What happened
On October 18, 1968, at the Yverdon airfield, a flight instructor was conducting a training session with two student pilots. During the flight, the instructor intended to demonstrate a specific "touch and go" procedure involving an obstacle clearance. After a normal landing, the instructor applied full power with the flaps set to 30 degrees.
As the Morane MS 880 B Rallye, registration HB-EDT, climbed to an estimated height of 10 to 20 meters, the aircraft began to sink while maintaining a high pitch attitude. The aircraft struck the ground heavily, causing the landing gear to collapse and the propeller to bend. The aircraft slid approximately 15 meters across the field. All three occupants escaped the wreckage without any injuries.
The investigation
Investigators examined the wreckage and the engine components following the accident. The engine and its accessories were dismantled and inspected, revealing no mechanical defects or irregularities that could have caused a loss of power. Furthermore, the investigation found no evidence of carburetor icing, as the ambient temperature and humidity levels were not conducive to such an occurrence.
To understand the aircraft's behavior, a flight test was conducted using an identical aircraft under similar weight and configuration conditions. The tests demonstrated that while the aircraft could maintain stability, it was capable of entering a state where it would stabilize in a nose-high, horizontal flight position at low speeds, rather than immediately stalling laterally.
Findings
- The primary cause of the accident was a loss of airspeed occurring during a maneuver performed at the extreme performance limits of the aircraft.
- The aircraft's flight manual and promotional materials may lead pilots to overestimate the performance capabilities of the Morane Rallye 880 B, particularly regarding its resistance to stalling.
- The aircraft was operating within its weight and balance limits at the time of the incident.