CTSW accident NC

[ODowneyEng]

NTSB Prelim: Flight Design CTSW
The Airplane Suddenly Yawed To The Right And Came Back Down To The Runway
Location: Marion, NC Accident Number: ERA21LA073
Date & Time: December 13, 2020, 10:45 Local Registration: N138CT Aircraft: Flight Design CTSW Injuries: 2 Minor
Flight Conducted Under: Part 91: General aviation - Personal
On December 13, 2020, about 1045 eastern standard time, a Flight Design CTSW, N138CT, was substantially damaged when it was involved in an accident near Marion, North Carolina. The pilot and the passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot reported that all preflight operations were routine for the cross-country flight to Frankfort, Kentucky. Shortly after liftoff at an airspeed about 46 knots, the airplane suddenly yawed to the right and came back down to the runway. The pilot elected to reject the takeoff. The airplane continued to veer to the right and the airplane departed the runway and entered an area of soft terrain. The nose wheel collapsed and the airplane nosed over.
  

[Tom Baker]

There was a recent question from someone in NC asking about an airplane turning hard right on takeoff. I wonder if this was the same airplane.

[BravoFoxtrot]

Looks like:

CTSW Right Rudder Hard Over? - Incidents - CT Flier Forum

[FlyingMonkey]

46 knots seems pretty slow for takeoff with two people in the airplane, depending on conditions and other factors of course.  It *sounds* like the airplane was coaxed off the runway before it was ready, and the right wing began to stall...when the airplane settled back to the runway and the pilot rejected the takeoff the inertia for the right turn was already in, and the airplane continued in that direction.  If he chopped the throttle abruptly that could exacerbate a right turn. 

Again, just speculation here, I'm just going by the very limited information here.  I'm glad all the injuries were minor.

[AGLyme]

That's sound right.  In the CTLSi, 46k is the rotate speed, Vx, w/15 degs of flaps is 52k.  My typical Vx is in the 60's however. 

It is something we can all learn from.  I feel badly for the pilot/owner.  There but for the grace of God... 

[okent]

My '08 AOI said 61, on my '13 it says 52.

[sandpiper]

My 2007 CTSW lists 51KIAS. I practice that occasionally but should the engine quit at less than 100 ft above runway it won’t be pretty. 

[AGLyme]

From a flying feel perspective, please review the rest of my sentence Bill.

the point is, I think Andy’s guess as to what happened based on his strong experience in type is probably accurate and we can all learn from it.

[Jim Meade]

18 hours ago, AGLyme said:

That's sound right.  In the CTLSi, 46k is the rotate speed, Vx, w/15 degs of flaps is 52k.  My typical Vx is in the 60's however. 

It is something we can all learn from.  I feel badly for the pilot/owner.  There but for the grace of God... 

I'm in learning mode here - why is your Vx different than the book Vx?  How is your aircraft configured so that your best angle of climb is different than the book?

[Jim Meade]

[Tom Baker]

23 minutes ago, Jim Meade said:

I'm in learning mode here - why is your Vx different than the book Vx?  How is your aircraft configured so that your best angle of climb is different than the book?

My guess is what he meant to say that his normal climb out speed is in the 60's instead of Vx @ 52.

[AGLyme]

Here is the relevant page from the manual I received with the plane.

 

[Jim Meade]

Best rate of climb is Vy, not Vx.  Vx is best angle of climb.

[AGLyme]

Jim and Bill, you brought important clarity to this discussion... the forum would be stale without your valuable insights.
The aim of this post I believe was/ is to armchair quarterback, probably unfairly because none of us were there, as to what most likely happened so the rest of us can learn from it.  Short of a mechanical failure, or a CG imbalance, or 3rd party interference (I read once that a pilot’s dog caused the pilot to crash)  it is most likely that the takeoff attempt was unsuccessful in the unbelievably brief rotate, Vx envelope.  I don’t think he made it to Anymore “V”’s.  I agree with Andy’s assessment.

