The Cheyenne 400LS is the largest and most powerful of Piper's turboprop twins, derived from the PA-31 Navajo. The 400LS has the Cheyenne III airframe but is powered by counter-rotating 1,000 shp Honeywell TPE331-14 engines with four-blade propellers.The cabin normally accommodates two crew plus six passengers with a rear restroom or seventh seat.