Runway Excursion, Sinarmas Super Air (Thrush S2R-T34 PK-PND) Kajui Airstrip KNKT.22.12.20.04

On 17 December 2022, a Thrush S2R-T34 aircraft, registered PK-PND was being operated by PT Sinar Mas Super Air (SMSA) in Kajui airstrip, Gunung Mas Regency, Central Kalimantan to perform an aerial topdressing of fertilizers over palm oil plantation.

There were two pilots on duty that day, each for morning and afternoon shifts. Prior to the morning shift, the left brake pads were change due to wear thickness limitation. After ensuring the brakes were working properly, the first pilot departed Kajui for the first sortie of the morning shift at 0735 LT. The first shift then ended at 1205 LT. During the shift change, the first pilot informed the second pilot that the left brake pads were replaced. The first pilot reported that the tail wheel was dirty and a bit difficult to unlock. The engineer cleaned and readjusted the tail wheel to solve the issue.

At 1205 LT, prior to the afternoon shift, the engineer refueled the aircraft in refueling area near Runway 36. Afterwards, the pilot performed the preflight procedures, and there were no abnormalities reported. At 1220 LT, the pilot started taxi to loading area near Runway 18 to fill in the aircraft with fertilizers. At 1225 LT, the aircraft departed Kajui for the first sortie of the shift. The weather was sunny, and the wind was calm.

At 1235 LT, the pilot landed and then taxied to loading area wanting to refill the fertilizers. But there was a problem with the fertilizers’ equipment. The pilot then decided to taxi to the parking area, while the problem was being settled. During the taxi maneuver, the pilot felt that the left brake less gripped and reported the issue to the engineer. Prior to the second sortie, the pilot tested the left brake and found it to be normal. The aircraft departed for its second sortie at 1255 LT. The aircraft landed at 1305 LT refilled the fertilizers prepared for the third sortie.

Prior to takeoff rolling, the pilot attempted to direct the aircraft to the right since the aircraft was on the left side of the runway with the left wheel touching the grass. But the aircraft kept going straight. Afterwards, the aircraft shifted more to the left. Both left wheel and tail wheel were on the grass in the shoulder, while the right wheel was on the edge of the runway. Despite of the power increased along with the pilot’s effort to veer to the right, the aircraft went straight ahead. The pilot then felt the aircraft jumped a little and attempted to dump the fertilizers. But the aircraft rolled over and landed upside down. The aircraft was substantially damaged, and the pilot suffered minor injury due to the impact forces.

KNKT acknowledged the safety action taken by SMSA to address Runway Excursion issue by defining Temporary Emergency Procedure. However, there still safety issues remain to be considered. Therefore, the KNKT issued safety recommendation to encourage the implementation of the operational control procedures and reporting system for a safer flight operation. Nonetheless, the investigation is continuing. Should any further relevant safety issues emerge during the course of the investigation, KNKT will immediately bring the issues to the attention of the relevant parties and publish as required.