$75m AND SEVEN YEARS WORK

Press, Volume CVIII, Issue 31809, 14 October 1968, Page 14

$75m AND SEVEN YEARS WORK

An engine which cost s7sm to develop powers the National Airways Corporation new Boeing 737 twin-jet. It is the Pratt and Whitney JTBD-7 turbo-fan.

The development programme for this engine, which has been continuing for almost seven years, was financed by the manufacturers without any contributions from the United States Government. t It turned out to be. a risk which paid off because already 2000, each of which takes a month to assemble, have been ordered for four different aircraft types: the Boeing 727, the 737, the Caravelle Super B, and the Douglas DC9. The JTBD was the product of many engineering skills and required 8m man-hours in its development programme. It was a co-opera-tive effort in the face of severe competition and it represented a definite financial risk since it was the first Pratt and Whitney airline service jet turbine engine developed entirely with company funds. During the development

programme engineers worked a “stable” of 12 experimental engines. Tests were conducted where actual flying conditions were simulated. Engine Test The engine design began in April, 1960, after conferences between airframe and engine specialists. No actual orders were obtained until the October of that year. : The first engine was 1 tested in April, 1961. And • almost two years later it ’ passed the certification tests ' of the Federal Aviation ! Agency. : The first flight of the Boeing 727 was in February, ■ 1963; about a year later in ’ January, 1964, it went into ’ commercial service. Since then the engine has com- ; pleted more than 3m operat- ■ ing hours. J Continual Check The engines were > thoroughly checked time r and again, day after day, week after week, and month t after month. At the con-

elusion of the Initial phase of the development programme the engine was put through the Federal Aviation Agency certification tests. It was run for 150 hours, then disassembled and inspected. On the basis of these and other supporting tests, the certificate was issued, attesting to its suitability for commercial operation. Only then was the delivery of production engines begun. Never Completed It appears that an engine is never really completed; ways are constantly devised of making it even better. The JTBD is now authorised to operate for 3600 hours before an overhaul. When it first went into operation in 1964 its time between overhauls was 800 hours. It takes a month—and thousands of dollars —to overhaul an engine but when completed it is equivalent to a new engine. Each JTBD-7 engine weighs 30961 b and provides up to 14,0001 b of take-off thrust.