PPRuNe Forums - View Single Post - Interviews with D P Davies on certificating aircraft
Old 21st Dec 2017, 08:53
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longer ron
 
Join Date: Dec 2007
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Originally Posted by LeadSled
Folks,
At the risk of a bit of controversy, and having flown B707-300 and -320 modified as required to be UK registered, (total about 8000 h on various versions, on various registers) versus the FAA certified aeroplane, it is my opinion that the ARB required mods. were overall detrimental to the operation of the aircraft.
Excerpt from Tex Johnston 'Jet age Test Pilot'

During the second flight of the Dash80 we ran into rough air while doing stability and control work at 2,000ft ,gear and flaps down,speed below 200mph.Again I noted the Significant tendancy to Dutch Roll.In my test report I recommended additional attention to directional stability.
Directional stability was eventually improved by using the ventral fin and/or larger Fin (vert stabilizer).But it is clear even from the Dash 80 2nd flight that directional stability was marginal at best - Johnston had hoped that good training would suffice but he did realise after the Braniff 707 training accident (plus his own observations with other airlines problems) that aircraft modifications were essential and he did not pull any punches with Boeing about the subject.

From a safety point of view it had become clear that directional stability improvements were essential for the 707 so not sure how that could be detrimental ?
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