Bell 206 down in Pearl Harbor, no fatalities

[r22butters]

iChris, thank you for the detailed explanation on the 206. I'm a student pilot and studying these events and learning as much about them is very important to me.

 

Not meaning to switch topics too much, but I'm curious about the r44 video.

 

r22butters, you mention that the 44 is too heavily loaded for that airspeed. I'm having trouble telling, but did the pilot attempt to get out of that settling with power situation by applying forward cyclic and then up collective per the specified emergency procedure? If he did, was there simply not enough time AGL altitude to actually recover i.e. gain enough forward airspeed to climb out? As well, if he did, I assume that that recovery maneuver would be negatively affected by too much weight, right?

 

Thanks in advance.

 

That wasn't settling with power. He was at full throttle.

[takefootoff]

That wasn't settling with power. He was at full throttle.

 

So are you saying that he couldn't have been in settling with power because he was full throttle?

[r22butters]

I'm saying that he fell to the Earth because he was at full throttle, lost ETL (or was already below ETL and suddenly required more power possibly due to a change in wind direction when he turned) and had no power left to stop the descent.

 

As opposed to losing ETL and falling because he entered the Vortex Ring State (ie. settling with power).

Edited February 25, 2016 by r22butters

[takefootoff]

ok, gotcha. so, hot, high and heavy combined with dropping out of ETL.

[adam32]

https://www.yahoo.com/gma/video/pilot-helicopter-crashed-water-speaks-001039194.html

[iChris]

I'm saying that he fell to the Earth because he was at full throttle, lost ETL (or was already below ETL and suddenly required more power possibly due to a change in wind direction when he turned) and had no power left to stop the descent.

 

As opposed to losing ETL and falling because he entered the Vortex Ring State (ie. settling with power).

 

Settling with power, where the power available doesn't meet the power required. ETL is not a determining factor. If the power available does not meet the power required, the helicopter will settle regardless of being in or out of ETL.

 

Edited February 26, 2016 by iChris

[iChris]

https://www.yahoo.com/gma/video/pilot-helicopter-crashed-water-speaks-001039194.html

 

Thanks...

 

https://youtu.be/RYVkYEqR9ik

Edited February 26, 2016 by iChris

[r22butters]

Settling with power, where the power available doesn't meet the power required. ETL is not a determining factor. If the power available does not meet the power required, the helicopter will settle regardless of being in or out of ETL.

 

Isn't it possibe to have just enough power available with ETL then suddenly find yourself without enough power upon losing ETL, i.e. headwind becomes tailwind?

 

For what its worth, "power required exceeding power available" was never refered to as "settling with power" during my training, nor any flight review since,...but I won't get into that tired old debate. :-D

[iChris]

Isn't it possibe to have just enough power available with ETL then suddenly find yourself without enough power upon losing ETL, i.e. headwind becomes tailwind?

 

For what its worth, "power required exceeding power available" was never refered to as "settling with power" during my training, nor any flight review since,...but I won't get into that tired old debate. :-D

 

Correct that’s also a possibility. As the inflow decreases the power required increases.

 

On the other hand, as we increase airspeed, Inflow increases, which decreases the power required due to a reduction of the induce flow at the rotor. In other words, a reduction in induced drag. Some advanced textbooks do not even use the term effective translational lift or ETL, it’s simply termed inflow. That my make it easier for some.

 

Edited February 26, 2016 by iChris

[Pohi]

If you are at max gross weight and out of ground effect and then slow down below etl, you can start to settle with max power applied. I think that would be one of the classic power settling type situations. It's not vortex ring state, its just not enough power to maintain level flight at airspeed below etl.

[ridethisbike]

Sooooo... back on topic. iChris, are you saying the pilot botched the end of the auto? If that clip is the end of the auto, he was mighty high to be finishing off his flare...

[iChris]

If you are at max gross weight and out of ground effect and then slow down below etl, you can start to settle with max power applied.

 

It would depend on max power being above or below power required. Again it’s a power available vs. power required situation.

 

In the first curve below, max power required OGE is 96 HP. As the helicopter slows from 20 KTS to a zero airspeed hover OGE, maximum power applied (available) is also 96 HP. Power available equals Power required, no settling occurs, even though the helicopter is below ETL.

