What happened
On October 19, 2002, a Boeing 737-300, registration G-IGOX, operating a charter flight from Naples Capodichino to London Stansted, experienced intense structural vibrations during the initial climb. At an altitude of 5,500 feet and an indicated airspeed of 250 knots, both the flight crew and passengers felt medium-intensity vibrations throughout the cabin.
While the crew found flight controls and onboard systems to be operating normally, they could not identify the source of the shaking. During the flight, air traffic control informed the crew that debris, including rubber fragments and a panel presumably from the aircraft's landing gear, had been found on the runway at Naples. To verify the integrity of the landing gear, the crew performed a low-altitude flypast of the Milan Linate control tower at 1,000 feet. Although onboard indications suggested the gear was extended and secure, the aircraft subsequently landed at Milan Linate. Following the landing, inspections revealed that the outer tire of the right main landing gear had burst, a gear door panel was missing, and a 40x20 cm hole had been created in the wing-to-fuselage junction. Impact marks were also found on the right flap.
The investigation
The ANSV investigation focused on the cause of the tire failure and the subsequent structural damage. Investigators examined the condition of the landing gear and the debris found on the Naples runway. The investigation revealed that the burst tire and the missing panel were part of a sequence of events triggered during the takeoff roll at Naples.
Technical analysis of the tires involved showed that both the burst tire and an adjacent tire on the right gear had been recently retreaded. The investigation determined that the limits previously applied to the retreading process for these specific Bridgestone-manufactured tires were inadequate. Consequently, the manufacturer, Dunlop, implemented new restrictions limiting the number of retreads (remoulds) to a maximum of three per tire.
Findings
- The primary cause of the vibrations and structural damage was the burst of the outer right main landing gear tire during the takeoff roll.
- The tire failure caused a landing gear door panel to detach, which then struck the aircraft's structure.
- The impact of the detached panel and tire fragments resulted in a hole in the wing-fuselage junction and damage to the right flap.
- The retreading limits for the specific tire type were insufficient, leading to the failure of the regenerated tire.