What happened
On the afternoon of 5 July 2009, a Britten Norman BN2A Mk III Trislander, registration ZK-LOU, was performing a scheduled flight from Great Barrier Aerodrome to Auckland International Airport. The aircraft, operated by Great Barrier Airlines, was carrying a pilot and 10 passengers. Following standard procedures, the pilot performed after-start checks and a power check while holding the brakes before commencing the takeoff roll on runway 28.
During the initial climb, at an altitude of approximately 500 feet, the pilot noted an irregular pattering sound and observed that the propellers had become out of sync. While attempting to resynchronize the engines and adjusting controls to compensate for a drop in manifold pressure and RPM on the right engine, a loud bang occurred. The pilot subsequently observed that the entire propeller assembly for the right engine had detached, leaving significant oil spray across the engine cowling. The separation of the propeller caused debris to strike the fuselage, shattering Perspex and dislodging interior lining.
Despite the loss of the propeller, the aircraft remained airborne. The pilot executed engine failure procedures, notified the company, and transitioned into a downwind pattern for a landing. Due to a strong headwind and concerns regarding potential wind shear, the pilot opted for a flapless landing. The aircraft landed safely on the runway, and the pilot taxied to the apron to assist the passengers.
Findings
- The incident resulted in 3 injuries, consisting of minor abrasions and scrapes to three passengers.
- The primary cause of the event was the uncontrolled separation of the right engine propeller assembly during the climb phase.