Bell 525 fatal accident July 2016
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During a crash investigation the company can't release any information even to employees not directly involved in the investigation. Bell cannot even comment on the investigation other than to confirm that one is in progress. Soothing investors and customers is not a license to release anything. After the NTSB releases a report, Bell may be able to make comments, but not before.
Given that this is a helicopter model in development, and not one that anybody is currently flying beyond the OEM and development team, the need or urgency to release an interim report or bulletin with alerts to users as the investigation progresses (like in the recent Bergen crash) isn't present. I'd suggest patience to all.
Given that this is a helicopter model in development, and not one that anybody is currently flying beyond the OEM and development team, the need or urgency to release an interim report or bulletin with alerts to users as the investigation progresses (like in the recent Bergen crash) isn't present. I'd suggest patience to all.
It rather depends on the complexity of the task on hand. And this is obviously more complicated for a new model especially when it crashed during expansion of the envelope. The difficult task in that case is to find out whether it was due to a mechanical malfunction an unanticipated effect (aerodynamic, aero-elastic, etc.) or something in the interaction man -machine while in yet unproven terrain. On the plus side they might have more data due to instrumentation and chase aircraft.
For Bell finding the real cause will indeed be urgent because it will be important for the future of this type.
I am not referring to speed of investigation, but the urgency (in time) of issuing any bulletin or report. Since nobody else is flying this helicopter the only people with an interest are already involved in the investigation.
OK, fair enough!
Indeed for any one else besides Bell themselves there is no urgency in obtaining the information what went wrong.
Latest On Accident
From Rotor And Wing:
Pretty well says it al. 40 knots beyond original Vne doing engine out tests, loss rpm, and the rotor stalled and/or experienced blow back.
The Sultan
The No. 1 525 prototype’s main rotor blades appear to have struck its tail and nose during a high-speed, engine-out test that ended with the July 6 crash that killed its two pilots, Rotor & Wing International has learned.
“We saw signs consistent with a blade strike on the tailboom,” the National Transportation Safety Board’s investigator-in-charge for the probe, John Lovell, told R&WI, adding that investigators also believe “the nose was struck.”
The fly-by-wire Bell Helicopter super-medium, twin-engine helicopter broke up in midair during a flight to expand its operating envelope that included a test of the 525’s performance in one-engine-inoperative conditions as the aircraft approached its never-exceed speed (Vne), Lovell said. Bell early last March said it had flown the 525 above 200 kt in a shallow dive. A flight tracking service, Flightradar24, had reported July 6 that its last data set on the 525 flight put the aircraft at 199 kt at 1,975 ft.
Prior to the breakup, Lovell said, “data indicates that main rotor rpm dropped significantly.” He also said some of the aircraft’s main rotor blades “appeared to have dropped from their normal plane” of rotation.
Test pilots in a Bell 429 chase aircraft reported that some of the main rotor blades were moving out of plane before the aircraft broke up over Italy, Texas, about 30 nm south-southwest of the flight’s launch point, Bell’s Xworx research center at Arlington Municipal Airport.
“We saw signs consistent with a blade strike on the tailboom,” the National Transportation Safety Board’s investigator-in-charge for the probe, John Lovell, told R&WI, adding that investigators also believe “the nose was struck.”
The fly-by-wire Bell Helicopter super-medium, twin-engine helicopter broke up in midair during a flight to expand its operating envelope that included a test of the 525’s performance in one-engine-inoperative conditions as the aircraft approached its never-exceed speed (Vne), Lovell said. Bell early last March said it had flown the 525 above 200 kt in a shallow dive. A flight tracking service, Flightradar24, had reported July 6 that its last data set on the 525 flight put the aircraft at 199 kt at 1,975 ft.
Prior to the breakup, Lovell said, “data indicates that main rotor rpm dropped significantly.” He also said some of the aircraft’s main rotor blades “appeared to have dropped from their normal plane” of rotation.
Test pilots in a Bell 429 chase aircraft reported that some of the main rotor blades were moving out of plane before the aircraft broke up over Italy, Texas, about 30 nm south-southwest of the flight’s launch point, Bell’s Xworx research center at Arlington Municipal Airport.
The Sultan
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careful with your assumptions
FR24 shows groundspeed
A flight flown at Vne in IAS terms can give a completely different TAS or Groundspeed value depending on local ambient winds and density altitude.
