Piper Aztec Guide and Specs : A Class Of Its Own

Introduction

Introduced in 1962 as a more powerful version of its older ‘Apache’ sibling, the first Piper Aztec featured 250 horsepower, normally aspirated Lycoming engines, a swept tail, and seating for five. Manufactured until 1982, the model moved through series A through F.

The -B series rapidly followed in late 1962, with six-place seating, a longer nose, and some systems changes. The -C series was launched two years later with the trusty injected IO-540-C4B5 series engines or the turbocharged TIO-540C1A. Arriving in 1969 and 1971 were the -D and -E series, respectively. The D received some control and instrument panel changes, while the E provided a single-piece windshield and a long, pointed nose. In 1976, the final F-model underwent upgraded systems, cambered wingtips, and extensions to the tail-plane tips.

A great success story, the manufacture of the Piper Aztec ran for 20-years producing almost 5,000 aircraft. Affectionately known by those who fly her as the ‘Aztruck’, the aircraft was never a stand-out in any one class, but as a load-hauler, with a roomy cabin, docile flight characteristics, good short-field performance, and acceptable fuel economy, the Aztec was in a class of its own.

1979 Piper Aztec F Specifications

Engines

   

Weights and Capacities

 

Model:

Lycoming IO-540-C4B5

 

T/O / Landing Weights Normal:

5,200/4940 lbs

Cylinders:

Six

 

Standard Empty Weight:

3,184 lbs

Displacement:

540 cu inches

 

Max. Useful Load:

1,600 lbs

Horsepower:

250 each engine

 

Baggage Capacity:

150 / 150

Aspirated

Fuel Injection

 

Oil Capacity – per engine:

12 qts

TBO:

2000 Hours

 

Passenger Configuration:

5

T/O Manifold Press:

   

Crew:

1 Pilot

         

Propellors

   

Aircraft Dimensions

 

Model:

Hartzell HC-E2YR series

 

Wing Span:

37 ft

Blades:

2

 

Length:

30.21 ft

     

Height:

10.3 ft

Fuel:

   

Internal Baggage Volume:

40.6 cu ft

Octane:

100

     

Capacity:

140 US Gallons

     

Burn @ 75% Power:

27.4 GPH

     

Pa23-250 Prices

The Aztec retailed at circa US$50,000 on its first release in 1962, rising to US$70,000 by the time the F series appeared in 1971.

Today, you will find a wide range of prices depending on the model, total hours, and engine status. Good condition early A or B models with approximately 4,000 TTAF and high-time engines command asking prices of US$60 – 70,000. At the other end of the scale, F models with average hours and low-life engines can sell at circa US$180,000.

Average prices are US$90 – 100,000, with many good condition, privately owned aircraft available.

Pa23-250 Performance & Handling

Pa23-250

With a similar profile wing to the Piper Cub, it’s unsurprising that the Aztec is a stable and comfortable aircraft without many vices. It can haul full fuel and six passengers with such a high-lift wing, so it’s an excellent load lifter and an ideal first twin for low hour pilots, with a low VMC of 79 knots and a stall speed of 59 knots.

A stable IFR platform, the aircraft control forces are heavy in roll and yaw while lighter in pitch. With such a high-lift wing and bulbous shape, the Aztec was never a speed demon, with the F model having a max structural cruise of 175 knots and a never exceed speed of 221. Expect a lower-level cruise to true out around 150 to 160 knots. Fuel consumption in cruise is adequate, with consumption between 26 to 28 gallons per hour at 75% power.

Single-engine performance is as dire as most light twins, with a single-engine rate of climb in an F series touching 230 feet per minute on a good day.

1979 Piper Aztec F Performance and Handling Specifications

Cruise Speed (Kts)

   

Stall Speed (kts) (Flaps up)

61

75% @ 4,000 ft

177 knots

 

Stall Speed (kts) (Flaps down)

55

55% @ 10,000 ft

152 knots

     
     

Service Ceiling (ft)

19,800

Fuel Consumption (GPH)

   

Service Ceiling (ft) Single Eng.

6,400

75%

27

     

65%

25

 

Best sea-level rate-of-climb (fpm)

1490

55%

22

 

Single-engine rate-of-climb (fpm)

230

         

Max Range (nm)

   

Take-off Ground Roll (ft)

1,190

75% @ 7,500 ft

830

 

T/O Dist. over 50-foot obstacle

1,980

55% @ 16,000 ft

985

     
     

Landing Ground Roll (ft)

951

Est. Endurance (hrs)

   

Ldg Dist. Over 50-foot obstacle

1,695

65% power

8.6

     
     

Do Not Exceed Speed (kts)

221

     

Max Structural Cruise Speed (kts)

175

Pa23-250 Maintenance and Schedule

The Piper Aztec is no more or less maintenance hungry than most other light-twins if looked after. The basic inspections are carried out at 100-hour intervals with mandatory annual inspections; the engines have 2,000-hour TBO’s and the propellers at 2,400 hours.

