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-   -   Light aircraft down near McKinlay, Qld (https://www.pprune.org/pacific-general-aviation-questions/655646-light-aircraft-down-near-mckinlay-qld.html)

C206driver 4th Nov 2023 11:36

Recording equipment
 

Originally Posted by 43Inches (Post 11533080)
My first thoughts were pressurization with the altitude involved. The speed seems to indicate that perhaps there was quite a bit of headwind at 280 giving them a GS of around 220kts, then descent to 150 and they were making 250kts, possibly indicating less headwind. The track also looks like it made a slight right turn at one point and is missing Isa by some distance, which further lends to possible pressurization issues. The final part looks like possibly power loss, windmilling prop would slow it down fast at that level, left engine, slows, stall warning disconnects autopilot and it rolls and descends to the left, which is the path it would follow if the crew were not in a position to control it. I'm not familiar with the 695A but if it has multiple tanks it could have run one dry by then if the pilot was unconscious. In any case it's another bad day for GA. Does the 695A have recording equipment? if so that might be the only real clue to what has happened.

If by recording equipment you mean Flight Data Recorder (FDR)? This aircraft’s MTOW was 5080KG so not required as far I am aware

PoppaJo 4th Nov 2023 12:24


Originally Posted by KRviator (Post 11533072)
What'd cause the descent from FL280 -> FL150 and climb back to 280 early in the piece? Do the firescan ops require that, or could it be indicative of a pressurisation issue?

Seems like having a look en route at the Carnarvon gorge fires.

compressor stall 4th Nov 2023 20:15


Originally Posted by Horatio Leafblower (Post 11533151)
A friend of mine was killed in a GAM Aerocommander at Killmore Gap when the wings clapped.
I can't help but wonder how much low level FAC/Bird-Doggin' this machine has done.
How very sad for the friends and families. So sad.

It may have done so, but - with the usual caveats of ADSB data - in instance it looks like they were trucking along in the cruise at FL280 then lost 100kt over 2 mins pretty much level, then turned sharply left into an increasing speed descending turn.

reefrat 4th Nov 2023 23:59

Google mentions several wing spar failures

Alice Kiwican 5th Nov 2023 00:08

Never flown a 690 but could it have been an engine issue so pilot brings aircraft back to single engine safety speed (blue line). For some reason he loses control and aircraft stalls and enters a spin from which it never recovers? Would that be a possibilty for the aircraft losing 100kt ground speed in 2 minutes?

roundsounds 5th Nov 2023 01:58


Originally Posted by KRviator (Post 11533072)
What'd cause the descent from FL280 -> FL150 and climb back to 280 early in the piece? Do the firescan ops require that, or could it be indicative of a pressurisation issue?

It would be easy to omit resetting the cabin Alt following the intermediate descent to FL150.

Cilba 5th Nov 2023 01:23

Would the aircraft have had an aural cabin altitude warning?

aroa 5th Nov 2023 02:54

KR Av. Do those “students “ that are training in PNG get taught valley flying and techniques to escape.
A friend of mine and another acquaintance both met their demise out of the step turn having ‘dry gulched’ themselves in valleys with lids on. Trouble is all those jungle clad valleys in PNG look the same.

Thread. RIP the 695 three. Another mystery to be solved.

Horatio Leafblower 5th Nov 2023 02:57


Originally Posted by compressor stall (Post 11533388)
It may have done so, but - with the usual caveats of ADSB data - in instance it looks like they were trucking along in the cruise at FL280 then lost 100kt over 2 mins pretty much level, then turned sharply left into an increasing speed descending turn.

Ja ja ja but you and I both know fatigue is cumulative. It's less about what the aircraft was doing today as what it has been doing for the last 20 years.
I probably spend too much time thinking about these things as I pole around in 1970s twins with 30,000 hours.

VH-MLE 5th Nov 2023 05:22

"It would be easy to omit resetting the cabin Alt following the intermediate descent to FL150."
I've never flown this type, but if it's like most other pressurised turboprop aircraft, FL150 would be close to a sea level cabin at around max differential pressure, so even if the pressurisation controls weren't touched, the cabin should not have got higher than say 13000 to 15000ft on the subsequent climb, which gives a time of useful consciousness of > 30 mins, which means a failure to reset the pressurisation controls shouldn't be a relevant factor on its own. Just my 2 lire's worth...

A very nasty accident for sure & hopefully there'll be enough information to determine the cause & provide a report in about 10 years time... RIP to crew & condolences to friends & family.


