What happened
On May 2, 2011, a P.180 Avanti II, registration OK-PIA, was performing an IFR approach to runway 06 at Prague Ruzyně Airport. During the ILS approach, the crew discovered that the landing gear failed to extend. After two unsuccessful attempts to deploy the gear normally, the crew executed an emergency extension procedure using the manual pump.
Following the emergency extension, the crew requested a change in flight profile to allow for a VFR approach to runway 13. After landing on runway 13, the crew discovered that the brakes were non-functional and the nose wheel steering was inoperable. The crew used differential engine thrust to vacate the runway and taxi to taxiway P, where they shut down the engines and the electrical system.
After the aircraft was towed to the South apron, the pilot attempted to retract the flaps. Upon switching the aircraft's electrical system back on, the nose gear unexpectedly retracted. This caused the nose of the aircraft to drop, striking the ground with the open nose gear doors, resulting in damage to the doors and the nose gear mechanism.
The investigation
The ÚZPLN investigation focused on the mechanical failure of the landing gear and the subsequent ground incident. Investigators examined the hydraulic system and the functionality of the landing gear extension and retraction mechanisms. A technical inspection by a maintenance organization confirmed a malfunction in the electro-hydraulic unit (P/N 201033002). Additionally, the investigation looked into the crew's decision-making regarding the missed approach and the subsequent ground handling of the aircraft.
Findings
- The primary cause of the incident was a mechanical failure of the electro-hydraulic unit (P/N 201033002), which caused the valve settings to remain in a position that prevented proper gear locking.
- The nose gear collapse occurred because the electrical power restoration triggered the retraction of the nose gear.
- The main landing gear remained extended only due to the weight of the aircraft and the specific kinematics of the gear design.
- The crew's initial decision-making regarding the missed approach procedure did not strictly align with published procedures, though they followed the operator's emergency checklists for the gear extension.
- There were no injuries to the crew or passengers.