Firefighting Chinook Crash
 

Sad to see - not sure on status of the crew.

2 pilots on board helicopter that crashed into Salmon River, medical teams on scene

Published at 8:50 pm, July 21, 2022 | Updated at 9:09 pm, July 21, 2022

https://s3-us-west-2.amazonaws.com/a...by-860x543.jpg
A CH-47D Series “Chinook” Helicopter, similar to the one featured in the image above, crashed Thursday afternoon near Salmon.
SALMON — A helicopter battling the Moose Fire crashed into the Salmon River on Thursday afternoon. It happened around 3:30 p.m., according to ROTAK Helicopter Services, and two people were on board.

“It is with heavy hearts that we confirm … a CH-47D Series ‘Chinook’ helicopter operated by ROTAK Helicopter Services with two pilots on board was involved in an accident in the area near Salmon,” ROTAK Helicopter Services said in a statement to EastIdahoNews.com. “Emergency medical teams are responding to the scene.”

A spokeswoman with the U.S. Forest Service tells EastIdahoNews.com that an incident management team is handling the situation but further details were not released, including the conditions of the pilots.

“ROTAK Helicopter Services is working closely with all appropriate agencies and will issue a full statement as information is confirmed. Company leadership asks for prayers and privacy on behalf of the involved families at this time,” the statement said.
https://s3-us-west-2.amazonaws.com/a...moose-fire.jpgLocation of Moose Fire. | Courtesy US Forest Service

The Moose Fire started Sunday about five miles southwest of North Fork in the Salmon-Challis National Forest. The Forest Service says helicopters have been used this week to support ground firefighting resources with water bucket drops.

EastIdahoNews.com will post updates as we learn more.

Oh no they haven't had them long.
https://www.colheli.com/columbia-hel...pter-services/

https://cimg6.ibsrv.net/gimg/pprune....5d7bf2c87.jpeg

Looks like they were scooping from the river. Possibly caught the bucket on a rock or submerged tree?

Looks like fairly sallow water....and if you got hung up.....jettisoning the bucket would cure that situation.

My wager is there was a mechanical problem of some kind.

Initial Accident report should have some info re accounting for all the Blades and gearboxes.

Well the condition of the pilots is known and it isn’t good: https://mynorthwest.com/3573069/2-pi...-in-idaho/amp/

Very sad news indeed. Condolences to family, friends and co-workers. RIP
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Accident Video from Twitter
 

horribly sad

Farewell and Godspeed to two of our fellows.

OH

I saw that earlier. What causes that kind of rotation in a 47? SASless?

I was wondering the same thing. Some sort of driveline issue, uncoupling or just slowing down one set of rotors?

I am going to guess a flight control linkage failure.

There is nothing in the rotor drive system that would input a yaw rotation as in a single rotor helicopter with a Tail Rotor drive failure.

I will watch it a couple of more times and see what stands out.

If it was a swashplate failure I would think the pitch attitude would have not remained as flat as it did.

As best as I could tell both rotors were being driven....as if the Synchronization Shaft or one of the gearboxes had failed the blades would have done themselves in and that would be very visible along with the bits and pieces of blades and aircraft being scattered all about.

As best as can see it....it appears the blades stay in phase during several screen shots which would suggest it was not a rotor rotation problem.

They were able to keep the aircraft reasonably level until right at the very end when it looks as thought the nose is beginning to pitch up while the vertical rate of descent is increasing which could also mean the aft head was not responding to a increase in power or up Thrust Lever (Collective) and the forward head was.

That should make me think the problem was in the aft head....either in the flight control linkages or a mechanical failure of an actuator...or a swashplate failure of some kind.

AFCS/SAS does not have the authority to input a yaw input that cannot be over ridden by the Crew.....in normal situations.

There have been a couple of total upsets in flight that caused the Crews to lose control of the aircraft and in one case it was thought the aircraft had done a complete roll.

This is one account.....not that it has anything to do with crash in Idaho.

Also....my comments are just guesses.....and are not anything but that.

http://chinook-helicopter.com/Flight...x_May_1998.pdf



My heart goes out to the Crew.....they were flying that thing to the very end.

A very sad event.
RIP

They didn’t even have time to punch off the bucket and line as things were happening very quickly +- 13 seconds from apparent loss of control to impact by my watch.
Thanks SASless for your insightful comments.
I hope the cause is discovered quickly.

I have discussed the video with another very experienced Chinook Pilot and he pointed out some things he sees that add to my input here.

His perceptions are similar and I agree with his description of what he "saw" as I noticed that as well....generally looking at the Aft Rotor Blades and their coning angle during the video as it progresses.

The camera angle and quality of the video does make it hard to make out the full range of movement and angles but does help.

The crucial issue shall be if all of the control linkages and structure supporting them were recovered.

To say the control linkages are a bit complicated on the Chinook is a bit of an understatement but as in any aircraft it can be traced if the parts are still there to be examined meaning if there is a missing bolt, a failed rod end, or a broken mounting flange or other mechanical failure it should be discoverable.