Duck Pilot 5th Nov 2023 06:19

Obviously the new CASA rules haven’t done anything to improve safety.

If CASA decided to proactively engage with industry and provide good clear advice, opposed to convoluted and difficult to interpret requirements, industry would be able to focus more on their day to day operations opposed to playing ping pong with CASA inspectors over trivial rubbish.

With regards to the cause of this accident, who knows however it’s pretty obvious that the pilot experienced some kind of upset at FL280 and lost control. Structural, pressurisation or engine related who knows just yet.

It would be interesting to know what the airspeed margin in between the normal cruise IAS and VMCA is at FL280 for the aeroplane. If it’s critical, it would be interesting to know if simulated engine failures are demonstrated and practiced during initial training on the aircraft type at high altitudes.

clark y 5th Nov 2023 06:31

With respect to the first descent, you’d think there would be some communication with ATC. I’m guessing ATC would have picked up the descent and at least a “Confirm ops normal” call was made.
If it was a normal descent to try to find a better ground speed etc, there would be a communication trail.

Xeptu 5th Nov 2023 07:22

Why am I feeling like this is a training exercise that has gone wrong.
An engine out at FL280 will require a cruise descent, first action, it's well above single engine service ceiling. The sequence is consistent with Vmca stall.

Mr Mossberg 5th Nov 2023 07:28

Does anyone know if JO was the pilot?

Cedrik 5th Nov 2023 08:22


Originally Posted by Mr Mossberg (Post 11533584)
Does anyone know if JO was the pilot?

No he wasn't

Mr Mossberg 5th Nov 2023 09:04

Cedric, thanks for the advice.

43Inches 5th Nov 2023 09:45


Originally Posted by Xeptu (Post 11533579)
Why am I feeling like this is a training exercise that has gone wrong.
An engine out at FL280 will require a cruise descent, first action, it's well above single engine service ceiling. The sequence is consistent with Vmca stall.

Considering they had more than enough time to react and initiate the descent it lends even more weight to the idea the pilot was not in a state to be able to handle it. Even if they did mishandle the initial failure and slowed to stall, you would think the pilot would have been able to recover if they were conscious, they had more than enough altitude to have several goes at recovery. Considering that if it was engine failure, at 28,000 feet all you have to do to recover from the yaw/roll excursion is to close the power lever on the live engine and fly straight in a descent. The ADSB data suggests it just slowed straight ahead on autopilot, as it was all straight and level until the speed was minimal, then it turned to the left and descended. I would think that given how the airspeed decayed over time, in straight and level flight, it does not fit with a structural failure. And if you knew a wing was falling off or failing and were slowing for whatever reason I'm sure they would have issued a mayday. I find it hard to move away from the idea it was pressurisation related. The last point of communication will be telling on what may have happened. Again I have no experience with AC 695(A) or it's pressurisation system, is it possible that the descent to FL 150 somehow put the pressurization in a descent mode and then the climb back to FL 280 it was not put back in a mode to accommodate for the climb back up.

PoppaJo 5th Nov 2023 10:16

Seems plausible. Would also explain the slight track deviation without correction. Would be interesting to know if ATC heard anything from them after being cleared back to the upper level.

lucille 5th Nov 2023 10:31

Vmca unlikely to be an issue at FL280. The engines would only be developing a fraction of their sea level rated HP up there.

Was the aircraft in one piece at time of impact?

TBM-Legend 5th Nov 2023 10:41


Originally Posted by 43Inches (Post 11533658)
Considering they had more than enough time to react and initiate the descent it lends even more weight to the idea the pilot was not in a state to be able to handle it. Even if they did mishandle the initial failure and slowed to stall, you would think the pilot would have been able to recover if they were conscious, they had more than enough altitude to have several goes at recovery. Considering that if it was engine failure, at 28,000 feet all you have to do to recover from the yaw/roll excursion is to close the power lever on the live engine and fly straight in a descent. The ADSB data suggests it just slowed straight ahead on autopilot, as it was all straight and level until the speed was minimal, then it turned to the left and descended. I would think that given how the airspeed decayed over time, in straight and level flight, it does not fit with a structural failure. And if you knew a wing was falling off or failing and were slowing for whatever reason I'm sure they would have issued a mayday. I find it hard to move away from the idea it was pressurisation related. The last point of communication will be telling on what may have happened. Again I have no experience with AC 695(A) or it's pressurisation system, is it possible that the descent to FL 150 somehow put the pressurization in a descent mode and then the climb back to FL 280 it was not put back in a mode to accommodate for the climb back up.


remember the Paine Stewart Lear 35 accident


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