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Its purpose was to diminish the turbulence in the air flow into the carburetor so as to obtain the best possible fuel-air ratio for fuel distribution throughout the engine. At the time of the takeoff at Charleston, Captain Wright was using only cold air and consequently any stoppage of the hot air duct would have had no effect on the functioning of the engine.
Subsequent to the issuance of the Report of the National Bureau of Standards, in order to further explore the possibility suggested in that report that the right engine of NC 13359 had stopped because the air flow had been obstructed by small rags of the type which were found in the carburetor grid of that engine, a test was conducted by representatives of the Safety Bureau with the cooperation of representatives of PCA. This test was witnessed by representatives of the National Bureau of Standards and of the Aircraft Airworthiness Section of the Civil Aeronautics Administration. The engine employed in this test was identical with the one involved in the accident at Charleston. The test consisted of introducing rags approximately 1 inch wide and from 7 inches to 12 inches long into the cold air intake scoop. The engines were run up to 28 inches manifold pressure[1] at 2150 r.p.m. and 61 rags were introduced by hand, one at a time, from behind the propeller before any effect upon the engine was noticed. The engine r.p.m. then dropped to 2000 and the manifold pressure fell to 27 inches but the engine continued to operate normally with no perceptible variation.
- ↑ Between the time Captain Wright began his take-off and the time the right engine lost power, the engines of NC 13359 were being operated at 34 inches manifold pressure. To this extent the test conditions differed from the conditions in actual flight. However, it appears that this difference is not sufficient to affect substantially the validity or usefulness of the results of this test.
