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Piper PA-31 Navajo / Chieftain
Embraer EMB-820
Schafer Comanchero


piper-pa31-350
PA31-350 Navajo


On 30 September 1964 Piper flew the prototype of a new twin-engine executive aircraft which was then the largest built by the company. Identified at first as the Piper PA-31 Inca, the aircraft had been redesignated as the PA-31 Navajo when deliveries began on 17 April 1967.

A six/eight-seat corporate/ commuter transport of cantilever low-wing monoplane configuration with retractable tricycle landing gear, it was powered by two 224kW Avco Lycoming IO-540-K flat-six engines, and was available in optional Standard, Commuter and Executive versions with differing interior layouts.

Made available at the same time was the optional PA-31T Turbo Navajo, which differed only by having two 310 hp /231kW TIO-540-A turbocharged engines.

In 1974 an additional model of the Turbo Navajo was made available, the PA-31-325 Turbo Navajo C/R, which introduced a 242kW version of the counter-rotating engines installed in the Chieftain.

The Turbo Navajo B, cruising at 251 mph at 24,000 feet (404 km/h at 7000 meters); 223 mph at 12,000 feet (359 km/h at 3600 meters), featured new nacelle compartments increased luggage space 42 percent - 62 cubic feet (1.76 cu.m) and hold an additional 300 pounds (136 kg) total 650 pounds (295kg.), seating for up to nine people.

Production of the PA-31 Navajo ended and at the same time the company introduced for 1973 the PA-31-350 Navajo Chieftain which had the fuselage lengthened by 0.61m so an extra pair of seats could be fitted to the cabin, and was powered by two 350 hp / 261kW TIO-540-J2BD turbocharged engines driving counter-rotating propellers.

 

 Piper-31-350
Piper PA-31-350 Navajo Cheftain

 

Piper expanded their 1976 medium-twin line by offering the Navajo C/R. This airplane has 325-hp engines that eliminate the critical engine characteristics that stem from both propellers rotating in the same direction; the Navajo C/R's left propeller turns in the conventional clockwise direction, but the right prop rotates counter-clockwise. The Navajo CR had wing lockers.

The basic model remained in production until 1983 by which time 1785 were built. Included in this total were the higher powered (325 hp) models which featured contra-rotating engines.

The engine variations provide the main performance difference among the models. The plain Navajo is a 3500-gross, 2,174-useful airplane, with a 310-hp turbo-charged but otherwise unfettered TIO-540. The Navajo CR is the same airplane, with the same engine for that matter, ex-cept that the horsepower rating has risen to 325, magnetos are pressurized, and the right-hand engine turns its propeller inboard, which the left one does anyway. The benefits of counter-rotation are minutely improved single-engine performance and speeds, largely theoretical improvement from the neutralization of slipstream and prop-wash effects, and the minimization of P factor. Gross weight remains the same, while useful weight drops a tad as a result of the CR's capacious wing lockers.

The range was extended in 1970 by introduction of the PA-PA-31P Pressurized Navajo with a fail-safe fuselage structure in the pressurised section and two 317kW Avco Lycoming TIGO-541-E1A engines. The pressurised PA31P seated six was marketed for business high-fliers: 259 were built from 1970 till 1977.


The Chieftain is 24 inches longer than the CR, has a 7,000 gross and a 350-pound greater useful and the same engine. But horsepower has now been boosted to 350 with a tuned induction system and a slightly larger compressor.

One hundred and sixty seven Navajo Chieftains were licence built in Brazil by Embraer circa 1981, as the EMB-820.

In 1984 A piston-engined version of the turbine Cheyenne I known as the PA31P-350 Mojave was introduced but production ceased that same year after only 50 had been completed. It incorporated the Chieftain II wings, pressurised Cheyenne I fuselage, and a Chieftain tail, with the powerplant of the PA-315-350 Chieftain. Production of the PA-31P Pressurized Navajo ended during 1977, at which time a total of 248 had been built.

Schafer Aircraft Modifications Inc was founded 1977, and from 1979 developed modifications for other aircraft. Included were installing turboprop engines to Piper Navajo as the Schafer Comanchero, turboprop engines to Piper Chieftain as the Comanchero 500.

Production of the PA-31 Navajo started in 1973 and, after 1825 were built, ceased in 1983.