There is no credible reason why an aircraft should be operating for certification purposes at Vne+40 kts, but in any case the report quoted states that they were approaching Vne, so the speeds quoted are meaningless or misleading.
Nobody here has the info required to work out what happened, so it would be better to stay quiet on any reasons why the aircraft and crew were lost, both on this programme and on the AW609 (but then again this is a rumour site so anything stated here should be taken with a huge dose of salt).
Thoughts from the southwest of the UK are of course with the crews families and the Bell employees involved.
DM
A flight flown at Vne in IAS terms can give a completely different TAS or Groundspeed value depending on local ambient winds and density altitude.
There is no credible reason why an aircraft should be operating for certification purposes at Vne+40 kts, but in any case the report quoted states that they were approaching Vne, so the speeds quoted are meaningless or misleading.
Nobody here has the info required to work out what happened, so it would be better to stay quiet on any reasons why the aircraft and crew were lost, both on this programme and on the AW609 (but then again this is a rumour site so anything stated here should be taken with a huge dose of salt).
Thoughts from the southwest of the UK are of course with the crews families and the Bell employees involved.
DM
DM
Bell stated they were out at 200 kts and that would be from the card not FR24. As to reasons why the requirement is to demonstrate operations at 1.11 Vne. So if Bell was looking to expand to 180 knots, 200 would be the test point. Being out their testing engine failure is high risk, not something a line or armchair pilot would ever get close to. Some of us have.
The Sultan
Bell stated they were out at 200 kts and that would be from the card not FR24. As to reasons why the requirement is to demonstrate operations at 1.11 Vne. So if Bell was looking to expand to 180 knots, 200 would be the test point. Being out their testing engine failure is high risk, not something a line or armchair pilot would ever get close to. Some of us have.
The Sultan
Sultan, are you suggesting there was a mixup re the specific tests to be conducted at the power on Vne ( actually 1.11 times that value ) and the OEI Vne as described in Advisory Circular 29-2C Para 29-1505?
As you implied, that testing is rather critical and typically the flight test cards and briefings are carefully ( very carefully ) constructed, so I kind of suspect I've misinterpreted your writing.
As you implied, that testing is rather critical and typically the flight test cards and briefings are carefully ( very carefully ) constructed, so I kind of suspect I've misinterpreted your writing.
Sultan's ego must place a large load on his Rotor System....perhaps the Vibrations are getting to him.
I suppose he fails to grasp the experience level and background of a great many who attend this Forum.
Save your gratuitous remarks and stick to what ol' Joe Friday insisted upon will you...or as close to facts as you can get anyway.
Do you know exactly what the Task was that day, the details of the plan and brief, and the profile and Test Points being sought when the accident happened or are you just passing along some talk overheard at a Tavern somewhere?
I suppose he fails to grasp the experience level and background of a great many who attend this Forum.
Save your gratuitous remarks and stick to what ol' Joe Friday insisted upon will you...or as close to facts as you can get anyway.
Do you know exactly what the Task was that day, the details of the plan and brief, and the profile and Test Points being sought when the accident happened or are you just passing along some talk overheard at a Tavern somewhere?
JD
160 was the original Vne so I was just responding to why would anyone fly beyond VNE. Two reasons are expansion of the original envelope and the need to demo 1.1 Vne. As to AEO vs OEI Vne's those are defined in the end by testing the actual characteristics of the aircraft. That appears to be what Bell was doing. They may actually have a goal of a 200 Kt Vne. I was just throwing out the rationale of why testing at such speeds.
Finally. Not an expert on the nuances of Part 29, but you have to be able to transition from AEO Vne to OEI Vne so engine loss at Vne is required testing.
The Sultan
160 was the original Vne so I was just responding to why would anyone fly beyond VNE. Two reasons are expansion of the original envelope and the need to demo 1.1 Vne. As to AEO vs OEI Vne's those are defined in the end by testing the actual characteristics of the aircraft. That appears to be what Bell was doing. They may actually have a goal of a 200 Kt Vne. I was just throwing out the rationale of why testing at such speeds.
Finally. Not an expert on the nuances of Part 29, but you have to be able to transition from AEO Vne to OEI Vne so engine loss at Vne is required testing.
The Sultan
Sultan: Not at 1.11Vne.
Look The Advisory Circular defines the testing requirements and is online. Have a read and you'll see what they had to do, and, important to your implication, not do.
