Piper Sequoya

The Piper Aerostar (formerly the Ted Smith Aerostar) is an American twin-engined propeller-driven executive or light transport aircraft, designed by Ted R. Smith. It was originally built by Ted Smith Aircraft Company, but the design was acquired in 1978 by the Piper Aircraft Corporation, which continued production of the aircraft as the PA-60.

Development

After having designed the Aero Commander and Jet Commander, Ted R. Smith founded the Ted Smith Aircraft Company in 1963 to build a new line of aircraft. The first Aerostar prototype, the Model 320, was built with two Lycoming IO-320 engines and first flew in November 1966. The same aircraft was upgraded with a pair of Lycoming IO-360 engines and a more streamlined vertical fin and renamed the Model 360; it was subsequently upgraded again with IO-360s and renamed again as the Model 400. The aircraft finally entered production as the Aerostar 600 with two Lycoming IO-540-K engines, first flown in December 1967. Also produced, and the base of most of the subsequent models, was a version with turbocharged engines, the Aerostar 601.

The aircraft were originally built at Van Nuys, California, but in 1968 the company was bought by the American Cement Company. The acquisition was not a success, and in 1969 the company was sold again to Butler Aviation, a major fixed base operator and owner of Mooney Airplane Company. The new company was renamed Aerostar Aircraft Corporation, and plans were made to move production to the Mooney plant at Kerrville, Texas, but Butler got into a dispute with American Cement over alleged corrosion problems with the airframe; the U.S. Federal Aviation Administration (FAA) investigated and found that no such problem existed, but the dispute resulted in a two-year production hiatus and cancellation of the plant relocation plan. In 1971, Smith attempted to repurchase the rights and announced he would be building an all-new design that was better than the Aerostar, but negotiations broke down. The Bellanca Aircraft Company and Chance Vought also expressed interest in acquiring the design.

In 1972, Ted Smith successfully bought back all the rights to the aircraft and began manufacturing Aerostars under the Ted R. Smith and Associates banner in Santa Maria, California, introducing the pressurized Aerostar 601P along with the Aerostar 700 Superstar. In 1976, the company name was changed to the Ted Smith Aerostar Corporation. 1974 saw the introduction of the successful 601P, which introduced cabin pressurization, allowing more convenient high-altitude operation; the designers were able to adapt the fuselage to pressurization without having to limit its service life. The 601P and the 601B, which was introduced in 1977, both feature improvements to the turbocharging system to increase engine reliability and ease engine operation; the improved turbo system and a greater wingspan improve climb performance.

Smith died suddenly in 1976. In 1978, the Aerostar line was acquired by the Piper Aircraft Corporation, which continued to build two variants, the 600A and 601B, and then re-introduced the 601P. Piper continued using the basic Ted Smith model designation system but prefixed each model as the PA-60. Piper introduced the enhanced 602P, which was initially marketed as the Sequoya, and also put the 700 Superstar into production as the 700P. The 602P was the first model with a turbocharger system built and certified by the engine manufacturer, rather than a turbo system designed and installed by Ted Smith or Piper. After discontinuing production of the non-pressurized models, Piper moved production to Vero Beach, Florida, building the last Aerostar there in 1984.

Smith conducted engineering studies for a jet-powered Aerostar, and also envisioned turboprop power and a single-engine trainer aircraft using the same basic airframe, but these plans never came to fruition during the aircraft's production run.

Design

The Aerostar emerged as a mid-wing cantilever monoplane powered by two wing-mounted piston engines, with retractable landing gear in a tricycle configuration. It is designed to seat six, and is distinguished from light twins of similar size and weight by its high wing loading, careful attention to fine aerodynamic details, a mid wing, and in early models, the absence of cowl flaps; Smith was adamant that they were not needed because of the refined cooling system design. Despite this, the later 700P used cowl flaps because engine cooling of earlier models proved marginal if the system is not maintained rigorously.

The engines of early 601s are turbonormalized—they retain the higher compression ratio typical of a non-turbocharged engine, and the turbo system is designed to primarily to compensate for increasing altitude by providing more boost pressure as the outside air pressure declines. Later models featured a redesigned turbo system intended to increase reliability and be more forgiving of improper operation by the pilot. Unusual Aerostar design features include electrically operated remote fuel valves, which avert the need to run fuel lines into the cockpit; electro-hydraulic nosewheel steering; a flight control system that relies on push-pull rods and torque tubes rather than cables; and unusually thick and stiff wing skins, which—together with the high wing loading—give the Aerostar an unusually smooth ride in turbulence.

Some disadvantages of the aircraft compared to its competitors are the absence of a nose baggage locker, and a cabin that can only be accessed through a single clamshell door next to the pilot's seat; aircraft occupants other than the pilot in command must climb over the folded pilot's seat to access their seats.

