Go Back  PPRuNe Forums > Aircrew Forums > Military Aviation
Reload this Page >

US Navy TexanT6 crash fatal 10-23

Military Aviation A forum for the professionals who fly military hardware. Also for the backroom boys and girls who support the flying and maintain the equipment, and without whom nothing would ever leave the ground. All armies, navies and air forces of the world equally welcome here.

US Navy TexanT6 crash fatal 10-23

Old 10th Nov 2020, 08:30
  #81 (permalink)  
 
Join Date: Jan 2011
Location: Chicago or Cheshire
Posts: 636
Just my uninformed 2c.

The feathered prop tells us they were conscious. My guess - loss of situational awareness during recovery attempts by the PIC, and a young Ensign too overwhelmed to issue a Mayday or unilaterally eject.

Tragic regardless.
Fonsini is offline  
Old 10th Nov 2020, 09:42
  #82 (permalink)  
 
Join Date: Nov 2000
Location: UK
Age: 66
Posts: 1,201
Picking over the bones and gloating speculation with your expert knowledge will be a great comfort to the bereaved.
​​​​I hope you feel good about your contribution.
beardy is offline  
Old 11th Nov 2020, 02:20
  #83 (permalink)  
 
Join Date: Mar 2005
Location: N/A
Posts: 4,015
The feathered prop tells us they were conscious
Don't understand how you come to that conclusion, the PT-6 prop will go to the feather position in the event of an engine failure under the action of the feathering spring and counter weights as oil pressure in the servo decreases. If manually feathering the servo pressure is dumped immediately where as in an engine failure case, and the feathering is not done manually, the prop will move to towards the feather as servo pressure slowly bleeds off.

https://www.flight-mechanic.com/prat...peller-system/
megan is offline  
Old 11th Nov 2020, 13:06
  #84 (permalink)  
 
Join Date: May 2011
Location: BOQ
Age: 77
Posts: 534
Our family T-6/T-34 instructor told me something else of interest.

In the T-34C they taught both spins and circuit oriented cross-controlled departures. In the T-6 syllabus, spins are taught, but not cross-controlled departures. Minimum entry altitude for spins, 16,000'. Not recovered by altitude, they use 10,000' also in training.

Looking at that plot from 'ugly jet' driver in post #47, if accurate, it shows an altitude of 2300' and airspeed of 112 mph (98 knots) in the vicinity of Foley. Those engine-out patterns (practice or real) are flown at minimum 120-125 knots. Indications of something other than incapacitation going on here?

Last edited by OK465; 11th Nov 2020 at 13:29.
OK465 is offline  
Old 11th Nov 2020, 22:49
  #85 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 78
Posts: 1,412
Thanks, Okie. I had not seen the last data point Ugly posted if that's it.

Dunno about the T-6, as my UPT didn't have any planes with a prop. IP would yank throttles back and announce engine failure. So I was taught to get to the best glide speed or even best lowest descent AoA, then use your SA to turn to nearest field, or at least a nice place to bail.You know, FAC tells you best bailout heading if you got hit bad.

So your idea has merit and I am surprised at that low speed.
gums is offline  
Old 12th Nov 2020, 04:04
  #86 (permalink)  
 
Join Date: Apr 2000
Location: USA
Posts: 194
OK465 the speed is ADS-B data driven and it is relative to position and not what the aircraft is indicating (i.e. a vertical path would theoretically indicate zero speed). It looks like a LOC and no visible bump in descent rate to show a recovery attempt. The path track shows them maneuvering in the box and the turn to the west is not towards a viable and usual "practice" field. You are correct this is way too low to be doing spin entry and recognition according to the syllabus.

