What happened
On September 25, 2003, an Alitalia McDonnell Douglas MD-82, registration I-DACU, was climbing through FL 160 near the Teano VOR during a scheduled passenger flight from Naples Capodichino to Milan Linate. During the climb, the crew heard a loud noise originating from the rear of the aircraft, coinciding with instrument indications showing zero thrust from the right engine.
The flight crew immediately implemented the emergency procedure for "ENGINE FIRE SEVERE DAMAGE OR SEPARATION." After isolating the malfunctioning engine, the crew declared an emergency and requested a return to Naples. The emergency declaration was later canceled, and the aircraft landed safely without further incident. There were no fatalities or injuries among the 67 passengers and 6 crew members on board.
The investigation
The ANSV investigation was significantly hindered by the fact that the event was not reported by official authorities, but rather by a passenger nearly two years after the occurrence. This delay prevented investigators from accessing critical radar data and real-time communications.
Technical analysis of the right-hand Pratt & Whitney JT8D-217C engine revealed that while recent maintenance had been performed according to schedule, the engine had recently undergone repairs for foreign object damage (FOD) to the fan blades just six days prior to the event. Upon disassembly, investigators found that the 3rd and 4th stage low-pressure turbine (LPT) rotor blades had fractured at the root, causing extensive damage to the stator clusters and resulting in an uncontained failure that perforated the LPT casing.
Findings
- The primary cause of the engine failure was the fracture of 3rd or 4th stage LPT rotor blades.
- While fractographic analysis could not definitively confirm the mechanism, the failure was likely due to high cycle fatigue (HCF), a known phenomenon in this engine series.
- The failure was uncontained, meaning engine components were projected outward with enough force to penetrate the engine casing.
- The delay in reporting the event by institutional bodies meant the investigation was limited to documentary evidence rather than real-time data.
Safety action
No specific safety recommendations were issued by the ANSV, as the technical issue regarding LPT blade fatigue was already known to the manufacturer and authorities, and new legislative frameworks and protocols between ANSV and ENAC had since been established to prevent delayed reporting of significant aviation events.