Stall / Spin · NTSB WPR10LA429
FINNEY THORP T-18 — Willcox, AZ
| Date | August 26, 2010 |
| Location | Willcox, AZ |
| Aircraft | FINNEY THORP T-18 (amateur-built) |
| Purpose of flight | Personal |
| Conditions | Day · Visual Meteorological Cond |
| Phase / occurrence | Maneuvering-low-alt flying Aerodynamic stall/spin |
| Pilot age | 46 |
| Pilot total time | 500 hrs · Building experience |
| Time in type | Unknown |
| Fatalities | 2 |
Probable cause
NTSB findings
- Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Airspeed-Not attained/maintained - C
- Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
What happened
The airplane was observed in the traffic pattern, about 500 feet above ground level, when it made a steep left turn to enter the downwind leg. The turn continued as the airplane entered a left descending spiral until it impacted the ground in a nose-low attitude. Postaccident examination of the airframe and engine revealed no evidence of a mechanical malfunction or failure that would have precluded normal operation.
The Pilot Operating Handbook for the airplane indicated that the airplane has an abrupt stall with a tendency to drop a wing, especially if the airplane is in an uncoordinated turn during the stall. There is very little warning preceding the stall. Stall recovery can be quickly affected by releasing back pressure on the stick; however, a secondary stall may occur if the stick is brought back abruptly after recovery without sufficient airspeed. It is likely that during the initial steep turn, the airplane entered an aerodynamic stall from which the pilot was unable to recover at the low altitude.