What happened
On February 4, 2020, a Beechcraft B1900D, registration OB-1875-P, operated by Aero Transporte S.A. (ATSA), was performing a scheduled passenger flight from Jorge Chávez International Airport in Lima to Pías Aerodrome. During the takeoff roll at Lima, the inner wheel of the right main landing gear (position No. 3) detached from the aircraft.
The flight crew did not realize the wheel had been lost during the departure phase. The aircraft continued the flight to Pías without any operational issues or changes to the flight profile. It was only after the aircraft had landed and taxied to the parking area that ground security personnel at Pías informed the crew that the right main gear wheel was missing. Simultaneously, airport authorities in Lima located the detached tire near the perimeter fence at the intersection of taxiways A and B.
The investigation
The CIAA investigation focused on the mechanical failure of the landing gear assembly. Investigators examined the remains of the right main landing gear and found that the internal and external bearings of the No. 3 wheel had fragmented and disintegrated.
Technical analysis revealed that the hub cap seal was in poor condition, which likely compromised the grease seal and allowed external contaminants to enter the assembly. The investigation also noted the existence of a non-mandatory Service Bulletin (Beech 1900-32-7) that recommended replacing hub caps on B1900D models to prevent similar contamination issues. Furthermore, the investigation looked into maintenance inspection protocols, noting that existing 50-hour and phase inspections only required visual checks of the bearings and did not specifically mandate evaluating the integrity of the hub cap seals.
Findings
- The fragmentation and disintegration of the two bearings in the right main landing gear wheel caused the wheel to detach during takeoff.
- Contamination and lack of lubrication within the bearing assembly were the primary drivers of the failure.
- The degraded condition of the hub cap seal allowed external elements—potentially introduced by irregular runway surfaces containing water, dirt, or sand—to enter the assembly and obstruct the free rotation of the bearings.
- Existing maintenance inspections (50-hour and Phase 3/4) did not include specific checks for the operational integrity of the hub cap seals.