The private pilot reported that the engine cylinders had been replaced and the flight was to continue a cylinder break-in period. The engine run-up and propeller check were completed during the taxi to the runway to keep the ground run-up to a minimum.
After engine start, no anomalies were noted.
Break-in procedures called for lower cylinder head temperatures and less than full power at the beginning of takeoff, according to the pilot. After the Cessna 170B took off and reached about 100′ above ground level (agl), he slowly reduced rpm and the manifold pressure to about 65% power.
At 200′ agl, the engine lost partial power. The engine briefly regained some power, but it then lost power again.
The pilot executed a forced landing in mesquite tree-covered terrain near Ingleside, Texas.
A post-accident examination and functional test of the engine revealed no anomalies that would have precluded normal operation. The pilot stated that he believed the engine lost power due to carburetor ice, and the weather conditions at the time of the accident were conducive to serious carburetor icing at cruise power. It is likely that the engine lost power due to carburetor icing.
Probable cause: The loss of engine power during takeoff due to carburetor icing, which resulted in a forced landing.
NTSB Identification: CEN16LA078
This January 2016 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
I think that what can best be learned from this is that a Carb Air Temperature gauge is a lot cheaper than a wrecked airframe. It is better to know exactly what the conditions are in the outflow than to just guess and end up getting it wrong. When you consider how many of these that we see carb ice as the suspected cause it should be a no-brainer to install a carb heat gauge, whatever the cost it is cheaper than a wrecked aircraft. If this aircraft had one and if there was indeed carb icing conditions present it would have shown that and the carb heat applied. If the engine stopped anyway than that narrows down the possibilities and this loss of carb ice to blame could hopefully lead to a better investigations.
So the lessone is anyone breaking in an engine is supposed to risk carb ice and crash?
How do you arrive at that conclusion from the comments so far?
In reference to the Cessna 170B accident with the Continental engine the cause of the accident has in some opinions been contributed to carburetor ice. I don’t totally agree with this assessment. In my 60+ years of working on Continental engine have found numerous times that the main cause was when new cylinders or new piston rings are installed the piston ring end gap was to close. If this happens on takeoff the rings rapidly expand and causes the gap to close up. This will increase the friction between the cylinders and the pistons and drags the engine down resulting in complete engine stoppage. In addition the cylinders may go out around because of the extreme heat. Once the engine cools down every thing returns to normal. Engine should be torn down and cylinder walls, pistons, and connecting rods inspected for damage.
The design of the Luscombe 8A fuel system during climb out the fuel tank and the carburetor are approximately at the same level. This results in engine fuel starvation. Once the nose is lowered the engine will pick up power. When using carburetor heat on takeoff the rate of climb is at a more shallow angle and the fuel will continue to flow to the carburetor. This is not an issue if the fuel tanks are in the wings.
Carb heat on takeoff would actually help reduce CHT. Carb heat causes reduced power output by creating a richer mixture. There is absolutly no reason not to use carb heat on takeoff when carb icing conditions are present unless a maximum performance takeoff is required by runway length. (Yes I know intake air is unfiltered with carb heat on) My first airplane was a 1939 Luscombe Model 8 converted to an 8A that was placarded to require carb heat on every takeoff regardless of OAT or conditions.
While the pilot was concerned about cylinders getting too hot and/or wearing too much on the “break -in” equal concern for what has been for years the most consistent cause of partial or total loss of engine power on takeoff and go arounds, CARB ICE, was absent.