Design changes and inspection problems are likely to delay the maiden voyage of a homegrown passenger jet being developed by a unit of Mitsubishi Heavy Industries Ltd. till the end of 2012, the Nikkei business daily reported.

Mitsubishi Aircraft Corp. had hoped to have a prototype of the Mitsubishi Regional Jet, or MRJ, take its first flight between April and June, 2012, the daily said.

The design had to be changed because the company started using aluminium to make the main wing of the aircraft, the Nikkei learned.

Additionally, Mitsubishi's effort to strengthen inspection oversight and the process of transport certification are expected to delay the process, the paper noted.

The proposed delay may not impact deliveries to customers, scheduled to begin in 2014, as Mitsubishi has set a longer testing period than usual, the daily reported.