What happened
On 20 June 2005, a DHC-8-311, registration G-BRYU, arrived at Aberdeen Airport operating as a passenger flight. During the disembarkation of the 28 passengers and 4 crew members, a ground staff member signaled to the commander that an abnormality was visible near the nose of the aircraft. Upon inspection, the commander observed smoke emerging from a vent located under the right-hand side of the nose section. After ensuring all passengers had safely exited, the commander instructed the First Officer to alert the Aberdeen Fire and Rescue Service (AFRS) and initiated an evacuation via the forward exit. Before leaving the aircraft, the commander confirmed that all electrical power had been disconnected.
The investigation
Following the alert, the AFRS attended the scene. Although smoke was visible, the fire service determined that the smoke had ceased by the time they arrived, and no extinguishing agents were required. A subsequent technical inspection by an engineer identified a tiny hole in a hydraulic pipe. This leak had sprayed fluid into the high-temperature area of the weather radar, creating a vapor that appeared as smoke. The investigation suggested that the leak was likely caused by chafing or fretting due to contact between the pipe and the surrounding structure or adjacent piping.
Findings
- The visible smoke was actually hydraulic fluid vaporized by the heat of the weather radar.
- The leak originated from a small hole in a hydraulic pipe caused by contact with nearby components.
- At the time of the incident, the operator had noted a high frequency of hydraulic leaks across its Dash 8 fleet.
Safety action
In response to the high rate of leaks, the operator implemented an Engineering Technical Requirement. This mandate required repetitive inspections of rigid and flexible hydraulic tube installations in the nose gear bay, nacelles, wing roots, and rear fuselage during 'A' and 'C' checks to ensure adequate clearance between pipes and structures. Following the introduction of these inspections, the rate of hydraulic leaks across the fleet's eight aircraft was significantly reduced.