For some light bedtime reading......Section 11 pertains to the Flight Control system.


https://chinook-helicopter.com/Publi...Operations.pdf

Re possible swashplate failure: We suffered one of those in 1996 with the first hover of a production 53E. High hover. Swashplate bearing failed-quick overheat and rotating part of swashplate slowed down, dragging all pitch links-blades cut tail off and basically fell in from 200+ ft. It did immediately catch fire but the crash crew was on it in 38 seconds.
This CH-47 video is a bit different. I did notice the aft rotor seemed to have a bunch of conning as it got closer to the ground and the front not so much, yet the pitch attitude wasn’t far off level, so my visual assessment is contradictory. What does seem to say “ controls “ is that they didn’t punch off the bucket.
Just out of flight school and landing a UH-1D on the pad called Chinook Hill on the north side of Cairns, one of our CH-47 initial pre-production machines suffered “ floating SAS links “, but that created an exceedingly wobbly ( pitch, roll and yaw excursions ) hover, which they finally lost and it hit on its side. All walked away. Again, a very different failure flight path.
We also had a aft transmission output bearing failure, but the crew got it back to Cairns and landed on the north sod. That made some smoke.
None of these point a finger on the subject event here. The only good aspect is that the wreckage looks to be all there and not burned, so the failure mode ( and I’d side with your mechanical assessment ) should be accessible. That the yaw axis ( and vertical ) was abnormal, but not pitch nor roll is the first place to look. The yaw rate was enough to dis-orient somewhat, but I’m thinking that they had to be applying high forces to increase collective before they hit, yet the video did not reflect any of that. So: control jam suggests itself as a possibility.
Hope they get some expert help in looking thru the control system. We had a UH-60A fatal at Ft Bragg that took just over 6 months before finding the missing* part ( and related maintenance error-safety missing )
*Against protests that it wasn’t necessary, that the initial metal detector search was beyond thorough in the first place, the H-60 Engr Chief forced a repeat search, which found the nut 4 ft or so buried in the ground.
By now, I bet someone has taken out a CH-47-come to a hover at say 250 ft-made a 1-2 inch left pedal input while keeping the other controls fixed, and observed the initial behavior of the machine ( just to take that off the table ).
.

Brother Dixson,

My unit lost an aircraft and crew in an accident....where the aircraft pitched up and nearly went inverted on short final to an LZ while carrying a sling load of 105 Howitzer Ammo.

It landed almost flat and rolled onto one side and immediately burst into flames....and all but the cockpit section and dense metal objects were consumed in the fire and explosions of the Ammo which landed on top of the wreckage.

I was not privy to the Accident Report...but later un-official reports suggested it was a swashplate failure.

As an aside to the hover yaw pedal exercise you mention.....during Transition (Brits call it Conversion Training) at Fort Sill.....I used to land the aircraft in a Confined Area...and do the usual IP (CFI) chat about Vertical Take Off capability....copying that given during initial flight training for Huey pilots and did so in a dead pan boring as possible monotone to lull the Student into day dreaming about anything but what was being said. When I noticed some eyes glazing over and eyelids beginning to droop out of boredom.....I stated that I would demonstrate a vertical takeoff from a confined area to the Student.

Then after doing the crew pre takeoff visual clearance routine....I would smoothly raise the Thrust Lever (Collective) to Max Power (by that time in the flight we were at a low fuel level in an empty helicopter that had BAGS of power)....and up we went...as we cleared the trees I input a boot full of left pedal (all but to the stop boot full) and around we went....straight up....to 3,000 feet (about 2500 feet AGL)....and came to a stationary hover. The G forces were noticeable....holding your. head straight up took some doing.....it was in plain terms....exciting.

As most of our Students were experienced Huey pilots with a prior tour in Vietnam flying in a hot humid climate with max loads....the demonstration was very impressive to them.

When I asked if they liked that...which every one of them did....we did a vertical descent into the confined area and I let them do one.....not one of them pulled max power without some coaching.

That was a "conversion" of Huey Pilots into Chinook Pilots.

The sad news is a loaded Chinook in hot conditions (speaking of the A Model) had the same performance problems as did the Hueys when loaded to max for the conditions.

I would think the yawing would have been more disconcerting than dis-orienting.....Chinooks in my experience don't have yawing tendencies as do single rotor helicopters thus that would. have been a far more surprising situation for the crew.

The A Models with the sharp ended aft pylon was far more unstable in yaw than were all of the later models with the square ended pylon.

Shutting off the SAS on an A Model in a steepish turn could allow you to learn what droop stop pounding sounded like at 100 Knots sideways with full opposite pedal input.

That lesson learned was rarely repeated on purpose.

The later models are far more forgiving in that situation.

As the Salmon river in the general area appears to be about 3000ft,with probably a high density altitude,is it possible that the aircraft entered a very localised plume of hot air from the fire,and as the initial rate of climb appears to be slow,just ran out of power,turned to avoid and entered a vortex-ring state,and didn`t/couldn`t dump the load...?

Well.....I guess someone had to conjure up a way to blame VRS.....congratulations upon being the winner!

Do you have any notion of what a US Forest Service Helicopter Load Calc Form is about and how aircraft loading is determined?

Here is a beginning point for you.

https://www.doi.gov/sites/doi.gov/fi...alculation.pdf

The bucket is can be jettisoned by multiple means.....but was not for some reason.that has not been reported at this time.

The bucket was empty, so the speculation about performance issues is not valid.
The aft rotor disc isn't so much coning allover, but tilted strongly to one side. This is giving it the appearance of coning during a quick look, but that's not what's really going on. The frwd rotor disc doesn't appear to be tilted. This would eliminate a control failure between the cockpit flight controls and the upper mixing unit, where the yaw input gets split into frwd/aft. So that leaves the control linkages between the upper mixing unit and the aft swashplate.
It looks like the pilot tried to fly out of it after the initial 270 degrees of rotation. That's also when the descent was initiated. To me this looks like the flight crew were reacting to the emergency but ran out of altitude and ideas...

But why initiate a descent when it would seem you only have a yaw issue? Ingrained habits from flying tail rotor aircraft?