What happened
On September 3, 2010, a Boeing 737-400, registration TC-SGE, operated by SAGA Airlines, was performing a charter flight from Poznań-Ławica Airport (EPPO) to Izmir, Turkey. During the takeoff roll, as the aircraft approached and exceeded V1 speed, the crew experienced slight vibrations. Shortly after liftoff, a LOW PRESSURE warning illuminated for the hydraulic system, and the crew found it impossible to retract the landing gear despite multiple attempts.
The crew declared an emergency and requested to return to the airport, positioned approximately 4NM south of the airfield. The aircraft reached an altitude of about 5,000ft AGL before returning to land. During the landing roll, the crew utilized alternate steering for the nose gear. A post-landing inspection revealed that the inner tire of the right main landing gear had burst, causing significant damage to the aircraft, including severed hydraulic lines in the right main gear bay and a puncture in the upper right wing skin caused by tire fragments.
The investigation
The PKBWL investigation team examined the aircraft's Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR), crew licenses, and technical maintenance records. The team also reviewed airport security footage and inspected the runway surface. Analysis of the FDR was conducted in collaboration with the BEA in Paris. The investigation focused on the condition of the tire, the maintenance history of the landing gear, and the presence of any foreign object debris (FOD) on the runway.
Findings
- The explosive failure of the inner right main gear tire occurred at a speed of 132 kts (CAS) near the end of the takeoff roll.
- The tire in question was a retreaded unit that had completed 178 takeoff and landing cycles.
- Significant wear was observed on both the inner right and left main gear tires, including localized tread depletion and damage to the tread edges.
- The damage to the tread edges suggested the possibility of low tire pressure.
- The operator did not perform any tire pressure checks beyond the standard requirements mandated by the manufacturer.
- No foreign objects were found on the runway or taxiway that could have initiated the failure.
- The crew's actions and the response from ground services were found to be entirely correct.
- The damage to the hydraulic lines, while causing the gear retraction failure, ultimately served as a safety factor by preventing further complications during the emergency landing.