EFATO at Shobdon

[Broadlands]

Well landed in the field by the pilot. Not the first time this airfield has had aircraft problems. Apparently carb icing ....on take off on the hottest day of the year!

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1440x960/35254245_6dbd_4064_87bc_9c0f8ed671f6_4fc0638d4f0a5ed13ae73aa e41bc52025f5bdb0f.jpeg

[pilotmike]

Carb icing might just about be possible at high 20s Celcius, but not likely unless exceptionally humid.

Given the temperature, I suspect fuel vapourisation to be far more likely, especially if MOGAS was used instead of AVGAS.

Evidence of either is difficult to find after the event, except possibly finding small amounts of water in the carb after any icing has melted.

[Fostex]

Carb ice more common in warm humid wx. Only time I have ever encountered it was doing power check in SEP prior to departure. Conceivable that ice present in carb inlet manifold came loose on opening throttle and caused obstruction.

Well handled by PIC.

[Big Pistons Forever]

Well handled by PIC.

If the cause of the loss of power was carb ice then it was definitely not well handled by the PIC. Given that the least likely case for the development of carb ice is with full throttle operation, there was carb ice, probably a lot of carb ice, present at the start of the take off run. Therefore the engine would not have made the minimum static full throttle RPM of 2280 for the C 152. This should have resulted in a low speed reject.

I find it disappointing that few pilots verify full power is being developed at the start of the takeoff run. This will not be redline RPM but the POH specified static RPM which will be considerably less than redline. Note this is for fixed pitched props. For variable pitch props the engine should make field baro MP minus half inch, on takeoff.

I think one of the generalizated failings of flight training is that much time is spent on how to react to an engine failure yet very little on how to ensure the engine doesn’t fail in the first place. A review of accident reports where there was an engine failure shows that approximately 80% of the engine failures were caused by the actions or inactions of the pilot

This engine failure falls in the 80% group because appropriate and timely action by the pilot will always succeed in addressing a power loss caused by carb ice.

[SAPEG3T]

I hear that the engine was producing varying levels of power down to the ground, and the pilot was able to hop over a ditch in the field after touching down.

Top work! Not often you see little old Shobdon on the main page of PPRuNe!

[B2N2]

With some guesstimate numbers of 30C and slightly higher then standard pressure the Density Altitude comes to about 2000’

https://wahiduddin.net/calc/calc_da.htm

What are the chances of having taxied and done the run-up and takeoff with the mixture full rich?
I’m leaning ( pun intended ) in the direction of Big Pistons Forever.

[Fostex]

I take your points on board regarding the causal factors for the incident BPF, all of which are valid. However I was talking about the pilots handling of the incident once EFATO had occurred. No panic or stall/spin, maintained airspeed and landed safely in a field with no damage to him/her self and no apparent damage to aircraft. That is a good recovery and I am sure that lessons will be learned from it.

[Auxtank]

If big pistons is correct in his assumption, and I believe he might well be, if things had been done as per the chklst - the PIC wouldn't have had to deal with the EFATO in the first place.
Mind you, it appears that he did deal with it extremely well.

[double_barrel]

....
....
I find it disappointing that few pilots verify full power is being developed at the start of the takeoff run. This will not be redline RPM but the POH specified static RPM which will be considerably less than redline. Note this is for fixed pitched props. For variable pitch props the engine should make field baro MP minus half inch, on takeoff.

I think one of the generalizated failings of flight training is that much time is spent on how to react to an engine failure yet very little on how to ensure the engine doesn’t fail in the first place.

.....
....


Thanks for flagging that. It's a good point. I was never taught to check engine RPM at the start of the take-off run. I do routinely use the 50:70 rule to check that I am accelerating appropriately, but I learned that from YouTube not an instructor, and it won't pick-up a small power drop. I will add RPM check to my scan.

[SAPEG3T]

It should be added that this was from a touch and go

[meleagertoo]

Gotta love those 'tie downs'.
I never got my head around the notion that an aircraft with a 500Kg empty weight and a wing able and allowed to lift 3000Kg (ie MAUW x 4.4g) is in any way inconvenienced from blowing away or flipping over by 25Kg of water under each wing - half the weight of a large pilot.

Seems no more than wishful thinking to me!

[B2N2]

It should be added that this was from a touch and go

Which leads to another interesting option...a rich-cut if (again) the mixture was too rich for the conditions and the throttle slammed.

[Maoraigh1]

If that is a C150 with an O-200 then carb ice doesn't surprise me. I was taught "carb heat off after landing". A Group member had been taught "carb heat off on short final, ready for go-around".
I tried it. Fortunately a full-stop landing. The engine spluttered when I opened the throttle ​​​to do a 180.
I often start the take-off run with carb heat hot. I've had vapour lock with mogas. Confirmed by opening the gascolator drain - froth came out.
( O-200 carb ice experience in Jodel DR1050 and Bolkow 208C.)