 

In the second curve below, the helicopter slows from 20 KTS to13 KTS OGE, maximum power applied (available) is only 79 HP; however, power required has increased to 85 HP. Power required exceeds the power available, settling occurs, even though the helicopter is still in ETL.

 

 

 

Edited February 26, 2016 by iChris

[iChris]

Sooooo... back on topic. iChris, are you saying the pilot botched the end of the auto? If that clip is the end of the auto, he was mighty high to be finishing off his flare...

 

This is a real world situation, not practice to a smooth runway with power recovery as backup. No, he didn’t botch the auto. Real world situations sometime leave you in an unfavorable position. He appeared to have flared early and high to avoid the crowd on the grassy area and maybe to avoid falling short and landing in the rocks. As one witness noted, that grassy area was full of people.

 

 

Edited February 27, 2016 by iChris

[Astro]

I fly around water a lot (coastline/shoreline) in a helicopter not equipped with floats and I've always figured that in an auto I'd just go for the water, that way I could avoid hitting anything I didn't see until the very last minute. After watching this video and hearing about the survivors injuries though, I can't help but wonder?

 

When you hit hard on land the skids are going to absorb a lot of the impact as they bend out, but if you hit hard on water the skids will just cut through the water and the fuselage (and thus the occupants inside) will absorb more of the impact, which will lead to more serious injuries.

 

Am I correct?

[rockapotomus]

iChris and r22butters, thanks so much for the detailed explanations.

 

Astro, I'm very curious about your question as well.

[Wally]

I fly around water a lot (coastline/shoreline) in a helicopter not equipped with floats and I've always figured that in an auto I'd just go for the water, that way I could avoid hitting anything I didn't see until the very last minute. After watching this video and hearing about the survivors injuries though, I can't help but wonder?

 

When you hit hard on land the skids are going to absorb a lot of the impact as they bend out, but if you hit hard on water the skids will just cut through the water and the fuselage (and thus the occupants inside) will absorb more of the impact, which will lead to more serious injuries.

 

Am I correct?

 

Going to the water presents problems as well as advantages. The difference in impact damage between land and water wouldn't be a consideration for me. Going to the water, at least with conventional "floats on skids", results in a much softer landing than the skids do on the ground. I would guess that a water landing would dissipate energy similarly without skids. It is much harder to guess absolute altitude above water in the terminal part of the landing, especially a forced landing, even with training and practice, making a controlled, minimal impact landing much less likely.

 

But, impact isn't necessarily the main problem. Watch the video again, and you will see the REAL survival issue for occupants: the aircraft doesn't float long and almost always rolls over as it settles, disorienting everybody and presenting serious challenges exiting the aircraft even if you're trained and prepared for the emergency. Being trapped in the aircraft or being physically/intellectually compromised in the effort can easily be fatal.

Edited February 27, 2016 by Wally

[iChris]

 

“The pilot reported to the [NTSB] investigator-in-charge, that while in cruise flight over Ford Island, he felt a vibration followed by a grinding noise. Shortly after, the pilot heard a loud bang, scanned the instrument panel and saw that the engine instruments indicated the engine was still running, however, rotor r.p.m. decreasing.

“The pilot initiated an autorotation to a grassy area near Contemplation Circle at the World War II Valor in the Pacific National Monument. As the pilot neared his intended landing area, he observed multiple people within the area. The pilot stated he initiated a left pedal turn, attempting to land close to the shoreline. Subsequently, the helicopter descended rapidly into the water, about 20 feet from the shoreline.

His account and the video do not match.

 

 

By the way, what is your account on why the pilot's account does not match?

 

A few others have the same view...

Edited February 28, 2016 by iChris

[SBuzzkill]

The profile that he's in at the start of the video just doesn't quite fit with what the bottom of an auto should look like. I may be missing something but the attitude, descent rate, and airspeed fits that of a powered approach. It looks to me in the video that he doesn't lose power until right after the video clip starts and really is never in an auto, but instead just using rotor inertia.

 

Also, he is too shallow and slow in the video for an autorotation to the shore and does not appear to turn to miss anything because he was never within glide distance of the shore (during the video).

 

I could be completely wrong though, I'm just comparing what is written in the report to my impressions on seeing the video.

 

Edit: I'm also not trying to discredit the pilot's skills or honesty, just his ability to recall the event accurately. Our brains do funny things in stressful situations...

Edited February 29, 2016 by SBuzzkill

[Nearly Retired]

Chris, with all due respect, I think Senior Buzzkill nailed it.

