and data recorder, or “black box,” is a critical part of the accident investigation; some black boxes in previous Osprey accidents have not survived those crashes. The recorder is being sent to a lab for data retrieval and analysis of the data is expected to take several weeks, the Air Force said. In addition, the Navy salvage ship USNS Salvor was able to recover most of the Osprey's wreckage from the sea floor and transport it to Marine Corps Air Station Iwakuni for analysis. The Air Force was able to determine within days of the crash that a material failure — that something went wrong with the aircraft — and not a mistake by the crew — led to the deaths. The military's entire Osprey fleet has been grounded since Dec. 6. The government of Japan, the only international partner flying the Osprey, has also grounded its fleet.
WASHINGTON
The Air Force has recovered the flight data recorder from a CV-22B Osprey that crashed off the coast of Japan in late November with its data intact, which could provide valuable clues for investigators as to what caused the fatal accident. Eight Air Force Special Operations Command service members were killed in the Nov 29 crash, which occurred off the coast of Yakushima Island in southwestern Japan. The Osprey was on a routine training flight enroute to Okinawa. Finding the voice and data recorder, or “black box,” is a critical part of the accident investigation; some black boxes in previous Osprey accidents have not survived those crashes. The recorder is being sent to a lab for data retrieval and analysis of the data is expected to take several weeks, the Air Force said. In addition, the Navy salvage ship USNS Salvor was able to recover most of the Osprey's wreckage from the sea floor and transport it to Marine Corps Air Station Iwakuni for analysis. The Air Force was able to determine within days of the crash that a material failure — that something went wrong with the aircraft — and not a mistake by the crew — led to the deaths. The military's entire Osprey fleet has been grounded since Dec. 6. The government of Japan, the only international partner flying the Osprey, has also grounded its fleet.
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ASHINGTON (AP) — The Pentagon believes it has identified the mechanical failure that led to a fatal crash of an Osprey aircraft in Japan and the grounding of the fleet for two months, a U.S. defense official told The Associated Press.
The Pentagon’s Joint Safety Council is now working with the Air Force, Navy and Marine Corps on their plans to get Osprey crews ready to fly again, said Navy Rear Adm. Chris Engdahl, chairman of the council and commander of Naval Safety Command.
The Air Force investigation is continuing into the Nov. 29 Air Force special operations command CV-22 crash, which killed eight service members. The crash led to a rare grounding on Dec. 6 of about 400 Osprey aircraft across the three services. Japan also grounded its fleet of 14 Ospreys following the crash.
The official who said the mechanical failure had been identified declined to say what the failure was. It has opened the door to discussions on return to flight because mitigations can be put in place. The official was not authorized to discuss the investigation publicly and spoke on condition of anonymity.
The Pentagon’s Joint Safety Council is now working with the Air Force, Navy and Marine Corps on their plans to get Osprey crews ready to fly again, said Navy Rear Adm. Chris Engdahl, chairman of the council and commander of Naval Safety Command.
The Air Force investigation is continuing into the Nov. 29 Air Force special operations command CV-22 crash, which killed eight service members. The crash led to a rare grounding on Dec. 6 of about 400 Osprey aircraft across the three services. Japan also grounded its fleet of 14 Ospreys following the crash.
The official who said the mechanical failure had been identified declined to say what the failure was. It has opened the door to discussions on return to flight because mitigations can be put in place. The official was not authorized to discuss the investigation publicly and spoke on condition of anonymity.
The Air Force said Tuesday that investigators have determined a parts failure occurred during an Osprey crash in Japan in November that killed all eight airmen on board, but the root cause of the crash is still unknown.
Air Force Special Operations Command said in a statement that the two investigations into the deadly crash, a Safety Investigation Board probe and an Accident Investigation Board inquiry, are still ongoing.
"At this time, the material failure that occurred is known, but the cause of the failure has not been determined," Air Force Special Operations Command said. "Engineering testing and analysis is ongoing to understand the cause of the material failure, a critical part of the investigation."
This statement is odd.. Sounds like a part failure due to material failure, Sounds like they do in fact understand the material failure, but cannot explain how a material quality concern was not detected, nor an impending failure in a component. This does explain continued grounding however.
Air Force Special Operations Command said in a statement that the two investigations into the deadly crash, a Safety Investigation Board probe and an Accident Investigation Board inquiry, are still ongoing.
"At this time, the material failure that occurred is known, but the cause of the failure has not been determined," Air Force Special Operations Command said. "Engineering testing and analysis is ongoing to understand the cause of the material failure, a critical part of the investigation."