There are plenty of airworthiness directives (AD), as you would expect from an aircraft of this age. Some are quite extensive, requiring repetitive inspections of airframe components, although replacing the components removes the requirement for the AD.

Pa23-250 Modifications and Upgrades

PA

The first stop for a new Aztec owner would be Diamond Aire, a Montana shop specializing in modifications for the Piper Aztec and Apache. From new instrument panels to wing tip modifications, new throttle quadrants, and engine nacelles, Diamond Aire will also provide extensive 1,000-hour major inspections to return your aircraft to a known state.

MICRO Aerodynamics provides a micro vortex generator kit for the Aztec wings that lowers VMC and stall speeds. In addition, I understand a Robertson R-STOL kit is also available for the Aztec, further improving landing and take-off performance while supporting slower safe speeds, crisper handling, and lower power requirements for take-off and climb-out. There are also modifications to increase fuel tip-tank capacity, manufactured and marketed by Met-Co-Aire, California.

Propeller manufacturer, Hartzell, has released a new scimitar two-blade propeller that provides a further 2-knots to the Aztec speed.

Pa23-250 Where To Find Replacement Parts

With so many Aztecs produced, many aircraft are ‘parted out’ upon being retired from service. Second-hand or reconditioned parts are available from large aircraft wreckers across the country.

Also, with the rise in FAA-PMA approved manufacturers, many have niched down to support a particular aircraft type and finding trim (knots2u, Texas Aeroplastics or AvFab), landing gear components (Aircraft Supply, or Preferred Air parts), or lighting (Whelen Aerospace Technologies or AeroLeds) for your Aztec is not too difficult. The more generic components such as filters, wheels, tires, and brakes are off the shelf and stocked by large aviation suppliers like Aircraft Supply, Aircraft Spruce & Specialty, or Wag Aero.

Pa23-250 Common Problems

One well-known area to watch on aircraft like the Aztec and its smaller cousin, the Twin Comanche, is the use of bladder fuel tanks and fuel leaking. Signs of fuel staining around the inboard wing vents are a sure sign of fuel leaking and running down inside the wing to the wing root.

If it occurs when tanks are full, it may be that the seal of the bladder tank at the filler is poor and requires rectification. It may also suggest the tanks are leaking due to bladder porosity requiring repair or replacement. Floats & Fuel Cells in Tennessee provide replacement bladders for the Aztec.

The engine cowls on an Aztec are notoriously time-consuming and difficult to remove and replace. There are now STC mods on the market providing one-piece cowls that will truly repay you in maintenance time saved.

The Aztec was well-known to pitch nose-up quite heavily when first lowering the flaps. Later model aircraft alleviated this through the use of an interconnected system between the flap and stabilator system.

Piper has issued an AD for turbocharged Aztecs that requires replacing the turbocharger oil tank and making some modifications to fire-shrouds to prevent possible in-flight fires.

Pa23-250 Insurance Options

Piper

The standard aviation insurance all aircraft owners take is liability coverage, while hull coverage is optional. The greater the experience of the owner/pilot, the lower the premiums. Liability coverage covers damage caused by the aircraft, including passengers, while hull coverage covers damage to the aircraft itself.

For a private pilot with 1,000 hours total time, an IFR/MEL rating, and 250 hours on multi-engined aircraft, the 2021 cost per year for US$1,000,000 liability coverage is in the range of US$900 to US$1,150 per year. Pilots with less experience can expect this range to rise to between US$1,100 to US$1,375 per year.

If the insurance includes additional hull cover for US$90,000, the annual premium for the experienced pilot will be between US$1,985 to US$2,240 per year, while the lesser experienced pilot can expect US$2.910 to US$3,760 per year.

Pa23-250 Model Resale Value

There are seven aircraft factors influencing resale and many economic factors. The seven aircraft factors are:

  • Airframe Total Hours

  • Engine Hours Since Overhaul

  • Installed equipment, specially avionic fit-out

  • Maintenance schedule compliance

  • Damage history

  • Paint condition

  • Interior condition

These seven items are all within the control of the owner. If an owner has taken a ‘maintenance only as required’ approach to their aircraft, they can expect that the lower resale value will more than recoup the money they might have saved. Those owners who try to operate their aircraft on a shoestring are pursuing false savings.