 

What we see at the very start of the video is a Bell 206 in what appears to be an OGE hover - or a normal, Bob-approved, very conservative, shallow, slow straight-in approach with a flat cabin attitude. Suddenly, "something" happens. The ship yaws to the left and drops out of the sky like a bank safe. We hear the tail rotor increasing in RPM. This is not LTE or RVS or WSPS or whatever the kids are harping on these days that is the cause of every accident since Igor. (In fact, didn't Leonardo's ornithopter get into a famous case of SWP before he deemed the project "not financially or technically feasible given the limitations of the tools and materials we have available at this time"...you know, sort of like the V-22 now?)

 

And if we look at an overhead shot of the intended LZ, we see that the whole thing is surrounded by a rocky, aesthetically unappealing seawall. Turning to "land near the shore" would've done nothing better for him; he got as close to the "shore" as feasible. And anyway, he didn't turn - the ship yawed.

 

This is why, in general, it is unwise for a pilot to give ANY sort of statement after an accident: We get things wrong. For years, organizations like AOPA have counseled us to JUST SHUT UP after an accident. Instead say, "Errrr, I'll get back to you." Pilots who are involved in accidents should not play NTSB Investigator and try and tell people the hows and whys of what happened before the wreckage has even stopped smoking (that's what we Monday Morning Quarterbacks are for!). Because what we perceive happened in our minds is not always what happened in reality. Same with witness' statements.

 

Fortunately in this case we have video evidence! We don't need to be NTSB accident investigators to make some well-edumacated statements about WHAT WENT WRONG! ...And so...what went wrong, Bob?

 

My best guess is that the freewheeling unit started coming apart. It probably made some bad grinding noise that was evident in the cockpit. (Maybe it was also dragging the engine/rotor down, maybe not.) The pilot wisely decided to put it down and selected the big grass area right there at the Pearl Harbor site and advised ATC of his intention. He kept the power *on* since the engine was still running - again, good choice: If the grinding was coming from the seizing transmission (and how could he know?), then you most definitely want to keep the power ON. There is no caution light on the dash for "Impending Short-Shaft Failure." Me, I might have suspected the main transmission too given the scarcity of info available to us dumb pilots.

 

Just get it on the ground, that was his good plan. He probably thought he had it made - he was on short-short final, he was level...everyt'ing was copacetic, mon'. And then...at the very last moment...the FWU or the input drive shaft let go, catching him by surprise. When it broke, the now-unloaded engine oversped before the governor could react. And because of the goofy design of the 206/407/505 drivetrain, the overspeeding engine took the tail rotor up with it...which caused the nose to yaw LEFT. At that point all he could do was hang on and pull.

 

Maybe I'm wrong. it's a very short video clip and we really don't see what was happening much before the "event." But I agree with SBuzzkill that it surely did not look like the bottom of an auto to me either.

[iChris]

“The pilot reported to the [NTSB] investigator-in-charge, that while in cruise flight over Ford Island, he felt a vibration followed by a grinding noise. Shortly after, the pilot heard a loud bang, scanned the instrument panel and saw that the engine instruments indicated the engine was still running, however, rotor r.p.m. decreasing."

 

“The pilot initiated an autorotation to a grassy area near Contemplation Circle at the World War II Valor in the Pacific National Monument.”

 

Well, what would a prudent pilot do at altitude under that situation? He would lower collective and enter autorotation to prevent further rotor RPM decay. We know that the helicopter was at altitude because, that is one of the requirements for helicopters without floats. The pilot must maintain glide distance to shore in case of an engine failure.

 

The definition of Autorotation; flight without engine power or insufficient engine power, where the air approaching from below the rotor disk keeps the rotor up to a safe operating speed.

 

"As the pilot neared his intended landing area, he observed multiple people within the area. The pilot stated he initiated a left pedal turn, attempting to land close to the shoreline. Subsequently, the helicopter descended rapidly into the water, about 20 feet from the shoreline."

 

So what should we expect from this last minute maneuvering and the flare? If properly executed we should see at the end, complete arrestment of descent rate, near zero ground speed, and a leveling of the helicopters attitude. What we’re seeing is the end of an autorotation where all those things were accomplished, to a near pause to a hover, at the cost of rotor RPM. However, it was accomplished a bit high and there weren’t enough turns remaining to cushion the last 15-20 feet, resulting in a rapid plunge into the water. Too high of a flare is normal in these situations because it is normally more difficult to determine your distance above water.

