JS41, Venetia Mine South Africa, 2022
JS41, Venetia Mine South Africa, 2022
On 3 January 2022, the right propeller of a BAe Jetstream 41 was hit by a very large bird during its landing roll at Venetia Mine. The impact caused overload fracture and separation of one of its blades with debris then penetrating and damaging an unoccupied part of the passenger cabin as well as significant secondary damage to the right engine. The accident was attributed to the absence of wildlife management at the licensed but not regularly manned airport. The bird involved was identified as a Kori Bustard, which is Africa’s heaviest flying bird and can weigh up to 19kg.
Description
On 3 January 2022, the right propeller of a BAe Jetstream 41 (ZS-NRJ) being operated by SA Airlink on what was described as a scheduled commercial passenger flight from Johannesburg to Venetia Mine was hit by a large bird during its destination landing roll in day VMC. The impact broke off one of the propeller blades which then penetrated the fuselage but fortunately there were no passengers seated in the vicinity of the fuselage breach. Extensive damage was also caused to the right engine so the eventual taxi-in used only the left engine. None of the four passengers and three crew members were injured but substantial damage to the passenger cabin was caused by pieces of the damaged propeller blade.
The right hand propeller after the impact with one blade severed near the root. [Reproduced from the Official Report]
Investigation
An Accident Investigation was opened by the Accident and Incident Investigations Division (AIID) of the South African Civil Aviation Authority (SACAA) in accordance with the prevailing Annex 13 guidance. The CVR and the FDR were removed from the aircraft and relevant data were subsequently downloaded.
The 42 year-old Captain had a total of 6,851 hours flying experience of which 2,136 hours were on type. The 34 year-old First Officer had a total of 2,401 hours flying experience of which 510 hours were on type.
What happened
During descent from the en-route cruise altitude of FL210 with approximately 15 nm to go, the flight crew called the airport on VHF to announce their imminent landing. The airport attendant performed the runway inspection (which is always undertaken prior to either a landing or a takeoff) and called the flight to confirm that the runway was clear.
The aircraft touched down on the 1538 metre-long 15 metre-wide runway 08 but as it decelerated, a Kori Bustard, a very large native bird, became airborne from the long grass to the right of the runway and flew in the direction of the aircraft. When the bird collided with the aircraft’s right propeller, which by this time was (routinely) in reverse pitch with a negative blade angle to assist deceleration, the aircraft ground speed was approximately 43 knots. FDR data showed that at impact, the engine reverse torque had been between 50% and 35% with the propeller rpm at about 1180.
Debris from the propeller blade severed by impact penetrated the fuselage and caused damage inside the cabin. Such fragments damaged some of the stringers just below the seat track of row 3 and caused minor damage in the seat track area with more extensive damage to the lower cabin wall area. Several right engine components were seriously damaged by the severe vibration which followed the bird impact - the front outboard engine mount failed, the propeller gearbox was dislodged and broken and the combustor casing was dislodged.
The fuselage at the re-enforced propeller plane ice shedding guard was breached by blade debris. [Reproduced from the Official Report]
Damage at row 3 inside the cabin. [Reproduced from the Official Report]
Occupant injury was avoided because, according to the cabin crew, nobody was seated in row number 3 for landing, as the passenger who had been seated there “for weight and balance purposes” earlier in the flight had “vacated the seat during the flight to occupy one of the empty seats at the back of the aircraft” and had not returned there for the landing.
Why it happened
The Operation of the Airport:
It was noted that at the time of the accident, the Airport held a Class 3 Licence subject to annual renewal which was valid until 31 October.
The Airport Operations Manual was found to contain an organogram which reflected five responsibilities which reported to the Accountable Manager of the Mine which it served:
- The Rescue and Fire Department (from the mine).
- The Air Traffic Service personnel.
- The Aerodrome Manager.
- The Quality Assurance Manager.
- The Aerodrome Safety Officer (from the mine) who was also the “airfield attendant”.
It was not evident how these positions contributed to the protection of visiting aircraft from wildlife hazards generally especially as the “ill-kept” airport perimeter fence was all that was available to guard against wildlife hazards given that it was “surrounded by a dense forest with wild animals” and “security gates (in the fence) were sometimes left open and unattended”.
The Kori Bustard:
This species is Africa’s heaviest flying bird and can weigh up to 19kg. The bird involved was estimated to have weighed approximately 18kg which significantly exceeded the certification of both the airframe and the aircraft propellers, the latter being only able to withstand a force of up to “approximately 3.6kg”. It was also noted that “the extremely low collision speed with a slow-moving bird in combination with the low propeller speed and reverse blade angle was unusual” and it was concluded that the unfavourable impact angle had contributed to the extent of propeller damage.
The Probable Cause of the event was formally documented as “a bird strike on the propeller blade caused the overload fracture and separation failure of the blade”.
Two Contributory Factors were identified as:
- The inadequate control of wildlife at the airfield.
- The inadequate number of trained personnel to monitor and deter possible wildlife presence during aircraft operations.
Two Safety Recommendations were made based on the Findings of the Investigation as follows:
- that the Venetia Mine airport operator should ensure the addition of adequately trained staff to monitor wildlife around the airport during aircraft operations
- that the Venetia Mine airport operator should prepare a mock runway (a cleared patch covered with grass) for birds to fly to when chased from the active runway during aircraft operations.
The Final Report of the Investigation was approved on 17 January 2023 and published on 6 February 2023.