Reprinted from: Rotor
Journal – No.44 May/June 2002 (published by Eurocopter)
Statistics show that overall, a difference
of only 2% exists between single and twin-engine flight safety. A
striking contrast to this figure is the 30 to 50% increase in the
acquisition and operating costs of a twin-engine helicopter.
Is it going too far to consider the twin-engine solution to be the
answer to all current problems? In fact, twin and single-engine helicopters
offer practically the same degree of safety. Evidence shows that 95%
of the causes of helicopter accidents (ground impacts, power line
collisions, etc) have nothing to do with whether the aircraft was
a twin or single-engine model. It is only amongst the remaining 5%,
which includes accidents caused by equipment failure not due to maintenance
faults, that the single-engine helicopter proves to be more accident-prone.
Statistics show that overall, a difference of only 2% exists between
single and twin-engine flight safety. A |
striking
contrast to this figure is the 30 to 50% increase in the acquisition
and operating costs of a twin-engine helicopter. American government
agencies, who base their decisions on studies with results comparable
to those above, enforce much more liberal regulations, which they
currently have no plans to change. Faced with the same situation,
Europe is moving towards a much stricter policy via the JAR OPS
3(JAR OPS 3 is the set of regulations governing public-transport
helicopter operations in Europe). It should not be forgotten that
single-engine helicopters also have several persuasive selling points
in terms of flight safety. For example, in "hot and high"
conditions, a single-engine model can perform missions that a twin-engine
model generally cannot -or at least not with the same power margin.
A careful comparison of the advantages that both models have to
offer should logically lead to a relaxation of the JAR OPS 3. The
strengths and weaknesses of both aircraft could then be considered
in order to optimize their usage.
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