What aircraft was involved and where did it happen?

The accident on 2020-07-08 involved a Piper PA-34-200, registration ZS-ISD, at Runway 10L, Port Alfred Aerodrome, ZA.

What was the probable cause of the accident?

The nose landing gear failed to extend because a loose up lock-stopper caused the roller assembly to jump out of the steering track, creating a mechanical jam during gear retraction.

Nose gear failure leads to nose-down landing at Port Alfred

A Piper PA-34-200 experienced a nose landing gear failure during a systems evaluation flight, resulting in a nose-down touchdown on a grass runway.

What happened

On 8 July 2020, a Piper PA-34-200, registration ZS-ISD, departed Port Alfred Aerodrome (FAPA) for a systems evaluation flight. The flight, conducted by a pilot and an aircraft maintenance engineer, was intended to test the landing gear following recent adjustments. After taking off and retracting the gear, the aircraft returned to the aerodrome approximately 40 minutes later.

Upon attempting to land, the pilot found that the nose landing gear failed to extend, leaving only the main gear lights illuminated and triggering a 'gear unsafe' warning. Despite cycling the gear and attempting the emergency extension procedure as outlined in the Pilot’s Operating Handbook, the nose gear remained retracted. After several low-level fly-pasts to allow ground engineers to visually confirm the failure, the pilot proceeded with a landing on Runway 10L. The aircraft touched down on the grass surface, and as the nose lowered, the aircraft skidded and came to rest in a nose-down attitude. There were no injuries to the occupants, though the aircraft sustained minor damage to the nose cone, gear doors, and one propeller blade.

The investigation

The SACAA AIID investigation focused on why the nose gear failed to deploy via both normal and emergency systems. The inquiry examined the aircraft's maintenance history, noting that the aircraft had been parked outside during the COVID-19 lockdown and had been treated with an oil-based corrosion preventative compound.

Technical examination of the landing gear revealed that the nose gear up lock-stopper had become loose during flight. This loosening caused the roller assembly to exit its intended steering track. When the gear was retracted after takeoff, the out-of-track condition caused the assembly to jam against the steering track channeling, physically preventing the gear from descending.

Findings

The primary cause of the incident was that the nose gear up lock-stopper became loose, which forced the roller assembly out of its track.
This mechanical jam rendered both the standard hydraulic extension and the gravity-fed emergency extension systems ineffective.
The maintenance organization had implemented a practice of inhibiting the undercarriage with a corrosion preventative compound during the lockdown period, though the Aircraft Maintenance Manual provided no specific guidance for this procedure.

Safety action

It is recommended that maintenance organizations implement robust procedures, such as dual inspections, to ensure that critical aircraft and engine components are properly secured and that engineers strictly adhere to established maintenance protocols.