Undetermined · NTSB CEN20LA169
RANS S-12 — Delta, CO
| Date | May 3, 2020 |
| Location | Delta, CO |
| Aircraft | RANS S-12 (amateur-built) |
| Purpose of flight | Flight Test |
| Conditions | Day · Visual Meteorological Cond |
| Phase / occurrence | Prior to flight Miscellaneous/other |
| Pilot age | 81 |
| Pilot total time | 675 hrs · Building experience |
| Time in type | Unknown |
| Fatalities | 1 |
Probable cause
NTSB findings
- Aircraft-Aircraft oper/perf/capability-Performance/control parameters-(general)-Attain/maintain not possible
- Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Angle of attack-Capability exceeded
- Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot
What happened
The pilot of the test flight was attempting to correct airplane stability issues before the flight. A witness assumed that the pilot was planning to perform a high-speed taxi test rather than flight, and that the airplane’s takeoff was unintentional. After takeoff, the airplane was seen in the airport traffic pattern at 300-400 ft above ground level. Witnesses then observed the airplane change pitch and bank while the engine was heard increasing to full power and then decreasing. The airplane stalled, impacted terrain, and was destroyed by impact forces.
Post-accident examination of the airplane confirmed flight control and engine continuity. There were four ballast bags (about 25 lbs each) and two dumbbell weights (marked 35 lbs). All the ballast bags and one dumbbell weight were in the passenger seat area. High-speed taxi testing is not a test area of aircraft stability and control. Given the pilot’s previous statement of his intentions and the presence of ballast/weights in the passenger seat area, it is likely that he was experimenting with airplane stability and control when the airplane exceeded its critical angle of attack, which led to an aerodynamic stall.