What aircraft was involved and where did it happen?

The accident on 2005-07-31 involved a Piper PA-34 SENECA, registration EC-JHQ, at Aeropuerto de Sabadell (Barcelona), ES.

What was the probable cause of the accident?

The nose gear collapsed because a bolt in the down lock link mechanism had been bent by the stresses of previous hard landings, preventing the gear from properly locking in the extended position.

Nose gear failure leads to runway excursion in Piper PA-34

A Piper PA-34-200 experienced a nose gear collapse during landing at Sabadell Airport, resulting in a runway excursion and propeller damage.

What happened

On July 31, 2005, a privately operated PIPER PA-3-200, registration EC-JHQ, was performing a local visual flight from Sabadell Airport. The flight, which included the pilot and two passengers, proceeded normally for approximately 81 minutes.

During the landing phase on runway 13, the pilot followed standard procedures, extending the landing gear during the final approach. The touchdown was smooth; however, as the aircraft began to taxi following the landing, the pilot noticed the nose of the aircraft sinking. Despite attempts to pull back on the controls to maintain the nose position, the elevator lost effectiveness as the aircraft decelerated. Consequently, the nose gear collapsed, causing the nose to strike the runway. The aircraft slid along the asphalt, deviating slightly to the left, and came to a stop halfway down the runway. The propellers also impacted the pavement. There were no injuries among the three occupants, though the aircraft sustained damage to the nose gear doors, the forward fuselage, and both propellers.

The investigation

The investigation focused on the mechanical integrity of the nose gear assembly. The aircraft utilized a hydraulic tricycle landing gear system where the nose gear is held in position by a spring-loaded mechanism. Specifically, the investigators examined the "down lock link," which is responsible for securing the drag brace in a straight position to lock the gear.

Upon inspection of the locking mechanism, investigators found that the drag brace was not being held firmly by the down lock link, creating a condition where the gear could easily disengage. Further disassembly of the down lock link revealed that the bolt connecting the link to the retraction link was severely bent at the ball joint area.

Findings

The nose gear retraction was caused by the inadequate securing of the drag brace by the down lock link.
This failure was a direct result of insufficient length in the down lock link tensioner, caused by the deformation of the bolt connecting the link to the retraction link.
The deformation of the bolt was caused by bending stresses, which likely originated from one or more hard landings.
While a service bulletin (No. 1123A) existed to provide inspection and replacement instructions for nose gear components due to similar incidents in the Piper PA-34 fleet, the aircraft had recently been purchased and had only undergone a 50-hour inspection, which did not include an inspection of the down lock link.