Incident Description
On April 14, 2015, the crew of a Piaggio P180 Avanti II received a task to perform an inter-hospital medical flight from EPWA (Warsaw Chopin Airport) to EPSC (Szczecin-Goleniów Airport). While taxiing, the pilot conducted a check of the nose wheel steering system. After completing all procedures, the pilot found that nose wheel steering was not functional. The second pilot confirmed the malfunction. The captain decided to abort the task and return to the base using differential braking to steer the aircraft. During this maneuver, the captain noted difficulties in performing tight turns and vibrations originating from the nose wheel area. After stopping the aircraft, the second pilot inspected the steering connection and discovered that the pin connecting the steering system to the nose wheel had fallen out of its sleeve, causing the loss of steering control. The second pilot reconnected the steering system using the pin and secured it with its integral locking cotter pin. During subsequent taxi for the engine run-up test, no irregularities in nose wheel steering operation were observed. The planned task was then completed without further issues.
Cause
The cause of the incident was improper assembly of the pin connecting the steering actuator yoke with the strut, specifically characterized by shallow insertion of the pin into the socket of the actuator yoke end.
Contributing Factor
A contributing circumstance was an inaccurate pre-flight inspection, during which the improper assembly of the pin was not noticed.
Preventive Actions Taken
The operator informed operational and technical personnel servicing Piaggio P180 Avanti aircraft about the incident. Emphasis was placed on selecting and ensuring proper lighting during night maintenance tasks and on the necessity of precise post-task inspections.
Proposed Systemic Changes
The investigation report proposed several systemic changes: (1) Amend the company's standard operating procedures for Piaggio P180 Avanti I and II to include a note requiring verification of the correct pin security by pulling on one end of the locking cotter pin before flight. (2) Add a task description for personnel involved in the hangaring/unhangaring procedure of the Piaggio P180 to the company manual. (3) Mark the lower part of the pin red along the length corresponding to proper installation, so that an improper installation would expose the natural color of the pin. (4) Attach a red ribbon to the towbar with a quick-release fastener; when the towbar is disconnected, the person must install the pin correctly and secure the ribbon, and when connecting, the steps are reversed.
Safety Recommendations
No safety recommendations were formulated by the investigation commission.