Re the R/W note above. Doing the OEI Vne testing by itself would explain some Nr droop, but typically not result in the comment " significantly "*. The comments re the blades going out of track and the possibility of both nose and tail strikes opens up all sorts of possibilities, but one needs the telemetry data to make sense of what was going on.
*The FAA does not require simultaneous twin engine cuts on a twin engine Cat A machine. The military does, dependent on the rules set up for the particular aircraft. One day the Project Pilot on the CH-53D asked me if I was doing anything ( I wasn't ) and he needed me to help him do the twin cuts at max speed, max weight, with appropriate pilot delay time. Now that defined significant rotor speed droop ( high 70 % as I recall ). I still have a copy of the data traces. The aircraft rolled left very quickly and in fact my right leg got whacked pretty good when Frank put in full right cyclic. But the blades remained in track etc. Now, we had done a buildup at incremental speeds up to the max speed point and things had gone quietly, so the reaction at the final data point was without prior evidence that we were on the edge ( of rather severe stall ). This is not a suggestion at all re the Bell 525 situation, simply an observation that significant Nr droop ( depending on how the writer defines " significant " ) needs an explanation.
We can be certain that all of these aspects have already been examined in detail by the Bell investigative folks.
Look The Advisory Circular defines the testing requirements and is online. Have a read and you'll see what they had to do, and, important to your implication, not do.
Re the R/W note above. Doing the OEI Vne testing by itself would explain some Nr droop, but typically not result in the comment " significantly "*. The comments re the blades going out of track and the possibility of both nose and tail strikes opens up all sorts of possibilities, but one needs the telemetry data to make sense of what was going on.
*The FAA does not require simultaneous twin engine cuts on a twin engine Cat A machine. The military does, dependent on the rules set up for the particular aircraft. One day the Project Pilot on the CH-53D asked me if I was doing anything ( I wasn't ) and he needed me to help him do the twin cuts at max speed, max weight, with appropriate pilot delay time. Now that defined significant rotor speed droop ( high 70 % as I recall ). I still have a copy of the data traces. The aircraft rolled left very quickly and in fact my right leg got whacked pretty good when Frank put in full right cyclic. But the blades remained in track etc. Now, we had done a buildup at incremental speeds up to the max speed point and things had gone quietly, so the reaction at the final data point was without prior evidence that we were on the edge ( of rather severe stall ). This is not a suggestion at all re the Bell 525 situation, simply an observation that significant Nr droop ( depending on how the writer defines " significant " ) needs an explanation.
We can be certain that all of these aspects have already been examined in detail by the Bell investigative folks.
Last edited by JohnDixson; 26th Jul 2016 at 14:25. Reason: Additional thought x 2
Also, OEI is not AEI so it's not clear if this was being flown with one engine or not. I'd venture to suggest that at only 3000' or so, it would not be a dual cut. If it was indeed following a dual cut, it would be interesting to see if there are any similarities to the fatal AB139 accident that occurred during high speed autorotation testing (both bailed but FTE struck).
212, for a Cat A aircraft, Part 29 does not require a simultaneous dual engine cut. It does require single engine cuts from dual engine flight and requires cutting the second engine from whatever speed the applicant selects for the OEI maximum speed ( usually OEI VH ). Part 29 also requires testing to whatever the applicant selects for the Vmax autorotation speed. That can have its own set of things to watch out for. After one reads all the testing required in that sub part G of the advisory circular and then comparing to the limited info in the referenced article, there is no certainty of exactly what the initial conditions were.
JD
Nothing I said or read say both engines were cut. As to Part 29 Sikorsky should read it for 30 minute loss of lube.
This was development/envelope expansion. Is not AEO all engines operating?
The Sultan
Nothing I said or read say both engines were cut. As to Part 29 Sikorsky should read it for 30 minute loss of lube.
This was development/envelope expansion. Is not AEO all engines operating?
The Sultan
Yes AEO is - I wrote AEI.
Not that startling given who wrote it!
You can go back and edit your post to reflect the correct term so that what you wrote fits what you meant to write. (Heh, I just edited that last word since I wrote "wrote" instead of "write" and missed it the first time. Super example, eh?)
@TheSultan: John D has been sharing in good faith ... I'd encourage all of us to do likewise.
@SASless: winding up Sultan? Let's keep it classy.
@TheSultan: John D has been sharing in good faith ... I'd encourage all of us to do likewise.
@SASless: winding up Sultan? Let's keep it classy.
Last edited by Lonewolf_50; 27th Jul 2016 at 22:13. Reason: typing spazz