What happened
On July 15, 2011, a Diamond DA 40 D, registration PH-FLD, departed from Lelystad Airport for a private flight. During the takeoff roll, once the aircraft reached approximately 30 knots, the nose began to pitch up unexpectedly, lifting off the ground prematurely. The pilot responded by pushing forward on the controls and verifying the trim position to continue the takeoff, which was completed at roughly 60 knots.
As the aircraft climbed, the pilot encountered increasing difficulty managing the elevator. Significant physical force was required to change the aircraft's attitude, though roll and directional controls remained functional. After the second pilot also experienced these heavy control forces, the decision was made to perform a precautionary landing. The aircraft executed a right-hand turn at approximately 250 feet and landed in a field of standing crops. There were no injuries to the two occupants, and the aircraft sustained no damage.
The investigation
The investigation focused on identifying the cause of the heavy elevator controls. Investigators examined the aircraft's digital engine control (FADEC) data, which revealed that the engine was set to 83% power during takeoff, rather than the 90-100% required by the checklist.
A technical inspection of the elevator and trim systems, including the Bowden cable and control rods, revealed no mechanical obstructions or system failures. Investigators also ruled out interference from the autopilot system or physical obstructions like the stick boot.
To replicate the conditions, a manufacturer test flight was conducted using the same weight and performance parameters. By setting the aircraft to a full nose-up trim, investigators successfully simulated the heavy control forces and the nose-up tendency observed during the takeoff roll.
Findings
- The primary cause of the control difficulties was an incorrect trim condition.
- A nose-up trim setting significantly increases the physical force required to manipulate the elevator, especially as airspeed increases.
- While the aircraft's mechanical systems were fully functional, the pilot's reliance on a partially completed checklist contributed to the incident.
Safety action
- The investigation highlighted that the partial completion of checklists is a critical safety risk.
- Proper verification of the trim setting during the 'Before Take-off' phase is essential to ensure the aircraft is configured for safe operation.