What happened
On July 15, 1964, a Beechcraft Baron B55, registration D-ILPU, was performing a VFR flight from Lausanne to Bern with the pilot and his family. During the flight near Fribourg, the aircraft experienced a total loss of electrical power. Upon realizing the radios and electrical systems were dead, the pilot attempted to manually extend the landing gear using the onboard hand crank.
At approximately 16:13 CEST, the aircraft touched down on the paved runway at Bern-Belpmoos. Immediately upon contact, the nose gear collapsed. As the aircraft continued its rollout, the main landing gear also failed, with the left side collapsing entirely. This caused the left wing and both propellers to strike the ground, resulting in significant damage to the airframe, propellers, and wing. A small fire ignited under the left fuel tank but was quickly suppressed by the airport fire brigade. There were no fatalities and no injuries among the five occupants.
The investigation
Investigators examined the state of the aircraft immediately following the accident and found that while the nose gear mechanical indicator showed "GEAR DOWN," the gear was not actually locked. Further inspection revealed that the hand crank could still be turned approximately 10 more times, indicating the gear had not been fully extended.
Regarding the electrical failure, investigators found the onboard batteries were completely discharged. While no specific technical defect was found in the electrical system, the investigation noted that the generators were found in the "ON" position at the scene, despite the pilot's claim of having switched them off. This suggested the generators may have been left off during flight, leading to the battery depletion.
Findings
- The primary cause of the accident was that the manually extended landing gear was not fully extended or locked at the time of touchdown.
- The pilot likely ceased cranking the gear prematurely because the increased physical resistance of the mechanism, combined with the nose gear indicator reaching the "GEAR DOWN" zone, led to the mistaken belief that the gear was secure.
- The pilot had not previously practiced the manual extension procedure in a practical setting.
- A contributing factor was the failure to follow the manual's instruction to pull the landing gear circuit breaker, which could have allowed the gear to move back toward the "UP" position if the switch was accidentally toggled.