Carefree, AZ, USA
N6897N
Cessna T210N
The airplane hit the ground short of the runway following a failure of the engine to respond to throttle command on short final approach. The pilot said that on short final with the landing gear down and full flaps, the airplane started settling. The pilot added power and the engine failed to respond. The pilot said that it was his habit to use the low fuel boost pump for landing even though the Pilot Owner Handbook (POH) did not call for it. In the POH section 7, Airplane and System Descriptions, it shares an information note: "If the engine-driven fuel pump is functioning and the auxiliary fuel pump switch is placed in the ON position, an excessively rich fuel/air ratio is produced unless the mixture is leaned." With the low (yellow) boost pump switch on during a reduced power approach, if the throttle is increased the boost pump goes to high and the engine can be flooded with an excessive rich mixture. According to the Cessna Pilot Safety and Warning Supplements booklet under Fuel Pressure Switch Operation/Normal Auxiliary Fuel Pump Operation, it states in part: "During cruise, the auxiliary fuel pump(s) may be used at any time to clear excessive fuel vapor, as evidenced by an unstable fuel flow indication; however; the auxiliary fuel pump(s) should be turned off prior to descent. Failure to turn off the pump(s) could cause a power failure at reduced throttle settings or with a rapid throttle advance due to an excessively rich mixture, especially if the throttle switch rigging or fuel pressure switch settings are out of tolerance." No anomalies were found during an examination that would have precluded the engine from functioning normally.
On March 22, 2005, about 1350 mountain standard time, a Cessna T210N, N6897N, collided with a fence during a forced landing following a loss of engine power at Carefree Sky Ranch, Carefree, Arizona. The pilot operated the airplane under the provisions of 14 CFR Part 91. The private pilot and two passengers received minor injuries; two passengers received serious injuries. The airplane was substantially damaged. Visual meteorological conditions prevailed for the personal flight, and no flight plan had been filed. The flight originated at Show Low, Arizona, at 1230. The pilot obtained a preflight weather briefing from Prescott Automated Flight Service Station for a flight from Carefree to Show Low, Chinle, Arizona, Show Low, and back to Carefree. The pilot reported that he departed Show Low for Carefree, after picking up three passengers. He departed about 1230, with approximately 55 gallons of fuel on board. His cruise altitude was 10,500 feet, and the flight time was approximately 1 hour. According to the pilot's airport approach sketch, he was performing left-hand maneuvering turns around "Black Mountain," then a left downwind turning a base leg beyond a noise sensitive residential area with an extended base to final. On short final with the landing gear down and full flaps, the airplane started settling. The pilot added power and the engine failed to respond. A post accident examination of the airplane and engine was conducted at Phoenix, Arizona. The pump was received with open/uncapped fuel lines. The engine and accessories were examined, as was the fuel system components of the airplane. The Dukes electric boost pump was removed for functional testing. The initial test indicated a high amp draw and the pump did not rotate. A subsequent examination was conducted confirming the high amp draw. The motor was separated from the pump. The motor spooled up normally to an undetermined rpm. The pump shaft was turned slightly and became free to turning. The assembled combination then ran as an assembly. The pilot told Federal Aviation Administration inspectors that it was his habit to use the low fuel boost pump for landing, even though the Pilot Owner Handbook (POH) did not call for it. In the POH section 7; Airplane and System Descriptions, it shares an information note: "If the engine-driven fuel pump is functioning and the auxiliary fuel pump switch is placed in the ON position, an excessively rich fuel/air ratio is produced unless the mixture is leaned. Therefore, this switch should be turned off during takeoff." With the low (yellow) boost pump switch on, during a throttle back approach, and needing to perform a go-around, as the throttle goes forward the boost pump goes to high (red rocker switch) and can flood the engine at low power, unleaned. According to the Cessna Pilot Safety and Warning Supplements booklet under Fuel Pressure Switch Operation/Normal Auxiliary Fuel Pump Operation, it states in part: "During cruise, the auxiliary fuel pump(s) may be used at any time to clear excessive fuel vapor, as evidenced by an unstable fuel flow indication; however; the auxiliary fuel pump(s) should be turned off prior to descent. Failure to turn off the pump(s) could cause a power failure at reduced throttle settings or with a rapid throttle advance due to an excessively rich mixture, especially if the throttle switch rigging or fuel pressure switch settings are out of tolerance."
the pilot's improper use of the fuel boost pump contrary to the procedures specified in the pilot owner handbook and other documents.
Source: NTSB Aviation Accident Database
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