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Aero Commander twins
Aero Commander model 695A operated by the US National Oceanic and Atmospheric Administration
Role	Utility and business aircraft
Manufacturer	Aero Design and Engineering Company Aero Commander Rockwell-Standard Corporation North American Rockwell Rockwell International Gulfstream Aerospace
First flight	23 April 1948 (Model L3085)
Introduction	October 1952
Produced	1951-1986

The Aero Commander 500 family is a series of light-twin piston-engined and turboprop aircraft originally built by the Aero Design and Engineering Company in the late 1940s, renamed the Aero Commander company in 1950, and a division of Rockwell International from 1965. The initial production version was the 200-mph, seven-seat Aero Commander 520. An improved version, the 500S, manufactured after 1967, is known as the Shrike Commander. Larger variants are known by numerous model names and designations, ranging up to the 330-mph, 11-seat Model 695B/Jetprop 1000B turboprop.^[1]

Design and development

Updated Aero Commander Panel

The idea for the Commander light business twin was conceived by Ted Smith, a project engineer at the Douglas Aircraft Company.^[2] Working part-time after hours throughout 1944, a group of A-20 engineers formed the Aero Design and Engineering Company to design and build the proposed aircraft with a layout similar to their A-20 bomber.^[2][3] Originally, the new company was going to build three pre-production aircraft, but as the first aircraft was being built, they decided to build just one prototype.^[2] The final configuration was completed in July 1946 and was designated the Model L3805.^[2]

Registered NX1946, the prototype first flew on 23 April 1948.^[2] The L3805 accommodated up to five people and was powered by two Lycoming O-435-A piston engines.,^[1] it was an all-metal high-wing monoplane with retractable undercarriage using components from a Vultee BT-13 Valiant. The market segment planned for this aircraft to be sold to small feeder airliner firms and was originally designed to carry seven passengers, but instead found use in the private business aircraft and military market.^[4]Walter Beech test flew the aircraft in 1949 and expressed interest in buying the project, but passed on it, to instead develop the Beechcraft Twin Bonanza. Fairchild Aircraft also evaluated the prototype at its Hagerstown, Maryland, headquarters.^[3]

The prototype flew successfully and the company leased, at no cost, a new 26,000 square-foot factory at Bethany near Oklahoma City to build a production version, certified on 30 June 1950. Nearly 10,000 hours of redesign work went into the model, including more powerful Lycoming GO-435-C2 engines, with a combined rating of 520 horsepower. The production model was named the Commander 520. The first Commander 520 was rolled out of the new factory in August 1951. Serial number 1 was used as a demonstrator, then sold in October 1952 to the Asahi Shimbun Press Company of Tokyo.

Operational history

In military service, it was initially designated the L-26, though in 1962 this was changed to U-4 for the United States Air Force and U-9 for the United States Army.

Bob Hoover's Shrike Commander on display

Under ownership of Rockwell in the 1960s, World War II pilot R. A. "Bob" Hoover demonstrated the Shrike Commander 500S for decades in a variety of "managed energy" routines, including single-engine and engine-out aerobatics.^[5][6] His Shrike Commander is displayed in the colors of his last sponsor, Evergreen International Aviation, at the Steven F. Udvar-Hazy Center of the Smithsonian Air and Space Museum. Bob Odegaard continued the tradition in 2012, flying a 1975 Shrike 500S in a Bob Hoover tribute routine.^[7]

One U-4B became a presidential transport aircraft for Dwight D. Eisenhower between 1956 and 1960. This was the smallest "Air Force One," and the first to wear the now-familiar blue-and-white livery.

As of 2004, Shrike Commanders remained in service with the United States Coast Guard and United States Customs Service.^[1]

A single 560F was operated by the Belgian Air Force as the personal transport of the late king Boudewijn from 1961 to 1973.^[8]

The unpressurized, long-fuselage 680FL was operated as a small package freighter by Combs Freightair in the 1970s and 1980s, and by Suburban Air Freight in the 1980s and 1990s. The aircraft was popular with pilots, because it was extremely "pilot friendly" and with its 380 hp supercharged engines did well in icing meteorological conditions. A number are still operated on contracts for cargo and fire control applications, as their piston engines offer good fuel specifics at low altitudes and longer loiter times.