Speaking for myself, an average pilot with median intelligence... In the takeoff phase, I don’t stare at the airspeed indicator reviewing all of the takeoff to cruise steps... things happen very very quickly during the rotate to climb phase.  I focus on going straight and adjusting for P factor and crosswind.  And I glance at the ASI for rotate  and then I do... and then I go immediately flat.  See Ed’s recent post.  Gaining airspeed quickly shooting for the dump flaps to 0 Degs as quickly as possible resulting in greater speed and climb.

[Jim Meade]

You're referring to Jerry Naylor of Monticello Iowa who's CTSW crashed and the NTSB concluded that his large dog interfered with the controls and he couldn't regain control before impact.  I only met Jerry once so can't say I knew him. He was 90.

As Andy says, his scenario is  speculation.

Each of us has his own preferred and habitual take-off scenario and we begin to think that is what everyone does or should do so we project our perspective into the accident and assume we know more than we really do.

When I bought my Champ a few years ago, I was getting some tailwheel refresher.  Now, this man was in the incipient stages of brain cancer, though no one knew it at the time, but it was affecting in subtle ways his reasoning.  As soon as we got some speed up in the Champ he very strongly insisted I get the tail up.  Well, he'd learned in a Cub.  In the back seat of a Cub you can't see much in the three-point stance and those pilots want to get the tail up as quickly as they have rudder control so they can see.  I can see much better from the front of the Champ so the tail-up injunction was not so appropriate.  As you know, some tail wheel experts even recommend that in the right airplane one takes off with the tail just off the ground.  My friend in the initial stages of brain cancer was going back to his set habits of how to fly a tail wheel and assigning them to the situation in the Champ even though it wasn't really germaine.  We all have a tendency project our experience when we speculate about events we don't know much about.

Was the guy practicing short or soft field take-offs?  What was the condition of the runway?  How long was "shortly after take-off"?  2 seconds?  10 seconds?  50 feet?  Did he see 46kias just at rotation?  What as the wind?  Was he holding for a strong crosswind and when airborne didn't release the rudder quickly enough or crab into the wind?  Is the pilot telling the truth?

I don't think we can come to any conclusions at all from the very limited information we have in the OP.

[sandpiper]

On 12/30/2020 at 9:32 PM, WmInce said:

John, are you talking about best angle of climb (Vx)?

The CTSW Aircraft Operating Instructions (AOI) pages 6-1 and 8-4, lists 66 kts. for Vx at flaps 0°.

Bill,

My CTSW manual shows Vx with flaps 15 as 51K and 66K @flaps 0. I should have specified flap setting in my post.

My normal take off is with 15 degrees flaps. I rarely look at the airspeed indicator until off the ground at which point I accelerate to 60K until 500' MSL (320 AGL). At this point I am over the departure end of the 3000" runway. I then begin to clean up the aircraft as it accelerates to 86K which is Vy at -6 flaps.

There are other ways to do this but this is my way and I am comfortable with it. To each there own as long as it is safe.

By the way, Happy New year not only to you but to all on this forum.

Edited January 1, 2021 by sandpiper
added information

[sandpiper]

1 hour ago, WmInce said:

I don't see that.

What page is it on? AOI or Supplemental Training Manual?

I'll need to go look at the manual. I posted those numbers on the panel back in 2007 when I got the plane. Hope I didn't misread.

[sandpiper]

Bill,

Look at page 8-4, section 8.4 Normal Takeoff in the AOI. It gives climb speeds at MTOW with flaps 15. All those years ago I somehow made the call that the numbers were reversed for 600 kg and 472.5 kg. I think I had discussions with the Western Distributor and maybe FD USA at the time but it also just makes sense that at 600 kg (1320#) the climb airspeed should be the higher number, 51K, not the 42K shown in my manual, and that the 42K they listed for 600 kg is really for the 472.5 kg. 

