What happened
On 10 July 2018, an Airbus Helicopters EC1s7B, registration G-EMEA, was performing a commercial passenger flight when the nose landing gear collapsed during touchdown at Aberdeen Airport. While the landing gear appeared to deploy normally, the flight crew heard a crunching noise and noted the aircraft settling into an unusual nose-down attitude.
Following the impact, the crew maintained a low hover to allow the 16 passengers to disembark due to a low fuel state. The aircraft was then moved to a different stand, where ground engineers used sandbags to support the forward fuselage to prevent further damage.
The investigation
An investigation by the operator's engineering organisation revealed that the separation of the A-frame from the nose landing gear actuator was caused by the failure of the pintle pin. Technical examination determined that a critical bushing, which should have been installed within the A-frame, was missing.
Records showed that approximately 50 flying hours earlier, the A-frame had been replaced during routine maintenance to address steering issues. The required procedure dictated that the pintle pin bushing from the old component should have been transferred to the new A-frame. This transfer did not occur. The investigation noted that the design of the nose landing gear makes it difficult to visually confirm the presence of the bushing once the actuator is attached, and a subsequent independent inspection failed to detect the omission.
Findings
- The primary cause of the gear collapse was the failure of the pintle pin due to the absence of the required bushing.
- The maintenance task was performed incorrectly, as the technician failed to transfer the bushing during the A-frame replacement.
- Human factors contributed to the error, including the engineer's lack of experience with this specific task and the fact that they were supervising a team of non-type rated engineers.
- Fatigue was a contributing factor, as the engineer had only taken two rest days in the previous 31 days, violating company fatigue management protocols.
- Maintenance oversight occurred because shift managers failed to identify the breach in rest requirements.
Safety action
Following the incident, the manufacturer issued a Safety Information Notice (SIN) to alert other operators to the failure mode. This was followed by an Alert Service Bulletin (ASB) 32A003, which mandated inspections of the pintle pin bushing. This action was later made mandatory by EASA via Airworthiness Directive 2018-0190. The operator also implemented a 'complex task' job card for this specific maintenance procedure and revised its fatigue management and workload monitoring processes.