What happened
On 30 May 2003, a Pazmany PL-2, registration G-OPAZ, was involved in an incident at Boscombe Down Aerodrome, Wiltshire. The aircraft had just finished a private flight consisting of one hour of local general handling and five touch-and-go landings on the grass-surfaced Runway 17.
As the pilot taxied from the grass runway onto the asphalt taxiway, the aircraft had to traverse a three-inch step down followed by a short rise onto the level taxiway surface. While maneuvering at a slow walking pace with idle power, the nose wheel dropped down the edge of the grass surface. During this movement, the tips of the wooden propeller made contact with the taxiway surface. The pilot immediately shut down the engine and stopped the aircraft, subsequently notifying other traffic of the obstruction via radio.
The investigation
The investigation focused on why the aircraft's ground clearance was insufficient to prevent the propeller from striking the ground. While the damage was limited to the propeller blades, a subsequent inspection of the nose oleo strut revealed a defect. Investigators found that a silver soldered joint had failed, resulting in a leak of both hydraulic fluid and nitrogen charge.
Findings
- The primary cause of the propeller strike was the full compression of the nose oleo strut.
- A defective silver soldered joint in the nose oleo allowed the nitrogen and hydraulic fluid to escape.
- The pilot noted that leakage may have been occurring prior to the flight, and the impact of the five touch-and-go landings and taxiing on the grass surface likely exacerbated the loss of pressure.
- The loss of pressure caused the nose of the aircraft to sit lower than normal, reducing the clearance between the propeller and the ground.