Then look on page 8-5, section 8.12, Short Field Takeoff Procedure. It says that, with flaps 15, to rotate at 44K. This further tells me that the 42K climb figure stated in section 8.4 is really for the  472.5 kg weight, not 600K.

For my plane the rotation at 44K and climb at 51K is doable at 1320#. Whereas, rotating and climbing at 42K at 1320# is not something I am going to try except at altitude as I don't think it would be safe and probably not doable.

I hope I didn't make my explanation more convoluted than it needed to be. Is your manual the same as mine? Some of the early manuals were not the best.

Anyhow, thats where my 51K climb speed comes from.

[FlyingMonkey]

BTW, I was going to make a thread about this, but it seems related to this, so...

I recently changed my standard takeoff operations from long (3000' or more) paved runways.  I used to always takeoff at 15° flaps, to get off the ground as soon as possible.  recently I experimented with 0° flaps, and I think it works better, for me at least, for the above mentioned circumstances.  The airplane rolls on the runway longer and takes off at about 10kt faster.  But it accelerates faster, and climbs better due to the lower drag.
 

YMMV, but it seems to work better for me.  On grass or short runways I still use 15°.

[sandpiper]

19 hours ago, WmInce said:

Just for clarity . . . the only point I'm trying to point out is this. In the CTSW, 51 kts. is not the correct Vx (best angle of climb), as published in the AOI.

Again, here is the reference . . . CTSW Aircraft Operating Instructions (AOI), pages 6-1 and 8-4, lists 66 kts. for Vx at flaps 0°.

Bill,

I agree that the manual states Vx at 0 degrees flaps is 66KIAS.

But, if you go to the Flight Design USA web site which, unlike my erroneous AOI with revision date of 30-Dec-2006, they have an updated revision dated 29-Apr-2008. Look under their "Flight Training" and click on "Pilots Useful Documents".Then download AOI CTSW and go to page 8-4, section 8.4 Normal Take Off. There it tells us to climb at 51K with 15 degrees flaps at MTOW of 600 kg (1320#). 

I have always taken that to mean that Vx with flaps 15 is 51K and is the configuration/speed to use to get over a 50' obstacle. I don't like doing it but the plane is capable unless the engine stumbles or quits. Then it becomes unsafe and potentially deadly. I think anyone putting themselves in a position to have to do this to get over an obstacle is nuts and shouldn't have put themselves in that position in the first place. I know my CTSW at gross, at my home airport which is 175" MSL, will do it but it makes me uncomfortable.

Anyway, not trying to be argumentative. Just trying to present my best case. But, if my interpretation is wrong, I would really like to know. 

 

[sandpiper]

9 hours ago, WmInce said:

I use flaps 15°, 60 kts., until 500 agl.

Similar here. 

[Jim Meade]

Do any of you try to maintain 5200 RPM or better on climbout?  If so, what flap settings and IAS do you use?

[Bill3558]

The airport in Marion 9A9 is grass.  Perhaps his plan was to accelerate in ground effect.

I have landed there a couple of time.  The pilot of the CT came out to greet me.  He flys for a regional airline.  He said his landings are a challenge and we discussed techniques.  Not sure if it was the same guy. Hope not. 

[sandpiper]

15 hours ago, Jim Meade said:

Do any of you try to maintain 5200 RPM or better on climbout?  If so, what flap settings and IAS do you use?

No. At my initial climb speed of 60K I get about 5100. After accelerating at about 500" to 86KIAS It might be getting closer to 5200.

My prop is pitched to give me 5600 RPM with level flight at 3000' MSL full throttle. I won't repitch to get 5200 on my initial climb.

[Jim Meade]

I try to get to 5200 pretty quickly on take-off, at the expense of a little climb angle, although I like to get high early.

Rotax SL-912-016R1 30 Dec 16 says in 3.1.2: (I'm paraphrasing but not changing meaning)

2.  Take-off at wide-open-throttle should be not less than 5200 RPM

3.  Continuous use of less than 5200 RPM at WOT should be avoided.

I suppose it's all in how one interprets those guidelines.