Aerostar model numbers nominally refer to the total installed engine horsepower, but some model numbers vary from the precise total, particularly the later models.

Operational history

During the time of production, the Aerostar held the speed record for fastest twin piston general aviation aircraft, capable of cruise speeds from for the earliest 600 models to for the later 700 models. Light construction, low drag, and powerful engines contribute to fast climb rates, while allowing high operating altitudes and class-leading fuel efficiency.

A study of Aerostar accidents by ''The Aviation Consumer'' from 1978 to 1982 showed that the Aerostar had an accident rate of 12.9 per 100,000 flight hours, substantially more than the rate of the comparable Beechcraft Baron 58 at 4.9 per 100,000 hours. A similar study conducted by ''Aviation Safety'' compared the safety records of eight similar models of twin-piston-engine aircraft and found that the Aerostar had the highest accident and fatal accident rate. According to the studies, the leading cause of Aerostar accidents was engine failures on takeoff. ''The Aviation Consumer'' notes that the Aerostar's high wing loading, which contributes to its high cruise speed, also gives it relatively unforgiving flying qualities on takeoff and landing; the aircraft requires relatively long runways, and pilots must keep the airspeed high during approach to avoid falling behind the power curve, which can cause an excessive sink rate. The wing flaps of the Aerostar slow the aircraft relatively quickly, which may induce this problem, so pilots typically do not use the full 20-degree flap setting until the aircraft is close enough to the runway to ensure a safe landing.

The Aerostar has a history of accidents stemming from fuel mismanagement by the pilot. Most later Aerostars have a fuselage fuel tank and individual fuel tanks in each wing, which all feed into a common chamber near the fuselage tank; the common chamber in turn normally feeds the engines. However, the relative lack of wing dihedral may cause the wing tanks to feed unevenly when used in this manner, causing a fuel imbalance as flight progresses. This problem can be mitigated by using the fuel valves to crossfeed fuel from one wing tank to the opposite engine, bypassing the common chamber; however, the wing tanks are prone to unporting when they are mostly empty, causing engines to lose power or stop running. This hazard can be exacerbated if electrical power is lost, as the electrically operated fuel valves will become inoperable, preventing the pilot from switching back to the fuselage tank. To mitigate these problems, a 1984 airworthiness directive (AD) required owners to install individual, more accurate fuel gauges for each wing tank, a dedicated low-fuel warning light, and placards explaining correct crossfeed procedures.

The Aerostar has a history of problems with the clamshell-style entry door, which is located directly in front of the left-hand propeller, making it critical for the door to be secured before takeoff. A number of accidents have resulted from the upper half of the door coming open in flight and in some cases separating from the aircraft. Although it was not conclusively listed as causal, an unsecured upper door is widely thought to have contributed to a 1988 crash that killed pilot and auto racing driver Al Holbert. That year, the FAA issued an AD requiring inspection of the door rigging, a placard explaining proper door operation, and a dedicated door-ajar warning light. In addition, the FAA has issued warnings regarding an aftermarket door strut which required an installation procedure that may damage a door gusset; the gusset may break in flight and cause the door seal to fail, potentially causing uncontrolled decompression in pressurized versions of the Aerostar.

Although nominally a six-seat aircraft, owners often remove center-row seats because most Aerostars have inadequate payload to simultaneously carry six people, their baggage, and a large fuel load, and removing the seats improves access and legroom in the third-row seats, which are quieter than the other seating positions and are therefore preferred by many passengers.

The Aerostar has a reputation for high maintenance requirements and servicing costs due to a cooling system design that is intolerant of poor maintenance, a lack of working space around various aircraft systems, and a turbo system that is sensitive to exhaust system problems.

The Aerostar type certificate and manufacturing documentation were sold in 1991 to former Ted Smith Aerostar employees Jim Christy and Steve Speer, who operate Aerostar Aircraft Corporation (originally Machen Incorporated), providing maintenance and support for the aircraft and continued research and development. In 2006, Speer restarted design studies for a jet-powered Aerostar, and in 2010, Aerostar Aircraft first flew the Aerostar Jet, a 601P refitted with a pair of wing-mounted Pratt & Whitney CW615F engines, providing an estimated maximum cruise speed of . In 2014, Aerostar Aircraft said it was investigating production of the aircraft.