 

Gallery


Certification:

FAA A20SO
PA-31
31-1 to 31-659
31-661 to 31-711
31-752 to 31-7612110
31-7712001 to 31-7912124
31-8012001 to 31-8312019

FAA A20SO
PA-31-325
31-7300932 to 31-7612110
31-7712001 to 31-7912124

FAA A20SO
PA-31-350
31-5000 to 31-7652176
31-7752001 to 31-7952250

FAA A8EA
PA-31P
31P-1 to 31-7630019

FAA A8EA
PA-31P-350
31P-8414001 to 8414050

Specifications:

PA31-300 Navajo
Engine: 2 x Lycoming IO-470-M, 300 hp

PA31-310 Navajo
First built: 1967
Engine: 2 x Lycoming TIO-540-A2C, 310 hp
TBO: 1800 hrs
Fuel; 100/100LL
Prop: Hartzell 3 blade, constant speed 80 in
Seats: 6/8
Length: 32.6 ft
Height: 13 ft
Wingspan: 40.7 ft
Wing area: 229 sq.ft
Wing aspect ratio: 7.2
Max ramp wt: 6536 lbs
Max take off wt: 6500 lbs
Standard empty wt: 4003 lbs
Equipped Weight; 4529 lbs
Max useful load: 2533 lbs
Max landing wt: 6500 lbs
Payload full std Fuel; 1650 lbs
Baggage Capacity; 350 lbs
Wing loading: 28.4 lbs/sq.ft
Power loading: 10.5 lbs/hp
Fuel Capacity; 192 US gals
Usable Fuel; 187.3 US Gals / 1124 lb
Climb rate: 1300 fpm @ 94 kt
Climb gradient: 830 ft/nm
Rate of climb @ 8000 ft: 1220 fpm
Best Angle of Climb; 80 mph
Absolute Ceiling;    27,300 ft
Certificated ceiling; 24,000 ft
SE rate of climb: 245 fpm @ 94 kt
SE climb gradient: 157 ft/nm
SE ceiling: 15,200 ft
Max speed: 227 mph
Never exceed ; 236 mph
Cruise @ 65% power @ 8,000ft: 176 kts
Cruise @ 65% pwr @ 18,000 ft: 192 kts
Cruise 75% 22,000 ft Best Power: 213 mph
Cruise 75% 22,000 ft Best Economy: 208 mph
Cruise 65% 24,000 ft Best Power: 202 mph
Cruise 65% 24,000 ft Best Economy: 196 mph
Cruise 55% 24,000 ft Best Power: 182 mph
Cruise 55% 24,000 ft Best Economy: 171 mph
Max Range (with res) 75% 22,000 ft Best Power: 870nm
Max Range (with res) 75% 22,000 ft Best Economy: 1005 nm
Max Range (with res) 65% 24,000 ft Best Power: 910 nm
Max Range (with res) 65% 24,000 ft Best Economy: 1052 nm
Max Range (with res) 55% 24,000 ft Best Power: 922 nm
Max Range (with res) 55% 24,000 ft Best Economy: 1068 nm
Fuel Consumption 75% Best Power: 37.5 US gph
Fuel Consumption 75% Best Economy: 29.7 US gph
Fuel Consumption 65% Best Power: 33.0 US gph
Fuel Consumption 65% Best Economy: 26.0 US gph
Fuel Consumption 55% Best Power: 28.7 US gph
Fuel Consumption 55% Best Economy: 22.7 US gph
Fuel flow @ 65% power @ 18,000ft: 172 pph
Endurance @ 65% power @ 18,000ft: 6.3 hr
Stalling speed clean: 78 kt
Stall speed gear/flaps down: 74 kt
Turbulent air penetration speed: 159 kt
Retractable undercarriage
Trims; Elevator, Rudder, Aileron
Min Control (Vmc); 74 mph
Take-off Ground Run; 1720 ft
Take-off 50ft; 2290 ft
Landing 50 ft; 1521 ft
Accelerate/stop; 2450 ft

