| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On 30 March 2018, at about 1420 Eastern Daylight-saving Time (EDT), a SAAB 340B was en-route to Moruya, New South Wales (NSW), with three crew members and 10 passengers on board. During final approach, the pilot monitoring[1] (PM) selected gear down. Immediately following, the crew received a hydraulic system caution indication. The “Hydraulic Light ON” requires the action of “Memory Items” and then the conduct of the “Abnormal Checklist”.
While conducting a holding pattern above Moruya airport, the flight crew carried out failure management procedures. The crew verified that the nose gear was down and locked but did not receive a down and locked indication for the main gear. The crew contacted operations to confirm the manufacturer’s recommended speeds for gear-down flight, and landing distance calculations for a zero-flap landing in Sydney. In consultation with the company emergency response team, they made the decision to divert the aircraft to this airport.
The PM declared a PAN PAN[2] and advised air traffic control (ATC) that the aircraft required a landing on runway 16 at Sydney due to the crosswind on runway 07 and a long final approach. In addition, the crew advised that the aircraft would need to be shut down on the runway prior to being towed to the parking bay. The flight attendant was advised of the need for a precautionary cabin preparation.
On descent into Sydney, the flight crew extended the landing gear with the hand pump extension and received a down and locked indication. The flight crew subsequently obtained a clearance for a long final to ensure a stable approach, and completed a flapless landing. The aircraft was brought safely to a stop on the runway where it was shut down in accordance with standard operating procedures for a hydraulic malfunction and then towed to the bay.
Following the incident, engineering fault isolation identified a faulty relay in the hydraulic system. The relay was replaced in accordance with the aircraft maintenance manual, functional checks were carried out and the aircraft was returned to service.
Safety message
This incident highlights the importance of having experienced flight operations and engineering support staff to assist well-trained flight crew with making decisions in the event of a technical failure in-flight. Clear communication with ATC also resulted in a safe outcome.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.
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- Pilot Flying (PF) and Pilot Monitoring (PM): procedurally assigned roles with specifically assigned duties at specific stages of a flight. The PF does most of the flying, except in defined circumstances; such as planning for descent, approach and landing. The PM carries out support duties and monitors the PF’s actions and the aircraft’s flight path.
- PAN PAN: an internationally recognised radio call announcing an urgency condition which concerns the safety of an aircraft or its occupants but where the flight crew does not require immediate assistance.