Cessna 210C N3611Y accident near Blum, Texas

Probable cause

The pilot's excessive leaning of the fuel mixture, which resulted in a loss of engine power, and the pilot's failure to extend the landing gear in accordance with the airplane emergency checklist, which resulted in a gear-up landing.

NTSB analysis

The pilot stated that she was about 20 minutes into a cross-country flight with the airplane at a cruise altitude of 3,500 ft mean sea level (msl) when the engine started to run roughly. The pilot suspected vapor lock because of the hot weather conditions and attempted to restore engine power. She switched the fuel selector positions from the right to the left fuel tank, but when the roughness worsened, she switched the selector back to the right tank. She selected the boost pump to LOW and then HIGH, and retarded throttle control, all of which had no effect on engine operation. The engine began to lose power rapidly and then quit; the propeller windmilled.

The pilot began an approach for a forced landing on a field with flaps at 30° and the landing gear retracted. She said that it would take her about 3 minutes to manually pump the landing gear down and that she did not have enough time to lower the landing gear due to the airplane's altitude. The landing on the field was "firm," and the airplane quickly slid to a stop and sustained substantial damage during the gear-up landing.

The airplane emergency checklist for a forced landing after a complete engine failure required extension of the landing gear if the landing surface is smooth and hard and does not mention the need to extend the landing gear using manual extension; the windmilling engine would provide power to the hydraulic pump to operate the flaps and also to extend the landing gear normally. Postaccident examination of the field showed that the surface was hard and in good condition to perform a landing; however, the pilot stated that she could not determine this when she was 2 miles from the field when she decided to land there.

The density altitude near the departure airport was about 3,500 ft msl, which would have required full rich fuel mixture at takeoff.

Postaccident examination of the airplane revealed that the left and right fuel tanks were each about half full, the throttle and propeller controls were in the full forward positions, and the mixture control was near the idle cutoff position. The pilot stated she did not remember advancing the mixture control to full rich when the engine roughness occurred and did not change the mixture control position after landing. Advancement of the mixture control to full rich would have increased fuel flow to mitigate restrictions to fuel flow, if present. There were no anomalies noted during the postaccident test run of the engine. Thus, it is likely that the pilot leaned the fuel mixture too much when the airplane reached cruise altitude, which resulted in the subsequent loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN18LA287 for the full record.