Twin Commander 840 Specs and Description

Background/History

The turboprop-powered developments of the piston-powered Aero Commander family of light twin-engine aircraft enjoyed a two decade-long production run and were built by three manufacturers before production finally ceased in 1985. The first Turboprop Commander to fly, based on the stretched and pressurized 680FLP Grand Commander, was the 680T which utilized a pair of Garrett AiResearch TPE331 turboprop engines and entered production in 1965. North American Rockwell purchased the manufacturing rights to the Commander line in 1967 and in turn, sold them to Gulfstream American in 1980. The Twin Commander product line continued to evolve through the 1970s with the introduction of the 690, 690A, 840 and 980 models. The ultimate development of the line came with the Twin Commander 900 powered by the TPE331-5 engine and the Twin Commander 980 and 1000, both powered by the TPE331-10. Ultimately, 122 Twin Commander 840s were manufactured before production ceased in 1984.

Power

The Twin Commander 840 is powered by two Garrett AiResearch (now Honeywell) TPE331-5-254K turboprop engines rated at 840shp, driving three-blade constant speed propellers. The engines are flat rated to 718shp each and have an inspection interval of 5,400 hours. Many of the aircraft have converted to the TPE 331-10 engines which delivers more torque with better climb and cruise performance. TBO may be 5000 Hrs.

Avionics

The Twin Commander 840 series would typically have dual Collins Proline avionics installed to include nav/coms, DME, autopilot, transponder, ADF and color weather radar.

Design Features

The Twin Commander 840 is a light, twin engine turboprop business aircraft configured as a cantilever high-wing monoplane with a conventional tail. The airframe is of aluminum monococque construction and features a deep square-oval fuselage, low-slung beneath the high wing and riding low on the retractable tricycle landing gear. The landing gear has a single wheels on all three strut assemblies. The aircraft has a large vertical stabilizer with the horizontal stabilizer set at a moderate angle of dihedral. The wing planform is tapered with a straight leading edge and the trailing edge swept forward. The wingtips are swept upward to reduce drag and improve lift.

Accomodations

The Twin Commander 840 cabin is normally configured to seat a pilot and five additional passengers in an executive layout. A typical seating arrangement would include an aft bench seat and two additional rear facing seats. An entry door is located on the port side of the fuselage forward of the wing. A small lavatory is positioned forward, opposite the entry door. The aft fuselage contains a baggage compartment with an exterior access door on the port side of the fuselage. Cabin height is 4.5ft., width is 4.1ft. and length is 9.5ft. Total cabin volume 224 cu. ft. with baggage volume at 70 cu. ft.