Re: Boeing 767 main gear tilt

Date:         14 Jul 97 20:27:00 
From:         Pete Mellor <>
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Fran=E7ois Airault <> wrote:
>> Also, what kind of weight is required to force the rear wheels down
>> after touchdown ?  At low weights, the aircraft has a tendency to
>> "tiptoe" after landing. I think the A340 needs around 50 tons on the
>> mains to fully settle down.

An anonymous correspondant wrote:
>I'm afraid I don't understand the question.  Can't help you.  :-)

I assume the original question refers to the pressure required
to compress the shock-absorbers and activate the weight-on-wheels
(WOW) switches. On modern automated aircraft, these switches
need to be activated in order for ground spoilers to deploy
and dump lift so that the aircraft stays on the deck.

The fact that a) *both* WOW switches had to be activated and
b) the oleos were a bit "stiff" and did not compress when the
pilots "greased" the 'plane down, were two important factors
in the Warsaw accident where an A320 did not "know" it was on
the ground until too late, and overshot the runway.

What the precise tonnage per gear is required in the case of
the B767 and the A340, I'm afraid I don't know.

Peter Mellor, Centre for Software Reliability, City University, Northampton
Square, London EC1V 0HB, UK. Tel: +44 (171) 477-8422, Fax: +44 (171) 477-8585