Cessna 421C N421SY

Summary

On 9 December 2011 at about 20:24 local time, a Cessna 421C registered N421SY, operated by Quest Aviation Inc., was involved in an accident near Sioux Falls, South Dakota, United States. 4 people were on board and 4 died. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

9 December 2011 at 20:24

Classification

Accident

Location

Sioux Falls, South Dakota, United States

Nearest airport

Joe Foss Field (FSD)

Coordinates

43.5922, -96.7519

Aircraft

Cessna 421C

Registration

N421SY

Category

Airplane

Engines

2

Operator

Quest Aviation Inc.

Operating rule

Part 135: Air Taxi & Commuter

Phase of flight

Not recorded

Route

Sioux Falls → Rapid City

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN12FA100

4 people died.

The pilot’s failure to maintain adequate airspeed after shutting down one engine, which resulted in an inadvertent aerodynamic stall and impact with terrain. Contributing to the accident was the pilot’s failure to follow the guidance contained in the pilot’s operating handbook, which advised feathering the propeller of the secured engine and retracting the flaps and landing gear.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

Shortly after the airplane lifted off, the tower controller informed the pilot that a plume of smoke was visible behind the airplane. No communications were received from the pilot after he acknowledged the takeoff clearance. Witnesses reported that white smoke appeared to be trailing from the area of the left engine during takeoff. The witnesses subsequently observed flames at the inboard side of the left engine. The airplane began a left turn. As the airplane continued the turn, the flames and trail of white smoke were no longer visible. When the airplane reached a southerly heading, the nose dropped abruptly, and the airplane descended to the ground. Witnesses stated that they heard an increase in engine sound before impact. A postimpact fire ensued. The accident site was located about 3/4 mile from the airport. A postaccident examination determined that the left engine fuel selector and fuel valve were in the OFF position, consistent with the pilot shutting down that engine after takeoff. However, the left engine propeller was not feathered. Extensive damage to the right engine propeller assembly was consistent with that engine producing power at the time of impact. The landing gear and wing flaps were extended at the time of impact. Teardown examinations of both engines did not reveal any anomalies consistent with a loss of engine power. The left engine oil cap was observed to be unsecured at the accident site; however, postaccident comparison of the left and right engine oil caps revealed disproportionate distortion of the left oil cap, likely due to the postimpact fire. As a result, no determination was made regarding the security of left engine oil cap before the accident. Emergency procedures outlined in the pilot’s operating handbook (POH) noted that when securing an engine, the propeller should be feathered. Performance data provided in the POH for single-engine operations were predicated on the propeller of the inoperative engine being feathered, and the wing flaps and landing gear retracted. Thus, the pilot did not follow the emergency procedures outlined in the POH for single-engine operation.

Quoted verbatim from the NTSB record.