The Spanair flight JK3203 accident was notified to the Air Accidents Investigation Branch (AAIB) by the Air Traffic Control (ATC) Watch Manager at Liverpool Airport.
The investigation was conducted by: Mr D King (Investigator-in-Charge), Miss G M Dean (Operations), Mr S W Moss (Engineering) and Mr R James (Flight Recorders). During the course of the investigation, Mr P D Gilmartin was appointed to replace Mr King as Investigator-in-Charge.
The Spanair flight JK3203 carried out an automatic landing at Liverpool at 1232 hrs with the copilot (FO) being the pilot flying.
The right main gear collapsed on touchdown and the commander took over control shortly afterwards.
The aircraft continued travelling along the runway, maintaining approximately the centreline, and came to rest with the right wing in contact with the ground.
A successful passenger evacuation of Spanair flight JK3203 was carried out using the forward escape slides and the left overwing emergency exit.
The following causal factors were identified:
- The right main landing gear cylinder failed immediately upon touchdown due to the application of spin-up drag loads on a section of the cylinder containing a major fatigue crack 3.2 mm long and 1.0 mm deep and several other smaller cracks associated with it.
- The origins of these fatigue cracks could not be identified but other embryonic cracks were found which were associated with surface irregularities arising from a grit-blasting process during manufacture. Abnormal loading, possibly due to an occurrence of a mode of fore-and-aft vibration known as ‘gear walking’ is thought to have been responsible, at some time in the aircraft’s history, for propagating the cracks to a depth at which continued growth was possible under normal loading. Alternatively, some abnormal loading may have relaxed the beneficial compressive surface stresses induced by shot-peening at the critical section and allowed propagation from the same surface defects.
- Inspection and other mandatory preventive measures taken following two similar accidents did not prevent the occurrence of this third accident. This was probably due to the small size of cracks which are required to be detected before reaching a critical dimension.