What aircraft was involved and where did it happen?

The accident on null involved a Piper PA23-250F, registration EI-WMN, at IE.

What was the probable cause of the accident?

The nose landing gear failed to lock in the down position during landing, driven by mechanical free play in the down-lock latch assembly and hydraulic system irregularities.

Nose Landing Gear Collapse During Landing at Shannon Airport

A Piper PA23-250F aircraft experienced a nose gear collapse on touchdown at Shannon Airport, resulting in substantial damage to the propellers and aircraft nose.

What happened

On 2 December 2019, a Piper PA23-250F with registration EI-WMN was performing an aerial work operation when it experienced a landing gear failure at Shannon Airport. While approaching Runway 24, the pilot noted that the nose landing gear indication light was flickering. As the aircraft crossed the runway threshold at approximately 95 knots, a red landing gear warning light and an audible alert activated, signaling that the gear was not correctly locked.

As the aircraft' and main wheels made contact with the runway, the nose landing gear collapsed. The impact caused the aircraft's two propellers to strike the runway surface, leading to bent propeller tips and damage to the aircraft's nose section. The pilot, who was the sole occupant, escaped the aircraft without injury, and no fire occurred during the event.

The investigation

The AAIU examined the aircraft's recent maintenance history and the mechanical state of the hydraulic and landing gear systems. The investigation looked into a previous flight to Kerry Airport where the pilot had observed similar flickering in the nose gear light. Investigators also performed technical testing on the aircraft's hydraulic 'powerpak' and the landing gear selector mechanism. Additionally, the condition of the electrical wiring and the mechanical integrity of the down-lock latch assembly were scrutinized.

Findings

The investigation identified significant free play in the nose landing gear down-lock latch hook pivot as a primary technical factor.
Anomalies within the hydraulic powerpak and the presence of air in the hydraulic system likely contributed to the failure to maintain pressure in the down line.
During testing, the landing gear selector lever was found to not return to the neutral position correctly, and release detent screws on the powerpak were found to be loose.
Electrical issues were noted in the indication light assembly, specifically poor condition in the soldered joints of the bulb fitting.
The pilot's trust in the landing gear indication system may have been compromised due to the flickering light observed on a prior flight, an issue that had not been reported to the operator before the return flight to Shannon.