AW139 incident - Houma
 

Some conflicting information, but certainly seems to have been a challenging situation to deal with, that had a good outcome: https://aviation-safety.net/wikibase/283731

Wow, stuff even the sim instructors hadn't thought of!

Great effort to walk away from it with everyone safe :ok:

Excellent Airmanship....and I bet you the Checklist did not have pages enough for the problems encountered.

This is a story I would live to listen to being told by the Crew.

Very well done!

Now for the investigation to determine not only what happened....but why....to ensure another crew does not ever have to deal with such a problem again.

Certainly sounds like something you don't want to happen at night 100nm from land, or in IMC above mountains!

Errrr......ahhhh......call me a Scaredy Cat but I would not want to have that happen to me while setting on the Ramp.

Boredom is good!

Concur with comments above. Does it sound like the crew was facing a multiple basic instrument failure that was beyond the 10 to the minus 9 probability?
Edited: Oh, and combined with similarly improbable engine control issue?

Video of it here:

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Will not let me post link---remove the four "z" at begining

Been removed now it seems

Some photos at the Houma Fire Department Facebook Page.....

https://www.facebook.com/houmafire

Congratulations to the crew for a job well done! A great demonstration of the adage: “never stop flying the aircraft”! I only hope that I could do as well!

Video

The ASN report says they chopped the engines at 200' but that looked like a powered approach all the way to the ground - with judicious use of the Engine Mode .switches.

Bloody good job all round, probably make an excellent CRM lecture.

Considering the situation, what a greaser! Chapeau to the crew.

I dare say this is what you call the Right Stuff.

The question I am looking for will be what caused he Flight Control issues that were reported.

Some 139 pilots might weigh in on that.

One discussion of the AW-139 I have read stated the Aircraft had mechanical linkages combined with an AFCS that had equal authority to that of the Pilot.

So am I right to think with the Essential buses gone awry due to an electrical fire....would that somehow cause a problem where the Pilots could lose "control" of he aircraft due to the AFCS being left in a mode that could not be removed by the Pilots using normal means to do so?

Or....would the Pilots have to over power the AFCS and Force Trim by manual use of the flight controls?

Just some guessing at probable causes based upon what media reports are out at this time thus remaining in the "asking' and "guessing" mode of query.

Assuming the AFCS and FMS had been set to track "NAV" or "HDG" and maintain 6,000 Feet....and you could not get the AFCS to respond to any other commands....what would the control forces that would be felt by the Pilots?

I also assume the Essential Buses power their associate Emergency buses which means if all four buses are failed....there is not much left to work with in coping with the problems.

How are the Engine Control switches. powered.....which bus are they fed by?

For sure this shall be a very interesting Investigation to figure out what happened, why, what issues the Pilots had to deal with, and how they managed to do so in such am excellent manner.

I'm not a 139 pilot, but this doesn't sound any different to most AFCS systems, especially with upper modes. SAS has fast acting low authority (5-10%) actuators, ATT has slow moving, high authority (100%) actuators. Neither has the power to not be overcome by pilot input, even if the FTR or trim release do not function.

What amount of physical force would be required to overpower the AFCS actuators and the Force Trim Gradient.....assuming that is what you had to do?

If both DC Essential buses failed....would that also take out. the DC Emergency buses?

What capabilities would be lost re systems control...AFCS, Stick Trim, Force Trim Release, flight instruments, Engine control....etc?

Looking for 139 specific answers.

Looks powered at the end, then engines to idle, high flare pulling all the rpm off and a somewhat high ROD to runway impact that cleaned the gear off. Speed looked good for a full-on auto. Can't be too critical of the touchdown without knowing what was going on inside - what engine/flight instrumentation was still working, were the pilots fighting any AFCS or autopilots.

Ah yes, the mysteries of the AW139 electrical system, makes you wish you paid more attention in class. This might lead to a 76-style bus recovery mod.

The rate of descent is way too low for a full down auto from any height in a 139 - it looks like they waited until they were very low to chop the second engine, I suspect the first was chopped just before the big flare.

When the EECs fail the engines should revert to manual control but beeping the ECLs would need electrical power - ISTR they can be moved manually but can't remember if the link from ECL to FCU is mechanical or electrical.

I presume if they had to use the Eng Mode switches, and they worked, that there was some electrical power somewhere.