This looks to be normal ops in the box doing low speed maneuvering. The aircraft recovers and accelerates from a series of low speed turns at a steady altitude of 8000'. It then accelerates in level flight (which would indicate an addition of thrust) to 250ish knots at 8000'. The rate of increase likely indicates they had a clean airplane with gear and flaps up. When reaching 250ish knots there is a loss of altitude and a loss of speed. This could be an engine failure as you don't usually lose speed and altitude especially if you just gained speed back in level flight. Something caused them to go down and slow down. (keeping in mind this is ADS-B speed so I may be reading too much into it). This burble happens after a turn to the west. They are steady on heading and level and speed decays which also could indicate a loss of thrust. This decay lasts a very short time and then they depart to a steady state descent to impact and we have no idea of actual airspeed of the aircraft given the rapid rate of descent.

Megan, good insight on the prop driving to feather in an engine failure If they had an engine failure. My experience is the low oil pressure feather event is a very slow occuring event and full feather likely wouldn't occur in the very short time from from controlled maneuvering possible engine out to LOC and impact in this case. It would seem that the crew feathered the prop is the most likely given the timeframe.

There is something else her from incapacitation, a bird strike, or some form of catastrophic airframe or control failure. The instructor had a very good reputation and was very experienced. There has to be more here than a simple LOC and spin. The acceleration while level and turn to the west and descent while losing speed then complete LOC is puzzling. Add no radio call and the mystery deepens.

The squadron is back up and flying at this time. I hope the accident team gets insight into this one. Losing two crew is tragic, not knowing what happened and preventing the same circumstance to cause another hull and crew loss would make it more so.

Last edited by Ugly Jet Captain; 12th Nov 2020 at 04:45.
Ugly Jet Captain is offline  
Old 12th Nov 2020, 13:28
  #87 (permalink)  
 
Join Date: May 2011
Location: BOQ
Age: 77
Posts: 534
UJC,

Good comprehensive info and viewpoint. Thanks.

One comment:

I may be wrong here concerning your particular plot and what data was transmitted to who, it's been awhile, but having flown both B-738 and A330 sims with early ADS-B "In" capability simulated and displayed in the cockpit, I seem to recall our ADS-B speed data was KTAS taken directly from the displayed traffic ADCs before transmission, and was not relative position dependent (i.e. ground speed). IIRC we had a time referenced on board interval management software that was based on KTAS. Ground based info may be different. (If I'm wrong, unlike some people, I'll concede. )

In any case, my source tells me that in the T-34 or T-6, a cross-controlled departure condition can instantly flip you inverted.

OK465 is offline  
Old 12th Nov 2020, 14:23
  #88 (permalink)  
 
Join Date: Aug 2009
Location: Texas
Age: 62
Posts: 5,659
EDIT: For UJC. Sorry, I missed your post, nice summary.
Originally Posted by OK465 View Post
Our family T-6/T-34 instructor told me something else of interest.
In the T-34C they taught both spins and circuit oriented cross-controlled departures.
The cross control departure that was taught was called "skidded turn stall" and it was done dirty: gear down flaps up, 100 knots (pattern airspeed).
There was a T-34C mishap in January of 2006 in Corpus Christi that was probably that. Based on where the crash was (near the 90 position for the outlying field) and the rapidity with which it occurred, and the eye witness statements, OCF below pattern altitude so it was over in a hurry. (Might also have been an approach turn stall ... )
In the T-6 syllabus, spins are taught, but not cross-controlled departures. Minimum entry altitude for spins, 16,000'. Not recovered by altitude, they use 10,000' also in training.
Ah, so they have not changed the syllabus since I last saw it. Interesting to know.
Looking at that plot from 'ugly jet' driver in post #47, if accurate, it shows an altitude of 2300' and airspeed of 112 mph (98 knots) in the vicinity of Foley. Those engine-out patterns (practice or real) are flown at minimum 120-125 knots. Indications of something other than incapacitation going on here?
How strong was the wind? If someone had already feathered an engine, and had not had a successful restart, and was making for a paved surface rather than ejecting, is it possible that a pilot was making an adjustment to profile and lost control? Not gonna speculate, as it appears that a possible LOC may have been at a higher altitude.

