Colombia B206 crash 20.dec.21
 

There is a good video here:


https://ne-np.facebook.com/SkyHunter...57959727754883


https://cimg1.ibsrv.net/gimg/pprune....bfc3c38d41.jpg
https://cimg2.ibsrv.net/gimg/pprune....e634d1b3a6.jpg
https://cimg3.ibsrv.net/gimg/pprune....33e26952e0.jpg


https://aviation-safety.net/wikibase/271015

Good to see the blades haven't caught on something...
The sound says it all.

Wonder what his pre-flight performance planning involved and if he used a power check to confirm it before committing to landing? I suspect very little and no to be the answer.

Must be tall to get the lever that deep into the armpit. :E

Always best if you can recover RRPM before crashing.

Wish the industry developed the simple gouge we had for the Huey for their aircraft, simple in the extreme. In the Hueys case it was fly at 60 knots at the height you wish to land (or low altitude above the pad), note torque, pull power until rotor bleed, note torque, calculate difference between two torque figures. The gouge then gave figures (forget now but just to make up some) difference of 11 pounds or more OGE hover possible, between 10 and 7 IGE hover possible, between 6 and 4 a zero/zero possible, less than 4 means running landing required.

We had a similar procedure many years ago for the Wessex Megan :ok:

As a rough guide, this has worked for all bell products I have flown, (206B3, 206L4, 407, Huey, 205):

1. Set up for a steep approach to be 100 feet above the obstacle in front of you.... for the sake of explanation we will call this the "decision point". You would aim to arrive at the decision point in a deceleration to little to no airspeed and less than 300fpm descent and almost hover power.
2. Just as you reach the decision point, assuming you have made the approach smoothly, you will push the nose over slightly to stop the deceleration and you will feel a little drop..raise the collective a tad to stop the drop and note your pedal position, TQ and TOT.

From those numbers you need the following to hoverIGE:From those numbers you need the following to hover OGE.a. An extra one and half inch of left pedal
b. An extra 15% TQ
c. An extra 50 degrees of TOT

How does that work with a headwind say 15 kts?

One has to assume the wind will be roughly the same once down close to the ground and works fine, just zero the ground speed.

Of course ass others have noted there are other ways to check also, can you maintain 300 fpm climb at 60kts you should be able to hover, you can also try HOGE at the same altitude MSL, but next to the pinnacle with 100' AGL to be able to get out if you cannot hover, Many different ways to check.

And if all else fails you could read the performance section of the RFM I suppose?

Well let's not get too logical..... lol

Fixed wing driver here.
So you guys are saying at that altitude above MSL he didn't have enough available power to hover OGE then proceed to a safe landing?
When he pulled more collective, main rotor RPM decayed and the horn sounded...
Is the procedure Gordy is referring to effectively giving you the option to put the nose down and fly away from the landing attempt if you don't have enough power while still having sufficient altitude?

Yes, but that is the key phrase.... Altitude and/or speed are your friend.

Well, its a good start. But as winds, turbulence and downdrafts not always is faverable, a HOGE according to the chart on the spot isnt always possible.

I havent ever really been on the wrong side in the charts but still aborted at least hundred landings(or final touch down part of) due to insufficient power/reaching max allowed torque etc.

Tartare - in simple terms, a helicopter uses more power to hover than it does in cruise flight and so speed is your friend.

If you haven't got speed but have the altitude to dive on speed, then that is also your friend.

The difference in power required from zero airspeed hover to 15 to 20 Kts IAS is very marked and so, coming below that speed without having sufficient power to hover is going to cause you problems - as in the Colombian accident.

He could have made a steeper approach, all the way to the ground without coming to the hover at all - the brit mil call this a zero speed landing - but he would have to offload pax before trying to depart.

As AAKEE says, the winds around hills are often at odds to the main flow with up and downdraughts and turbulence - that is why HOGE power isn't enough, you need a thrust margin to allow for those factors if you want to stay safe.

Gordy - your technique actually seems very similar to the LDP for many PC1 profiles.

Any wind is always to your advantage and the stronger the better. Makes it easier to identify as there are more cues. And in my experience I have never seen the wind blow into the ground. Steep approach to a site like that is textbook myth that unfortunately is still talked about. Pinnacle approach is much easier done climbing up to the site from below. If you run out of performance it will be patently obvious. The aircraft will turn around on its own to face back where you came from! The type of approach in the video without knowing your performance and verifying is just “suck it and see”. As with most things in aviation “ hope” is still not a good strategy! Seems that flight school must have been just a convenient lunch venue?

“Altitude is your friend”.

Aircraft performance reduces with increasing altitude so it’s probably more correct, in a case like this, to say that height above the surface is your friend…

Yes, that would be a better way to put it..... I was attempting to be concise.

Very interesting - thank you gentlemen.

That is simply untrue, I've used that day and night in hot and high situations in the past.

Coming level or for beneath retaining an escape route is a great technique and one I have used and taught many times over the years, especially at night where rates of closure are more difficult to assess.

However in the Colombian accident it doesn't look like he thought about escape routes as he could have approach from a slightly different direction and retained the ability to dive away as he got to Nr decay.

Just wondering how they will recover this helicopter?

Repair it on site or bodily move it to be repaired ? Either way, a very tricky job I suspect.

Apparently it was at about a bit more than 10,000 odd feet and it was not the first flight of that aircraft up to that spot. Not saying it was the same operator at the helm though.

