Re: What happened to the BA146?

From:         Don Stokes <Don.Stokes@vuw.ac.nz>
Organization: Victoria University of Wellington
Date:         25 May 96 14:40:21 
References:   1
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rsolene@sisna.com writes:
>Why didn't the airplane's designer's realize that this aircraft would
>present 4X as many maintenance problems?  Why didn't the airlines?  Why
>wasn't the aircraft designed for just two higher thrust power plants?
>I remember asking myself these questions when I watched these planes
>enter service with PSA in large numbers and I couldn't help but wonder
>what its advantage was.

It comes down to the 146's intended mission: to serve small,
noise-sensitive airports, leading to two major factors in design:

1. Noise.  The four hair driers aout there on the wing are a lot quieter
  than two engines on a comparable twin -- basically, if you double the
  power of an engine, you get to quadruple the noise.  Also, you need less
  power in a 4-engine aircraft, since on a twin the thing has to be able to
  _climb_ on one engine to satisfy safety requirements, whereas a 4-engine
  aircraft has three engines in reserve for an engine-out situation.

2. Short field performance.  The 146 is an STOL design, and works by
  blowing engine exhaust into the flaps to increase lift at low speeds.
  four engines, ie two sets of exhaust distributed over each flap, puts a
  lot less stress on the flap.

These features are at the expense of speed and altitude -- the wing has
negligible sweepback (required for near-sonic flight), and the engines
don't really have enough grunt.  But where speed doesn't matter (coz
before you're at sufficient altitude to use it, you have to come down
again), the 146 is fine.

As to the engines -- most of the maintenance problems were because the
early engines were basically faulty -- it's not a "number of engines"
problem, although having twice as many rather exacerbates the problem.  I
believe they are now as reliable as anyone else's.  I've never been held
up by a broken 146 when flying with Ansett NZ, who use them exclusively
on main routes.

I suspect, and I really don't know for sure, that the smaller engines are
as if not more economical to run (maintenance aside) than the larger
engines found on a twin.

--
Don Stokes, Network Manager, Victoria University of Wellington, New Zealand.
don@vuw.ac.nz(work) don@zl2tnm.gen.nz(home) +64 4 495-5052 Fax+64 4 471-5386