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Old 6th April 2011 | 11:52
  #3082 (permalink)  
Chris Scott
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Joined: Jan 2008
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From: Blighty (Nth. Downs)
R/H Main L/G down before impact, or after?

Hi HN39 (and PFR),

Don't have a picture, I'm afraid. You will recall that PJ2, you and I had a short discussion the day before yesterday, ending here:
http://www.pprune.org/tech-log/39510...ml#post6350925

Earlier, not being a structures man, I tried clumsily to explain that the MLG is mounted on the rear spar, near the apex of a triangle formed at the point of intersection of a diagonal spar with the rear spar. The triangle formed (sometimes called the Bermuda Triangle) has as its base, I think, the keel of the centre-section fuselage. The MLG assembly, as you said, retracts inboard so that the tyres nearly touch the keel as they rest in the main-gear bay.

Again, I stand to be corrected by an airframes expert, but the triangles surrounding each of the main-gear bays must be about the most robust structures of the airframe. They may have survived the impact, protecting the main gear legs if they were retracted.

The photo of the R/H MLG on page 5 of the "Présentation BEA":
http://www.bea.aero/fr/enquetes/vol....4avril2011.pdf
does not show anything inboard of the extended leg, but that does not necessarily mean that the visible part of the rear spar has broken away from the "Bermuda Triangle": we will find out later.

If the MLG was in the retracted position on impact, the disturbance to the MLG up-lock and the ripping-off of the lightweight main doors could allow the leg to drop suddenly or gradually into the position shown; perhaps like a gravity-extension procedure.

Chris

Last edited by Chris Scott; 6th April 2011 at 12:33. Reason: Minor clarifications
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