What happened
A flight instructor and a student pilot were performing spin practice maneuvers at approximately 3,000 feet above ground level when they failed to recover. The Cessna (type not specified in source) entered a nose-down spiral and impacted a field.
The investigation
Examination of the wreckage indicated that the rudder was jammed beyond its left travel limit. Investigators discovered that the two rudder bumpers had been installed inverted. Specifically, the right side rudder bumper had moved past the rudder stop and become locked behind it.
Review of the aircraft's 28-year maintenance history showed no specific mention of the rudder bumpers, though work had been performed near them on several occasions. The paint on the inverted bumpers was consistent with a paint job completed approximately eight years before the accident. Investigators could not determine if the bumpers were installed incorrectly during production or during a previous maintenance event.
Additionally, the manufacturer had issued a service bulletin roughly three and a half years prior to the accident. This bulletin provided an enhanced rudder stop, bumper, doubler, and attachment hardware intended to prevent the rudder from overriding the stop bolt during full-scale operation. The aircraft involved had not been updated with this enhanced hardware, though compliance was not required under 14 CFR Part 91.