Quebec's health and safety board CNESST has ruled that a window-washing company is fully responsible for an incident that killed a 53-year-old worker in April.

Rafael Marchante died on April 10 when a mobile crane overturned and crushed him.

Marchante and his 19-year-old son were washing windows on UQAM’s Paul Gerin Lajoie Pavilion that Sunday morning.

The CNESST said the company, Lavage de Vitres Haute Performance, made several mistakes.

The crane, parked by another employee, was deployed at what it considers an extreme angle to reach some of the windows at UQAM.

Further, the crane was not properly levelled; instead, a plank of wood was placed over uneven terrain and under the support.

The window washers then got into a support basket suspended by the crane, and the crane was extended behind the truck.

The leverage was too much for the crane, and the left support leg sank. The mobile crane then tipped backwards.

The window washers fell to the ground, and Marchante was struck in the head by part of the crane. He died instantly and his son was badly injured.

The CNESST said the death and injury could have been avoided if the legs had been on solid ground, and if the crane's arm had not been extended so far to the rear of the truck.

“When the crane tilted, the chip fatally hit the worker aboard the window cleaning platform. And secondly, the operation of the crane beyond the lifting limit allowed by the manufacturer contributed in the sliding of the left rear stabilizer cylinder out of its support and destabilized the crane,” said CNESST spokesperson Alexandra Burnet.

Lavages de Vitres Haute Performance has been fined an undisclosed amount, but it ranges from $16,137 to $65,269.

The company is also barred from using cranes to wash windows.

The provincial agency is recommending all companies that use cranes carefully review safety measures, and operation instructions for their equipment.

Quebec's Federation of Labour (FTQ-Construction) is calling for mandatory training of all crane operators in a bid to reduce accidents and injury.