Re: DC-10-30 (and -10's ??) #2 Thrust rever

From:         Francisco Marreiros <marreirs@rogerswave.ca>
Organization: Rogers Cablesystems Ltd.
Date:         15 Mar 96 01:05:27 
References:   1 2 3 4
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>>lchiluku@ucsd.edu (Chilukuri)
>>A related question: Is it true that Mexicana has disconnected their squat
>>switches, in order to be able to come down fast?
>bareynol@cca.rockwell.com (Brian A. Reynolds) wrote:
>This seems a bit strange.  If the squat switch is activated you're already
>down!
>
>Note that DC-10's/MD-11/DC-9 family do not have main gear switches.
>Functions related to main gear on ground (such as autobrakes and spoilers)
>use a signal telling them that the wheels have spun up.
>
I also find it difficult to believe that Mexicana has disconnected the
squat switches on the DC-10s. If i understand the question correctly
the concept of disconnecting the squat switches would be to fool the
aircraft into thinking it is in ground mode therefore allowing systems
such as ground spoilers,which deploy to a greater angle than speedbrakes
destroy lift further and allow the aircraft to descend quicker.

I have said concept because it is probably not impossible but very
difficult to accomplish, not to say illegal but thats another issue.

My statements are in referance to the DC10 as i am more familiar with
this type. As Brian has stated this aircraft does not have main gear
ground sensing switches but uses wheel spinup. The four aft main wheel
speed transducers provide input for the auto ground spoiler system. These
transducers would have  to be sensing spinup for the spiolers to deploy,
modifiying them in any way would invariably affect the antiskid and
autobrake systems.

The DC-10 does have a ground sensing control mechanism located on the
nose gear that provides a means of establishing a ground/flight mode
of operation for certain systems.In this system there are two ground
sensing switches. These switches also provide imputs for number of other
systems ie: pitot heat, aoa probes heat, ground idle control, auto pitch
trim any many more that i cant recall at this moment.

I therfore find it difficult to believe that either system would be
tampered with as these systems affect many other systems directly and
indirectly.

The speedbrakes are a proven system of destroying lift, extending these
panels past their designed angle ! who knows??

I hope this is of any help to your question.




Francisco