What happened
On January 10, 2006, a Cessna T303 aircraft, registration OK-ELO, was performing a CPL skill test at Ostrava-Mošnov Airport (LKMT). Following a successful landing on runway 22, the examiner instructed the pilot undergoing the test to perform a "touch-and-go" maneuver.
Immediately before the takeoff phase of the maneuver, the aircraft suddenly veered to the left, moving toward the left edge of the runway. The pilot was unable to correct the direction using either the steering or the brakes. Consequently, the examiner took control of the aircraft and performed an emergency landing. The aircraft traveled approximately 250 to 300 meters from the touchdown point before coming to a stop 48 meters from the left edge of the runway.
There were no injuries to the crew. The aircraft sustained significant damage, including a damaged forward fuselage, crumpled skin at the wing-to-fuselage junction, a broken nose landing gear, and damaged gear covers. Propeller blades on both engines were bent backward.
The investigation
The ÚZPLN investigation focused on several technical aspects of the aircraft's landing gear. Experts analyzed the damage to the left wing's leading edge, the fracture characteristics of the nose gear strut, the condition of the main brakes, and the technical state of the nose landing gear itself.
Technical inspections revealed several maintenance-related deficiencies in the nose gear assembly. Investigators found that a defective inner tube had been installed during a recent tire change, leading to underinflation. Additionally, a tire of a different construction than recommended by the manufacturer was in use, making it difficult to detect shape deformations. The investigation also identified that the hydraulic fluid level in the lateral oscillation damper was 30% below the manufacturer's specification, and the gas pressure in the strut was also below required levels. Furthermore, excessive play was found in the gear control mechanism, and a limiting stop for the gear strut's rotation was missing.
Findings
- The primary cause of the excursion was a technical failure of the nose landing gear.
- The combination of underinflated tires, low gas pressure in the strut, and insufficient hydraulic fluid in the lateral damper caused unbuffered lateral oscillations.
- These oscillations caused the nose gear fork to pivot approximately 90 degrees to the left, making the aircraft uncontrollable during the maneuver.
- The crew was unable to prevent the excursion due to the sudden nature of the mechanical failure.