Variants

;Model 320
:First prototype, powered by two Lycoming IO-320 engines
;Model 360
:Modification of first prototype with two Lycoming IO-360 engines and a redesigned empennageTaylor 1967, p. 360.
;Model 400
:Modification of first prototype with two IO-360 engines; type certified, but did not enter production
;Model 500/500P
:Projected versions with fuel injected engines, to be non-pressurized and pressurized respectively; none built
;
:Initial production model with two Lycoming IO-540-K engines, 282 produced under four different company names
;600A
:Model 600 with some minor detail changes and improved engines, 206 built
;600E
:Designation used for aircraft sold in Europe
;601 (later PA-60-601):This aircraft still holds the land closed speed record for a production piston twin
:Model 600 with 290 hp turbocharged Lycoming TIO-540 engines, 117 built
;601B
:Model 601 with increased wingspan and improved turbo system, 44 built
;601P (later PA-60-601P)
:Pressurized version of 601 with increased gross weight, increased wingspan and improved turbo system from 601B, 492 built
;602P Sequoya (later PA-60-602P)
:Piper-developed version of 601P with 290 hp Lycoming TIO-540-AA1A5 engines, 124 built
;620
:The prototype pressurized Aerostar with TIO-540 engines, one built (at Van Nuys in mid-1969)
;700 Superstar
:Prototype of stretched fuselage variant with two IO-540M engines, one built
;700P (later PA-60-700P)
:602P with counter-rotating Lycoming TIO-540-U2A engines, 26 built
;702P
:New modification of 700P with a reinforced nose gear allowing for higher takeoff weight
;800
:601P with stretched fuselage, enlarged tail and two Lycoming engines, one built
;Super 700
:Machen/Aerostar Aircraft conversion of 601P or 602P with three-bladed Hartzell propellers, Lycoming TIO-540-U2A engines, and increased gross weight
;Speedstar 850
:A modification to replace the twin piston engines with a single nose mounted turboprop
;Aerostar Jet
:601P with two Pratt & Whitney CW615F engines; one converted

File:Smith Aerostar 601 CF-BBA ABIN 01.07.71 edited-3.jpg, Ted Smith-built Aerostar 601 in 1971
File:piper pa-60-600 aerostar n70vb arp.jpg, Piper PA-60-600 Aerostar, built in 1977
File:N6081p.jpg, A Piper Sequoia 602P at Paris Air Show Le Bourget in 1981
File:Aerostar Turbine.jpg, An experimental turbine powered Aerostar FJ-80 in 2011
File:1980Aerostar601p.jpg, 1980 Aerostar 601P
File:SPEEDSTAR850.jpg, Speedstar 850
File:Aerostar 600 KLVK.jpg, Aerostar 600

Accidents and incidents

* On September 30, 1988, Al Holbert, auto racing driver and winner of the informal Triple Crown of endurance racing, was killed when the Piper PA-60-601P he was piloting, aircraft registration ''N14HR'', crashed after takeoff from Ohio State University Airport. Eyewitnesses said the aircraft seemed to struggle to gain altitude, and then crashed during an apparent turn back to the airport, catching fire on impact. The National Transportation Safety Board (NTSB) attributed the crash to a pilot-induced stall. The accident report noted that the upper half of the cabin door was found open; it is speculated that the door opened on takeoff and Holbert was trying to close it when he lost control of the aircraft.
* On April 4, 1991, in the Merion mid-air collision, Piper PA-60-601 ''N3645D'' collided with a Bell 412SP helicopter, ''N78S'', over Lower Merion Township, Pennsylvania, during a visual inspection of the Piper's nose landing gear. The collision killed all four pilots in both aircraft along with John Heinz, United States Senator for Pennsylvania, who was the sole passenger in the Piper. Wreckage fell on an elementary school and nearby houses, killing two schoolchildren, severely burning a third, and causing minor injuries to four other bystanders. The NTSB attributed the accident to poor judgment and decision-making by the pilots of both aircraft. A contributing factor was a lack of direction in the PA-60 flight manual regarding procedures if the cockpit indicator light did not show that the nosegear was down and locked; landing with improperly deployed gear would have been safer than the improvised aerial inspection, the NTSB said.
* On January 4, 1995, Piper PA-60-601P ''N720EM'', piloted by Eduardo Mata, former conductor of the Dallas Symphony Orchestra, crashed into a ravine and exploded after an engine failure during climbout from Cuernavaca Airport, killing Mata and his single passenger. Investigators were unable to determine the cause of the engine failure.

Specifications (700P)

See also

References

Notes

Citations

Bibliography

* ''The Illustrated Encyclopedia of Aircraft'' (Part Work 1982–1985), 1985, Orbis Publishing
* Michell, Simon. ''Jane's Civil and Military Aircraft Upgrades 1994–95''. Coulsdon, UK: Jane's Information Group, 1994. .
* Simpson, R.W. ''Airlife's General Aviation'', 1991, Airlife Publishing,
* Taylor, John W. R. ''Jane's All The World's Aircraft 1967–68''. London: Sampson Low, Marston & Company, 1967.

External links

Aerostar Aircraft Corporation
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{{Piper

1960s United States civil utility aircraft
Aerostar
Mid-wing aircraft
Aircraft first flown in 1967
Twin piston-engined tractor aircraft
Aircraft with retractable tricycle landing gear