Watching the video the aircraft is still OGE when it tops out on N1. Maybe it did just have IGE performance. At that altitude in a Jet Banger you would need all your ducks in a row.

Looking at a bit of historic METAR data from nearby it could have been as bad as ISA +20?

Another trap when operating at those altitudes is that you need to check that max N1 is available with a "topping check". Not everybody does them to see and it can certainly rip your nightie.

Most FCU's are slightly out and a missing .5% will end your day thanks to the exponential curve.

2°41'55.97"N 76°52'18.59"W if you are interested. There seems to be a road or track of some sort up there.

At least they walked away - luck.

Probably external load it out on a Mi8 or similar metal.

I’ve landed 206 B3’s at up to 12500 in ISA + 15 and the limit was always ToT not N1.
I could manage 1 pax at 12.5k and 2 at approximately 11k.
I can’t remember what Tq numbers I was getting but generally not close to maximum.

That should be a "bread and butter" approach for any commercial B206 pilot. He had a bit of useful height and maybe a bit of useful airspeed when the rotor was heard to droop. His mistake is obvious. As soon as you hear the rotor start to droop the corrective action should be instinctive, and that does not mean you droop the rotor further in any attempt to land. The pilot needlessly pranged a serviceable helicopter through improper technique, and improper recovery action.

Agreed. In a 206B3 with an engine producing on-spec power you should be TQ limited up to about 8,000 ISA+15, and TOT or N1 limited above that.

That repair will need a jig so it can't be done in-situ, it's too badly banged up. I suspect the recovery/repair cost is likely to be significantly more than what the helicopter is worth, so not economic to repair. Push it over the side or cut it up into smaller pieces and sling it off the mountain bit by bit. Anyway, it's for the insurer to deal with now.

Nah, plenty to salvage and sell.
That's potential FrankenRanger material right there :}

So that means the pilot would have overtorqued and overtemped her anyway, before experiencing RRPM drop and losing tail rotor effectiveness?

Definitely overtemped. I wonder how many times the little red light has had to be reset, or maybe it had just burned itself out from overuse.

Not overtorqued if N1 or TOT limited - by definition. If N1 limited then no overtemp either, but BellRinger seems to suggest that it would have been TOT limited at that DA, so yes it would have overtemped in that case.

The C20/28/30 engine FCU will keep squirting more and more fuel into the engine until it arrives at N1 topping. So if you get to a TOT limit before the N1 limit, and keep demanding more power until N1 topping (when you can get no more power), you can seriously toast the engine. I've had a 206B3 at 11 grand ISA+15 but I can't recall which limit you will get to first, but it certainly won't be a torque limit. I always have my eyes shut whenever VFR above about 3 grand because it's not a place I like being. Over-torque a 206 engine and you aren't so much harming the engine, but the powertrain 'ant gonna like it and the AOG inspection might get real expensive to fix. I've got a hunch that cooking an engine without an over-torque might not be as expensive as the damage is confined to the engine hot section. All academic here as the accident aircraft is probably not economic to fix and is destined for the scrap heap, or the miracle room at the FrankenRanger factory.

Mi-8 bit overkill.

​​​A Bell 212 would manage it. We lifted out a Longranger recently with a Bell 212 Eagle from a greater altitude than that. Blades, Hub and Mast off, dump any extra weight (battery etc).

Still value in the hull. Probably BER for rebuild but value in spares. Someone will likely buy it after the loss adjuster puts it out for bids.

maybe overkill, but still cheaper given what’s available in the region. And you could lift it without removing anything.

Gullible, For someone who seems to be an expert on turbine engine management and operations at high altitudes seems odd that you are ****ting yourself at just 3000 feet.

Yeah, I get the heebie jeebie's and out of my comfort zone when I can see the ground far below me. Makes me want to find a cloud to hide in.

Not an unusual condition for pilots Gullibell - plenty of threads over the years on pprune about it.

I don't normally have a problem when enclosed in an aircraft - although I hate heights like ladders and cliffs - but I flew a Gazelle with the doors off at only 1000' agl and felt distinctly uncomfortable in turns when I was looking straight down at the ground.

Found a number of chaps who were nervous flying at altitude, anything over 1,500', possible transmission failure being the cause. Had to be told 1,500 is OK for small arms but 50 cal goes a lot higher then that. Took one lad to 16,000 to show him the scenery.

The main concern for many was uncontained fire at altitude, especially when gearboxes had a high proportion of magnesium in them.

Not heard of that one prior crab, if you were of neurotic bent there is plenty to worry about, chap had vibrations (F-28) so went into power on auto to get to the ground as quick as possible, flared, nice landing, during the cool down the passenger said "Looks like someone has been here before us", pointing to a tail rotor in the bushes. Pilot climbed out to find the end of the tail boom had been chopped off, but couldn't see how it could possibly have happened. Turned out the forward bolts on the transmission had sheared and when pulling power to terminate the transmission rotated rear wards so chopping the boom, on lowering collective transmission fell back into place. Manufacturing fault in machining the bolt holes placing stress on one side of the bolt heads.

Always had thoughts of one of my instructors and Groomsmen, Jerry Hardy ex RN, who died in a Bristow 76 at Aberdeen when it threw a blade. Doesn't take altitude to kill you. Jerry on right doing the mail run for the HMY Britannia when the ship visited Oz 1970.


https://cimg9.ibsrv.net/gimg/pprune....de5539586a.jpg