During a proficiency flight, one of the pilots was demonstrating a slow-flight recovery procedure. He added power and began retracting the Cessna 182’s flaps.
When the flaps passed through 10° toward fully retracted, he felt an uncommanded right yoke control movement.
As he applied more pressure to the control yoke to maintain level flight, both pilots heard a loud pop, and the uncommanded right yoke control movement stopped.
The pilots assessed the airplane and noted that the right flap was buckled. They then conducted a precautionary landing without incident at the airport in Springfield, Illinois.
A post-accident examination found that the inboard portion of the right flap had become dislodged from its track and that the flap had shifted outboard and contacted the aileron.
Further examination of the flap system found that a doubler patch had been improperly installed on the lower trailing edge skin. The improper installation altered the curvature of the lower trailing edge skin and infringed on the normal actuation of the flap rollers.
Both the inboard and outboard brackets surrounding the flap track had fractured due to the repeated stress applied during the flap roller actuation.
A review of the public agency’s fleet of airplanes found similar curvature of the lower trailing edge skin and bracket damage due to the improper installation of doubler patches.
The NTSB determined the probable cause as the improper installation of a doubler patch, which prevented the right flap from actuating and moving properly and led to the subsequent interference with the aileron.
NTSB Identification: CEN15IA076
This December 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.