On August 15, 1997, a Piper PA-12 (registration N2849M) operated by Alvin M. Terry was involved in an aviation accident near Longmont, CO. Investigators recorded the probable cause as: The pilot's improper use of rudder and brakes during a ground loop, which resulted in loss of directional control. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot attempting a landing on Runway 29 experienced a bounce and subsequent loss of directional control due to overcorrection, resulting in significant structural damage to the airframe.
What happened
The pilot initiated an approach with the intention of landing on Runway 29, citing light winds with a south component as the primary factor for this selection. Upon touchdown, the aircraft bounced off the pavement and began to veer toward the left side of the runway. In response to this deviation, the pilot applied corrective inputs that proved excessive.
As the airplane continued to swerve across the surface, the pilot attempted another correction by steering to the right. This maneuver inadvertently involved the inappropriate use of rudder pedals and wheel brakes simultaneously. The combination of these inputs caused the aircraft to ground loop violently. Meteorological data indicated a computed crosswind component of 3.5 knots and a tailwind component of 6 knots during the event.
The violent motion resulted in severe structural failure. The left main landing gear was completely sheared off its mounting points. Additionally, both the forward and aft spars of the left wing were bent, indicating significant stress on the airframe structure during the incident.
Probable cause
The pilot's improper use of rudder and brakes during a ground loop, which resulted in loss of directional control.