Last edited by Lonewolf_50; 12th Nov 2020 at 14:36.
Lonewolf_50 is offline  
Old 12th Nov 2020, 19:06
  #89 (permalink)  
 
Join Date: Aug 2013
Location: Not lost, but slightly uncertain of position.
Posts: 13
Tragic accident and sadly two young military aviators lost.

Having flown approximately 150 hours on the T-6 during my pilot training, I can report that the aircraft exhibits very good characteristics for a trainer. Firstly it has a very comfortable cockpit layout, and more important, it is has very nice and forgiving handling qualities. It does not flip you upside down unless you mishandle it grossly, and it will let you know way in advance when you approach the edge of the envelope. It will talk to you with increased buffet and even a stick shaker, when you approach a stall, and if you intend to spin, you have to provoke it with crossed controls during entry and throughout the incipient spin. If you center up the controls and unload a bit during the incipiant spin, it will recover instantly. Regarding the spin in the T-6, I don't remember it as being flat-ish at all.

The Mk16 Light seats are very capable, and I am not familiar with any escape system failures with this type of seat in this aircraft type. Pull any handle, front or backseat, and the sequencer will eject the rear seat first, and the front seat in quick succession, regardless if the canopy det-cord works or not.

I wonder if they were either incapacitated, if the seat failed somehow, or if they misjudged the altitude needed for recovery, and therefore did not initiate the ejection. The report will show...

F-16GUY is offline  
Old 12th Nov 2020, 19:31
  #90 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 78
Posts: 1,412
Thanks, F-16 Guy.

I would love to talk with a few recent UPT grads. but the "bug" is limiting social contact at the local pubs.

Other than the Viper and the Deuce, the other planes I flew always gave you lottsa warnings. The Viper and Deuce did not suddenly go out of control by flipping and yawing and...., they just descended. You could get the Deuce down to 90 knots in a climb and then descend at 10,000 FPM and feel real good. The Viper didn't have wing rock or even moderate buffet, it just rolled/yawed and most of the time ended up descending at 30 deg AoA until impact or using the MPO feature to rock it out.

I have always sided with the "crew" on this forum and look for mechanical failures beyond control of the operator(s). In this case, I can not see Gee Loc. I see something more insidious.

Another nickel on the grass.
gums is offline  
Old 13th Nov 2020, 01:02
  #91 (permalink)  
 
Join Date: Mar 2005
Location: N/A
Posts: 4,015
If someone had already feathered an engine, and had not had a successful restart
With the PT6 you can feather the prop without shutting down the engine, enhances the glide no end.
megan is offline  
Old 13th Nov 2020, 11:22
  #92 (permalink)  
 
Join Date: Aug 2007
Location: Sydney
Posts: 16
Megan, certainly true that a PT6 can feather the prop whilst the gas generator keeps running but I suspect not in this installation. The PC9 and I suspect theT6 had a single power control lever (PCL) and to shut the engine down, a lever or tab in front of the PCL is lifted and the PCL moved ‘over the decent’ and the propeller is feathered and the fuel is cutoff to the FCU. I once managed to have one during shutdown feather when I lifted the PCL over the detent slowly and the gas generator kept running until I moved the PCL back further. Obviously not quite rigged as per the book. There is one reported incident that I am aware of where the PT6A-62 engine in aPC9 failed and both pilots swore that the PCL was moved to shutdown but the prop didn’t feather. They normally would have comfortably glided to the runway but the prop drag meant that they both needed to use the Martin Baker let down. Thankfully successfully.

