Date: 25 Jun 99 01:32:48 From: "David R. Hendrickson" <firstname.lastname@example.org> Organization: Eskimo North (206) For-Ever References: 1 Followups: 1
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JbTex <email@example.com> wrote: > I once heard pilots talking about a "squat switch" in the main > landing gear of airliners. They mentioned that it prevented > the deployment of the thrust-reversers until the landing aircraft's > weight settled onto the landing gear. If this is true, are the > armed spoilers also kept retracted by this switch, or must they > deploy prior to the full "squat"? Also, are there other systems > controlled by squat/not-squat status? Thanks though i've worked on '27s and '57s, the following is for newer '37s, mostly NextGens': 737's have the squat switch in the right main gear well with a cable running down the right leg to the scissor link. for the TR's you can electronically fake a jacked plane being on the ground by putting the #1 and #2 Air/Ground Override systems on the PSEU (Prox Switch Electronic Unit, formerly EGADS; Electronic Gear and Door System) in the Ground mode. the plane thinks it's on the ground. the PSEU is in the forward EE bay, forward of the nose gear. you can make some systems on a plane that's on it's gear think it's in the air by using the reverse of the above. the armed ground spoilers are kept retracted by the squat switch. you must remove the bolt from the cable at the scissor and pull the cable down to deploy them (if on jacks...), the electronic trick doesn't work. some systems look at the condition of the six air/ground prox switches (2 on each gear). others look at a combination of everything. on the FMC in the cockpit, you can't get into the mainenance screens if the plane's not in Ground mode. Take Off Warning, Ram Air inlets, the NextGen's overwing hatches...lots of systems look at the air/ground condition of the aircraft... hope this helped... dave -- David R. Hendrickson firstname.lastname@example.org http://www.eskimo.com/~riffraff Microsoft has announced that shipment of Windows 2000 has been postponed to the first quarter of 1901.