PA31-325 Navajo C/R
First built: 1975
Engine: 2 x Lycoming TIO-540-F2BD, 325 hp
TBO: 1600 hr
Prop: Hartzell 3 blade, constant speed 80 in
Seats: 6/8
Length: 32.6 ft
Height: 13 ft
Wingspan: 40.7 ft
Wing area: 229 sq.ft
Wing aspect ratio: 7.2
Max ramp wt: 6540 lb
Max take off wt: 6500 lb
Standard empty wt: 4099 lb
Max useful load: 2441 lb
Max landing wt: 6500 lb
Wing loading: 28.4 lbs/sq.ft
Power loading: 10 lbs/hp
Max useable fuel: 1425 lb
Climb rate: 1220 fpm @ 100 kt
Climb gradient: 720 ft/nm
Rate of climb @ 8000 ft: 1100 fpm
Certificated ceiling; 24,000 ft
SE rate of climb: 255 fpm @ 97 kt
SE climb gradient: 157 ft/nm
SE ceiling: 15,300 ft
Max speed: 228 kts
Cruise @ 65% power @ 8,000ft: 180 kt
Cruise @ 65% pwr @ 18,000 ft: 196 kt
Fuel flow @ 65% power @ 18,000ft: 195 pph
Endurance @ 65% power @ 18,000ft: 7.1 hr
Stalling speed clean: 72 kt
Stall speed gear/flaps down: 70 kt
Turbulent air penetration speed: 159 kt
Retractable undercarriage and counter-rotating prop

PA31-350 Navajo Chieftain
Engine: 2 x Lycoming TIO-540-J2BD, 350 hp
TBO: 1600 hr
Prop: Hartzell 3 blade, constant speed 80 in
Seats: 6/10
Length: 34.6 ft
Height: 13 ft / 3.96 m
Wingspan: 41 ft 8 in / 12.4 m
Wing area: 229 sq.ft / 21.27 sq.m
Wing aspect ratio: 7.2
Max ramp wt: 7045 lb
Max take off wt: 7000 lb / 3175 kg
Standard empty wt: 4421 lb
Max useful load: 2824 lb
Max landing wt: 7000 lb
Wing loading: 30.6 lbs/sq.ft
Power loading: 10 lbs/hp
Max useable fuel: 1416 lb
Climb rate: 1120 fpm @ 101 kt
Climb gradient: 665 ft/nm
Rate of climb @ 8000 ft: 980 fpm
Certificated ceiling; 24,000 ft / 7315 m
SE rate of climb: 230 fpm @ 106 kt
SE climb gradient: 130 ft/nm
SE ceiling: 13,700 ft
Max speed: 231 kt / 428 km/h / 266 mph
Cruise @ 65% power @ 8,000ft: 181 kt
Cruise @ 65% pwr @ 18,000 ft: 197 kt
Fuel flow @ 65% power @ 18,000ft: 185 pph
Endurance @ 65% power @ 18,000ft: 7.4 hr
Stalling speed clean: 77 kts
Stall speed gear/flaps down: 74 kts
Turbulent air penetration speed: 162 kt
Retractable undercarriage

PA31P
Engines Lycoming TIGO-541-ElA, 425 hp
TBO 1,200 hr
Propellers Hartzell three-blade, constant speed, full-feathering, 93-in. dia
Length 34 ft. 6 in
Height 13 ft. 3 in
Wingspan 40 ft. 8 in
Wing loading 34.1 lbs./sq.ft
Seats 6/8
Empty weight 5,611 lb
Useful load 2,189 lb
Payload with full fuel 773 lb
Gross weight 7,800 lb
Power loading 9.18 lbs./hp
Fuel capacity, equipped 236 USG/1,416 lb
Baggage area 42 cu. Ft
Minimum runway requirement 2,700 ft
Rate of climb 1,740 fpm
Single-engine rate of climb 240 fpm
Single-engine service ceiling 12,100 ft
Maximum speed 280 mph/243 kt
Endurance, maximum cruise (incl. allowance for climb) 4 hr
Normal cruise (@ 24,000 ft.) 244 mph/212 knots
Endurance, normal cruise (incl. allowance for climb) 5 hr
Long-range cruise (@) 24,000 ft.) 222 mph / 193 kt
Endurance, long-range cruise (incl. allowance for climb) 6.3 hrs
Stall speed (clean) 92 mph/80 knots
Stall speed (gear, flaps down) 83 mph/72 knots

PA31P-350 Mojave
Engines: 2 x Lycoming TIO-540-V2AD, 350 hp
Cruise: 210-234kt @ FL18
Pressure differential: 5.2 lb
Seats: 7
Useful load: 2516 lb
Range: 1300 nm

EMB-820C Navajo Chieftain

piper-pa31-ld

Piper PA-31 Navajo

 

 


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