I also believe that just because the engine fails, the prop will not necessarily feather. If the gas generator isn’t seized it will windmill and provide enough oil pressure to not feather the prop. With no oil pressure the feather weights and ATM will certainly feather it but it depends if the PCL has commanded the prop to feather or there is no oil pressure.
Beez51 is offline  
Old 17th Nov 2020, 06:06
  #93 (permalink)  
 
Join Date: May 2003
Location: SAUDI
Posts: 340
Apologise for thread drift. Good points Beez 51. It was not common but no overtly rare that on shutdown in the PC9 that the prop did not feather due to misalignment of the S86 or may have been S82 (long time ago) micro. You than could sit there and watch as the prop slowly move to feather. If memory serves, up to one minute. And as you stated whilst gilding at 120kts, with air flow through the engine, and the micro connection failing, there was a lot of speculation of as to whether the prop would feather with oil px still provided. Many discussions on what to do including a stall turn, but if you couldn’t hang for more than a minute not going to work.

On the comment of the engine failing and the prop not feathering with air flow through the engine, once the S86/82 micro is made (hopefully aligned correctly) that opens a valve in the CSU that dumps the oil (return to engine) so no oil/px to stop the spring from working.
finestkind is offline  
Old 18th Nov 2020, 01:44
  #94 (permalink)  
 
Join Date: Apr 2000
Location: USA
Posts: 194
Here are the flight track logs for BB207. This is the last 6 minutes of the data. I added a turn direction, heading change and rate of turn. Keep in mind that a standard rate turn is 3 degrees per second.

The aircraft looks to be in a steady state and in control as it exits the box and head to the SW. More than likely they were heading to an outlying field nearby. Unfortunately there is a data skip in the last minutes of the flight but in that 64 second interval the aircraft the aircraft appears to be in stable flight in a slight left turn to the south. I don't see any GLOC type data prior to that as it looks like a planned let down.


BB207 data from Flightaware

19 seconds after the slight left turn and an increase in the rate of descent the aircraft is over the town of Foley.at 2250' descending at 4579 ft per minute and the data ends after that. It would appear that the LOC happened between 3000-4000 feet and resulted in a loss of forward velocity (could be a spin as there isn't enough data). The data is pretty small at the end but the data prior to 05:21:26 shows an aircraft under control.

The LOC at a low altitude from the steady rate of descent and seemingly in control aircraft would explain the lack of Mayday or any distress call. It also would explain the lack of a bailout to a degree as the time from LOC to impact was very short. To me it looks like they took a bird impact or the aircraft had a major structural or control issue. This was not a crew that rode an aircraft in from 8000' as it first looked it is a low altitude LOC with a very short window to eject.
Ugly Jet Captain is offline  
Old 18th Nov 2020, 13:16
  #95 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 78
Posts: 1,412
Scary plot, Ugly, and many thanks.

Our experience in the Viper was no kidding gee-LOC and not oxygen system problems that have been alluded in the T6, F-22 and F-35. The GLOC usually resulted in lack of ability to do much for a minute or so - figure 60 to 90 seconds, even if able to mumble. Whereas some physiological phenomena like CO poisoning or some exhaust fumes or OBOG malfunction involving bleed air or ...... likely takes longer to recover or maybe never.

My episode was with student studly looking up over his shoulder and pulling hard, then relaxing the gee. At first I thot he was "extending" to gain energy before turning back to the bandit. We were not real low, and maybe 15 deg nose down, so I gave him 5 - 10 seconds before looking forward to see his head bouncing off the canopy rail. Gums asks..." Ski, ski!" ( had a Eastern Euro name,so to be accurate, that was on the tape). "Knock it off!!" on radio to the bandit. "I got it", says Gums while recovering and then telling the bandit we were RTB. We had adopted procedures after an LOC episode to preclude further medical problems. Student recovered fully about 90 seconds or so from when I noticed the relaxed gee, so he was likely "out of it" for almost two minutes.

The profile for this one resembles LOC (from whatever cause), and if the plane was fairly well trimmed, you would not see much variation in flight path unless one of the crew was putting pressure on the stick, even tho unconscious. The Helios crash in 2005 is one to see, although the loss of oxygen happened slowly.

Sure hope we look hard at the OBOGs.