The Aztec is no better or worse than most twins in that it requires regular maintenance to maintain value. You will find some very cheap Aztecs for sale; however, the price should send up a warning flag, as it suggests some major maintenance is required, or the general condition of the aircraft is poor and neglected.

A reasonable condition Aztec will command between US$90,000 and US$100,000. The Aztec is a popular aircraft, ideal for training and first-time twin conversions, and therefore it can be expected to maintain resale price if looked after and appropriately maintained.

The caveat is the more significant question on the resale value of twin-engined aircraft in general. With less than 70 twin aircraft manufactured in 2010 compared with thousands in the 1970s, if the demand for twin-engined aircraft continues to drop, it’s anyone’s guess where your resale goes from there.

Pa23-250 Owner Reviews

PA 23

Of the owner reviews I have read, all speak well of the aircraft. Big, heavy, stable, and roomy are some of the adjectives. Easy to fly, with no bad habits, owners comment on how stable the aircraft is when instrument flying.

Most owners traded off the much lower capital cost of the Aztecs against the higher operating costs. When making comparisons against expensive high-end single-engined aircraft such as the Piper Saratoga or Cessna Centurion, although the operating costs are lower, the economics still work while getting system redundancy as a bonus.

All report cruise speeds between 170 – 185 knots on 27 gallons per hour, in the low tens-of-thousands of altitude. Annuals appear to cost between US$2,500 to US$1,500, depending on age and condition.

Every owner cites the cost of insurance as an issue, and one recommends getting an instrument rating to decrease annual premiums.

The consensus across the owners is that as a cheap, comfortable, and capable twin-engined aircraft, the Aztec takes a lot of beating. None appear ready any time soon to make a change.

Pa23-250 Similar Aircraft

Aircraft of similar configuration, age, and role include the Beechcraft Baron 55, Piper Pa-34 Seneca, and the Cessna 310.

All sell in the same price range and have relatively comparable specs. Where the Aztec has the edge, however, is its consistency through those specifications. Each of the contenders outdoes the Aztec in one or maybe two areas. The Aztec is solid across all, whether it’s service ceiling, cruise, short-field performance, cabin space, or the most impressive of them all, its load lifting capability. You pay your money, and you take your choice, but if it’s a good all-rounder you’re after, as a stable IFR platform, lifting good loads into and out of short fields, the Aztec is hard to go past.

Pa23-250 Clubs You Can Join

There are no clubs dedicated to the Piper Aztec; however, a Piper Apache club is dedicated to the Aztec’s older sibling. The club welcomes all Pa23 owners and may be found at the following website https://piperapacheclub.com/

FAQ

Question: What does service ceiling mean?

Answer: An aircraft’s service ceiling is defined as the height at which the aircraft cannot climb at a rate greater than 100 feet per minute.

Question: What is the meaning of the term TBO?

Answer: TBO means Time Between Overhaul, which is the manufacturer’s recommended running time, in hours or calendar time, before overhaul.

Question: To what does TTAF refer?

Answer: TTAF stands for Total Time Airframe, which refers to the number of flying hours the airframe has accumulated since new. Thus, it is an indication of age and use.

Question: Aircraft Gross Weight refers to what?

Answer: Gross Weight is the total aircraft weight, including pilots, passengers, fuel, oil, and cargo.

Question: What does max structural cruise mean?

Answer: Maximum structural cruise, or Vno, refers to the airspeed above which the aircraft should be flown only in smooth air. Above this speed, turbulence or rapid control deflections increase the chance of structural damage.

Question: What are FAA-PMA Approved Parts?

Answer: FAA refers to the Federal Aviation Administration, and PMA means Parts Manufacturer Approval. It is an approval granted to a parts manufacturer to manufacture specific aircraft components.

Question: To what does the term IFR/MEL refer?

Answer: IFR means Instrument Flight Rules. When pilots are flying IFR, it means they are under the control of Air Traffic Control. MEL, in this case, refers to Multi-Engine – Land. Both refer to ratings or approvals that a pilot must achieve to enable the operation of a multi-engined aircraft or flight under instrument flight rules.

Question: What is an STC?

Answer: An STC refers to a Supplemental Type Certificate. An STC is an approved modification to an aircraft, engine, or component. All aircraft, engines, and components have type certificates that approve their use. That is why an approval to modify them is classed as ‘supplemental’.

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