Piper PA-25 Pawnee
|Pawnee glider tug|
|Status||Agricultural aircraft and glider tug.|
The PA-25 Pawnee was an agricultural aircraft produced by Piper Aircraft between 1959 and 1982. It remains a widely used aircraft in agricultural spraying and is also used as a tow plane, or tug, for launching gliders or for towing banners. On April 15, 1998, The New Piper Aircraft, Inc. officially sold the PA-25 series aircraft to Latino Americana de Aviación S.A in Argentina. The sale included all drawings, engineering data, parts inventory, tools, catalogs, and manuals. All support of any nature became the responsibility of the new owners. The USA type certificate for the PA-25 Pawnee is currently held by LAVIA ARGENTINA S.A. (LAVIASA). 
Design and development
The PA-25 Pawnee was designed by Fred Weick  as a rugged, easy to maintain agricultural aircraft. The Pawnee is a single-engined low-wing monoplane constructed of steel tubing and covered with fabric. The emphasis of this design was on pilot safety with the fuselage structure designed to collapse progressively during a low speed crash, typically experienced during crop spraying operations.
Early models of the Pawnee had a single fuel tank located between the agricultural hopper and the engine. The NTSB recommended to Piper Aircraft that the early model PA-25's with a fiberglass fuel tank be retrofitted with a rubber fuel cell to minimize the chance of catastrophic failure and postcrash fire resulting from a crash. The later Pawnee D version featured twin fuel tanks mounted in the outer wing panels, further improving crashworthiness.
- Initial production version fitted with a 150hp Lycoming O-320 engine. 800lb payload.
PA-25-235 Pawnee B
- Fitted with a 235hp Lycoming O-540-B2B5 six-cylinder engine. The Pawnee B featured a larger hopper and an increased payload of 1,200lb.
PA-25-260 Pawnee C
- The Pawnee C was an upgraded version of the 'B' model and was available with a 235hp or a 260hp high compression version of the O-540 engine and either a fixed pitch or constant speed propeller. The fuselage of the Pawnee C featured a quickly detachable 'turtledeck' panel to ease the rinsing out of spilt corrosive agents from the fuselage structure and to facilitate servicing and inspection of components housed in the rear section of the fuselage.
PA-25-260 Pawnee D
- The Pawnee D was also powered by a Lycoming O-540 of 260hp but featured fuel tanks fitted in the outer wings and metal covered ailerons and flaps.
Accidents and incidents
- 9 August 1974 a crop-spraying Pawnee was involved in a fatal mid-air collision in Norfolk, UK with a Royal Air Force McDonnell Douglas Phantom FGR2 .
- 24 April 1996 a Piper PA-25-150 (modified by extending the canopy forward and installing a passenger seat in hopper area) being used to develop a supplemental type certificate (STC) was involved in a fatal crash near Buffalo, MO in which an FAA flight test engineer was killed but the test pilot survived.
- 6 February 2010 a glider-towing Pawnee was involved in a multiple fatality accident near Boulder Colorado Municipal Airport after colliding with a Cirrus SR20. All in both powered craft were fatally wounded, however the Schweizer 2-32 glider released and landed safely.
Specifications (PA-25-235 Pawnee)
Data from: Macdonald Aircraft Handbook 
- Crew: One
- Capacity: 150 US gal (568 l) or 1,500 lb (545 kg) of chemicals
- Length: 24 ft 9 in (7.55 m)
- Wingspan: 36 ft 2 in (11.02 m)
- Height: 7 ft 2 in (2.19 m)
- Wing area: 183 ft² (17.0 m²)
- Empty: 1,457 lb (662 kg)
- Loaded: 2,900 lb (1,317 kg)
- Maximum takeoff: 2,900 lb (1,317 kg)
- Powerplant: 1 x Lycoming O-540-B2B5, 235 hp (175 kW)
- Maximum speed: 102 kts (188 km/h)
- Range: 300 miles (500 km)
- Service ceiling: 13,000 ft (3,963 m)
- Rate of climb: 630 ft/min (192 m/min)(at MTOW)
- Wing loading: 15.9 lb/ft² (77.5 kg/m²)
- Power/Mass: 0.0810 hp/lb (0.133 kW/kg)
- Green, William. Aircraft Handbook. London. Macdonald & Co. (Publishers) Ltd., 1964.