 

What can be said, he probably wasn’t maintaining sufficient altitude to be within glide distance of shore; therefore, was not in a position to make the grass area and probably came to realize that near the end.

 

We don’t know much about where the helicopter was prior to the video. The pilot says he experienced problems over Ford Island. if you look at the photo below, that landmass to the right of the helicopters skid is Ford Island. The solid line points to where (circle) he eventually ended up (3/4 miles from the shore of Ford Island) and the dotted redline is the general direction back to the airport (3 miles). Somewhere in that area is were the auto started. Note, that photo was taken from the same helicopter on a prior tour flight over the Arizona Memorial.

 

We don’t really have enough to counter the pilot's explanation; moreover, his explanation is plausible. Also, it is my belief that the short shaft or freewheeling unit, whichever one is academic, since both are in series, one equals the other, failed at altitude necessitating the pilot’s entry into autorotation. There is no indication that situation changed during the descent. So what we see in the video is a main rotor no longer being driven by the engine.

 

We could wrap this thing up in short order if we got a look at the helicopter and found out exactly where he started his auto descent.

 

(CLICK PHOTO TO ENLARGE)

Edited March 1, 2016 by iChris

[iChris]

More on the issue of floats, FAA's intent on the rule:

 

We have rewritten the ‘‘Helicopter Floats’’ section in this final rule (§ 136.11) to address the ability of a helicopter to power-off glide to beyond the shoreline. If the helicopter operator knows the performance of the helicopter (as published by the manufacturer) would allow the helicopter to glide (autorotate) beyond the water to a landing spot, the operator may not need helicopter floats.

 

Operators must make sure that the ability to glide (autorotate) to land when the engine fails will include the ability to put the aircraft down safely in an area beyond the shoreline. We define shoreline in part 136 subpart A, and it excludes areas that are intermittently under water at the time of the flight, or areas that are otherwise unsuitable for landing such as a vertical cliff. The burden is on the operator to know the power-off gliding distance for existing conditions at the time of flight. Thus, the operator must determine how far over the water they may go.

 

The Hawaii operators’ history of helicopter floats is well established, and they hardly commented about the issue. We believe there will be no reduction in safety because the helicopter float final rule language requires the available shoreline to be suitable for landing once the glide is completed. Although this section includes power-off gliding distance, which SFAR 71 did not, it still requires the landing to be done at a location beyond the shoreline. While there is a great deal of land that may be within power-off gliding distance in Hawaii, the terrain is often dangerous and a landing would be nearly impossible on such terrain.

 

Final Rule, 72 Fed. Reg., 6904; CFR 136.11 (Feb. 13,2007)

 

Also see; §136.1; §136.11; Appendix A of Part 136

Edited March 1, 2016 by iChris

[Nearly Retired]

Well Chris, I guess you, me and Buzzkill are seeing two different things. And what I see is at variance with what the pilot told the FAA. But who knows.

 

To me, the helicopter at the beginning of the video is definitely *not* at the bottom of a prematurely terminated autorotation. If you flare a Bell 206 at the bottom, AS SOON AS you level, the ship will fall through to the ground. But that is not what we see. We see a ship that is apparently still under power, making a powered, shallow approach.

 

But almost immediately, "something" happens. Engine and tail rotor RPM go *up*, main rotor RPM and the helicopter go *down* and the nose yaws as those things happen. It is at this point that I believe the input drive shaft (or freewheeling unit) completely let go. The power loss happened right down near the ground, not up high. And the way the 206 works, there *probably* could not have been a "partial" failure of the FWU - it was either transmitting power or not.

 

I do not believe for one second that the pilot initiated an autorotation when he was over Ford Island - or at all for that matter. Nope. His description of the events is at odds with what we see in the video. I don't think he's being deliberately misleading. Rather, I think he's just confused. Things happened very, very fast...*AND* he ended up violently in the drink with everyone else. It must have been a very traumatic event - even more so given that one of his passengers died.

 

We can forgive him if his recollection of the events is not 100% accurate.

[Astro]

More on the issue of floats, FAA's intent on the rule:

 

We have rewritten the ‘‘Helicopter Floats’’ section in this final rule (§ 136.11) to address the ability of a helicopter to power-off glide to beyond the shoreline. If the helicopter operator knows the performance of the helicopter (as published by the manufacturer) would allow the helicopter to glide (autorotate) beyond the water to a landing spot, the operator may not need helicopter floats.

