What happened
On February 15, 2006, a Boeing 737-45S, registration OK-FGR, operated by Czech Airlines (ČSA), was performing flight OK 650 from Prague-Ruzyně (LKPR) to London Heathrow (EGLL). Approximately four minutes after takeoff, a passenger alerted the cabin crew to a hole in the aircraft wing. The pilot requested a flight crew member, traveling as a passenger, to inspect the damage. The inspection revealed a hole approximately 20 x 10 cm in the ground spoiler area, roughly 1 meter from the fuselage.
Following the discovery, the pilot decided to abort the climb and return to Prague-Ruzyně. During the holding pattern, the crew assessed the situation and noted that the damage appeared consistent with debris from a landing gear tire. The pilot requested airport rescue and fire services to inspect runway 24 for debris. Ground personnel subsequently found tire tread fragments on the runway, confirming that the damage was caused by a single tire. The aircraft safely landed on runway 13. After taxiing, a technical inspection confirmed that the tire had not lost pressure, and the aircraft was able to proceed to the stand.
The investigation
The ÚZPLN investigation focused on the mechanism of the tire failure and the resulting damage to the aircraft structure. The investigation examined the tire itself, which was sent to Goodyear Aviation Tires for analysis. The inspection of the aircraft revealed that the detached tread pieces had struck the internal landing gear doors, the landing gear strut panel, the lower surface of the wing trailing edge, and the spoiler section, causing a hole in the composite structure and damage to the flap mechanisms.
Investigators also reviewed maintenance records, including the "Daily Check" performed prior to the flight, which had found the tire pressure and condition to be within limits. The investigation also looked into the operational history of the tire, which had been installed on the number 4 main gear wheel in November 2005 and had undergone 413 landings since its last retreading.
Findings
- The primary cause of the incident was the excessive deformation of an underinflated tire.
- The investigation determined that the tire underwent excessive deformation during operation, likely due to underinflation or a defect in the paired tire on the opposite side of the axle.
- This excessive deformation caused significant overheating of the tread, leading to the initiation of tread delamination.
- During the takeoff roll on runway 24, centrifugal forces caused approximately 60% of the tire tread to detach.
- The detached rubber fragments struck the aircraft's landing gear doors and wing components, resulting in structural damage to the spoiler and flap mechanisms.
- No evidence of foreign object damage (FOD) was found on the tire itself.