On April 17th 1967 Piper started to
deliver the first Navajos, its new 6-9
seat, twin-engined aircraft which was the
largest so far manufactured by them. Piper
was obviously targeting the emerging
market of private planes for businessmen ;
initial tests were performed by the
prototype which flew on September 30th
1964. It was powered by two Avco Lycoming
IO-540-M 300hp engines, and was named
Piper PA-31-300 Navajo.
Three versions were offered : a 8 seat
liaison aircraft, a 6 seat standard
aircraft and a 6 seat luxury aircraft. At
the same time Piper also started
production of the PA-31-310 Turbo Navajo B
fitted with two 310hp engines. Later in
March 1970 the PA-31P Pressurized Navajo
made its first flight with two 425hp
engines, and a pressurized cabin that
allowed it to reach 8,000 meters. The next
version was the PA-31-350 Navajo Chieftain
characterised by two 350hp engines and
especially a fuselage 61cm longer. But the
most advanced version, the PA-31T
Cheyenne, certified in 1973, had a
pressurized cabin and two Pratt&Whitney
Canada PTA-28 620hp engines. In 1974 the
PA-31-325 Turbo Navajo C/R was offered,
with the Chieftain's engines.
In 1977 the PA-31T with two 325hp engines
became the PA-31T Cheyenne II, after the
production of the ill powered PA-31T1
Cheyenne I (2xPTA-11 of 500hp). Then, in
1981, Piper produced the PA-31T2 Cheyenne
IIXL with a lengthened fuselage and two
750hp PTA-132 engines. By 1986 only the
PA-31-350, PA-31T1 and PA-31T2 were still
on the production line, and Piper decided
to roll out the PA-31P-350 Mojave, a
Cheyenne with 350 hp engines.
The Navajo six/eight seat cabin class twin
has been adapted to a number of commuter,
charter, air taxi, light freight and
executive transport roles, and has spawned a
series of developments.
The PA-31P-350 Mojave was
the last pressurised version of the PA-31
series to be built, while the PA-31-350
Chieftain was a stretched Navajo, built on
the smaller Navajo's success in the commuter
and charter roles.
The stretched Navajo
Chieftain first appeared in 1973, after
Piper began design work in 1971 (delays were
caused by the destruction of the second
prototype and early production aircraft due
to flooding at Piper's Lock Haven plant in
June 1972). Originally dubbed the Navajo II,
the Navajo Chieftain was intended to compete
against the Cessna 402 and to a lesser
extent the turboprop powered Beech 99.
The Piper Cheyenne is a
family of turboprop corporate aircraft based
on the popular Navajo and Chieftain piston
twins.
Although the first
Cheyenne was not delivered until mid 1974,
work on a turboprop version of the
Pressurized Navajo dates back almost a
decade earlier to the mid 1960s. The
prototype of the Cheyenne flew for the first
time on August 29 1969, but Piper had to
redesign the flight control systems to
handle the increased loads on the airframe
due to the higher speeds. Production
deliveries were further delayed due to
flooding at Piper's Lock Haven plant in June
1972.
Aimed directly at Beech's
successful King Air twin turboprop series,
the PA42 Cheyennes are larger developments
of the earlier PA31T Cheyennes (in turn
themselves turboprop developments of the
PA31 Navajo).
The PA42 Cheyenne III was
announced in September 1977. The first
production Cheyenne III flew for the first
time on May 18 1979 and FAA certification
was granted in early 1980. Compared with the
Cheyenne II the PA42 was about 1m (3ft)
longer, was powered by 537kW (720shp)
PT6A-41 turboshafts and introduced a T-tail,
the most obvious external difference between
the PA31T and PA42.
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