What happened
On December 29, 2018, a Boeing 737-800, registration LV-HKR, operated by Flybondi, departed Silvio Pettirossi International Airport in Paraguay bound for El Palomar, Argentina. During the takeoff roll, the tread of the number 2 main landing gear tire separated from the carcass. The departing fragments struck the aircraft's left flap, though the crew did not immediately notice any abnormality during the climb.
Following the departure, subsequent aircraft observed foreign object debris (FOD) on the runway. Airport personnel conducted a sweep and recovered rubber remnants from a main landing gear tire assembly. Air Traffic Control in Resistencia notified the crew of the debris as they entered Argentine airspace. While the crew could not confirm if the debris belonged to their aircraft, they opted to divert to Ministro Pistarini International Airport (Ezeiza) as a precaution. The aircraft landed safely at Ezeiza, where ground personnel confirmed damage to the inner left main gear tire.
The investigation
The investigation examined the mechanical state of the landing gear, the maintenance records of the operator, and the crew's decision-making process. Investigators analyzed the tire pressures of the remaining wheels and found significant discrepancies. Specifically, several tires showed pressures either exceeding the maximum limits or falling below the minimum requirements specified in the maintenance manual. The investigation also reviewed the company's procedures for monitoring and recording tire inflation pressures.
Findings
- The separation of the tire tread occurred during takeoff, with debris impacting the left flap.
- Inconsistent tire pressure monitoring was identified, as several wheels exhibited pressures outside of the manufacturer's prescribed limits.
- The investigation could not definitively pinpoint a single cause for the tread separation but identified three potential triggers: damage from foreign objects, runway surface irregularities, or defects in the tire retreading process.
- The crew's risk assessment and decision to divert to an alternate airport were deemed appropriate given the uncertainty of the situation.
Safety action
- The investigation recommended that Flybondi adopt a new system for controlling the execution and recording of tire pressure calibration tasks.
- A recommendation was made to the National Civil Aviation Administration (ANAC) to develop guidance for commercial and general aviation crews, encouraging the use of a preventive emergency declaration when facing operational uncertainties or unknown mechanical failures.