This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
I (PIC/right seat) was providing airplane transition flight instruction (intro to Cessna 182) to a private pilot (left seat). He was pilot flying.
Our agreed plan was to practice private pilot maneuvers in a local designated practice area.
The left seat pilot (pilot flying) conducted the preflight inspection in accordance with the checklist, while I observed. He extended the flaps and inspected them.
After we landed, we discussed his preflight observations further: Correct position, hinge tracks/channels aligned with no visible obstruction/abnormality; actuating rod intact and free of abnormalities with normal amount of movement.
Pilot flying retracted flaps in accordance with the starting engine checklist. I observed they appeared fully retracted.
While preparing for normal takeoff, he extended flaps to 10° in accordance with the checklist. I saw the cockpit indicator at 10°; both flaps appeared at 10°. After takeoff, pilot flying retracted the flaps at a safe altitude while airspeed was increasing between 70 and 80 KIAS. I saw the cockpit indicator at 0° and both flaps appeared fully retracted.
Pilot flying conducted approximately five steep turn maneuvers. All were within normal ranges, limitations, and tolerances. There had been no abnormal conditions or actions at that point.
Next, pilot flying conducted a power-off stall and recovery. While flying straight and level, pilot flying reduced airspeed by reducing throttle while maintaining altitude. He extended flaps from 0 to 10° at approximately 90-95 KIAS, and then incrementally to 30° as we slowed (within flap operating range throughout).
He reduced throttle to idle and used back pressure on the controls until the stall was induced. After the first buffet, he recovered appropriately using pitch to reduce angle of attack, smoothly adding full throttle, and retracting the flaps from 30° to 20°.
He used pitch to attain Vy (80 KIAS) and verified we had a positive rate of climb; we both verbalized each of these facts in the cockpit.
Then, he retracted flaps incrementally to 20° and then 10°. I observed the cockpit flap indicator approaching the 0° position.
Our airspeed had not increased significantly. There had been no abnormalities at that point.
Within approximately 5-10 seconds, I heard a “pop” noise (like a balloon popping) and saw the control wheel shake briefly. We both asked each other what had happened.
I listened to the engine noise and scanned the engine instruments; no abnormalities.
I took the flight controls (we both verbalized this). The airplane responded correctly to slight inputs for roll and pitch.
At that point, I started scanning the exterior and saw that the right wing flap was buckled in the center, with the inboard side still partially extended. The flap appeared intact and was not moving.
I needed a very slight (almost negligible) amount of right aileron control to maintain wings level.
We did not adjust the flap control level at any point afterward, including approach and landing. We discussed that I would fly, and he would handle checklists and other supporting tasks.
Given that the airplane was easily controllable, and there was no overt indication that the condition was worsening, I decided to return to our airport of origin because it was the nearest airport that I was most familiar with. Two of our alternates were contingency options in the event a larger, longer runway was needed.
I advised tower that we had a flap problem but did not need assistance at that time.
During approach and landing I used sideslip to correct for a left quartering headwind. This required left aileron and right rudder, reinforcing that the effects of the partially extended right flap were less than expected.
After landing, without moving any components, we visually inspected the right wing flap from the ground. I saw that the outboard track of the flap appeared to have retracted completely. Along the inboard track, there was a plate that appeared to have collided with bolts along the hinge track. I saw freshly shaved metal on both sides of the hinge track.
We looked at the outboard hinge, which was more difficult to see because the flap was retracted; the plate appeared to be in a higher position than that of the inboard side, and this position appeared to keep the plate clear of the bolts and other components.
Later that day, I became aware of a 2007 advisory circular (43-16A: Aviation Maintenance Alerts) that listed two similar prior occurrences in C182. It appears this is a known problem with C182 aircraft.
An airworthiness directive for inspections of other C182 airplanes should be considered, checking for friction marks or other evidence of damage to the associated plates and components.
Primary Problem: Aircraft