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.
The real question that needs to be asked was the repair an approved repair procedure. Based on the full narrative other planes had the same “improper installation” conducted, which either tells me that the repair facility is not following proper procedures or they are coming up with their own repair procedures. Improper installation of an approved repair procedure is negligence and should require training for personnel. A repair that is not authorized is a criminal act. A big difference.
One other failure mode for a Cessna flap is the needle bearings. They are not easy to get to. But a little needle dab of tri flow at annual will keep them from eventually freezing. A loud bang is also heard when the little guy finally quits one, otherwise, fine afternoon.
The wings can be maintained level with enough aileron and a speed reduction. It helps to NOT turn into the side where the flap has fully retracted. And it could help if you can get the normal flap out some to balance the load … unless the stuck one goes out further as well.
Aviation runs on money and is built on trust. In the absence on (enough) money the foundation of trust rerodes. Lots of accidents have a maintenance root cause. Because the flaws of poor or improprt wrenching may not show up for a long time – then suddenly fail a pilot just has to follow a strategy of “hope”. Hope the plane will perform as we hope and TRUST it will.