History of the Flight
On 18 February 2022, a Cessna 172 S, registered F-OOOO, operated by Aéro-Club de l'Aviation Civile de la Guadeloupe, departed Pointe-à-Pitre – Le Raizet airport for a local flight with a pilot and one passenger. The purpose was to show the local environment to the passenger, who also held a pilot license and wished to join the flying club. After a touch-and-go at Saintes–Terre-de-Haut aerodrome, during the initial climb the pilot retracted the flaps and turned the wheel to level the wings following light turbulence. The pilot and passenger heard a noise described as something snapping. The pilot turned the wheel again and felt no resistance; the wheel could be turned 90° to the right but the aircraft did not bank. After gaining altitude, the pilot verified all controls and found normal operation except for right roll control; left roll was still available. The pilot decided to return to Pointe-à-Pitre – Le Raizet. The pilot and passenger divided tasks and prioritized yaw control over roll. The pilot landed on the second attempt with flaps set to 10°.
Subsequently, while the maintenance workshop examined the aircraft, mechanics heard a noise and observed the left flap move downward. Inspection revealed that the aileron and left flap control cables had ruptured at their fittings.
Meteorological Information
At Pointe-à-Pitre airport, weather conditions included wind from 090° at 13 knots, visibility greater than 10 km, few clouds at 3,200 ft, broken at 3,900 ft and 7,800 ft, temperature 28°C, dew point 20°C, QNH 1017. Temporary conditions: visibility reduction to 3,000 m, showers, scattered clouds at 2,000 ft with towering cumulus.
Crew Experience
The 25-year-old pilot held an aeroplane commercial pilot license (obtained February 2020) and an instructor rating, with 487 total flight hours, including 60 hours in the previous three months, all on type. The 34-year-old passenger held an airline transport pilot license and had logged 6,050 flight hours.
Aircraft Information
F-OOOO was a Cessna 172 S built in 2004, purchased by the flying club in November 2011. At the last maintenance inspection on 2 February 2022, it had 7,071 flight hours; since then it flew about 20 hours. Maintenance documents showed no specific work on control cables other than scheduled checks. The control cables were last inspected in November 2021 without removal; no corrosion was observed. The maintenance manual indicates that cable damage such as internal corrosion can be difficult to identify and may require cable removal for proper inspection. The manual does not explicitly require checking fittings for corrosion. For aircraft operating in humid conditions, more frequent inspections are suggested.
Aileron and Flap Control Systems
The aileron control system consists of taut metal cables forming a closed circuit between the wheel and each aileron, and between the two ailerons. The failure occurred on the cable connecting the wheel to the right aileron. When the wheel was turned right, tension to move the right aileron up was lost, and the cable connecting the ailerons also lost tension, resulting in no roll effect. Turning left remained functional because the cables moving the left aileron up and the right aileron down were intact.
The flap control system uses an electric motor in the right wing to operate flaps. The left flap is controlled by the right flap via a closed-loop cable system. Failure of the left wing aft cable allows the left flap to move without pilot action to a partially extended position. In this incident, after the cable failure, the left flap moved down during maintenance inspection.
Failure Analysis
Examination showed the aileron and flap control cables had failed at their attach fittings, in the shank near the threaded end. Both failure areas displayed corrosion pitting on the outer surface and on fracture surfaces. The attach fittings were made of AISI 303 Se stainless steel, with an elastomer sleeve on the shank. Corrosion was found on the shank under the sleeve. The aileron control cable fracture surface was too corroded to determine failure characteristics; the corrosion predated the incident. No other anomalies were found that could have caused the failures. According to the manufacturer, the cables were most likely original, though not confirmed. The cables were safetied with lockwire.