Accident Overview
On March 1, 2024, at 1243 eastern standard time, a Cub Crafters PA18-150 airplane, registration N143CC, was substantially damaged when it collided with a hangar near Edgewater, Florida. The pilot was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a banner tow operation.
Sequence of Events
After dropping his banner, the pilot reported that during short final approach to the runway, at an altitude of about 20 to 30 feet, he heard a loud snap. The control stick became slack, and he lost aileron control. The airplane rolled right. The pilot attempted to control the aircraft using rudder and elevator. The airplane traveled between two aircraft on a taxiway and struck the side of a hangar, causing substantial damage to the fuselage and both wings.
Postaccident Examination
Examination revealed that the left aileron direct cable had separated at a pulley on the lower left side of the fuselage. The damage on the separated cable was consistent with having occurred before impact. The separated ends showed significant wear of the cable strands, consistent with rubbing against the pulley. The cable exhibited corrosion in multiple locations, and the area around the separation was coated with dirt, grime, and a greasy substance.
The aileron pulley at the separation location was checked for operation and was found to bind when rotated. The pulley was removed; its bushing and bolt displayed significant corrosion, and a small portion of the outer part of the pulley had broken free. The fracture area was coated with the same dirt, grime, and greasy substances, consistent with the fracture occurring before the accident.
Control continuity was established for the remaining flight control cables. Inspection of the right aileron direct cable revealed corrosion on portions outside the airframe structure. The corrosion caused stiffness, and when bent, large flakes of corroded metal broke free. About 10 broken cable strands were found in the right aileron direct cable, and wear damage was present where it passed through the right lower fuselage pulley. Further examination found corrosion on several structural tubes and the landing gear.
Engine examination revealed severe corrosion around cylinder bases; valve springs on several cylinders also showed corrosion but none had fractured. Visible exhaust leaks were present on the No. 2 and No. 3 cylinders at the exhaust riser flanges. No anomalies were found that would have precluded normal operation, and the pilot reported the engine was running normally and at the time of impact.
Maintenance History
Maintenance records showed the airplane had three 100-hour inspections in the past six months, with the last performed on February 2, 2024, 67.7 hours before the accident. The left aileron direct cable was replaced on June 11, 2015, at a tachometer time of 4,377.6; at the accident, the tachometer read 7,045.6, indicating 2,668 hours of service. The right aileron direct cable was replaced on September 23, 2021, and had been in service for 1,419.4 hours.
Before 2015, the aileron cables were stainless steel; maintenance personnel switched to galvanized steel cables. When asked why, the mechanic responded that they had found broken strands with stainless steel cables and were trying to improve longevity. The mechanic stated that anti-corrosion products were not routinely applied to the galvanized steel cables on the accident airplane.
The Piper Aircraft Corporation Inspection Report for the PA-18 includes an instruction to inspect aileron and flap cables, turnbuckles, guides, and pulleys for safety, damage, corrosion, and operation. Note 24 of that report states: "Examine cables for broken strands by wiping them with a cloth for their entire length. Visually inspect the cable thoroughly for damage not detected by the cloth. Replace any damaged or frayed cables."