Light aircraft crash - NT - 25/12/2022 - 2 dead

[RFguy]

C210 crash : Well, the weather radar/ time/ location of crash has good correlation.

Not sure why the pilot did not fly around the storm, if indeed that was the cause.

 

Always slow down to Vmaneuvering in turbulence !  It might be slower than you think if the aircraft is low in weight compared to max weight.

According to the (pressurized) P210N POH : (and same in a T(urbo)210N) 

empty weight abotu 2200, so 210 litres, 2 pax and some luggage and tie downs etc  probably  2950 lbs - IE around 111 kts

 

 

 

Edited March 27, 2023 by RFguy

[onetrack]

The pilot only had his CPL for less than a year, and his total logbook time was under 400 hrs. Inexperience must have played a large part in this crash, plus the fact he was piloting a high-hour aircraft, well-known for losing a wing in adverse conditions.

[Blueadventures]

9 minutes ago, onetrack said:

The pilot only had his CPL for less than a year, and his total logbook time was under 400 hrs. Inexperience must have played a large part in this crash, plus the fact he was piloting a high-hour aircraft, well-known for losing a wing in adverse conditions.

Agree plus maybe timetable schedule pressure.

[facthunter]

There was no pre-existing fault with the wing structure. Most concern for these plane s is the centre section carry through spar. It appears to be a massive overstressing of the wing spar itself. Most of his experience would have been in the area. Without some form of weather radar he would have been compromised avoiding cells..  Not a day to  fly at those levels in that  type of plane. Some of the most spectacular thunderstorm activity I've ever encountered is in that area and diversions to avoid cells more common than anywhere else.  Nev

[Old Koreelah]

8 hours ago, RFguy said:

According to the (pressurized) P210N POH : (and same in a T(urbo)210N) 

That doesn’t make sense; surely with higher weights, you’d need to reduce the speed in bumpy air?

[RFguy]

No.  google "FAA definition of Va". 

FAA defines this as : the airspeed at which the airplane, subject to a sudden control input , or , gust will stall rather than exceeding the design structural limitation / maximum load limit.

 

And more weight on board means higher stall speeds (as usual) .

 

If you fly faster, the wing can produce more lift. IE  for Va = 80 kts.....you are flying along at 70 kts and yank the column back  to maximum AoA. below Va, the wings dont fall off.

you are flying along at 100 kts, and yank the column back to maximum AoA , the wings produce a sh1t ton more lift (2.04x precisely) , you exceed the structural limitation of the aircraft, the wings fall off.

 

The relationship with flying in turb is that you are hit by a gust at some angle which emulates a higher AoA and hence instantaneous lift.  bad. 

 

See section on Dynamic Gust Loads  in https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25_341-1.pdf

 

 

 

 

 

Edited March 28, 2023 by RFguy

[Old Koreelah]

I see, they’re talking about the speed at which your wing no longer lifts, not the speed at which you risk structural damage.

[RFguy]

not quite  ,  It is the speed beyond where the the lift produced can damage the aircraft. 

 

example:  your aircraft is 1250 lbs, and rated for 2G.

and.. that the maximum lift AoA is 25 degrees. and it produces 2500 lbs of lift at 56 kts at 25 deg AoA.

 

now, say you are flying along at 5 deg AoA at 56 kts, and the wing is producing 1250 lbs = IE same as your weight, S&L flight.

then you yank the control stick back and produce 25 deg of AoA, -- now yoru airspeed is still 56 knots, and now the wing is producing 2500lbs,

which is 2x the 1250 lbs weight, - and thus 2G of force - this is the maximum you can tolerate.

 

if you yank the stick back and push the aircraft through the maximum lift AoA, and BEYOND , then the wing goes down the other side of the lift curve in a stall. no bother. 

So, you survived, the wings didnt fall off . But if you'd been flying S&L at 80 kts, and you yank the control stick back to produce 25 deg AoA, now the wing produces ( 80/56 )squared  = 2.04 x as much lift as at 56 kts, now you have 5000 lbs of lift, or 4G. your wings fall off. 

for a GUST and TURBULANCE   - and this is what I didnt first explain - this is for a fictional gust of  ,

if the aircraft gets belted up  by a gust, or the pilot applies some control input in resposne, 

IE  hit by a gust causing the aircraft attitude to change its AoA -  the aircraft goes from flying S&L to perhaps being steeply pitched up, high AOA- then below Va, this will result in lift  being below the maximum that the airframe can tolerate. 

