The flight on April 25th was Gita’s very first flight, as well as its first crash. After a successful completion of autotune, the switch to FBWA mode resulted in a rapid descent with no ability for climb. Numerous theories were brought up:
- FBWA controls were poorly tuned resulting an inadequate pitch up.
- The elevator surface area was too low to begin with.
- The foam horizontal stabilizer failed in air.
- The servo extensions disconnected.
- None of the above theories successfully explained the crash. The log files showed the FBWA responding properly. The elevator surface area was adequate for takeoff. The foam horizontal stabilizer was intact after the crash. The servo extensions were verified working, and an additional servo was placed for the elevator for redundancy.
The team went on to rebuild the fuselage and the tail surfaces. In this process, the fuselage and tail were both made stronger with more support structures. In the third flight attempt, the aircraft successfully took off and did not seem to have any issues with the pitch. It was almost as if the cause of the crash spontaneously disappeared. However, throughout the flight, the roll authority felt a bit off: it would oscillate in FBWA mode, despite the roll being tuned.
While going through the team’s safety checklist, one of the aileron servos was discovered to malfunction: it would work only intermittently. Sometimes, the elevator would also fail to work. Only after calling the flight off and taking the flight controller off the plane was the problem discovered: poorly soldered joints. Several of the servo pins, particularly those connected to aileron and elevator, lacked solder.
Resoldering the joints, Gita XI 12 took off again, this time with no roll nor pitch issues.