http://m.aviationweek.com/awin/six-factors-named-manas-kc-135-crash

HO LEE FUK!

I had never heard of "rudder hunting" before.

What a way to go!



Okay....ARFcom pilots, what say you?

Bueller...Bueller?

Anyone?

Anyone?

The report doesn't really give much info.    It's impossible to tell just how aggressive the Cpt was, when playing with those rudders.

We typically never touch the rudders in flight.  Only for takeoff and landing, for 10-20 seconds.  

Rudder malfunctions are extremely serious, and our training addresses it, but doesn't really dwell on just how fragile the tail section is.

There was one semi similar in a commercial airliner, forget the flight number. The airplane experienced wake turbulence and the pilot or copilot was incorrectly trained by the airline to use hard rudder inputs to smooth out the flight. Inputs that broke the tail off.

Can't happen in a Boeing narrow-body. Nope...

USAir 427

UAL 585 COS

Boeing and SWA busted their asses to make this go away...

TC

Wasn't that the one that went down in NY/NJ?

The -135 community really took that to heart.  We've chased all sorts of gremlins related to even minor rudder hunting that pilots would have ignored before Shell 77.  There was also a training element as well.

You're thinking of AAL 587.

Prior to this incident, pilots were taught that you can pretty much do whatever you want if you are at or below maneuvering speed.

That's not really taught anymore in primary training from what I have seen.

http://www.torch.aetc.af.mil/News/Article-Display/Article/580256/aircraft-malfunction-insufficient-training-lead-to-kc-135-crash-three-fatalities/

According to that link, it looks like Mama Blue is calling it "aircraft malfunction coupled with lack of aircrew training".

I'd be curious if there were other incidents of rudder hunting/Dutch rolling of KC-135s prior to that crash.  And what the aircrews did to recover from it???

I noticed the first article said the pilot/co-pilot tried to get the plane into auto-pilot....but I guess by that time the oscillations were so severe that auto-pilot wouldn't stay engaged.

Correct.

The pilot on the NY flight that went down was taught to 'pump the ailerons' to stabilize the aircraft since they hit hard turbulence from a larger aircraft that took off too soon before them.

At first, I was thinking of the jack screw failures on MD-83s.

But damn...a servo on the PCU.

Uhg. That sucks.

I know pilots have a reputation for 100% honest hot wash critique, but it pains me a bit for the aircrew's "inexperience" to be blamed when the AF admits they couldn't even simulate the event in training. I guess it's technically true, but feels (muh feelz!) a bit slimy as if the AF is trying to blame the pilot instead of the gear, when gear and training program failure is maybe a more apt target.

RIP guys.

Yes, just never that severe.  And plenty of events since.

The training, tech data, simulators, and flight manuals have all been changed because of the board's findings.

We all got the briefing on this after the investigation. The CVR is fucking terrible to listen to.

My brother (also a boom) was on a crew at Manas when it happened and I didn't hear from him for several hours after I got the word that a tanker went down. One of our AC's got a call out on SAT comms to our CP to relay that it wasn't any of our people.


Also, one of my friends was the crew chief that launched the jet. He hasn't been the same since, even though he couldn't have caught anything to save the crew.

I'm glad that stayed on the Ops side.  It had to be a long time after they knew they were in a bad way.

WHere is it

I saw the recreation as well. What really haunted me was how quiet the cockpit became in the 10 seconds or so before the aircraft broke apart. Once the A/C took over, the aircraft was almost out of control with that point. To think all they had to do was turn rudder power off and that crash would have been completely avoided is tragic.  Sadly the -1 (at the time) said to do otherwise.

Rudder hunting has been a problem for years, it's just rare to see it happen to that extent in flight.

You can turn the Rudder Power off ( turns off Hyd power to Rudder PCU ) on the 135. The reports are kinda vague but the pilots exasperated the problem by trying to use rudder inputs to counter the dutch roll.

[CptHindsight] Auto Pilot Off, RP off , feet off pedals and it would prob have settled out.[/CptHindsight]

I haven't seen it on open source. Not that I have looked for it though.

When I went thru CFIC I had several instructors and friends from Fairchild that knew them very closely and this had just happened.

RIP to Tyler, Tori and Tre.

Cliff notes: this accident was caused by bent linkage in the series yaw damper (prevents Dutch roll) and lack of crew awareness in Dutch roll recovery. As the aircraft accelerated, so did the Dutch roll.. the crew knew something was wrong but couldn't figure out what was going on... there were indications that the AC (aircraft commander) suspected the yaw damper was the issue, but at the time, corrective action was to turn the yaw damper back ON, since it fails in the OFF mode. But in this case, the yaw damper worked fine, it was just the linkage that made the rudder out of sync, causing the Dutch roll rather than dampening it as designed.

This accident scared them hell out of us in the 135 community, because for months no one knew wtf happened. I was under the strong opinion that the center wing fuel tank exploded like TWA800...

I always try to put myself in the crew's shoes and think honestly what I would have done..... to tell the truth, I don't think I would have figured out the problem, but I do think that ONE thing would have saved me... I would have slowed the fuck down! And especially stayed off the rudder. The fact that they kept accelerating, and worse yet, made rudder inputs coupled with improper Dutch roll recovery, sealed their fate. Very sad.

My sim partner in CFIC was roommates with the copilot's husband at the academy... she (the copilot) just returned from maternity leave and was just back on flying status. He also was a 135 guy and never flew the tanker again after the incident.

Mostly correct. The series yaw damper (SYD), which prevents Dutch roll, was fucked and doing the opposite of what it should. There are theories of what may have caused this malfunction,  but from what I am aware, this was the only recorded issue of this kind. This situation is not to be confused with the "hard over rudder" situations that have occurred in the past.

If only they had realized that shutting off power rudder would have worked sooner 

August 28, 1963, KC-135

I can say as a former 135 instructor pilot, that almost no one would have come to that conclusion off the bat. Hindsight, yup... makes perfect sense, but all we can do now is learn from the past and keep an open mind to understand what crews are thinking when bad shit goes down.

Just think about how many times we are flying when we don't realize that our head is actually way up our ass... sometimes it takes things like this,to remind us that "Fate is the Hunter."

What is rudder hunting?

Tagging a great convo


Thanks guys

Fancy term for uncommanded rudder movement, or uncommanded rudder occilations.

This was a tough one to see...  My dad was a nav in the -135 from 1991 to 2005 (Ohio ANG).  He ran the intel shop for the same Wing until he retired in 2012.

:(