This statement is odd.. Sounds like a part failure due to material failure, Sounds like they do in fact understand the material failure, but cannot explain how a material quality concern was not detected, nor an impending failure in a component. This does explain continued grounding however.
Over-running clutches can fundamentally slip, and re-engage. Seems this application has had more than it's fair share. Maybe the metal had issues, but Problem here is the sudden torque spike from the other engine goes through a drive shaft that usually is not loaded much, and could actually be loaded in the opposite direction. This spike could be big enough to bust things, but looks like in the June 2022 case anyway, it caused the remaining side to also have the hard clutch re-engagement. This would never happen in any conventional design where the engines power a gearbox that then powers the rotors. By keeping the engines outboard, that shaft is doomed to experience loads that include this impact- and it appears that the design did not address this load. It is a fundamental catastrophic failure mode that should be predicted and mitigated. Maybe future tiltrotor designs would be better to have inboard engines, and just tilt the prop gearbox.
Ecce Homo! Loquitur...
https://www.militarytimes.com/news/y...r-force-crash/
Pentagon to lift Osprey flight ban after fatal Air Force crash
WASHINGTON — The Pentagon will lift the ban on flights by the grounded V-22 Osprey next week, U.S. officials told The Associated Press on Friday, following a high-level meeting where Defense Secretary Lloyd Austin endorsed the military services’ plans for a safe and measured return to operations.
The officials said that Naval Air Systems Command, which grounded the controversial tilt-rotor aircraft about three months ago, will lift it and allow the services to begin implementing their plans to get the Osprey back into the air. Austin met with the top service leaders, including for the Navy and Air Force, on Friday morning, according to the officials, who spoke on condition of anonymity to discuss plans not yet made public.
The Osprey has been grounded for almost three months following a Nov. 29 Air Force Special Operations Command crash in Japan that killed eight service members. The Japan incident and an earlier August Osprey crash in Australia that killed three Marines are both still under investigation. The Air Force has said that it has identified what failed in the Japan crash, even though it does not know yet why it failed.
The decision to end the flight ban is up to Naval Air Systems Command, but Austin had asked for an informational briefing on the matter because of the significant safety concerns and the fact that three of the services and a critical ally are involved in the program. While Austin does not have approval authority in the return to flight process, U.S. officials said his endorsement of the services’ plan was considered a key step.
In the months since, the services have worked on plans to mitigate the known material failure by conducting additional safety checks and establishing a new, more conservative approach to how the Osprey is operated.
Pentagon to lift Osprey flight ban after fatal Air Force crash
WASHINGTON — The Pentagon will lift the ban on flights by the grounded V-22 Osprey next week, U.S. officials told The Associated Press on Friday, following a high-level meeting where Defense Secretary Lloyd Austin endorsed the military services’ plans for a safe and measured return to operations.
The officials said that Naval Air Systems Command, which grounded the controversial tilt-rotor aircraft about three months ago, will lift it and allow the services to begin implementing their plans to get the Osprey back into the air. Austin met with the top service leaders, including for the Navy and Air Force, on Friday morning, according to the officials, who spoke on condition of anonymity to discuss plans not yet made public.
The Osprey has been grounded for almost three months following a Nov. 29 Air Force Special Operations Command crash in Japan that killed eight service members. The Japan incident and an earlier August Osprey crash in Australia that killed three Marines are both still under investigation. The Air Force has said that it has identified what failed in the Japan crash, even though it does not know yet why it failed.
The decision to end the flight ban is up to Naval Air Systems Command, but Austin had asked for an informational briefing on the matter because of the significant safety concerns and the fact that three of the services and a critical ally are involved in the program. While Austin does not have approval authority in the return to flight process, U.S. officials said his endorsement of the services’ plan was considered a key step.
In the months since, the services have worked on plans to mitigate the known material failure by conducting additional safety checks and establishing a new, more conservative approach to how the Osprey is operated.
V-22 Returned to Flight
Finally, the V-22 has been cleared to return to flight. Details are few except that the problem was in the proprotor gearbox. Over the 30+ years of operation this gearbox has shown excellent reliability and no crashes have been attributed to it in over 750K flight hours, I can now see why it has taken so long to study this accident and why they stressed a material failure and not a design issue. The only problem I recall with the proprotor gearbox was due to maintainers using power washers to clean the outer gearbox of Mideast grime against the established practices. This resulted in corrosive cleaning fluid being blown past the mast seal and contaminating internal bearings and gears. If a corrosion pit is the ultimate source of this failure a plausible cause may be obvious.
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