 

If it gets hit by a gust etc  and the aircraft gets pushed HIGHER than its maximum lift AoA, no bother- the wing will stall - IE beyond the maximum  angle on the lift curve - IE putting an upper bound on the lift produced.

The same limit can occur if the wind gust vector is such that it produces a high AoA. Like, a gust from under forward of your nose. 

See section on Dynamic Gust Loads  in https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25_341-1.pdf

 

Edited March 28, 2023 by RFguy

[RFguy]

 Dynamic Gust Loads  in https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25_341-1.pdf

 

Required reading for everyone

 

everyone to read sections 5 and 6 from that AC. (dont need to read the lot) 

 

[facthunter]

I'm sure we're now ready for the exam. What normal pilot is going to understand that?. There are vital points to remember when you hit turbulence. Slow the plane down, don't make abrupt control inputs and only loosely keep the plane to a close level or speed.  Attitude is most important and MAINTAINING control. Why would any thinking person end up with full control deflection unless doing a 3 pointer?  Your usual ultimate structural fail  figure is around 3.5 G positive and aerobatic plane can be way above this. Fly with a "G" meter sometime and get a feel for the figures you hear about.

   The "G" figure which relates to structural damage is based on a weight Design max AUW for your particular plane. IF you fly overloaded those figures  (safety margin) REDUCE. same as if you overload any structure or piece of equipment. If the plane is already loaded say in a turn or a dive recovery the effect of a gust will compound the air loads you already have.   Nev

[aro]

4 hours ago, Old Koreelah said:

That doesn’t make sense; surely with higher weights, you’d need to reduce the speed in bumpy air?

If your aircraft has a MTOW of 1000 kg and max load factor of 4g it means the the wings can produce 4000kg of lift.

If you stall at 100 knots at 1000kg and 4g, it means that at that speed you can't overstress the wings.

However, at 800kg, 100 knots still gives you up to 4000kg of lift, but that is 4000/800 = 5g.

The wing still sees 4000kg and is OK, but other parts of the aircraft see the higher loads e.g. seats, baggage compartment floor load limits are based on the same 4g limit and might be damaged. The G load applies to the whole aircraft, not just the wings.

[RFguy]

Nice comment Nev :
"If the plane is already loaded say in a turn or a dive recovery the effect of a gust will compound the air loads you already have.   "

yes, very true.  
In the simulator, I've overdone the airframe a few times during (radical) upset recovery in IMC....I'll calculate at what height (minimum) a vertical dive and consumate airspeed is unrecoverable (IE insufficient height to pull the aircraft out of the dive without damaging the airframe) . 

Edited March 28, 2023 by RFguy

[facthunter]

Even if you have the height the excess speed may destroy the airframe. This was usually the spiral  situation rather than spin recovery. The "graveyard" spiral it was known as. Nev

[onetrack]

Failure to wash off speed when the circumstances dictate it, is behind a vast number of crashes - be it in the air, or on the road. Drivers seem to fail to appreciate there's a throttle there, that needs to be pulled back sometimes.

[facthunter]

With a "Clean" aeroplane the nose doesn't have to be pointing directly at the ground for long for you to be in trouble.  Nev

[onetrack]

Thunderstorms have taken down much bigger aircraft than C210's as well. Ansett-ANA Flight 325 flew into an area between two thunderstorms just offshore from Sydney on the evening of Nov 30, 1961. 

The pilots lost control of the aircraft right after hitting severe turbulence, and it appears they exceeded VNE whilst trying to regain control, resulting in the outer section of the starboard wing being torn off - which led to further inflight breakup.

The aircraft hit the Pacific Ocean at a speed estimated between 300 and 400 kts. All 15 on board were killed, and this was one of Australia's worst RPT crashes for a long time (apart from the Fokker F-27 crash off Mackay, the year before).

 

This crash led to the mandatory fitment of weather radar to all large Australian commercial airliners by June 1st 1963. The crash also led to improved communications between the meteorological services and ATC.

This was Australia's 3rd worst commercial air disaster between the end of WW2, to that date. Nev probably remembers this crash well.

 

https://en.wikipedia.org/wiki/Ansett-ANA_Flight_325

 

Edited March 30, 2023 by onetrack

[Carbon Canary]

A relevant article from AOPA neatly explains many of the points raised in this thread.
 

https://www.aopa.org/news-and-media/all-news/2020/may/flight-training-magazine/ol-maneuvering-speed