stardg

\Bitrix\Main\EventManager::getInstance()->addEventHandler('sale', 'OnSaleStatusOrderChange', ['Handler', 'OnSaleStatusOrderChange']);

class Handler {
	function OnSaleStatusOrderChange($event)
	{
		$parameters = $event->getParameters();
		if ($parameters['VALUE'] === 'F')
		{
			/** @var \Bitrix\Sale\Order $order */
			$order = $parameters['ENTITY'];
			/**
			 *
			 * Your code is here
			 *
			 */
		}

		return new \Bitrix\Main\EventResult(
			\Bitrix\Main\EventResult::SUCCESS
		);
	}
}