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
.

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?

As well as a possible control Link failure or a swashplate failure, it could also be a Piv or Swiv failure/Jam too. I last worked on D's and it's been some time since then. RIP guys.

It has been a long tome for me too Rigga.......can you recall which servos control the yaw input.....Pivoting or Swiveling Servos?

Also....correct. me if I am wrong....isn't there one place on each servo where Flight Control Systems 1 and 2 can transfer fluid if a seal is leaking?

The indication would be one Sump losing fluid and the other gaining fluid.

John Dixon and I each see the problem beginning with uncontrollable yawing of the aircraft that might have led to other issues.

Many years ago I had a Yaw Channel runaway in a Chinook whilst sitting on the side of a hill unloading troops (luckily on an exercise in deepest Yorkshire!). It was obvious looking out that the front disc was tilting left (into the hill) and we had to use cyclic to prevent it striking the ground; the downside was it increased the right tilt of the rear head to the point the droop stops were beaten to death on the rear head. We initially tried to increase power to lift off, at which point it was obvious yaw control was non existent, and we closed down PDQ. During this the rear blades carried out a sun roof modification to fuselage, and finally one blade ended up embedded in the port pillow tank. In retrospect I dread to think what would have happened if we had lifted off. I believe the reason was given as an autopilot malfunction! it also came out that it had happened a few days before whilst in the cruise but was 'easily' controllable, and the engineers found nothing untoward.

I watched that video and had the feeling of deja vu - there is a point just before it goes out of view when it looks like the aircraft has full 'into turn' yaw input thus indicating some form of loss of yaw control in the hover, and no forward motion to give directional control to get out of it.

My thoughts go out to the crew and their families.

Rumour, Innuendo and Hearsay:
I AM NOT A CHINOOK PILOT
I recall an RCAF pilot telling me +- 20 years ago about a failure mode that caused the aircraft to suddenly want to swap ends in forward flight. Can’t recall if it was a CH-46 Labrador or a CH-47 Chinook. It was apparently a fascinating event requiring a change of undergarments and the intervention of a surgical team to remove the seat cushion.
Vaguely recall his explanation as to what caused it but not enough to speculate. It was either a total failure of some system or sensor or a partial failure of same suddenly inputting incorrect swashplate movements. One rotor suddenly wanting to go left and the other right while in stable fwd flight.
A new Emergency Procedure with some highlighted “Immediate Action Memory Items” was created I believe.
I think that there was an similar incident some time ago that was discussed here or on another Aviation site years ago.

Was a Cockpit voice recorder fitted or an engine monitoring system ?

Shackman,

In the aircraft you had the SAS runaway....how would you describe the SAS system on yours to an American equivalent Model of the Chinook?

I am familiar with the US A, B, C-, and C models but not the D or later models and certainly not the many RAF versions.

On the three models I flew....there was a single Red Guarded Switch that turned the SAS ON and OFF. The C- and C model had the same plus a PSAS system for Pitch Attitude Hold.

On the machines I flew a quick flip of the Red Guard and Toggle With....and in theory the SAS links would have reentered or at least stayed where they were.

On some steepish slopes I have had some Droop Stop Pounding but never any damage.

I have had the unique thrill to hear them really clattering while in flight in the A Model when in a weak moment I turned the SAS off on a Student in a steepish turn and the aircraft got away from him and tried to swap ends at a hundred knots IAS....again no damage.

I can imagine yours was an experience that you will not forget....and I am very glad it was you and not me that got that thrill!

We were still learning about them when I started out on them....and flew some with single digit build numbers for the A Models.

The kind with the fixed aft gear with double wheels and had to be ground taxied using the Aft Gear and flight controls only.

Undemanded yaw and lowering of thrust/collective lever, apparently the pilot was unable to override or control the failure. I would suspect a Yaw and thrust lower control pallet debonding/detachment in the control closet?


https://cimg1.ibsrv.net/gimg/pprune....4c424b3fa.jpeg

There have been at least two other still unexplained, major accidents with Chinooks in U.K. that I know of, that were both possibly caused by critical flying control failures and both causing fatalities of experienced ex-colleagues known to both you and I.

Shy,

Are there Accident Reports available for those two crashes you mention?

SAS,

The first accident was in the Falkland Islands in 27/2/1987.
It’s been discussed here before but unfortunately the BOI report has been archived by MOD so I can’t find it.

