Cessna 337 N108LS accident near St. Augustine, Florida

Probable cause

The failure of the pilot and examiner to recognize that the rear engine was not developing power, which resulted in an attempted partial-power takeoff and the airplane’s subsequent descent and impact with terrain.

NTSB analysis

The pilot was conducting a practical test with a designated pilot examiner to add a multi-engine rating to her pilot certificate. After performing airwork in the local area, they returned to the departure airport to conduct takeoffs and landings. The pilot initiated the takeoff and reported that the airplane accelerated to 85 mph, then rotated as normal. She then reported that the airplane “discontinued climbing”; shortly thereafter, the examiner took control of the airplane. The examiner stated that there was inadequate runway remaining on which to land; however, the airplane would not fly out of ground effect. He maneuvered to avoid obstructions and the airplane impacted terrain with a descent rate between 400 to 600 feet per minute.

Postaccident examination of the front engine and its systems revealed no evidence of preimpact failure or malfunction. The rear propeller was found in the feathered position. Onboard engine monitor data for the accident flight revealed that, during the accident takeoff, the front engine was operating normally, while the rear engine was operating at a level below idle power. A successful postaccident test run of the rear engine revealed no evidence of malfunctions or anomalies that would have precluded normal operation. The airplane owner’s manual advised that, during takeoff, the pilot should apply rear engine power first, followed by front engine power, and monitor the engine instruments throughout the takeoff roll for signs of power loss. A placard on the instrument panel advised, “Do not initiate single engine take-off.”

Although the reason that the rear engine was operating at such a low level during the accident takeoff could not be determined, both pilots should have recognized that the rear engine was not operating as expected during the takeoff roll and aborted the takeoff. The continuation of the takeoff in this condition resulted in the airplane’s inability to climb and its subsequent descent and impact with terrain.

Text from the NTSB. Open the NTSB docket for ERA19LA282 for the full record.