What happened
On July 11, 2001, an Alitalia MD-82, registration I-DACR, was operating a scheduled flight from Rome Fiumicino to Palermo Punta Raisi. During the approach to Palermo, the crew discovered that the nose landing gear (NLG) had failed to lock in the extended position, evidenced by a red "NOSE" warning light on the upper instrument panel. Despite attempting emergency procedures, the gear remained unsecure.
After a low pass over runway 25 to confirm the gear status with air traffic control, the pilot decided to return to Fium to ensure a safer landing environment. During the subsequent approach to Fiumicino, the crew attempted both normal and alternate extension procedures, both of which failed. To prevent further damage or potential engine ingestion of debris, the pilot opted to land using the alternate procedure, which kept the main gear door in an open position. The aircraft touched down on runway 16C with the nose gear retracted, causing the nose of the fuselage to impact the runway. There were no injuries among the 24 passengers or 6 crew members.
The investigation
The ANSV investigation focused on the mechanical failure of the nose landing gear and the conflicting cockpit indications. Investigators examined the NLG upper lock link and found evidence of a fatigue crack originating from a burr on the component's surface. The investigation also scrutinized the maintenance and inspection processes for this specific part. Additionally, the investigators analyzed the failure of the left forward (1L) emergency slide to inflate during the evacuation and reviewed the cockpit's mechanical downlock indicator, which had erroneously indicated the gear was locked even though it was not.
Findings
- The primary cause of the incident was the fatigue failure of the NLG upper lock link, which prevented the nose gear from locking in the down position.
- A manufacturing or maintenance defect, specifically a burr on the component, acted as a stress concentrator that initiated the fatigue crack.
- The crew received contradictory information due to a mechanical downlock indicator that showed the gear was extended when it was actually unsecure.
- During the evacuation, the left forward emergency slide failed to inflate due to the displacement of an internal sleeve, though this did not impact the survival of the occupants.
- The pilot's decision to land using the alternate procedure was intended to mitigate the risk of foreign object damage (FOD) to the engines.