Safety concerns

Single-engine safety

Single-engine flight to Washington

In 1950, when the developers were working to satisfy Civil Aeronautics Authority (CAA) regulations for certification of the 500, they chose a novel method of demonstrating its single-engine safety and performance: they removed one of the two-bladed propellers, secured it in the aft cabin, and flew from Bethany to Washington, D.C. on one engine. There they met with CAA personnel, then replaced the propeller and returned to Oklahoma in the conventional manner. The flight received nationwide coverage in the press.^[9][10]

However, the stunt had been performed with the propeller stowed inside the aircraft, rather than dragging in the open on the front of the engine (as would happen in an actual engine failure). Consequently, the famous demonstration did not demonstrate an actual failed-engine scenario (in which the propeller normally creates substantial drag, and adds to single-engine control and performance problems).^[9][10][11]

NTSB Single-engine safety study

In fact, in a 1979 government study of light-twin engine-failure accident rates, reviewing accidents involving the 24 most popular model-groups of light twins between 1972 and 1976, the National Transportation Safety Board found that the piston-engined twin-Commanders had, by far, the worst number of engine-failure accidents, per hundred-thousand hours flown, of any popular light-twin model -- except for Piper's notoriously underpowered small-engine versions of the out-of-production Piper Apache (barely able to function on one engine).^[12][13]

The piston-powered Aero Commanders averaged slightly over 3.4 engine-failure accidents per hundred-thousand hours (vs. 6.9 for the Apache, and 2.9 for the next-worst, the Beechcraft Travel Air; the overall average for all models was only 1.6).^[12][13]

Hoover single-engine airshow routine

Countering the statistical evidence, Rockwell demonstration pilot Bob Hoover's famous airshow stunt routine, with the Shrike Commander, included a full aerobatic routine performed first with both engines, then with one engine out (and the critical engine, at that), then both engines out, gliding.^{[14][15][check quotation syntax]}

Turboprop Commanders' single-engine safety

The turboprop twin-Commanders -- with much more powerful engines (and most with longer bodies, allowing greater rudder leverage, critical for single-engine control^[10][11]) -- came out on the opposite end of the rankings, with one of the lowest rates of engine-failure accidents of all "light" twins examined, at only 0.4 per hundred-thousand hours.^[12]

Wing spar fatigue

Beginning in June 1991, senior engineers met with FAA officials to discuss concerns over the Aero Commander's main wing spar, which was believed to be susceptible to stress fatigue and subsequent cracking, and was believed to have resulted in a number of fatal crashes.^[16]
From approximately 1961 to 1993, 24 aircraft crashed when spar failures caused the loss of the wing in flight.^[16] Thirty-five more spars were found cracked during inspections.^[16]

Notable accidents

• On 19 June 1964, Senator Ted Kennedy was a passenger in an Aero Commander 680 airplane flying in bad weather from Washington, D.C., to Massachusetts. It crashed into an apple orchard in the western Massachusetts town of Southampton on the final approach to the Barnes Municipal Airport near Westfield.^[17][18] The pilot and Edward Moss, one of Kennedy's aides, were killed.^[19] Kennedy suffered a severe back injury, a punctured lung, broken ribs and internal bleeding.^[20]
  

• World War II hero and actor Audie Murphy died in an Aero Commander 680 crash while flying as a passenger on 28 May 1971. The aircraft was flying in bad weather at night and was on approach to Roanoke, Virginia when it flew into the side of Brush Mountain outside Blacksburg, Virginia, West of Roanoke. Four others and the pilot were also killed.^[21]
  

• On 11 August 2002, photographer Galen Rowell, his wife Barbara Cushman Rowell, pilot Tom Reid, and Reid's friend Carol McAffee were killed in an Aero Commander 690 crash near Eastern Sierra Regional Airport in Bishop, California.^[22]
  

Variants

Aero Commander 560 at Centennial Airport

Aero Commander 500-B at Colorado Springs Airport

Aero Commander 500U Shrike Commander

Aero Commander 680FL at Colorado Springs Airport

Aero Commander 680W at Eagle County Regional Airport

Aero Commander L.3805

Prototype, one built, Lycoming O-435-A engines.

Aero Commander 520

First production version, a developed L.3805 with a taller fin and larger cabin with two 260 hp Lycoming GO-435-C engines, 150 built.