That aircraft was on a post maintenance check flight and nosedived in almost vertically from about 1,000 feet, with the loss of five POB, I believe.

The second was the more well known and much discussed Mull of Kintyre accident.

The first accident made me determined, as the father of a young family, to avoid getting posted to Chinooks if at all possible. I terminated my commission less than a year before the second accident, which made me think I’d definitely made the correct decision.

I an familiar with the Mull of Kintyre accident...and the controversy that surrounds it.

How many Chinook crashes has there been in the Falklands?

One crashed on a hillside, one crashed from a hover immediately following a Transmission replacement, and then there was the fatal crash of the one you mentioned.....am I right on this?

I am thinking three crashes in the Falklands unless I am reading some articles wrong.

Accident summary ZA721, 27/2/87

At that time, the Chinook had a bad reputation within the RAF. Main gearbox failures was a worrying problem. The USA lost one in Germany, whilst flying a load of parachutists, causing multiple fatalities. The RAF lost one sometime later after the rear gearbox seized and came off the airframe, taking off the entire roof as far as the cockpit. Thankfully that was in the low hover and miraculously caused only minor injuries to the crew. I was later given details of that incident by the pilot himself. A good friend of mine, a very well respected crewman, was severely injured after a training trip went badly wrong (a practice engine failure was given and the second engine failed to respond). He never fully recovered from his injuries and died well before time, apparently from lung complications caused by inhalation of jet fuel. At the time of my concern, gearbox and engine chip lights were very common.

I still stand by my personal decision.

With as many transmissions the Chinook has....chip lights were always a common event but rarely did we find anything but a bit of fuzz.

The two main gearboxes....driving the Rotorheads had Chip Detectors that could be pulled while in flight which was the way we identified which one it was as both were on a single segment light.

The joke done by the FE's was to take a Ball Bearing about three times the size of the Magnetic Plug and come forward to the cockpit asking what the Pilot's thought of the metal lodged on the magnet.

At one time engine gearboxes had a lot of serious chips being created and we were changing them with real frequency.

Some units had those nose boxes as we called them....actually come to bits with internal failures thus causing an "engine failure" situation through lost input to the rotor train.

Tragic. At the very beginning a dark car is seen to (I think) reverse away quickly from the riverbank. It starts moving BEFORE the aircraft appears to be out of control. Is there a reason it moves away - something is already apparent amiss perhaps? Or is it coincidence? It would be interesting to speak to the driver.

I do agree: The rear disc appears tilted by 15-20° to the right.
Coning is moderate but it's visible. Looks like thrust is still available but massive tilt.
https://cimg6.ibsrv.net/gimg/pprune....cec198c944.jpg
From the front it appears the front Disc ist tilted to the opposite direction:
https://cimg8.ibsrv.net/gimg/pprune....9044f88f22.jpg
This might indicate that it was not a swashplate failure, but rather something in the general yaw control assembly.
On the other hand it could potentially also have been an aft swashplate failure countered by the pilots applying opposite cyclic (which then only worked on the front rotor thereby causing yaw).

Good observations....also I am thinking the Aft head tilt is greater than the forward head.

We might look at some of the RAF Chinook display videos and compare Aft Head movements to this video we have and see if there are any useful comparisons.

That still photo sure seems to show the Aft Blades in an unusual position.

The fact the two heads operate in reverse from one another complicates matters visually as it is hard to determine which had the failure and which was being used to counter it but we can safely assume it is something in the Yaw Control system that is failure due to the yawing seen in the video.

Chinooks just do not do that on their own normally.....as LTE is not an issue in the Chinook as it might be in a Single Rotor Helicopter.

There are aerodynamic issues that do affect the handling of the Chinook that will bite you but none that would create such a yawing moment or rate of rotation.

You youngsters that can still see....look at the video from the very beginning....and tell me if. you think the Bucket has been filled or not.

My impression is that was not filled as there is no bulging to it....just long and skinny looking.....or perhaps only partially filled.

It also looks to have swung out quite a distance as the video begins.

To my eye on the video the centre of rotation of the aircraft appears to be the hook, not the nose. Although this is difficult to judge it would imply a failure of yaw control as a whole rather than a failure of the control run to the aft head.

Agree the bucket looks empty - there is slack in the libe during the descent which to my mind wouldn't happen with a full bucket.

With rapid rate of rotation....I wonder what the Centrifugal forces the crew would have experienced.

It has been suggested the rate of rotation could have caused disorientation....which certainly could be a factor in what happened.