 

Operators must make sure that the ability to glide (autorotate) to land when the engine fails will include the ability to put the aircraft down safely in an area beyond the shoreline. We define shoreline in part 136 subpart A, and it excludes areas that are intermittently under water at the time of the flight, or areas that are otherwise unsuitable for landing such as a vertical cliff. The burden is on the operator to know the power-off gliding distance for existing conditions at the time of flight. Thus, the operator must determine how far over the water they may go.

 

The Hawaii operators’ history of helicopter floats is well established, and they hardly commented about the issue. We believe there will be no reduction in safety because the helicopter float final rule language requires the available shoreline to be suitable for landing once the glide is completed. Although this section includes power-off gliding distance, which SFAR 71 did not, it still requires the landing to be done at a location beyond the shoreline. While there is a great deal of land that may be within power-off gliding distance in Hawaii, the terrain is often dangerous and a landing would be nearly impossible on such terrain.

 

Final Rule, 72 Fed. Reg., 6904; CFR 136.11 (Feb. 13,2007)

 

Also see; §136.1; §136.11; Appendix A of Part 136

 

If the helicopter had been equipped with pop-out floats that would have at least given the pilot the option of setting it down on the water at the first sign of trouble (possibly before needing to auto). That may have been a much quicker option than trying to make it to the shore? Instead he had to go for dry land, and simply ran out of time. With floats he may have been able to set it down before losing control and dropping out of the sky?

 

Having pop-out floats on these types of operations gives the pilot more options to avoid an accident, not just after an auto is initiated.

[Nearly Retired]

Agreed, Astro. Except...

 

This was assuredly a very tough emergency for the pilot to troubleshoot...that is, *IF* the FWU didn't actually let go until the very end as I'm inclined to believe. If the freewheeling unit *did* let go up at altitude and he entered autorotation, then he really screwed it up at the bottom. I dismiss this scenario. I don't think he screwed up at all.

 

So what were his indications?

 

• Was there a chip light? Many 206's don't even have the FWU chip detector hooked into the chip light system. It's just...there...and you check it periodically (but it's not a preflight item like the temp strips on the drive shaft couplings are). So he might not have had a chip light and his Trans Temp/Pressure might have been fine.

 

• Was there grinding or other "bad noises" coming from behind?

 

• Was the MR RPM decaying as has been surmised by one guy who evaluated the video footage? It's not out of the realm of possibility that as the FWU was chewing itself up there might have been some drag produced that pulled the engine RPM down. I'm pretty sure that the FWU cannot "slip" like a clutch; it's either engaged or not...I...think.

 

It's really hard to know what's making noise in a 206, especially one with the doors off and the passengers jabbering in the ICS. Is it the trans? Is it the engine? If there were some bad noises going on *and* the MR RPM was decaying, maaaan, it would be hard to guess what was happening. I'd want to get on the ground - fast! I don't know that I'd chop the throttle and autorotate down to the water even if I had floats. I think I'd go for land.

 

Psychologically it would be very hard to make the decision to land in the water as long as the engine is still making power and there were decent LZ's in sight. I mean, it would be for me - unless I was on fire. Emergencies happen fast in helicopters. There's not a whole lot of time for troubleshooting and pondering the meaning of life. The best response often is, "Just put it down." As Matty says, just land the damn helicopter! And he did that.

 

So I'm thinking that floats *probably* would not have made much of a difference in this accident unless he popped them as a precaution during the approach. But I'm a pretty experienced 206 pilot, and I'm not sure even I would've done that. And by the time the FWU let go, it was too late - he was probably in the water before he knew what was happening.

There's a ton of stuff we don't know, of course. I'm just guessing at a lot of things here - educated guesses for sure, but at the end of the day just guesses. But it's a fascinating accident in that it appears to be caused by a very rare failure in a 206 and the fact that it was caught on video. We shall learn a whole lot from this one!

[Astro]

The only reason I ever look at these is to learn something, and what I've learned is that when flying passengers over water if I hear a grinding noise (or the like) I'm going to pop the floats and land now. A power on landing to the water beats an auto anywhere!

 

They could at least give us that option, by only using helicopters with floats for these types of operations.