Last edited by gums; 18th Nov 2020 at 13:26. Reason: spellcheck
gums is offline  
Old 18th Nov 2020, 13:51
  #96 (permalink)  
 
Join Date: May 2011
Location: BOQ
Age: 77
Posts: 534
UJC,

I'm a little confused by those heading change (which would seem to actually be track not heading) numbers. The two pieces of data coded red below 5000' feet show heading changes of only 22 degrees.

But a left turn from 154 to 045 would be a total track change of 109 degrees. And in the 19 seconds time shown for the turn, that would make the turn rate 5.7 deg/sec. (With an accompanying 95 knot loss of some kind of speed (even GS that's a bunch in 19 secs).

Maybe I'm reading it wrong.
OK465 is offline  
Old 18th Nov 2020, 15:25
  #97 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 78
Posts: 1,412
I tink your assumption is correct, Okie. We are seeing track and not heading.

So someplace below 5,000 ft we enter a "deadman's spiral" maybe. Some roll input and maybe back stick after another few seconds. Ground speed decreasing rapidly along with altitude and track changing to the left all the way. Even if unconscious, there could be control inputs from the crew. Our experience in the early days of GEE-LOC was relaxed pressure on the stick when the pilot fell asleep, so we saw little change in turn rate although aileron trim could still increase roll angle, not rate. Being as how we didn't have a moveable stick, and the thing was well away from our other arm and neither leg, then we can accept little if any pilot flight control inputs, huh?


Last edited by gums; 18th Nov 2020 at 16:09.
gums is offline  
Old 18th Nov 2020, 18:06
  #98 (permalink)  
 
Join Date: May 2011
Location: BOQ
Age: 77
Posts: 534
The below assumes the data is accurate:

The 106 degree turn from 260 to 154 was accomplished over 64 seconds. If done the short way around to the left, this equates to 1.6 degrees per second. A fairly lazy turn here.

Then it was increased to 5.7 deg/sec. 5.7 degrees/sec is not an overly aggressive turn, but over the short period of time it was instituted indicates to me a more impending requirement to get pointed in a particular direction arose. And they are descending to an altitude associated with practice/real engine out patterns near a field used for practicing these.

It's the 5 knot per second speed decay that is more concerning. If you're at 3700' and 192 in a descent (per the data) and you intend to be at 3000-2500' (high key) and 120 or so for the profile, a rapid decel would be appropriate, but attention to stopping the decel at 120, possibly with pitch only, would be competing with, but as paramount in importance as getting pointed in the right direction for the profile. The old slow down and go down.

I believe UJC is using LOC to refer to Loss of Control, not Loss of Consciousness. The technical acronym used in the T-6 for loss of control appears to be OCF, out of control flight. Does the T-6 have a speedbrake function? edit: Further reading indicates it does.
OK465 is offline  
Old 18th Nov 2020, 18:14
  #99 (permalink)  
 
Join Date: Jun 2002
Location: east ESSEX
Posts: 3,970
Just a thought ,or two;we don`t know what the `student`s experience is ,or what part of the training syllabus is the exercise,but it looks very much an early `general handling exercise`,at medium level,maybe a bit of aeros plus maybe a `demo `forced landing`....possibly overhead the airfield at Foley...

It could be that as part of the exercise the prop may be feathered(demo),but possibly the I/P and/or student are incapacitated/lose comms,someone recovers and turns back towards Foley ,(approx 3nm NE),but enters a spin,unable to recover from <2000ft...maybe the engine had failed,or failed to relight/unfeather....?
Lots of maybe`s/possibly etc,so we may never know...do T6s have a CVR/ADR as standard....perhaps someone from Valley may wish to contribute...?
sycamore is online now  
Old 18th Nov 2020, 19:06
  #100 (permalink)  
 
Join Date: May 2011
Location: BOQ
Age: 77
Posts: 534
From what I read, no CVR as such, but it does have a digital video recorder for mission debrief. I would think the DVR has audio, but don't know.
OK465 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.