Complex sentence: After a Stinson L-5 Sentinel aircraft spotted the group, the 1st Air Commando Group tasked Harman with rescuing them; his YR-4B was the only working helicopter among the four used by the group.
Split into simpler sentences: After a Stinson L-5 Sentinel aircraft spotted the group, the 1st Air Commando Group tasked Harman with rescuing them. His YR-4B was the only working helicopter among the four used by the group.