Preliminary data based on the notification from the Nepalese authorities:
The As350 B2, 9N-ALR small single engine helicopter operated and owned by Simrik Air Pvt. Ltd. Departed from Kathmandu Airport at 00:27 UTC on 30 June 2018. The chartered flight was on Grande Hospital - Bharatpur flight for medical purpose, where it has to pick up a group of doctor and nurses with necessary medical items. Approximately 25 DME NW to Tribhuvan International Airport, onto the rooftop helipad of Grande Hospital the aircraft attempted to land. During landing the skids were just touching the ground and the captain was on completing the landing procedure, however the aircraft swung to right and made three turns (as per eye witness). The captain lost the control, while swinging the aircraft skidded about 20 feet to left and fell down onto another rooftop nearby by 10 feet approx. The aircraft main rotor hit the down slopped roof, the tail stroked and windshield cracked thereby damaging the helicopter. The unhurt captain broke the windshield and escaped safely.