Aero Commander 560

Model 520 with swept tail, increased takeoff weight, seven seats and more powerful engines (two 270 hp Lycoming GO-480B engines) and refined wing,^[23] 80 built.

Aero Commander 560A

New undercarriage, stretched fuselage and other numerous refinements, 99 built.

Aero Commander 560E

Larger wings and greater payload, 93 built.

Aero Commander 560F

Powered with 350 hp Lycoming IGO-540 engines.

Aero Commander 360

Lightened version of the 560E with four seats and two 180 hp engines, one built.

Aero Commander 500

Economy version introduced in 1958, a 560E with 250 hp Lycoming O-540-A engines, 101 built.

Aero Commander 500A

First Aero Commander model – new nacelles to house 260 hp fuel-injected Continental IO-470M engines, 99 built.^[24]

Aero Commander 500B

500A with 290 hp fuel injected Lycoming IO-540 engines, 217 built.

Aero Commander 500U/Shrike Commander

500B with pointed nose and squared off tail, two 290 hp Lycoming IO-540 engines, replaced 500A, 500B, 560F and 680F, 56 built.

Aero Commander 500S/Shrike Commander

500U with minor changes, 316 built.^[25]

Aero Commander 680 Super

Development of 560A with supercharged 340 hp Lycoming GSO-480-A engines and increased fuel capacity, 254 built.

Aero Commander 680E

Lightened 560E and 560A type undercarriage, 100 built.

Aero Commander 680F

680E with new undercarriage and supercharged, fuel-injected 380 hp Lycoming IGSO-540 engines and new nacelles, 126 built.

Aero Commander 680FP

Pressurized version modified from 680F, 26 built.

Aero Commander 680FL Grand Commander

680F with stretched fuselage and larger tail, 157 built. After 1967 known as the Courser Commander.

Aero Commander 680FL/P Grand Commander

Pressurized version of 680FL, 37 built.

Aero Commander 680T Turbo Commander

680FL/P with Garrett TPE331-43 turboprop engines, 56 built.

Aero Commander 680V Turbo Commander

680T with increased takeoff weight and slightly improved cargo capacity, 36 built.

Aero Commander 680W Turbo II Commander

680V with pointed nose. squared off fin, one panoramic and two small cabin windows and weather radar, 46 built.

Aero Commander 695A Turbo Commander

Built for the National Oceanic and Atmospheric Administration.

1969 Aero Commander 681

Rockwell 681 Hawk Commander

680W with improved pressurisation, air conditioning system and nose, 43 built.

Rockwell 681B Turbo Commander

Marketing designation for economy version of the 681, 29 built.

Rockwell 685 Commander

690 powered by two 435 hp Continental GTSIO-520K piston engines, 66 built.

Commander 690

681 with new wing centre section and engines moved further outboard, two Garrett AiResearch TPE331-5-251K turboprops, 79 built.

Commander 690A

690 with changed flightdeck layout and increased pressurisation, 245 built.

Commander 690B

690A with improved soundproofing and internal lavatory, 217 built.

690C Jetprop 840

690B with increased wingspan, wet wing fuel tanks and winglets, two 840shp TPE331-5-254K turboprops, 136 built.

690D Jetprop 900

Similar to 690C with internal rear cabin extension, improved pressurisation and five square cabin windows, 42 built.

695 Jetprop 980

Similar to 690C with 735shp TPE331-10-501K engines, 84 built.

695A Jetprop 1000

690D with higher takeoff weight and more powerful TPE331-10-501K engines, 101 built.

695B Jetprop 1000B

695A with minor changes, 6 built.

Aero Commander 720 AltiCruiser

Pressurized version of 680, 13 built.

YL-26 → YU-9A

Aero Commander 520 evaluated by the US Army, 3 built.

YL-26A

Aero Commander 560 evaluated by the US Air Force, 1 built.

L-26B → U-4A

Aero Commander 560A sold to the US Air Force, 14 built.

U-4B

L-26C

L-26B → U-9B

Aero Commander 560A sold to the US Army, 1 built.

L-26C → U-4B

Aero Commander 680 Super sold to the US Air Force, 2 built.

L-26C → U-9C

Aero Commander 680 Super sold to the US Army, 4 built.

RL-26D → RU-9D

Commander 680 for US Army aircraft fitted with SLAR (side looking airborne radar), two built.

NL-26D → NU-9D

One built.

