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The Westpac rescue helicopter was being operated by Garden City Helicopters Ltd. on a hospital patient transfer flight between Ashburton and Christchurch on May 5, 2014, when it experienced a double engine power loss near Springston. The pilot made an emergency landing onto farmland, with no injuries sustained by the occupants and minor damage to the helicopter.
It was later determined that the double engine power loss had been caused by lack of fuel flow to the engines, despite there being a large quantity of fuel in the main fuel tanks. Investigators found that the aircraft’s two fuel prime pump switches (normally set to OFF during flight) were set to ON, while the two fuel transfer pump switches (normally ON during flight) were set to OFF.
This configuration prevented the fuel in the main tanks from reaching the engine supply tanks. Due to a design feature of the BK117, when starved of fuel, both engines lost power within seconds of each other. Based on the timing of the power loss, investigators concluded that the pilot had left the fuel transfer pumps off after starting the engines.
The TAIC determined that a contributing factor to the event was the pilot’s lack of recent experience on the BK117, including the absence of any competency assessment on the aircraft type in the previous five years. According to the TAIC’s report, Garden City Helicopters did not have any procedures in place to address the lack of recent experience, such as additional training, supervision, or a policy on the use of written checklists in such a situation. The pilot did not refer to a checklist when carrying out the normal pre-flight, before-start, and after-start procedures, which might have alerted him to the error in the fuel system configuration.
Another contributing factor identified by the TAIC was the pilot’s inability to detect the caution lights that would have alerted him to the incorrectly configured fuel system, due to the cockpit lighting dimmer switch being left on in daylight. A modification of the helicopter to enable the use of night vision equipment was found to have adversely affected the readability of the caution lights during daylight, when the cockpit lighting dimmer was on.
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The TAIC recommended that the Director of Civil Aviation review all modifications to the cockpit lighting on BK117 helicopters for night vision use, to ensure they do not unduly increase the risk of a similar incident occurring. The commission also recommended that Garden City Helicopters amend company policies, procedures, and practices relating to the management of pilot competency.
Key lessons identified by the TAIC were:
– pilots who lack recent experience on an aircraft type should refer to written cockpit checklists when carrying out normal and emergency procedures;
– pilots who fly multiple aircraft types concurrently must remain vigilant to inadvertently transferring habits and procedures from one type to another; and
– operators who require their pilots to fly different aircraft types must have robust policies and procedures that ensure the pilots are appropriately experienced, trained, and current on each aircraft type.
The complete report can be found on the TAIC website.