What happened
On October 17, 2007, a Cessna T 210J, registration OK-RAY, operated by FUN AIR s.r.o., departed Prague (LKPR) for Katowice (LKTB). During the final approach to Katowice, the pilot attempted to extend the landing gear, but the mechanism failed to deploy. The pilot attempted to use the manual emergency extension pump; however, after approximately three strokes, the pump lost resistance, leaving the main landing gear partially extended.
After consulting with the aircraft operator, the pilot decided to divert to Karlovy Vary (LKKV). Upon arrival at LKKV, further attempts to cycle the gear were unsuccessful. The pilot subsequently performed several approaches on the grass runway to test the aircraft's behavior. During the final landing on RWY 30 GRASS, the partially extended left main gear leg shifted into the wheel well, causing the aircraft to land on its belly. The engine was abruptly stopped when the aircraft's nose made contact with the ground. There were no injuries to the crew or passengers, though the aircraft sustained damage to the lower fuselage, gear bay covers, and propeller blades.
The investigation
The ÚZPLN investigation focused on the failure of the landing gear extension mechanism. Technical examination of the nose gear bay revealed a leak in a hydraulic hose (P/ 110) responsible for operating the gear door actuators. Investigators found evidence of a mechanical rub mark on the interior wall of the gear bay, measuring 30 x 10 mm, which had caused the metal braiding of the hose to fray and the Teflon liner to puncture. The area was contaminated with hydraulic fluid.
Findings
- The primary cause of the incident was a loss of hydraulic pressure due to a breached hydraulic hose.
- The failure was caused by the mechanical contact between the hydraulic hose and the landing gear bay wall.
- This contact likely occurred over a long period due to the hose's position and engine vibrations, causing the hose to deflect against the bay wall under pressure.
- Standard maintenance procedures for the Cessna T 210J do not require checking the clearance between the hose and the bay wall in the retracted position, making this specific defect difficult to detect during routine inspections.
- The pilot's decision to land on the grass runway was appropriate given the circumstances.