U.S. aerospace companies are seeking permission to sell airliner parts to Iran for the first time in three decades, in a key test of the temporary relief on sanctions given under talks to curtail Iran’s nuclear activities.

At least two leading manufacturers, Boeing (BA.N) and engine maker General Electric (GE)(GE.N), have applied for export licenses in a six-month window agreed by Iran and six world powers in November, industry officials and other sources familiar with the matter said.

If approved, the sales would be the first acknowledged dealings between U.S. aerospace companies and Iran since the 1979 U.S. hostage crisis led to sanctions that were later broadened during the dispute over Iran’s nuclear activities.