What happened
On December 26, 2009, a Cessna 310Q, registration PT-JCZ, operated by Aero Star Táxi Aéreo Ltda, departed from Salvador International Airport (SBSV) bound for Vera Cruz (SNVR). The flight was carrying one pilot and four passengers.
Shortly after takeoff, during the landing gear retraction sequence, a loud noise was heard originating from the nose gear. The pilot observed that the nose gear position indicator showed the gear was unlocked. Despite following emergency procedures to attempt to lock the gear, the pilot was unsuccessful. The main landing gear locked normally, but the nose gear remained in an unlocked state.
The pilot decided to return to SBSV for an emergency landing. After flying for approximately eighty minutes to manage fuel consumption, the aircraft touched down on runway 17. During the landing roll, the nose gear retracted, causing the aircraft to strike the ground. The impact resulted in light damage to the underside of the aircraft and the propeller tips. All five occupants were uninjured.
The investigation
CENIPA investigators examined the aircraft and found that the nose gear actuator rod had broken. Subsequent ground tests revealed that the nose gear retraction cycle could not be completed because the nose wheel failed to enter its well.
Further analysis of the nose gear strut determined that the component was not fully extending, creating a mechanical stop that prevented the wheel from seating correctly. This lack of extension was caused by insufficient nitrogen pressure. Investigation into the nitrogen loss revealed that an internal O-ring within the strut was worn, leading to a leak.
While the aircraft's maintenance records showed the last 200-hour inspection had been completed without reported issues, investigators noted that the strut's extension height might not have been properly evaluated during pre-flight inspections. Additionally, the investigation highlighted that the use of non-approved cleaning products on struts can cause premature wear to rubber and plastic components, potentially contributing to the O-ring failure.