Event Overview
On 10 July 2005, at approximately 14:56 UTC (16:56 local time), a Cessna 172M, registration I-UDDY, operated by Aero Club Milano, was conducting a training flight from Bresso Airport (LIMB) to Biella Cerrione Airport (LILE). The aircraft carried a student pilot and an instructor. The flight was a navigation training exercise, with the student pilot at the controls for most of the flight.
During the landing phase, immediately after touchdown, while decelerating, the aircraft yawed to the right. The instructor ordered the student to release the controls and attempted to counter the yaw, but found the rudder pedals completely ineffective. The instructor then applied brakes to slow the aircraft, which came to rest on the grassy area alongside the runway, near the parallel taxiway, and was subsequently taxied back to the parking area.
Damage
The occupants were uninjured. The left rudder control cable (P/N 05100105-339) was found broken. Additionally, the runway excursion caused damage to part of the runway lighting system: two runway lights near taxiway R2 were broken. The airport management company (SACE S.p.A.) conducted a site inspection the following day and confirmed the impact. Photographic evidence showed skid marks from braking and the two displaced lights.
Investigation Findings
Examination revealed that the left rudder control cable had failed approximately 1.5 mm inside the swaged fitting at the forward attachment to the rudder pedal. This location is difficult to access for visual inspection. Visual inspection of the fracture surface showed no signs of corrosion, indicating that the failure was most likely due to fatigue. Laboratory tests were not deemed necessary, as the loads on the cable are difficult to ascertain.
The Cessna 172 maintenance manual (Revision 1.03.2004) does not include specific non-destructive inspections of control cables at the critical attachment points; it only specifies checks on cable tension and correct routing.
Notably, the French DGAC had issued Recommendation Bulletin BR 2005/14(A) on 16 March 2005, recommending detailed visual inspection of control cable ends for cracks or corrosion, and immediate removal of cables showing such signs. This bulletin covered several aircraft types including the Cessna 172. It was based on FAA Special Airworthiness Information Bulletin CE-01-30 (11 July 2001) and Piper Service Bulletin 1048. The UK Civil Aviation Authority had also issued Airworthiness Notice No. 12, Appendix 65, on 18 March 2003.
As a provisional preventive action, the technical office of Aero Club Milano modified its maintenance procedures for Cessna 172 aircraft to include additional checks referencing FAA AC 43.13 and Piper SB 1048, with particular attention to cable integrity at swaged fittings.
Aircraft Information
The Cessna 172M (Reims Aviation, 1976) was a single-engine, high-wing, tricycle-gear aircraft. It had a Lycoming O-320-E2D engine (152 hp). At the time of the event, the aircraft had a valid standard airworthiness certificate and insurance. The last periodic inspection (500-hour airframe and 200-hour engine) had been performed on 5 July 2005, with 13 hours 50 minutes since. Total airframe hours were 6,202 hours 65 minutes. The control system (ailerons, flaps, rudder, trim) had been checked for travel and cable tension during that inspection, with no anomalies found.
Airport and Weather
Biella Cerrione Airport (ICAO: LILE) has a single asphalt runway 16/34, 1,481 m long and 30 m wide. Weather conditions were CAVOK with no wind.
Probable Cause
The investigation determined that the left rudder control cable failed due to a fatigue phenomenon, as evidenced by the fracture characteristics and absence of corrosion.