An Express Air Dornier Do 328 passenger plane, registration PK-TXN, was substantially damaged when it ran off the side of the runway after landing at Tanahmerah Airport (TMH). Express Air Flight XN9001 departed from Jayapura-Sentani Airport (DJJ) at 07:30 local time with an estimated arrival time at Tanahmerah (TMH) of 09:17. There were 36 people on board; two pilots, one cabin crew, 33 passengers. The pilot in command (PIC) was pilot flying. The crew flew the aircraft overhead Tanamerah and joined left downwind at 900 feet. Final approach was reported to have been normal with VREF 105 knots. The aircraft touched down at 09:17, towards the departure end of the runway 25 touch-down zone. The crew reported that the touched down was normal. During the landing roll the PIC used reverse thrust to slow the aircraft. After a landing roll of approximately 500 meters, reverse thrust was reduced and the condition levers were selected to minimum. The crew reported that without warning, the aircraft diverged abruptly to the right and they were not able to arrest the swing using full left rudder and left brake. The aircraft left the runway and stopped on the shoulder approximately 10 meters away from the edge of runway, and approximately 600 meters from touchdown area. The right wheels sank into the soft ground of the runway shoulder, and the left wheels and the nose wheels were on the shoulder. The right propeller blades fractured as they struck the ground and the propeller assembly was torn from the engine and came to rest approximately 4.5 meters from the right engine. The right engine was substantially damaged. All on board evacuated safely; there was no fire. Tanahmerah Airport (TMH) has a single gravel runway 07/25, 3111 feet (950 m) in length. Findings: – The PIC did not follow correct procedures for reducing the condition lever, did call condition lever to be selected to minimum position at higher aircraft ground speed. – The PIC lacked of confidence to land at Tanah Merah Airport, due to lack of flight experience using this type of aircraft and at the unusual condition of airport, not like the conditions of airport he used to fly in Europe.