What happened
On May 3, 2008, a Cessna 152, registration CS-DDO, was performing a local instructional flight at Cascais Municipal Aerodrome (LPCS) when a technical incident occurred during landing. The aircraft, operated by GESTAIR Flying Academy, was carrying a student pilot.
As the aircraft touched down on runway 35, the nose gear made contact with the pavement. Immediately upon touchdown, the pilot felt intense vibrations originating from the nose gear assembly. The pilot reacted quickly by cutting the engine and working to keep the aircraft within the runway boundaries. After bringing the aircraft to a halt, the pilot notified the control tower and the flight school. Upon inspection outside the aircraft, it was discovered that the nose wheel rim had disintegrated, leaving the tire held in place only by the wheel axle within the nose gear fork. Fragments of the rim were found scattered along the landing path on the runway.
The investigation
The GPIAAF examined the recovered fragments of the rim and found that one half of the rim exhibited recent fractures and significant drag wear, while the other half contained older, highly fragmented fractures. The investigation also noted that the general cleanliness and treatment of these parts were inadequate.
Investigators reviewed the aircraft's maintenance records, noting that a 100-hour inspection had been performed just three days prior to the incident. While the inspection protocol included a visual check of the landing gear and lubrication of the axle, it did not include more advanced methods such as borescope inspections or ultrasonic testing. Furthermore, the investigation found that the operator relied on external maintenance providers and lacked an internal system to monitor or audit the quality of the services provided by these third parties.
Findings
- The landing was performed normally, with a relatively smooth touchdown of the nose gear.
- The nose wheel rim contained pre-existing partial fractures that were not detected during previous inspections, likely because they were obscured by paint.
- The existing maintenance protocol was insufficient to detect internal or subsurface cracks, as it relied solely on visual inspections.
- The operator lacked a dedicated maintenance management system to oversee the airworthiness of the fleet and to audit the quality of work performed by external contractors.