Operators

Military operators

 Argentina

• 
  Argentine Air Force - 1 x 500B, 27 x 500U and 1 x 680 ^[26]
  


• 
  Argentine Army Aviation - 680V, 690A ^[27]
  

 Benin

• 
  Benin Air Force - 1 x 500B^[28]
  

 Colombia

• 
  National Army of Colombia^[29]
  

 Greece

• 
  Hellenic Army - 2 x 680FL^[30]
  

 Indonesia

• 
  Indonesian Army Aviation - 2 x 680FL^[31]
  

 Iran

• 
  Islamic Republic of Iran Air Force - 3 x 681B^[32]
  


• 
  Islamic Republic of Iran Army Aviation - 3 x 690, 2 x 690A^[33]
  


• 
  Islamic Republic of Iran Navy Aviation - 2 x 500S, 2 x 690, 6 x 690A^[34]
  

 Ivory Coast

• 
  Ivory Coast Air Force - 1 x 500B^[35]
  

 Kenya

• 
  Kenya Air Force - 1 x 680FP (no longer operated)^[36]
  

Kingdom of Laos

• 
  Royal Lao Air Force - 1 x 560 (no longer operated)^[37]
  

 South Korea

• 
  Republic of Korea Air Force - 3 x 520, 2 x 560F^[38]
  

 Mexico

• 
  Mexican Air Force - 20 x 500S^[39]
  

 Niger

• 
  Niger Air Force - 1 x 500B^[40]
  

 Pakistan

• 
  Pakistan Air Force - 1 x 680E (with radar nose), 1 x 680F^[41]
  


• 
  Pakistan Army Aviation - 1 x 690B^[42]
  

 Philippines

• 
  Philippine Air Force - 1 x 690 ^[43]
  

 United States

• 
  United States Air Force as the L-26 and U-4^[44]
  


• 
  United States Army as the L-26 and U-9^[44]
  

Civilian operators

An Iranian Police Aviation Aero Commander 690 flying over Tehran in 2009

 Iran

• Iranian Police Aviation

 United States

• 
  Texas Highway Patrol^[45]
  

Specifications (Rockwell Aero Commander 500S)

Data from Jane's All The World's Aircraft 1976–77^[46]

General characteristics

• 
  Crew: Two


• 
  Capacity: four passengers


• 
  Length: 36 ft 9¾ in (11.22 m)


• 
  Wingspan: 49 ft 0½ in (14.95 m)


• 
  Height: 14 ft 6 in (4.42 m)


• 
  Wing area: 255 ft² (23.69 m²)


• 
  Airfoil: NACA 23012 modified


• 
  Aspect ratio: 9.45:1


• 
  Empty weight: 4,635 lb (2,102 kg)


• 
  Max. takeoff weight: 6,750 lb (3,062 kg)


• 
  Powerplant: 2 × Lycoming IO-540-E1B5 air-cooled flat-six piston engines, 290 hp (216 kW) each

Performance

• 
  Maximum speed: 215 mph (187 knots, 346 km/h) at sea level (TAS)


• 
  Cruise speed: 203 mph (176 knots, 326 km/h) at 9,000 ft (2,750 m), 75% power, TAS


• 
  Stall speed: 68 mph (59 knots, 109 km/h) flaps and landing gear down, CAS
  


• 
  Minimum controllable speed: 75 mph (65.5 knots, 121 km/h)


• 
  Range: 1,078 miles (936 nmi, 1,735 km)


• 
  Service ceiling: 19,400 ft (5,913 m)


• 
  Rate of climb: 1,340 ft/min (6.8 m/s)

See also

• Bob Hoover


• Partenavia P.68

References

Notes

Bibliography

• 
  Andrade, John (1979). U.S.Military Aircraft Designations and Serials since 1909. Midland Counties Publications. ISBN 0-904597-22-9.
  


• 
  Andrade, John (1982). Militair 1982. London: Aviation Press Limited. ISBN 0-907898-01-7.
  


• 
  Simpson, R. W. (1995). Airlife's General Aviation. Airlife Publishing. ISBN 1-85310-577-5.
  


• 
  Taylor, John W. R. (1976). Jane's All The World's Aircraft 1976–77. London: Jane's Yearbooks. ISBN 0-354-00538-3.
  

External links

Media related to Aero Commander aircraft at Wikimedia Commons